Android 版本检测和更新的主要方法

现在很多APK都自带自动检测版本及更新，以便用户体验到最新的功能和体验。实现方法分2种情况。

1.Google APP Store上面已经有部署，这种比较简单，在自己的服务器添加一个检查版本更新的页面，返回需要的版本信息，也可以添加描述内容，这样可以在APK显示版本更新的具体内容。新开一个线程检测当前的版本号是否小于最新的version，如果是的话，则开始访问官方地址来更新。代码如下：

/* This Thread checks for Updates in the Background */
    private Thread checkUpdate = new Thread() {
        public void run() {
            try {
                URL updateURL = new URL("http://my.company.com/update");                
                URLConnection conn = updateURL.openConnection(); 
                InputStream is = conn.getInputStream();
                BufferedInputStream bis = new BufferedInputStream(is);
                ByteArrayBuffer baf = new ByteArrayBuffer(50);
                
                int current = 0;
                while((current = bis.read()) != -1){
                     baf.append((byte)current);
                }

                /* Convert the Bytes read to a String. */
                final String s = new String(baf.toByteArray());         
                
                /* Get current Version Number */
                int curVersion = getPackageManager().getPackageInfo("your.app.id", 0).versionCode;
                int newVersion = Integer.valueOf(s);
                
                /* Is a higher version than the current already out? */
                if (newVersion > curVersion) {
                    /* Post a Handler for the UI to pick up and open the Dialog */
                    mHandler.post(showUpdate);
                }                
            } catch (Exception e) {
            }
        }
    };

    /* This Runnable creates a Dialog and asks the user to open the Market */ 
    private Runnable showUpdate = new Runnable(){
           public void run(){
            new AlertDialog.Builder(Test.this)
            .setIcon(R.drawable.icon)
            .setTitle("Update Available")
            .setMessage("An update for is available!\\n\\nOpen Android Market and see the details?")
            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int whichButton) {
                            /* User clicked OK so do some stuff */
                            Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse("market://search?q=pname:your.app.id"));
                            startActivity(intent);
                    }
            })
            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int whichButton) {
                            /* User clicked Cancel */
                    }
            })
            .show();
           }
    };    
}

2.产品没有部署在应用商店，可以在返回数据里添加最新版本APK的下载路径，下载完毕后，执行下列代码进行安装：

protected void installApk(File file) {
        Intent intent = new Intent();
        intent.setAction(Intent.ACTION_VIEW);
        intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");
        startActivity(intent);
    }

3.一些类库，参考地址：

https://github.com/winsontan520/Android-WVersionManager/blob/master/library/src/com/winsontan520/wversionmanager/library/WVersionManager.java

https://code.google.com/p/android-query/wiki/Service