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：
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="vertical" > 6 7 <ScrollView 8 android:id="@+id/scrollView1" 9 android:layout_width="match_parent" 10 android:layout_height="wrap_content" > 11 12 <LinearLayout 13 android:layout_width="match_parent" 14 android:layout_height="wrap_content" 15 android:orientation="vertical" > 16 17 <TextView 18 android:id="@+id/tv" 19 android:layout_width="match_parent" 20 android:layout_height="wrap_content" 21 android:text="TextView" /> 22 23 </LinearLayout> 24 </ScrollView> 25 26 </LinearLayout>
增加一个读取文件线程类：
1 package com.example.mulitthreadactivitydemo; 2 3 import java.io.RandomAccessFile; 4 import java.util.ArrayList; 5 import java.util.List; 6 7 import android.util.Log; 8 9 public class FileRead { 10 11 boolean readend = false; 12 List<String> al = null; 13 private static final String Tag = "addfile"; 14 15 public class ReadNodesThread extends Thread {// 读取线程 16 17 public void run() { 18 al = new ArrayList<String>(100); 19 al.clear(); 20 readend = false; 21 int i = 0; 22 try { 23 String dirstr = "/storage/sdcard0/DCIM/test.txt"; 24 //RandomAccessFile raf = new RandomAccessFile("/sdcard/test.txt","r"); 25 RandomAccessFile raf = new RandomAccessFile(dirstr,"r"); 26 // try { 27 while (raf.getFilePointer() < raf.length()) { 28 al.add(raf.readLine()); 29 Log.i(Tag,"addfile = " + raf.readLine()); 30 // sleep(100);//如果测试文件太小，这里休眠是为了测试， 31 } 32 33 } catch (Exception e1) { 34 // TODO Auto-generated catch block 35 e1.printStackTrace(); 36 } 37 readend = true; 38 } 39 }; 40 41 }
最后修改下主类：
1 package com.example.mulitthreadactivitydemo; 2 3 import android.app.Activity; 4 import android.os.Bundle; 5 import android.os.Handler; 6 import android.widget.TextView; 7 8 public class MainActivity extends Activity { 9 10 FileRead fr=null; 11 Handler mHandler=null; 12 int curi=0; 13 Runnable updateui=null; 14 String[] tmp=null; 15 String s=""; 16 TextView tv=null; 17 18 class ReadListener extends Thread{//监听线程，当数据更新数目大于10条时，更新UI 19 20 public void run() 21 { 22 int i=0,newi=0; 23 while(!fr.readend) 24 { 25 newi=fr.al.size(); 26 if((newi-i)>10)//新增数据大于10条，更新UI 27 { 28 i=newi; 29 tmp=(String[])fr.al.toArray(new String[fr.al.size()]); 30 mHandler.post(updateui); 31 try { 32 Thread.sleep(100); 33 } catch (InterruptedException e) { 34 // TODO Auto-generated catch block 35 e.printStackTrace(); 36 } 37 } 38 } 39 //数据读完了 40 tmp=(String[])fr.al.toArray(new String[fr.al.size()]); 41 mHandler.post(updateui); 42 try { 43 Thread.sleep(100); 44 } catch (InterruptedException e) { 45 // TODO Auto-generated catch block 46 e.printStackTrace(); 47 } 48 } 49 }; 50 51 @Override 52 protected void onCreate(Bundle savedInstanceState) { 53 super.onCreate(savedInstanceState); 54 setContentView(R.layout.activity_main); 55 tv = (TextView) findViewById(R.id.tv); 56 fr=new FileRead(); 57 FileRead.ReadNodesThread readThread = fr.new ReadNodesThread(); 58 updateui = new Runnable()//更新UI的线程 59 { 60 @Override 61 public void run() { 62 // TODO Auto-generated method stub 63 64 int i=0; 65 66 for(i=curi;i<tmp.length;i++) 67 { 68 s+=tmp[i]+"\n"; 69 } 70 tv.setText(s); 71 curi=i; 72 }}; 73 readThread.start(); 74 ReadListener updateThread=new ReadListener(); 75 mHandler=new Handler(); 76 updateThread.start(); 77 78 } 79 80 }
运行效果：可以看到滚动条慢慢变短，则说明程序加载成功.
