案例—新闻客户端

1.创建程序

新闻客户端对应的布局文件（activity_main.xml）

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="cn.edu.bzu.anew.MainActivity">

<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" />
</FrameLayout>
</RelativeLayout>

2.创建news_item的布局

news_itemxml的布局如下：

<?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.编写界面交互代码

在（MainActivity）里编写代码：

public class MainActivity extends AppCompatActivity {
private ListView lvNews;
private List<NewsInfo> newsInfos;
private LinearLayout loading;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lvNews=(ListView)findViewById(R.id.lv_news);
loading=(LinearLayout)findViewById(R.id.loading);
fillData();

}
private void fillData(){
AsyncHttpClient client =new AsyncHttpClient();

client.get("http://10.61.28.176:8080/NewsInfo.json",new AsyncHttpResponseHandler(){
@Override
public void onSuccess(int i, org.apache.http.Header[] headers, byte[] bytes) {
try{
String json=new String(bytes,"utf-8");
newsInfos= JsonParse.getNewsInfo(json);
if(newsInfos==null){
Toast.makeText(MainActivity.this,"解析失败", Toast.LENGTH_LONG).show();
}else{
loading .setVisibility(View.INVISIBLE);
lvNews.setAdapter(new NewsAdapter(MainActivity.this,newsInfos));
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}

@Override
public void onFailure(int i, org.apache.http.Header[] headers, byte[] bytes, Throwable throwable) {

}
} );


}
}

4.创建NewsInfor类

public class NewsInfo {    private  String icon;    private  String title;    private  String description;    private  int type;    private  long comment;    public NewsInfo(String icon, String title, String description, int type, long comment) {        this.icon = icon;        this.title = title;        this.description = description;        this.type = type;        this.comment = comment;    }    public String getIcon() {        return icon;    }    public void setIcon(String icon) {        this.icon = icon;    }    public String getTitle() {        return title;    }    public void setTitle(String title) {        this.title = title;    }    public String getDescription() {        return description;    }    public void setDescription(String description) {        this.description = description;    }    public int getType() {        return type;    }    public void setType(int type) {        this.type = type;    }    public long getComment() {        return comment;    }    public void setComment(long comment) {        this.comment = comment;    }}

5.创建工具类解析xml文件

public class NewsAdapter extends ArrayAdapter<NewsInfo>{
public NewsAdapter(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);//传递position，获取当前位置对应的newsinfo新闻信息
View view=null;
viewHolder viewHolder;
if(convertView==null){ //判断convertView中是否加载了布局，有没有缓存。为空说明没有缓存
view=LayoutInflater.from(getContext()).inflate(R.layout.news_item,null);
viewHolder=new viewHolder();
viewHolder.siv= (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); //保存
}else{
view=convertView;
viewHolder=(viewHolder) view.getTag();
}
viewHolder.siv.setImageUrl(newsinfo.getIcon());
viewHolder.tv_title.setText(newsinfo.getTitle());//传递题目
viewHolder.tv_description.setText(newsinfo.getDescription());
viewHolder.tv_type.setText(newsinfo.getType()+"");
return view;
}
class viewHolder{//添加类，封装需要查找的控件
TextView tv_title;
TextView tv_description;
TextView tv_type;
SmartImageView siv;

}
}
6.配置服务器

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