Android实战-智慧城市(3)

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Android开发赛项实战开发

上回说到，Android实战-智慧城市(2)

软件设计

主页面

    主页面是个大工程，首先用ViewPager2+Fragment的方式实现了4页切换，与引导页不同的是每页有一个单独的Fragment页面，底部的四个按钮与四个页面相呼应

新闻内容页

    新闻内容页展示新闻内容，当点击了智慧城市页和新闻页的新闻后，即跳转到新闻内容页，展示对应的新闻和评论

修改HomeFragment0.java

    修改HomeFragment0.java中的startNewsActivity方法，使点击专题和新闻列表时发声页面跳转

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//    启动新闻内容显示页面
    private void startNewsActivity(int id) {
//        获取到点击的专题或新闻列表中的新闻的id并将新闻的id值传递给新闻显示页
        Intent intent = new Intent(getContext(), NewsHomeActivity.class);
        intent.putExtra("newsId",id);
        startActivity(intent);
    }

新闻详细内容的反序列化对象

    用于将请求到的新闻的详细内容的json反序列化
    NewsHomeBean.java

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package com.SmartCity.NewsHome;

public class NewsHomeBean {

    private String msg;
    private int code;
    private DataBean data;

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public DataBean getData() {
        return data;
    }

    public void setData(DataBean data) {
        this.data = data;
    }

    public static class DataBean {
        private Object searchValue;
        private String createBy;
        private String createTime;
        private String updateBy;
        private String updateTime;
        private Object remark;
        private ParamsBean params;
        private int id;
        private String appType;
        private String cover;
        private String title;
        private Object subTitle;
        private String content;
        private String status;
        private String publishDate;
        private Object tags;
        private int commentNum;
        private int likeNum;
        private int readNum;
        private String type;
        private String top;
        private String hot;

        public Object getSearchValue() {
            return searchValue;
        }

        public void setSearchValue(Object searchValue) {
            this.searchValue = searchValue;
        }

        public String getCreateBy() {
            return createBy;
        }

        public void setCreateBy(String createBy) {
            this.createBy = createBy;
        }

        public String getCreateTime() {
            return createTime;
        }

        public void setCreateTime(String createTime) {
            this.createTime = createTime;
        }

        public String getUpdateBy() {
            return updateBy;
        }

        public void setUpdateBy(String updateBy) {
            this.updateBy = updateBy;
        }

        public String getUpdateTime() {
            return updateTime;
        }

        public void setUpdateTime(String updateTime) {
            this.updateTime = updateTime;
        }

        public Object getRemark() {
            return remark;
        }

        public void setRemark(Object remark) {
            this.remark = remark;
        }

        public ParamsBean getParams() {
            return params;
        }

        public void setParams(ParamsBean params) {
            this.params = params;
        }

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public String getAppType() {
            return appType;
        }

        public void setAppType(String appType) {
            this.appType = appType;
        }

        public String getCover() {
            return cover;
        }

        public void setCover(String cover) {
            this.cover = cover;
        }

        public String getTitle() {
            return title;
        }

        public void setTitle(String title) {
            this.title = title;
        }

        public Object getSubTitle() {
            return subTitle;
        }

        public void setSubTitle(Object subTitle) {
            this.subTitle = subTitle;
        }

        public String getContent() {
            return content;
        }

        public void setContent(String content) {
            this.content = content;
        }

        public String getStatus() {
            return status;
        }

        public void setStatus(String status) {
            this.status = status;
        }

        public String getPublishDate() {
            return publishDate;
        }

        public void setPublishDate(String publishDate) {
            this.publishDate = publishDate;
        }

        public Object getTags() {
            return tags;
        }

        public void setTags(Object tags) {
            this.tags = tags;
        }

        public int getCommentNum() {
            return commentNum;
        }

        public void setCommentNum(int commentNum) {
            this.commentNum = commentNum;
        }

        public int getLikeNum() {
            return likeNum;
        }

        public void setLikeNum(int likeNum) {
            this.likeNum = likeNum;
        }

        public int getReadNum() {
            return readNum;
        }

        public void setReadNum(int readNum) {
            this.readNum = readNum;
        }

        public String getType() {
            return type;
        }

        public void setType(String type) {
            this.type = type;
        }

        public String getTop() {
            return top;
        }

        public void setTop(String top) {
            this.top = top;
        }

        public String getHot() {
            return hot;
        }

        public void setHot(String hot) {
            this.hot = hot;
        }

        public static class ParamsBean {
        }
    }
}

新闻评论内容的反序列化对象

    用于将请求到的新闻的评论内容的json反序列化
    NewCommentBean.java(这里打错了一个字母News打成了New)

