Android控件之ProgressBar用法实例分析

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical" 
 android:layout_width="fill_parent"
 android:layout_height="fill_parent">
 <!-- 长方形进度条，一开始不可见，直到点击按钮时才出现进度条 -->
 <ProgressBar android:id="@+id/progressBar"
  style="?android:attr/progressBarStyleHorizontal"
  mce_style="?android:attr/progressBarStyleHorizontal"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:visibility="gone"
  android:max="100" />
 <!-- 圆形进度条 -->
 <!--<ProgressBar android:id="@+id/progressBar"
  style="?android:attr/progressBarStyleLarge"
  mce_style="?android:attr/progressBarStyleLarge"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content" />-->
 <Button android:id="@+id/start" 
  android:text="启动进度条"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content" />
 <Button android:id="@+id/stop" 
  android:text="停止进度条"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content" />
</LinearLayout>

package com.ljq.pb;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
public class PbActivity extends Activity {
 private ProgressBar progressBar = null;
 private Button start = null, stop = null;
 // 定义Handler对象
 private Handler handler = new Handler();
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  progressBar = (ProgressBar) findViewById(R.id.progressBar);
  progressBar.setProgress(0);
  start = (Button) findViewById(R.id.start);
  start.setOnClickListener(new View.OnClickListener() {
   public void onClick(View v) {
    handler.post(runnable); //开始执行
   }
  });
  stop=(Button)findViewById(R.id.stop);
  stop.setOnClickListener(new View.OnClickListener() {
   public void onClick(View v) {
    handler.removeCallbacks(runnable);//停止执行
    progressBar.setProgress(0);
   }
  });
 }
 int pro=0;
 Runnable runnable=new Runnable(){
  public void run() {
   progressBar.setVisibility(View.VISIBLE);
   pro=progressBar.getProgress()+10;
   progressBar.setProgress(pro);
   //如果进度小于100,，则延迟1000毫秒后重复执行runnable
   if(pro<100){
    handler.postDelayed(runnable, 1000);
   }else{
    progressBar.setVisibility(View.GONE);
    startActivity(new Intent(PbActivity.this, TestActivity.class));
    handler.removeCallbacks(runnable);
    progressBar.setProgress(0);
   }
  }
 };
}