本文介绍了如何在安卓平台上实现一个新闻发布应用。通过创建activity_main.xml和news_item.xml布局文件，设计用户界面，包括新闻列表和详细信息展示。利用NewsAdapter自定义适配器，展示NewsInfo实体类的数据。同时，通过JsonParse工具类解析JSON数据，使用AsyncHttpClient进行网络请求，加载新闻列表。
1.activity_main.xml文件如下：
<?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>
news_item.xml文件如下：
<?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>
2.新建一个名为adapter的包名，新建一个NewsAdapter的类，内容如下：
package cn.edu.bzu.anew.adapter;import android.content.Context;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 java.util.List;import cn.edu.bzu.anew.R;import cn.edu.bzu.anew.entity.NewsInfo;
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;
}
}
3.新建一个名为entity的包名，新建一个NewsInfo的类，内容如下：
package cn.edu.bzu.anew.entity;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;
}
}
4.新建一个名为Tools的包，包下新建一个名为JsonParse的类，内容如下：
package cn.edu.bzu.anew.Tools;import com.google.gson.Gson;import com.google.gson.reflect.TypeToken;import java.lang.reflect.Type;import java.util.List;import cn.edu.bzu.anew.entity.NewsInfo;
/** * Created by Administrator on 2017/5/18. */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;
}
}
5.MainActivity的内容如下：
package cn.edu.bzu.anew;
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.io.UnsupportedEncodingException;import java.util.List;import cn.edu.bzu.anew.Tools.JsonParse;import cn.edu.bzu.anew.adapter.NewsAdapter;import cn.edu.bzu.anew.entity.NewsInfo;
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://10.51.9.254:8080/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) {
}
} );
}
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