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package com.SmartCity.NewsHome;

import java.io.Serializable;
import java.util.List;

public class NewCommentBean implements Serializable {

    private int total;
    private List<RowsBean> rows;
    private int code;
    private String msg;

    public int getTotal() {
        return total;
    }

    public void setTotal(int total) {
        this.total = total;
    }

    public List<RowsBean> getRows() {
        return rows;
    }

    public void setRows(List<RowsBean> rows) {
        this.rows = rows;
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public static class RowsBean implements Serializable {
        private Object searchValue;
        private Object createBy;
        private Object createTime;
        private Object updateBy;
        private Object updateTime;
        private Object remark;
        private ParamsBean params;
        private int id;
        private String appType;
        private int newsId;
        private String content;
        private String commentDate;
        private int userId;
        private int likeNum;
        private String userName;
        private String newsTitle;

        public Object getSearchValue() {
            return searchValue;
        }

        public void setSearchValue(Object searchValue) {
            this.searchValue = searchValue;
        }

        public Object getCreateBy() {
            return createBy;
        }

        public void setCreateBy(Object createBy) {
            this.createBy = createBy;
        }

        public Object getCreateTime() {
            return createTime;
        }

        public void setCreateTime(Object createTime) {
            this.createTime = createTime;
        }

        public Object getUpdateBy() {
            return updateBy;
        }

        public void setUpdateBy(Object updateBy) {
            this.updateBy = updateBy;
        }

        public Object getUpdateTime() {
            return updateTime;
        }

        public void setUpdateTime(Object updateTime) {
            this.updateTime = updateTime;
        }

        public Object getRemark() {
            return remark;
        }

        public void setRemark(Object remark) {
            this.remark = remark;
        }

        public ParamsBean getParams() {
            return params;
        }

        public void setParams(ParamsBean params) {
            this.params = params;
        }

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public String getAppType() {
            return appType;
        }

        public void setAppType(String appType) {
            this.appType = appType;
        }

        public int getNewsId() {
            return newsId;
        }

        public void setNewsId(int newsId) {
            this.newsId = newsId;
        }

        public String getContent() {
            return content;
        }

        public void setContent(String content) {
            this.content = content;
        }

        public String getCommentDate() {
            return commentDate;
        }

        public void setCommentDate(String commentDate) {
            this.commentDate = commentDate;
        }

        public int getUserId() {
            return userId;
        }

        public void setUserId(int userId) {
            this.userId = userId;
        }

        public int getLikeNum() {
            return likeNum;
        }

        public void setLikeNum(int likeNum) {
            this.likeNum = likeNum;
        }

        public String getUserName() {
            return userName;
        }

        public void setUserName(String userName) {
            this.userName = userName;
        }

        public String getNewsTitle() {
            return newsTitle;
        }

        public void setNewsTitle(String newsTitle) {
            this.newsTitle = newsTitle;
        }

        public static class ParamsBean implements Serializable {
        }
    }
}

显示html内容到Android页面

    通过截图中可以看出，请求到的新闻的内容是html格式，通过Html.fromHtml可以将html格式页面显示在TextView中，但是并不能显示图片，如果想使其动态显示图片，就需要重写ImageGetter类，具体实现可以看TextView实现图文混排

    创建MyImageGetter类继承ImageGetter类，在该类中重写了getDrawable(String source)方法，当Html.fromHtml解析<img>标签时会回调该方法，方法中的source就是img标签src属性的属性值，当回调该方法时，将source中的图片加载出来并以Drawable格式返回给Html.fromHtml，即可做到图片加载
    MyImageGetter.java

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package com.SmartCity.NewsHome;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LevelListDrawable;
import android.text.Html;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

import com.SmartCity.SoftData;
import com.bumptech.glide.Glide;
import com.bumptech.glide.request.target.CustomTarget;
import com.bumptech.glide.request.transition.Transition;

public class MyImageGetter implements Html.ImageGetter {
    private Context context;//上下文
    private TextView textView;//内容加载的TextView对象

    public MyImageGetter(Context context,TextView textView){
        this.context = context;
        this.textView = textView;
    }

