新闻客户端（AsyncHttpClient和SmartImageView的综合使用）

1. 实验目的

1. 掌握开源项目AsycHttpClient的使用

2. 掌握如何进行JSON解析

2.实验仪器

装有Android开发环境的计算机

3.运行效果图

4.程序实现

1.创建程序

创建一个名为“News”的应用程序，设计用户交互界面“News”程序对应的布局文件(activity_main.xml)如下：

2.创建ListView Item 的布局

由于使用到了ListView控件，因此需要为ListView的item创建一个布局。ListView的Item布局文件news_item.xml如下所示：

3.编写界面交互代码（MainActivity）

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  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://10.61.23.90:8080/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NewsInfo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NewsAdapter类

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{
    public NewsAdapter(Context context, List 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.创建JsonParse类

public class JsonParse {
    public  static ListgetNewsInfo(String json){
        Gson gson =new Gson();
        Type listType=new TypeToken> (){
        }.getType();
        ListnewsInfos=gson.fromJson(json,listType);
        return  newsInfos;
    }

7.添加权限

因为本案例需要访问网络，因此需要在AndroidMainfest.xml里配置相应权限。代码如下：

8.运行程序查看新闻