36.Android之多线程和handle更新UI学习

android经常用到多线程更新UI，今天学习下.

首先布局比较简单：

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical" >

     <ScrollView
         android:id="@+id/scrollView1"
         android:layout_width="match_parent"
         android:layout_height="wrap_content" >

         <LinearLayout
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:orientation="vertical" >

             <TextView
                 android:id="@+id/tv"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:text="TextView" />

         </LinearLayout>
     </ScrollView>

  </LinearLayout>

增加一个读取文件线程类：

 package com.example.mulitthreadactivitydemo;

 import java.io.RandomAccessFile;
 import java.util.ArrayList;
 import java.util.List;

 import android.util.Log;

 public class FileRead {

     boolean readend = false;
     List<String> al = null;
     private static final String Tag = "addfile";

     public class ReadNodesThread extends Thread {// 读取线程

         public void run() {
             al = new ArrayList<String>(100);
             al.clear();
             readend = false;
             int i = 0;
             try {
                 String dirstr = "/storage/sdcard0/DCIM/test.txt";
                 //RandomAccessFile raf = new RandomAccessFile("/sdcard/test.txt","r");
                 RandomAccessFile raf = new RandomAccessFile(dirstr,"r");
                 // try {
                 while (raf.getFilePointer() < raf.length()) {
                     al.add(raf.readLine());
                     Log.i(Tag,"addfile = " + raf.readLine());
                     // sleep(100);//如果测试文件太小，这里休眠是为了测试，
                 }

             } catch (Exception e1) {
                 // TODO Auto-generated catch block
                 e1.printStackTrace();
             }
             readend = true;
         }
     };

 }

最后修改下主类：

 package com.example.mulitthreadactivitydemo;

 import android.app.Activity;
 import android.os.Bundle;
 import android.os.Handler;
 import android.widget.TextView;

 public class MainActivity extends Activity {

     FileRead fr=null;
     Handler mHandler=null;
     int curi=0;
     Runnable updateui=null;
     String[] tmp=null;
     String s="";
     TextView tv=null;

     class ReadListener extends Thread{//监听线程，当数据更新数目大于10条时，更新UI

         public void run()
         {
             int i=0,newi=0;
             while(!fr.readend)
             {
                 newi=fr.al.size();
                 if((newi-i)>10)//新增数据大于10条，更新UI
                 {
                     i=newi;
                     tmp=(String[])fr.al.toArray(new String[fr.al.size()]);
                     mHandler.post(updateui);
                     try {
                         Thread.sleep(100);
                     } catch (InterruptedException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
                     }
                 }
             }
             //数据读完了
             tmp=(String[])fr.al.toArray(new String[fr.al.size()]);
             mHandler.post(updateui);
             try {
                 Thread.sleep(100);
             } catch (InterruptedException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
     };

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         tv = (TextView) findViewById(R.id.tv);
         fr=new FileRead();
         FileRead.ReadNodesThread readThread = fr.new ReadNodesThread();
         updateui = new Runnable()//更新UI的线程
         {
             @Override
             public void run() {
                 // TODO Auto-generated method stub

                 int i=0;

                 for(i=curi;i<tmp.length;i++)
                 {
                     s+=tmp[i]+"\n";
                 }
                 tv.setText(s);
                 curi=i;
             }};
         readThread.start();
         ReadListener updateThread=new ReadListener();
         mHandler=new Handler();
         updateThread.start();

     }

 }

运行效果：可以看到滚动条慢慢变短，则说明程序加载成功.