android4.4中关于不能再主线程下载和在主线程中更新UI的矛盾

来源：互联网发布：淘宝买灯具要3c认证吗编辑：程序博客网时间：2024/05/22 03:50

本人每次在使用android时总是喜欢用最新的sdk（其实是做系统就删了），这样就发现不知从什么时候起android就不让在主线程中下载东西，即使是很小的东西东不行。这也算是对程序的规范吧，因为如果在一段时间中不能下载完成，主线程一直处于假死状态，系统会强制关闭的。然而，我们经常需要在下载数据以后进行UI的更新。这又造成两个不在一个线程中。下面贴出一些代码来解决这个问题。

package com.yx.mp3player;

import java.io.StringReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

import com.yx.download.HttpDownload;
import com.yx.model.Mp3Info;
import com.yx.xml.Mp3ListContentHandler;

import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.app.Activity;
import android.app.ListActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.SimpleAdapter;

public class Mp3ListActivity extends ListActivity {

   private static final int UPDATE = 1;
   private static final int ABOUT = 1;
   private HandlerThread handlerThread;
   private Handler handler;
   private List<Mp3Info> mp3Infos = null;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_mp3_list);
       handler = new Handler();
   }

   @Override
   public boolean onCreateOptionsMenu(Menu menu) {
       // Inflate the menu; this adds items to the action bar if it is present.
       getMenuInflater().inflate(R.menu.mp3_list, menu);
       menu.add(0, UPDATE, 1, "更新");
       menu.add(0, ABOUT, 2, "关于");
       return true;
   }

   @Override
   public boolean onOptionsItemSelected(MenuItem item) {
       if(1==item.getItemId()){
           //用户点击更新按钮
           new Thread(new Runnable() {
               @Override
               public void run() {
                   //实现下载
                   String xmlStr;
                   xmlStr = downLoadXML("http://192.168.0.103:8080/mp3/resouces.xml");
                   mp3Infos = parse(xmlStr);
                   handler.post(new Runnable(){
                       @Override
                       public void run() {

//更新UI

                            List<HashMap<String,String>> list = new ArrayList<HashMap<String,String>>();
                           for (Iterator iterator = mp3Infos.iterator(); iterator.hasNext();) {
                               Mp3Info mp3Info = (Mp3Info) iterator.next();
                               HashMap<String,String> map = new HashMap<String, String>();
                               map.put("mp3_name", mp3Info.getMp3Name());
                               map.put("mp3_size", mp3Info.getMp3Size());
                               list.add(map);
                           }
                           SimpleAdapter simpleAdapter = new SimpleAdapter(Mp3ListActivity.this, list,
                                   R.layout.mp3info_item,
                                   new String[]{"mp3_name","mp3_size"},
                                   new int[]{R.id.mp3_name,R.id.mp3_size});
                           setListAdapter(simpleAdapter);
                           System.out.println("=================");
                       }});
               }
           }).start();


       }else if(ABOUT==item.getItemId()){
           //用户点击了关于按钮
       }
       return super.onOptionsItemSelected(item);
   }



   public String downLoadXML(String urlstr){
       HttpDownload httpDownloader = new HttpDownload();
       String result = httpDownloader.downLoad(urlstr);
       System.out.println("XML--->"+result);
       return result;
   }

   private List<Mp3Info> parse(String xmlStr){
       List<Mp3Info> infos = new ArrayList<Mp3Info>();
       SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
       try {
           XMLReader xmlReader= saxParserFactory.newSAXParser().getXMLReader();
           Mp3ListContentHandler mp3ListContentHandler = new Mp3ListContentHandler(infos);
           xmlReader.setContentHandler(mp3ListContentHandler);
           xmlReader.parse(new InputSource(new StringReader(xmlStr)));
       } catch (Exception e) {
           e.printStackTrace();
       }
       return infos;
   }
}

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