    @Override
//    Html.fromHtml解析<img>时会回调getDrawable方法，所以getDrawable返回的Drawable图片就会被绘制
//    参数中的source就是<img>标签中src属性的值
    public Drawable getDrawable(String source) {
//        实例化LevelListDrawable类，可以通过改变level的值来切换相应的图片，也可以向LevelListDrawable中添加图片队列
        LevelListDrawable levelListDrawable = new LevelListDrawable();
//        通过new CustomTarget<Drawable>将图片以Drawable资源动态加载到自定义的位置，这里的加载位置在LevelListDrawable类中
        Glide.with(context).asDrawable().load("http://" + SoftData.ipPort + source).into(new CustomTarget<Drawable>() {
            @Override
            public void onResourceReady(@NonNull Drawable resource, @Nullable Transition<? super Drawable> transition) {
                levelListDrawable.addLevel(1,1,resource);//把drawable资源加载到levelListDrawable中
//                为其设置边界，没有设置的话TextView将不能显示该Drawable
                levelListDrawable.setBounds(0,0,resource.getIntrinsicWidth(),resource.getMinimumHeight());
                levelListDrawable.setLevel(1);//设置对象级别
                textView.invalidate();//重新绘制textView界面
                textView.setText(textView.getText());//叠加覆盖原内容
            }

            @Override
            public void onLoadCleared(@Nullable Drawable placeholder) {
//                The Methods is Nothing
            }
        });
//        返回加载的Drawable文件资源文件，该文件会被Html.fromHtml绘制
        return levelListDrawable;
    }
}

评论列表的item布局

    activity_news_home_item.xml

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:orientation="horizontal"
    android:paddingTop="5dp"
    android:paddingBottom="5dp"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <ImageView
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:src="@mipmap/avatar"
        android:layout_width="48dp"
        android:layout_height="48dp"/>
    <LinearLayout
        android:orientation="vertical"
        android:layout_marginRight="10dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <LinearLayout
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
            <TextView
                android:text="nickName"
                android:id="@+id/nickName"
                android:layout_width="0dp"
                android:textColor="@color/black"
                android:textSize="14sp"
                android:layout_weight="1"
                android:layout_height="wrap_content"/>
            <TextView
                android:text="times"
                android:id="@+id/times"
                android:textColor="@color/black"
                android:textSize="14sp"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="wrap_content"/>
        </LinearLayout>
        <TextView
            android:id="@+id/comments"
            android:text="comments"
            android:gravity="left"
            android:textColor="@color/black"
            android:layout_marginRight="10dp"
            android:textStyle="bold"
            android:textSize="15sp"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>
    </LinearLayout>
</LinearLayout>

评论列表的适配器

    一个普通适配器而已

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package com.SmartCity.NewsHome;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import com.SmartCity.R;

import java.util.List;

public class NewsCommentAdapter extends RecyclerView.Adapter<NewsCommentAdapter.MyViewHolder> {
    private List<String> commentContents;//评论内容
    private List<String> commentUserNames;//评论者昵称
    private List<String> commentDates;//评论时间
    private Context context;//上下文

    public NewsCommentAdapter(List<String> commentContents, List<String> commentUserNames, List<String> commentDates, Context context) {
        this.commentContents = commentContents;
        this.commentUserNames = commentUserNames;
        this.commentDates = commentDates;
        this.context = context;
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.activity_news_home_item,parent,false);
        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        holder.comments.setText(commentContents.get(position));
        holder.times.setText(commentDates.get(position));
        holder.nickName.setText(commentUserNames.get(position));
    }

    @Override
    public int getItemCount() {
        return commentContents.size();
    }

    public class MyViewHolder extends RecyclerView.ViewHolder {
        private TextView nickName,times,comments;
        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            nickName = itemView.findViewById(R.id.nickName);
            times = itemView.findViewById(R.id.times);
            comments = itemView.findViewById(R.id.comments);
        }
    }
}

使最新评论列表绝对禁止滑动

    创建MyLinearLayoutManager类继承自LinearLayoutManager，重写它的canScrollVertically()方法，使其永远返回false，调用该类创建的LayoutManager设置为列表的LayoutManager时，该列表将无法被滑动，不会像recyclerView.setNestedScrollingEnabled(false);一样，禁止滑动再滑动时会显示蓝色底边
    MyLinearLayoutManager.java

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package com.SmartCity.NewsHome;

import android.content.Context;
import android.util.AttributeSet;

import androidx.recyclerview.widget.LinearLayoutManager;

public class MyLinearLayoutManager extends LinearLayoutManager {
    public MyLinearLayoutManager(Context context) {
        super(context);
    }

    public MyLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
    }

    public MyLinearLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public boolean canScrollVertically() {
//        重写canScrollVertically使其达到滑动的绝对禁止
        return false;
    }
}

新闻详情页面布局

    显示新闻详情
    activity_news_home.xml

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <!--    Title-->
    <LinearLayout
        android:background="@color/blue"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="58dp">
        <LinearLayout
            android:onClick="finishActivity"
            android:gravity="center"
            android:layout_width="58dp"
            android:layout_height="58dp">
            <ImageView
                android:src="@mipmap/back"
                android:layout_width="20dp"
                android:layout_height="20dp"/>
        </LinearLayout>
        <LinearLayout
            android:gravity="center"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="match_parent">
            <TextView
                android:text="新闻详情"
                android:textStyle="bold"
                android:textSize="18sp"
                android:textColor="@color/white"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>
        </LinearLayout>
        <LinearLayout
            android:gravity="center"
            android:layout_width="58dp"
            android:layout_height="58dp">

        </LinearLayout>
    </LinearLayout>
    <!--    Content-->
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <LinearLayout
            android:orientation="vertical"
            android:gravity="center_horizontal"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            <TextView
                android:gravity="center"
                android:text="title"
                android:id="@+id/title"
                android:layout_marginTop="10dp"
                android:layout_marginBottom="10dp"
                android:layout_marginRight="20dp"
                android:layout_marginLeft="20dp"
                android:textSize="20sp"
                android:textColor="@color/black"
                android:textStyle="bold"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>
            <View
                android:layout_marginRight="10dp"
                android:layout_marginLeft="10dp"
                android:background="@color/darker_gray"
                android:layout_width="match_parent"
                android:layout_height="1dp"/>
            <TextView
                android:id="@+id/content"
                android:textSize="18sp"
                android:textColor="@color/black"
                android:textStyle="bold"
                android:layout_margin="20dp"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"/>
            <TextView
                android:layout_marginRight="10dp"
                android:layout_marginLeft="10dp"
                android:textColor="@color/black"
                android:textSize="16sp"
                android:textStyle="bold"
                android:text="最新评论"
                android:gravity="left"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"/>
            <androidx.recyclerview.widget.RecyclerView
                android:layout_margin="10dp"
                android:id="@+id/recyclerView"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"/>
            <TextView
                android:text="没有评论\n快来成为第一个吧OvO"
                android:gravity="center"
                android:textColor="@color/black"
                android:textSize="25sp"
                android:textStyle="bold"
                android:id="@+id/noComment"
                android:visibility="gone"
                android:layout_margin="10dp"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"/>
            <LinearLayout
                android:orientation="horizontal"
                android:layout_marginBottom="20dp"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">
                <TextView
                    android:text="写评论"
                    android:layout_marginRight="100dp"
                    android:layout_marginLeft="10dp"
                    android:onClick="onClick"
                    android:textColor="@color/blue"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="wrap_content"/>
                <TextView
                    android:gravity="right"
                    android:text="全部评论"
                    android:id="@+id/allCommentSum"
                    android:onClick="onClick"
                    android:layout_marginLeft="100dp"
                    android:layout_marginRight="10dp"
                    android:textColor="@color/blue"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="wrap_content"/>
            </LinearLayout>
        </LinearLayout>
    </ScrollView>
</LinearLayout>

新闻详情程序设计

    两个难点：1.Html.fromHtml()加载图片；2.最新评论显示5条
    还有一个容易出错的地方：bundle传递对象
    NewsHomeActivity.java

