Android之APK的下载安装

功能描述: 
1. 下载远程服务器端的APK文件 
2. 同步显示下载进度
3. 下载完成自动安装


关键技术点:
1. SD卡文件读写

2. ProgressDialog的使用

3. 分线程请求网络

4. 安装APK

要下载的APK要提前安装到服务器的WEB内容中

	public void downloadAPK(View v){
		//1.启动主线程，显示提示视图：ProgressDialog
		final ProgressDialog dialog = new ProgressDialog(this);
		dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
		dialog.show();
		
		//准备用于保存APK文件的File对象：/storage/sdcard/Android/package_name/files/xxx.apk
		apkFile = new File(getExternalFilesDir(null),"update.apk");
		
		//2.启动分线程，请求下载APK文件，下载过程中显示下载进度
		new Thread(new Runnable() {
			
			@Override
			public void run() {
				try {
					// 1）.得到连接对象
					String path = "http://192.168.51.65:8080/web/ActivityDemo.apk";
					URL url = new URL(path);
					HttpURLConnection connection = (HttpURLConnection) url.openConnection();
					// 2）.设置
					//connection.setRequestMethod("GET");默认
					connection.setConnectTimeout(5000);
					connection.setReadTimeout(1000);
					// 3）.连接
					connection.connect();
					// 4）.请求并得到响应码200
					int responseCode = connection.getResponseCode();
					if(responseCode==200){
						//设置dialog的最大进度
						dialog.setMax(connection.getContentLength());
						// 5）.得到包含APK文件数据的InputStream
						InputStream is = connection.getInputStream();
						// 6）.创建指向apkFile的FileOutputStream
						FileOutputStream fos = new FileOutputStream(apkFile);
						// 7）.边读边写
						byte[] buffer = new byte[1024];
						int len = -1;
						while((len=is.read(buffer))!=-1){
							fos.write(buffer,0,len);
							// 8）.显示下载进度
							dialog.incrementProgressBy(len);
							//休息一会（模拟网速慢 时）
							//Thread.sleep(50);
							SystemClock.sleep(50);
						}
						fos.close();
						is.close();
					}
					// 9）.下载完成，关闭，进入3.
					connection.disconnect();
					//3.主线程，移除Dialog,启动安装
					runOnUiThread(new Runnable() {
						public void run() {
							dialog.dismiss();
							installAPK();
						}
					});
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}).start();
		
	}

	/**
	 * 启动安装APK
	 */
	private void installAPK(){
		Intent intent = new Intent("android.intent.action.INSTALL_PACKAGE");
		intent.setDataAndType(Uri.fromFile(apkFile), "application/vnd.android.package-archive");
		startActivity(intent);
	}