Android解决：使用多线程和Handler同步更新UI
时间：2014-04-20 20:59:31
[导读] 如果运行时，可以看到滚动条由条慢慢变短，则说明程序成功了。截图如下，建议选择大点的文件做测试。2. [图片] 2.jpg3. [代码]main.xml布局文件 0
如果运行时，可以看到滚动条由条慢慢变短，则说明程序成功了。截图如下，建议选择大点的文件做测试。
2. [图片] 2.jpg
3. [代码]main.xml布局文件
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<?xml version="1.0" encoding="utf-8"?> |
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<ScrollView |
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xmlns:Android="http://schemas.android.com/apk/res/android" |
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Android:layout_height="wrap_content" android:id="@+id/scrollView1"android:layout_width="fill_parent"> |
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<LinearLayout Android:id="@+id/linearLayout1" |
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Android:orientation="vertical" |
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Android:layout_width="fill_parent" |
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Android:layout_height="wrap_content"> |
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<TextView |
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Android:id="@+id/tv" |
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Android:layout_width="fill_parent" |
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Android:layout_height="wrap_content" |
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/> |
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</LinearLayout> |
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</ScrollView> |
4. [代码]FileRead.java
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public class FileRead { |
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boolean readend=false; |
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List<String> al=null; |
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public class ReadNodesThread extends Thread{//读取线程 |
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public void run() |
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{ |
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al=new ArrayList<String>(100); |
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al.clear(); |
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readend=false; |
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int i=0; |
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try { |
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RandomAccessFile raf=new RandomAccessFile("/sdcard/test.txt","r"); |
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//try { |
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while(raf.getFilePointer()<raf.length()) |
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{ |
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al.add(raf.readLine()); |
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//sleep(100);//如果测试文件太小，这里休眠是为了测试， |
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} |
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} catch (Exception e1) { |
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// TODO Auto-generated catch block |
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e1.printStackTrace(); |
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} |
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readend=true; |
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} |
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}; |
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} |
5. [代码]MultiThreadActivity.java
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public class MultiThreadActivity extends Activity { |
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FileRead fr=null; |
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Handler mHandler=null; |
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int curi=0; |
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Runnable updateui=null; |
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String[] tmp=null; |
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String s=""; |
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TextView tv=null; |
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class ReadListener extends Thread{//监听线程，当数据更新数目大于10条时，更新UI |
10 |
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public void run() |
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{ |
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int i=0,newi=0; |
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while(!fr.readend) |
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{ |
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newi=fr.al.size(); |
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if((newi-i)>10)//新增数据大于10条，更新UI |
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{ |
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i=newi; |
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tmp=(String[])fr.al.toArray(new String[fr.al.size()]); |
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mHandler.post(updateui); |
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try { |
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Thread.sleep(100); |
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} catch (InterruptedException e) { |
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// TODO Auto-generated catch block |
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e.printStackTrace(); |
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} |
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} |
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} |
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//数据读完了 |
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tmp=(String[])fr.al.toArray(new String[fr.al.size()]); |
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mHandler.post(updateui); |
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try { |
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Thread.sleep(100); |
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} catch (InterruptedException e) { |
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// TODO Auto-generated catch block |
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e.printStackTrace(); |
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} |
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} |
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}; |
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@Override |
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public void onCreate(Bundle savedInstanceState) { |
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super.onCreate(savedInstanceState); |
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setContentView(R.layout.main); |
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tv=(TextView)findViewById(R.id.tv); |
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fr=new FileRead(); |
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ReadNodesThread readThread=fr.new ReadNodesThread(); |
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updateui=new Runnable()//更新UI的线程 |
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{ |
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@Override |
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public void run() { |
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// TODO Auto-generated method stub |
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int i=0; |
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for(i=curi;i<tmp.length;i++) |
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{ |
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s+=tmp[i]+"n"; |
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} |
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tv.setText(s); |
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curi=i; |
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}}; |
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readThread.start(); |
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ReadListener updateThread=new ReadListener(); |
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mHandler=new Handler(); |
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updateThread.start(); |
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} |
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} |
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