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package com.SmartCity.NewsHome;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.RecyclerView;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.text.Html;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

import com.SmartCity.MyHttpRequest;
import com.SmartCity.R;

import java.util.ArrayList;
import java.util.List;

public class NewsHomeActivity extends AppCompatActivity {
    private int newsId;//新闻的id
    private TextView title,content;//标题和内容
    private MyHttpRequest myHttpRequest = new MyHttpRequest();//封装的服务器通信
    private NewsHomeBean newsHomeBean;//新闻详细内容的反序列化对象
    private Handler handler;//handler线程通信
    private NewCommentBean newCommentBean;//新闻评论的反序列化对象
    private List<String> commentContents;//评论的内容
    private List<String> commentUserNames;//评论者昵称
    private List<String> commentDates;//评论时间
    private RecyclerView recyclerView;//新闻内容下的“最新评论”列表
    private TextView allCommentSum;//全部评论数量
    private TextView noComment;//没有评论时显示的view
    private NewsCommentAdapter newsCommentAdapter;//评论列表的适配器

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_news_home);
        myHandler();//线程通信
        init();//初始化页面
        getNewsData();//获取新闻的详细信息
        getCommentData();//获取最新评论详细信息(最新评论最多5条)
    }

//    线程通信
    private void myHandler() {
        handler = new Handler(Looper.getMainLooper()){
            @Override
            public void handleMessage(@NonNull Message msg) {
                super.handleMessage(msg);
                if (msg.what == 1){
                    setNewsData();//设置新闻内容显示
                }
                else if (msg.what == 2){
                    setComment();//设置最新评论显示
                }
            }
        };
    }

//    设置新闻内容显示
    private void setNewsData() {
        if (newsHomeBean == null){
            MyToast("新闻内容获取失败: 未知原因");
        }
        else if (newsHomeBean.getCode() != 200){
            MyToast("新闻内容获取失败: " + newsHomeBean.getMsg());
        }
        else {
            String newsTitle = newsHomeBean.getData().getTitle();//新闻标题
            String newsContent = newsHomeBean.getData().getContent();//新闻内容
            title.setText(newsTitle);//设置标题
            /*
             * 这里就比较麻烦了，因为新闻内容是html格式，甚至内容中一些图片也是html格式，在Android页面中不可能将这些东西一一动态的创建出来
             * 那么就需要用到一个特殊的方法Html.fromHtml，但是他有一个巨大的缺点，不能绘制图片，所以我们需要重写它的一个方法来动态的加载图片
             * 这个方法就是ImageGetter，在MyImageGetter中有绘制html图片的具体过程
             *
             * 在android7.0以后，Html.fromHtml不支持设置flags，所以这里添加了版本判断
             * FROM_HTML_MODE_COMPACT：html块元素之间使用一个换行符分隔
             * FROM_HTML_MODE_LEGACY：html块元素之间使用两个换行符分隔
             */
//            实例化重写的ImageGetter类，在重写的MyImageGetter中加载文章中的图片
            MyImageGetter myImageGetter = new MyImageGetter(NewsHomeActivity.this,content);
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                content.setText(Html.fromHtml(newsContent,Html.FROM_HTML_MODE_COMPACT,myImageGetter,null));//显示新闻内容
            }
            else {
                content.setText(Html.fromHtml(newsContent,myImageGetter,null));//显示新闻内容
            }
        }
    }

    @SuppressLint("SetTextI18n")
    private void setComment() {
        if (newCommentBean == null){
            MyToast("评论内容加载失败: 未知原因");
        }
        else if (newCommentBean.getCode() != 200){
            MyToast("评论内容加载失败: " + newCommentBean.getMsg());
        }
        else {
            allCommentSum.setText("全部评论(" + Math.min(newCommentBean.getTotal(),99) + ")");
            if (newCommentBean.getTotal() != 0){
//                评论不为空时
                if (newsCommentAdapter == null){
                    noComment.setVisibility(View.GONE);//隐藏没有评论的提示
//                    使用重写的MyLinearLayoutManager使列表绝对禁止滑动
                    MyLinearLayoutManager layoutManager = new MyLinearLayoutManager(this,RecyclerView.VERTICAL,false);
//                    创建评论列表的适配器
                    newsCommentAdapter = new NewsCommentAdapter(commentContents,commentUserNames,commentDates,this);
//                    默认的分割线
                    recyclerView.addItemDecoration(new DividerItemDecoration(NewsHomeActivity.this,DividerItemDecoration.VERTICAL));
                    recyclerView.setAdapter(newsCommentAdapter);
                    recyclerView.setLayoutManager(layoutManager);
                }
                else {
//                    如果创建过评论列表的适配器则刷新数据
                    newsCommentAdapter.notifyDataSetChanged();
                }
            }
            else {
//                评论为空时显示没有评论
                noComment.setVisibility(View.VISIBLE);
            }
        }
    }

