android多线程下载

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >


    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="mana" />

</RelativeLayout>

package com.hbsi.csdn.mulltilinetest;


import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;


public class MainActivity extends Activity {
private TextView tv;
private Handler handler;


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView) this.findViewById(R.id.tv);
System.out.println(Thread.currentThread().getName());
handler = new Handler() {
public void handleMessage(Message msg) {
super.handleMessage(msg);
String text = (String) msg.obj;
tv.setText(text);
}
};
new Thread() {
public void run() {
for (int i = 0; i < 100; i++) {
try {
sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// tv.setText("mana"+i);
System.out.println(Thread.currentThread().getName());
Message msg = new Message();
msg.obj = "mana" + i;
handler.sendMessage(msg);
}


}
}.start();
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}


}