<ProgressBar 
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:progress="30"
/>

private ProgressBar pb_progressBar1;
pb_progressBar1=(ProgressBar) findViewById(R.id.pb_progressBar1);

if(progress<=100){
　　progress=pb_progressBar1.getProgress();
　　progress+=(int)(100*0.2);
　　pb_progressBar1.setProgress(progress);
}else progress=100;

package fry;

import com.example.Ex26ProgressBar.R;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;

public class Activity01 extends Activity implements OnClickListener{
  /*
   * 进度条ProgressBar使用方法
   * 1、在layout布局文件中创建ProgressBar控件
   * 2、用ProgressBar对象指向ProgressBar控件
   * 3、通过ProgressBar对象的getProgress()和setProgress()方法对进度进行修改
   * 
   */
  private Button btn_addProgress;
  private Button btn_minusProgress;
  private ProgressBar pb_progressBar1;
  private int progress;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity01);
    
    btn_addProgress=(Button) findViewById(R.id.btn_addProgress);
    btn_minusProgress=(Button) findViewById(R.id.btn_minusProgress);
    pb_progressBar1=(ProgressBar) findViewById(R.id.pb_progressBar1);
    
    btn_addProgress.setOnClickListener(this);
    btn_minusProgress.setOnClickListener(this);
    
  }
  @Override
  public void onClick(View v) {
    // TODO Auto-generated method stub
    switch (v.getId()) {
    case R.id.btn_addProgress:
      if(progress<=100){
        progress=pb_progressBar1.getProgress();
        progress+=(int)(100*0.2);
        pb_progressBar1.setProgress(progress);
      }else progress=100;
      
      break;
    case R.id.btn_minusProgress:
      if(progress>=0){
        progress=pb_progressBar1.getProgress();
        progress-=(int)(100*0.2);
        pb_progressBar1.setProgress(progress);
      }else progress=0;
      break;

    default:
      break;
    }
  }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical" >

  <!-- style设置控件样式 -->
  <!-- 用？来引用东西 -->
  <ProgressBar 
    style="?android:attr/progressBarStyleSmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    />
  
  <ProgressBar 
    style="?android:attr/progressBarStyleLarge"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    />
  
  
  <ProgressBar 
    style="?android:attr/progressBarStyleLargeInverse"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    />
  
  <ProgressBar 
    style="?android:attr/progressBarStyleHorizontal"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:progress="30"
    />
  
  <ProgressBar 
    android:id="@+id/pb_progressBar1"
    style="?android:attr/progressBarStyleHorizontal"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:progress="50"
    android:secondaryProgress="80"
    android:layout_marginTop="30dp"
    />
  
  <LinearLayout 
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:orientation="horizontal"
    >
    <Button 
    android:id="@+id/btn_addProgress"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="增加进度"
    android:layout_weight="1"
    />
  
  <Button 
    android:id="@+id/btn_minusProgress"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="减少进度"
    android:layout_weight="1"
    />
    
  </LinearLayout>
  

</LinearLayout>

progress=pb_progressBar1.getProgress();
progress+=(int)(100*0.2);
pb_progressBar1.setProgress(progress);