//    初始化界面
    private void init() {
        newsId = getIntent().getExtras().getInt("newsId");
        title = findViewById(R.id.title);
        content = findViewById(R.id.content);
        recyclerView = findViewById(R.id.recyclerView);
        allCommentSum = findViewById(R.id.allCommentSum);
        noComment = findViewById(R.id.noComment);
    }

//    获取新闻详细信息
    private void getNewsData() {
        new Thread(){
            @Override
            public void run() {
                super.run();
                newsHomeBean = (NewsHomeBean) myHttpRequest.myHttp("/prod-api/press/press/" + newsId,null,NewsHomeBean.class,null,"get");
                Message message = Message.obtain();
                message.what = 1;
                handler.sendMessage(message);
            }
        }.start();
    }

//    获取最新评论详细信息(最新评论最多5条)
    private void getCommentData() {
        new Thread(){
            @Override
            public void run() {
                super.run();
                newCommentBean = (NewCommentBean) myHttpRequest.myHttp("/prod-api/press/comments/list?newsId=" + newsId,null,NewCommentBean.class,null,"get");
                if (newCommentBean != null){
                    int commentSum = Math.min(newCommentBean.getTotal(), 5);//commentSum不能大于五
                    setList();
//                    for循环中反向取值，得到最新的评论内容(最新评论最多5条)
                    for (int i = 0,j = newCommentBean.getTotal()-1; i < commentSum; i++,j--) {
                        commentContents.add(newCommentBean.getRows().get(j).getContent());
                        commentUserNames.add(newCommentBean.getRows().get(j).getUserName());
                        commentDates.add(newCommentBean.getRows().get(j).getCommentDate());
                    }
                }
                Message message = Message.obtain();
                message.what = 2;
                handler.sendMessage(message);
            }
        }.start();
    }

//    设置List清空或创建
    private void setList() {
        if (commentContents != null && commentUserNames != null && commentDates != null){
            commentContents.clear();
            commentUserNames.clear();
            commentDates.clear();
        }
        else {
            commentContents = new ArrayList<>();
            commentUserNames = new ArrayList<>();
            commentDates = new ArrayList<>();
        }
    }

//    点击写评论或全部评论时跳转到评论页面
    public void onClick(View view) {
        // 这里有个坑，bundle+intent传递对象需要使用putSerializable
        // 这样被传递的类和被传递的类中的每个内部类必须需实现Serializable接口
        // 不然就报错，妈的
        Intent intent = new Intent(NewsHomeActivity.this,CommentActivity.class);
        Bundle bundle = new Bundle();
        bundle.putInt("newsId",newsId);
        bundle.putSerializable("newCommentBean", newCommentBean);
        intent.putExtras(bundle);//使用bundle把新闻的id和评论内容传递到全部评论页面
        startActivityForResult(intent,1);
    }

//    回调判断
    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
//        如果从评论页返回，刷新评论列表
        if (requestCode == 1){
            getCommentData();//刷新评论列表
        }
    }

//    提示弹窗
    private void MyToast(String message){
        Toast.makeText(this,message,Toast.LENGTH_SHORT).show();
    }

    //    结束页面
    public void finishActivity(View view) {  finish();  }
}

全部评论页面布局

    当点击写评论或全部评论时就会跳转到这一页
    activity_comment.xml

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <!--    Title-->
    <LinearLayout
        android:background="@color/blue"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="58dp">
        <LinearLayout
            android:onClick="finishActivity"
            android:gravity="center"
            android:layout_width="58dp"
            android:layout_height="58dp">
            <ImageView
                android:src="@mipmap/back"
                android:layout_width="20dp"
                android:layout_height="20dp"/>
        </LinearLayout>
        <LinearLayout
            android:gravity="center"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="match_parent">
            <TextView
                android:text="全部评论"
                android:textStyle="bold"
                android:textSize="18sp"
                android:textColor="@color/white"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>
        </LinearLayout>
        <LinearLayout
            android:gravity="center"
            android:layout_width="58dp"
            android:layout_height="58dp">

