Android 基础教程之Android ProgressBar的使用!

大家好，今天给大家讲一下Android中ProgressBar的使用，这个控件在开发中还是经常用到的，比如用户浏览网页的时候，中间肯定有个 传输过程，所以用进度条让用户耐心等待。再比如我在Android Market下载应用，它也会有进度条显示下载进度。我为什么要举这两个例子呢，是因为它们分别是圆形进度条和长形进度条的代表。如下面两张图：

图1.UC浏览网页圆形进度条效果。

图2.Google Market应用下载长形进度条效果.

下面我们看一下两都皆有之的Android自带的浏览器的效果图如下:

为了让大家更容易理解我将简单写一个Demo，大家可以按照我的步骤一步一步来。

第一步：新建一个Android工程命名为ProgressBarDemo.

 

第二步:修改main.xml代码如下(圆形进度条和长形进度条这里样式不同用系统自带的):

 

<?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">

     <TextView
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:text="Welcome to Mr Wei's blog" />
     <ProgressBar
         android:id="@+id/rectangleProgressBar"
         style="?android:attr/progressBarStyleHorizontal" mce_style="?android:attr/progressBarStyleHorizontal"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:visibility="gone"
         />
     <ProgressBar
         android:id="@+id/circleProgressBar"
         style="?android:attr/progressBarStyleLarge" mce_style="?android:attr/progressBarStyleLarge"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:visibility="gone"
         />

     <Button android:id="@+id/button"
             android:text="Show ProgressBar"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             />
 </LinearLayout>

第三步:修改ProgressBarDemo.java代码如下(如果这里有对Handler和Message不明白的地方可以去Android高 手进阶教程（九） 看下这个教程):

 

package com.tutor.progress;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
public class ProgressBarDemo extends Activity {

    private ProgressBar rectangleProgressBar,circleProgressBar;
    private Button mButton;

    protected static final int STOP = 0x10000;
    protected static final int NEXT = 0x10001;
    private int iCount = 0;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        //findView By id
        rectangleProgressBar = (ProgressBar)findViewById(R.id.rectangleProgressBar);
        circleProgressBar = (ProgressBar)findViewById(R.id.circleProgressBar);
        mButton = (Button)findViewById(R.id.button);

        rectangleProgressBar.setIndeterminate(false);
        circleProgressBar.setIndeterminate(false);

        mButton.setOnClickListener(new Button.OnClickListener() {

            public void onClick(View v) {

                rectangleProgressBar.setVisibility(View.VISIBLE);
                circleProgressBar.setVisibility(View.VISIBLE);

                rectangleProgressBar.setMax(100);
                rectangleProgressBar.setProgress(0);
                circleProgressBar.setProgress(0);

                //创建一个线程,每秒步长为5增加,到100%时停止
                Thread mThread = new Thread(new Runnable() {

                    public void run() {

                        for(int i=0 ; i < 20; i++){
                            try{
                                iCount = (i + 1) * 5;
                                Thread.sleep(1000);
                                if(i == 19){
                                    Message msg = new Message();
                                    msg.what = STOP;
                                    mHandler.sendMessage(msg);
                                    break;
                                }else{
                                    Message msg = new Message();
                                    msg.what = NEXT;
                                    mHandler.sendMessage(msg);
                                }
                            }catch (Exception e) {
                                e.printStackTrace();
                            }
                        }

                    }
                });
                mThread.start();
            }
        });
    }

    //定义一个Handler
    private Handler mHandler = new Handler(){
        public void handleMessage(Message msg){
            switch (msg.what) {
            case STOP:
                rectangleProgressBar.setVisibility(View.GONE);
                circleProgressBar.setVisibility(View.GONE);
                Thread.currentThread().interrupt();
                break;
            case NEXT:
                if(!Thread.currentThread().isInterrupted()){
                    rectangleProgressBar.setProgress(iCount);
                    circleProgressBar.setProgress(iCount);
                }
                break;
            }
        }
    };
}

 

第四步：运行上述工程，效果如下图: