android学习----ProgressBar 进度条

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进度条是一种非常实用的组件，下面我们来学习一下如何实用进度条

android提供了几个进度条的样式：

Widget.ProgressBar.Horizontal
Widget.ProgressBar.Small
Widget.ProgressBar.Large
Widget.ProgressBar.Inverse
Widget.ProgressBar.Small.Inverse
Widget.ProgressBar.Large.Inverse

ProgressBar组件的特有xml属性：

下面通过案例来学习ProgressBar

（1）编写布局文件 activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent" >        <ProgressBar         android:id="@+id/progress1"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:progress="20"        android:max="100"        android:layout_margin="20dp"        style="@android:style/Widget.ProgressBar.Horizontal"/>       <TextView         android:id="@+id/proText"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center_vertical"        android:layout_marginLeft="100dp"        android:text="当前进度:20%"/></LinearLayout>

（2）编写MainActivity.java

由于要更新主线程UI，因此需要定义Handler来更新主线程

package com.example.progressbar;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.view.Menu;import android.widget.ProgressBar;import android.widget.TextView;public class MainActivity extends Activity {private ProgressBar progressBar = null;  //定义ProgressBarprivate TextView textView = null; //定义TextViewprivate static final int PROGRESS = 0x1;private int mProgressStatus =20; //当前进度private Handler mHandler = new Handler();  //定义Handler,用于更新主线程UI@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//获取布局组件this.progressBar = (ProgressBar) findViewById(R.id.progress1); this.textView = (TextView) findViewById(R.id.proText);//开启线程new Thread(new Runnable() {@Overridepublic void run() { while (mProgressStatus < 100) {                     mProgressStatus = doWork();                     //更新进度条和进度内容                     mHandler.post(new Runnable() {                         public void run() {                         progressBar.setProgress(mProgressStatus);                         textView.setText("当前进度:"+mProgressStatus+"%");                         }                     });                 }}}).start();}private int doWork(){mProgressStatus = mProgressStatus+1;try{Thread.sleep(100);}catch(Exception e){e.printStackTrace();}return mProgressStatus;}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}}

运行后，效果如下：

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