        </LinearLayout>
    </LinearLayout>
    <!--    Content-->
    <LinearLayout
        android:orientation="vertical"
        android:gravity="center_horizontal"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/recyclerView"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_marginLeft="10dp"
            android:layout_marginRight="10dp"
            android:layout_weight="1" />

        <TextView
            android:text="没有评论\n快来成为第一个吧OvO"
            android:gravity="center"
            android:textColor="@color/black"
            android:textSize="25sp"
            android:textStyle="bold"
            android:id="@+id/noComment"
            android:visibility="gone"
            android:layout_margin="10dp"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>

        <LinearLayout
            android:gravity="center_vertical"
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="48dp">
            <EditText
                android:hint="请输入评论内容"
                android:paddingLeft="10dp"
                android:paddingRight="10dp"
                android:textSize="16sp"
                android:id="@+id/edit_comment"
                android:background="@drawable/edit_text_style"
                android:layout_weight="1"
                android:layout_width="0dp"
                android:layout_marginLeft="10dp"
                android:layout_height="38dp"/>
            <Button
                android:text="发送"
                android:textStyle="bold"
                android:textColor="@color/white"
                android:textSize="15sp"
                android:id="@+id/sendComment"
                android:background="@drawable/button_style2"
                android:layout_marginRight="10dp"
                android:layout_marginLeft="10dp"
                android:layout_width="58dp"
                android:layout_height="38dp"/>
        </LinearLayout>
    </LinearLayout>
</LinearLayout>

全部评论程序设计

    全部评论页面和新闻详情页面中的评论只有两个不同的地方：1.一个加载全部评论，一个加载部分评论；2.一个可以写评论，一个不可以写评论
    CommentActivity.java

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package com.SmartCity.NewsHome;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.DividerItemDecoration;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.SmartCity.Bean;
import com.SmartCity.MyHttpRequest;
import com.SmartCity.R;
import com.SmartCity.SoftData;

import java.util.ArrayList;
import java.util.List;

public class CommentActivity extends AppCompatActivity {
    private int newsId;//新闻的id
    private NewCommentBean newCommentBean;//评论内容的反序列化对象
    private Button sendComment;//发送按钮
    private EditText edit_comment;//输入的评论内容
    private RecyclerView recyclerView;//评论列表
    private MyHttpRequest myHttpRequest = new MyHttpRequest();//封装的服务器通信模块
    private Handler handler;//线程通信
    private List<String> commentContents;//评论内容
    private List<String> commentUserNames;//评论者昵称
    private List<String> commentDates;//评论时间
    private NewsCommentAdapter newsCommentAdapter;//评论列表的适配器
    private TextView noComment;//没有评论时显示的view
    private Bean bean;//通用的最简单的反序列化对象

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_comment);
        myHandler();//线程通信
        init();//初始化界面
        submit();//设置监听
        getData();//获取数据
        setComment();//加载评论列表
    }

//    线程通信
    private void myHandler() {
        handler = new Handler(Looper.getMainLooper()){
            @Override
            public void handleMessage(@NonNull Message msg) {
                super.handleMessage(msg);
                if (msg.what == 1){
                    setComment();
                }
                else if (msg.what == 2){
                    commentResult();//发送评论的结果
                }
            }
        };
    }

//    加载评论列表
    private void setComment() {
        if (newCommentBean == null){
            MyToast("评论内容加载失败: 未知原因");
        }
        else if (newCommentBean.getCode() != 200){
            MyToast("评论内容加载失败: " + newCommentBean.getMsg());
        }
        else {
//            评论内容为空时
            if (newCommentBean.getTotal() != 0){
//                是否实例化过评论列表适配器
                if (newsCommentAdapter == null){
                    noComment.setVisibility(View.GONE);//隐藏没有评论的提示
                    recyclerView.setVisibility(View.VISIBLE);
                    LinearLayoutManager layoutManager = new LinearLayoutManager(this,RecyclerView.VERTICAL,false);
                    newsCommentAdapter = new NewsCommentAdapter(commentContents,commentUserNames,commentDates,this);
//                    默认的分割线
                    recyclerView.addItemDecoration(new DividerItemDecoration(CommentActivity.this,DividerItemDecoration.VERTICAL));
                    recyclerView.setAdapter(newsCommentAdapter);
                    recyclerView.setLayoutManager(layoutManager);
                }
                else {
                    newsCommentAdapter.notifyDataSetChanged();
                }
            }
            else {
//                显示没有评论的提示
                noComment.setVisibility(View.VISIBLE);
                recyclerView.setVisibility(View.GONE);
            }
        }
    }

