Android解决：使用多线程和Handler同步更新UI

Android解决：使用多线程和Handler同步更新UI

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。

main.xml

<?xml version="1.0" encoding="utf-8"?>
<ScrollView 
xmlns:Android="http://schemas.android.com/apk/res/android"
android:layout_height="wrap_content" android:id="@+id/scrollView1" android:layout_width="fill_parent">
    <LinearLayout android:id="@+id/linearLayout1" 
    android:orientation="vertical"    
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"> 
<TextView  
android:id="@+id/tv"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"    
    />
    </LinearLayout>
</ScrollView>

FileRead.java

public class FileRead {
boolean readend=false;
List<String> al=null;
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 {
RandomAccessFile raf=new RandomAccessFile("/sdcard/test.txt","r");
//try {
while(raf.getFilePointer()<raf.length())
{
al.add(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;
}
};
}

MultiThreadActivity.java

public class MultiThreadActivity 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
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
tv=(TextView)findViewById(R.id.tv);
fr=new 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();
}
}