ProgressBar 进度条

进度条：
	1.默认进度条
	<ProgressBar
		android:layout_width="warp_content"
		android:layout_height="warp_content"

	/>
	2.
	<ProgressBar
		android:layout_width="warp_content"
		android:layout_height="warp_content"

		style="?android:attr/progressBarStyleSmall" //小圆形进度条
		style="?android:attr/progressBarStyleLarge" //大圆形进度条
		
		style="?android:attr/progressBarStyleHorizontal" 	//条形进度条
		android:max="100"									//进度条最大位置
		android:progress="50"								//进度条初使位置
		android:secondaryProgress="70"						//设置底色进度值
	/>
	
	常用函数：
		getProgress(); 获取当前进度值函数
		setProgress();设置进度值
		getSecondaryProgress();获取底层进度值函数
		setSecondaryProgress();设置底层进度值函数
		getMax();获取当前最大进度值函数
	
	一个条形进度条实例：
	final ProgressBar bar = (ProgressBar)findViewById(R.id.bar);
		
		Thread th = new Thread(new Runnable() {
			@Override
			public void run() {
				// TODO Auto-generated method stub
				while(true){
					int current = bar.getProgress();//取得当前进度值
					int max = bar.getMax();			//取得进度条最大值
					int secCurrent = bar.getSecondaryProgress();//取得底层当前进度值
					
					if(stateChange){
						if(current >= max){
							stateChange = false;
						}else{
							bar.setProgress(current+1);
							bar.setSecondaryProgress(secCurrent+1);
						}
					}else{
						if(current <= 0){
							stateChange = true;
						}else{
							bar.setProgress(current-1);
							bar.setSecondaryProgress(secCurrent-1);
						}
					}
					
						try {
							Thread.sleep(50);
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
				}
			}
		});
		
			
		th.start();