//    发送评论的结果
    private void commentResult() {
        if (bean == null){
            MyToast("评论失败: 未知原因");
        }
        else if (bean.getCode() != 200){
            MyToast("评论失败: " + bean.getMsg());
        }
        else {
            MyToast("评论发表成功");
            getCommentData();
            edit_comment.setText("");
        }
    }

//    初始化页面
    private void init() {
        sendComment = findViewById(R.id.sendComment);
        edit_comment = findViewById(R.id.edit_comment);
        recyclerView = findViewById(R.id.recyclerView);
        newsId = getIntent().getExtras().getInt("newsId");
        noComment = findViewById(R.id.noComment);
        newCommentBean = (NewCommentBean) getIntent().getExtras().getSerializable("newCommentBean");
    }

//    设置监听
    private void submit() {
//        点击发送按钮时
        sendComment.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String string = edit_comment.getText().toString();
                if (TextUtils.isEmpty(string)){
                    MyToast("评论内容不可为空");
                }
                else {
//                    发送评论内容
                    sendCommentContent(string);
                }
            }
        });
    }

//    发送评论内容
    private void sendCommentContent(String string) {
        new Thread(){
            @Override
            public void run() {
                super.run();
                String json = "{\n" +
                        "\"newsId\": " + newsId + ",\n" +
                        "\"content\": \"" + string + "\"\n" +
                        "}";
                bean = (Bean) myHttpRequest.myHttp("/prod-api/press/pressComment",json,Bean.class, SoftData.token,"post");
                Message message = Message.obtain();
                message.what = 2;
                handler.sendMessage(message);
            }
        }.start();
    }

    //    首次进入评论页面时加载
    private void getData() {
        setList();//清空或创建集合
        for (int i = 0,j = newCommentBean.getTotal()-1; i < newCommentBean.getTotal(); i++,j--) {
//            反向取值，得到最新的评论内容
            commentContents.add(newCommentBean.getRows().get(j).getContent());
            commentUserNames.add(newCommentBean.getRows().get(j).getUserName());
            commentDates.add(newCommentBean.getRows().get(j).getCommentDate());
        }
    }


//    获取全部评论的详细内容
    private void getCommentData() {
        new Thread(){
            @Override
            public void run() {
                super.run();
                newCommentBean = (NewCommentBean) myHttpRequest.myHttp("/prod-api/press/comments/list?newsId=" + newsId,null,NewCommentBean.class,null,"get");
                if (newCommentBean != null){
                    setList();
                    for (int i = 0,j = newCommentBean.getTotal()-1; i < newCommentBean.getTotal(); i++,j--) {
//                        反向取值，使最最新的评论在前
                        commentContents.add(newCommentBean.getRows().get(j).getContent());
                        commentUserNames.add(newCommentBean.getRows().get(j).getUserName());
                        commentDates.add(newCommentBean.getRows().get(j).getCommentDate());
                    }
                }
                Message message = Message.obtain();
                message.what = 1;
                handler.sendMessage(message);
            }
        }.start();
    }

//    设置List清空或创建
    private void setList() {
        if (commentContents != null && commentUserNames != null && commentDates != null){
            commentContents.clear();
            commentUserNames.clear();
            commentDates.clear();
        }
        else {
            commentContents = new ArrayList<>();
            commentUserNames = new ArrayList<>();
            commentDates = new ArrayList<>();
        }
    }

//    弹窗提示
    private void MyToast(String message){
        Toast.makeText(this,message,Toast.LENGTH_SHORT).show();
    }

//    关闭页面
    public void finishActivity(View view) {  finish();  }
}

    现在主页面已经全部搞定了，我这里“主页面”的设计范围是根据题目要求定的，下面这些功能都实现了，所以我说主页面全部搞定了

    从下一篇开始就是“个人中心页”的开发。欲知后事如何，且听下回分解