案例-----简易新闻客户端

本例将演示AsyncHttpClient和SmartImageView的综合使用。
1.目标：

1) 掌握开源项目AsyncHttpClient的使用
2) 掌握如何进行JSON解析

2.配置服务器：
由于需要从服务器上下载一个JSON，所以需要开启Tomcat服务器。在Tomcat根目录下找到bin文件夹，运行该文件下的startup.bat文件开启服务器,可在cmd下输入ipconfig来查看。然后在Tomcat的安装目录打开webapps文件夹，将NewsInfo.json文件放置在ROOT文件夹下。NewsInfo.json的代码如下：

[  {    "icon": "http://10.3.24.180:8080/images/a.PNG",    "title": "科技温暖世界",    "content": "进入一个更有爱的领域",    "type": "1",    "comment": "69"  },  {    "icon": "http://10.3.24.180:8080/images/b.PNG",    "title": "《神武》",    "content": "新美术资源盘点，视觉新体验",    "type": "2",    "comment": "35"  },  {    "icon": "http://10.3.24.180:8080/images/c.PNG",    "title": "南北车正式公布合并",    "content": "南北车将于今日正式公布合并",    "type": "3",    "comment": "2"  },  {    "icon": "http://10.3.24.180:8080/images/d.PNG",    "title": "萌呆了！汪星人抱玩偶酣睡",    "content": "汪星人抱玩偶酣睡，萌翻网友",    "type": "1",    "comment": "25"  },  {    "icon": "http://10.3.24.180:8080/images/e.PNG",    "title": "风力发电进校园",    "content": "风力发电普进校园",    "type": "2",    "comment": "26"  },  {    "icon": "http://10.3.24.180:8080/images/f.PNG",    "title": "地球一小时",    "content": "地球熄灯一小时",    "type": "1",    "comment": "23"  },  {    "icon": "http://10.3.24.180:8080/images/g.PNG",    "title": "最美公路",    "content": "最美公路，难以想象",    "type": "1",    "comment": "23"  }]

其中的10.3.24.180为自己主机的IP地址，另外还需要在ROOT下建立一个images文件夹来存放图片。 如果 在浏览器里输入http://10.3.24.180:8080/NewsInfo.json出现NewsInfo.json的内容则开启服务器成功。

3.新建一个项目
1)对应的布局文件（activity_main.xml）代码如下：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context=".MainActivity"    android:orientation="vertical">    <FrameLayout        android:layout_width="match_parent"        android:layout_height="match_parent">        <LinearLayout            android:id="@+id/loading"            android:layout_width="match_parent"            android:layout_height="match_parent"            android:gravity="center"            android:orientation="vertical"            android:visibility="invisible">            <ProgressBar                android:layout_width="wrap_content"                android:layout_height="wrap_content" />            <TextView                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="正在加载信息..." />        </LinearLayout>        <ListView            android:id="@+id/lv_news"            android:layout_width="match_parent"            android:layout_height="match_parent"            android:layout_marginTop="5dp"/>    </FrameLayout></LinearLayout>

2)ListView的Item布局文件news_item.xml如下所示：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="65dp">    <com.loopj.android.image.SmartImageView        android:id="@+id/siv_icon"        android:layout_width="80dp"        android:layout_height="60dp"        android:scaleType="centerCrop"        android:src="@mipmap/ic_launcher"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true"></com.loopj.android.image.SmartImageView>    <TextView        android:id="@+id/tv_title"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginLeft="5dp"        android:layout_marginTop="10dp"        android:layout_toRightOf="@id/siv_icon"        android:ellipsize="end"        android:maxLength="20"        android:singleLine="true"        android:text="我是标题"        android:textColor="#000000"        android:textSize="18sp" />    <TextView        android:id="@+id/tv_description"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@id/tv_title"        android:layout_marginLeft="5dp"        android:layout_marginTop="5dp"        android:layout_toRightOf="@id/siv_icon"        android:ellipsize="end"        android:maxLength="16"        android:maxLines="1"        android:text="我是描述"        android:textColor="#99000000"        android:textSize="14sp" />    <TextView        android:id="@+id/tv_type"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:layout_alignParentRight="true"        android:layout_marginBottom="5dp"        android:layout_marginRight="10dp"        android:text="评论"        android:textColor="#99000000"        android:textSize="12sp" /></RelativeLayout>

3)创建NewsInfo类，一定注意此类中的属性要与JSON文件中的相对应。

package bzu.edu.cn.imagebrowser.entity;/** * Created by yn on 2017/5/19. */public class NewsInfo {    private String icon;    private String title;    private String content;    private int type;    private long comment;    public long getComment() {        return comment;    }    public void setComment(long comment) {        this.comment = comment;    }    public int getType() {        return type;    }    public void setType(int type) {        this.type = type;    }    public String getContent() {        return content;    }    public void setContent(String description) {        this.content = content;    }    public String getTitle() {        return title;    }    public void setTitle(String title) {        this.title = title;    }    public String getIcon() {        return icon;    }    public void setIcon(String icon) {        this.icon = icon;    }}

4)自定义一个ListView适配器，代码如下：

package bzu.edu.cn.imagebrowser.adapter;import android.content.Context;import android.graphics.Color;import android.support.annotation.NonNull;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ArrayAdapter;import android.widget.TextView;import com.loopj.android.image.SmartImageView;import org.w3c.dom.Text;import java.util.List;import bzu.edu.cn.imagebrowser.R;import bzu.edu.cn.imagebrowser.entity.NewsInfo;/** * Created by yn on 2017/5/19. */public class MyAdapter extends ArrayAdapter<NewsInfo>{    public MyAdapter(Context context, List<NewsInfo> objects) {        super(context, R.layout.news_item, objects);    }    @NonNull    @Override    public View getView(int position, View convertView, ViewGroup parent) {        NewsInfo newsInfo=getItem(position);        View view;        ViewHolder viewHolder;        if(convertView==null){            view= LayoutInflater.from(getContext()).inflate(R.layout.news_item, null);            viewHolder=new ViewHolder();            viewHolder.siv_icon=(SmartImageView)view.findViewById(R.id.siv_icon);            viewHolder.tv_title=(TextView)view.findViewById(R.id.tv_title);            viewHolder.tv_description=(TextView)view.findViewById(R.id.tv_description);            viewHolder.tv_type=(TextView)view.findViewById(R.id.tv_type);            view.setTag(viewHolder);        }        else{            view=convertView;            viewHolder=(ViewHolder)view.getTag();        }        viewHolder.siv_icon.setImageUrl(newsInfo.getIcon());        viewHolder.tv_title.setText(newsInfo.getTitle());        viewHolder.tv_description.setText(newsInfo.getContent());        int type=newsInfo.getType();        switch (type){            case 1:                viewHolder.tv_type.setText("评论:"+newsInfo.getComment());                break;            case 2:                viewHolder.tv_type.setTextColor(Color.RED);                viewHolder.tv_type.setText("专题");                break;            case 3:                viewHolder.tv_type.setTextColor(Color.BLUE);                viewHolder.tv_type.setText("LIVE");                break;        }        return view;    }    class ViewHolder{        SmartImageView siv_icon;        TextView tv_title;        TextView tv_description;        TextView tv_type;    }}

5)创建工具类解析JSON文件，代码如下：

package bzu.edu.cn.imagebrowser.tools;import com.google.gson.Gson;import com.google.gson.reflect.TypeToken;import java.lang.reflect.Type;import java.util.List;import bzu.edu.cn.imagebrowser.entity.NewsInfo;/** * Created by yn on 2017/5/19. */public class JsonParse {    public static List<NewsInfo> getNewsInfo(String json)    {        Gson gson=new Gson();        Type listType=new TypeToken<List<NewsInfo>>(){        }.getType();        List<NewsInfo> newsInfos=gson.fromJson(json,listType);        return newsInfos;    }}

6)编写界面交互代码（MainActivity）:

package bzu.edu.cn.imagebrowser;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.LinearLayout;import android.widget.ListView;import android.widget.Toast;import com.loopj.android.http.AsyncHttpClient;import com.loopj.android.http.AsyncHttpResponseHandler;import java.util.List;import bzu.edu.cn.imagebrowser.adapter.MyAdapter;import bzu.edu.cn.imagebrowser.entity.NewsInfo;import bzu.edu.cn.imagebrowser.tools.JsonParse;public class MainActivity extends AppCompatActivity {    private ListView listView;    private LinearLayout loading;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        listView=(ListView)findViewById(R.id.lv_news);        loading=(LinearLayout)findViewById(R.id.loading);        fillData();    }    private void fillData(){        AsyncHttpClient asyncHttpClient=new AsyncHttpClient();        asyncHttpClient.get("http://10.3.24.180:8080/NewsInfo.json", new AsyncHttpResponseHandler() {            @Override                    public void onSuccess(int i,org.apache.http.Header[] headers, byte[] bytes) {                        String json;                        try {                    json = new String(bytes,"utf-8");                List<NewsInfo> newsInfos= JsonParse.getNewsInfo(json);                     if (newsInfos==null){                         Toast.makeText(MainActivity.this,"解析失败",Toast.LENGTH_LONG).show();                     }else{                         loading.setVisibility(View.INVISIBLE);                         listView.setAdapter(new MyAdapter(MainActivity.this,newsInfos));                     }                } catch (Exception e) {                            e.printStackTrace();                        }            }            @Override            public void onFailure(int i,org.apache.http.Header[] headers, byte[] bytes, Throwable throwable) {            }        });    }}

7)在清单文件中添加网络权限：

<uses-permission android:name="android.permission.INTERNET" />

4.运行程序效果图：

5.总结
本案例使用AsyncHttpClient和SmartImageView最终实现了获取服务器的JSON文件并将其解析出来显示到ListView上的功能。