android 自動更新的實現

主要原理是：

在應用啟動的時候，去取服務器上版本號 ，與當前應用的對比如果有更新則下載

下面這個是獲取當前應用的版本信息

private void getCurVersion() {
        try {
            PackageInfo pInfo = context.getPackageManager().getPackageInfo(
                    context.getPackageName(), 0);
            curVersion = pInfo.versionName;
            curVersionCode = pInfo.versionCode;
        } catch (NameNotFoundException e) {
            Log.e("update", e.getMessage());
            curVersion = "1.0.1";
            curVersionCode = 1;
        }

    }

下面則是通過java net包來get版本信息，進行比較

服務器端格式如下 version_1.0.2

HttpURLConnection 獲取輸入流，再用

BufferedReader 緩沖流，readline成String，再比較

private boolean check_update(){
		String getstring = null;
		String version=null;
		getCurVersion();
		try {
			
			URL myurl=new URL(app_check);
			
			HttpURLConnection urlconnection=(HttpURLConnection) myurl.openConnection();
			urlconnection.setReadTimeout(50000);
			urlconnection.setConnectTimeout(50000);
			urlconnection.connect();
			InputStream in=urlconnection.getInputStream();
			
			   BufferedReader buffread;
			   buffread=new BufferedReader(new InputStreamReader(in,"utf-8"));
			   String line;
				line=buffread.readLine();
				while(line!=null){
					getstring+=line;
					line=buffread.readLine();
					
				}
				int index=getstring.indexOf("version_");
				//2.0.1
				version=getstring.substring(index+8, index+13);
				in.close();
				Log.e("version",version);
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	    if(version!=null){
		if(version.compareTo(curVersion)>0)
			return true;
		else
			return false;
	    }
	    else
	    	return false;
	}

接下來則是彈出一對話框以及調用下載線程

private void showdownDialog(){
		 AlertDialog.Builder dialog = new AlertDialog.Builder(context);  
	        dialog.setTitle("軟件版本更新");  
	        dialog.setMessage("有最新的app更新");  
	       dialog.setNegativeButton("以後再說", new OnClickListener(){

			@Override
			public void onClick(DialogInterface arg0, int arg1) {
				// TODO Auto-generated method stub
				arg0.dismiss();
			}
	       
	       });
	       dialog.setPositiveButton("確定", new OnClickListener(){

			@Override
			public void onClick(DialogInterface dialog, int which) {
				// TODO Auto-generated method stub
				//確定裡面調用下載線程，同時顯示下載的那個進度對話框
				dialog.dismiss();
				cancel=true;
				downapk();
				showDownapk();
			}
	    	   
	       });
	       dialog.show();
	}

最後則是發出一個Intent廣播

private void setInstall(){
File apkfile = new File(apk_path);
if (!apkfile.exists()) {
return;
}
Intent i = new Intent(Intent.ACTION_VIEW);
i.setDataAndType(Uri.parse("file://" + apkfile.toString()), "application/vnd.android.package-archive");
context.startActivity(i);
}