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Asyntask

巢权
2023-12-01
package com.example.nm.myapplication;

import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;

import com.google.gson.Gson;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.display.RoundedBitmapDisplayer;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    ListView listView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView=(ListView) findViewById(R.id.list);
//        实现自己写的类
        asyn asyn = new asyn();
//     把地址放到execute里执行
        asyn.execute("http://www.93.gov.cn/93app/data.do?channelId=0&startNum=0");


    }
//    第一步自己写一个类继承AsyncTask
    class asyn extends AsyncTask<String,Void,String>{

        @Override
        protected String doInBackground(String... params) {

            StringBuilder builder=null;
            try {
//                这是主方法里传回来的地址
                URL url = new URL(params[0]);
                HttpURLConnection con = (HttpURLConnection)url.openConnection();
                con.setRequestMethod("GET");
                con.setReadTimeout(5000);
                con.setConnectTimeout(5000);
                if(con.getResponseCode()==200){
                    InputStream stream = con.getInputStream();
                    InputStreamReader reader = new InputStreamReader(stream);
                    BufferedReader buf = new BufferedReader(reader);
                    String s=null;
                    builder = new StringBuilder();
                    while((s=buf.readLine())!=null){
                        builder.append(s);
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
//            手动返回值
              return builder.toString();
        }

        @Override
//        这是手动重写出来的方法用来写解析和适配器的
        protected void onPostExecute(String s) {
            super.onPostExecute(s);

            Gson gosn = new Gson();
//            这里是上面定义过来的s
            bena bena = gosn.fromJson(s, bena.class);
            List<com.example.nm.myapplication.bena.DataBean> list = bena.getData();
            listView.setAdapter(new Adapter(MainActivity.this,list));


        }
    }
}
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