1 首先在程序启动的时候 向服务器发送请求 服务器会返回    String  newVerString="2|app.quannaojiaoyu.com......"

2 然后根据 “|”拆分为俩个list 元素   取第一个list 元素 和当前的版本号进行比较 如果此元素大于版本号 则发现新版本开始下载 url 为list的第二个元素  下载完毕即可安装

String newVerString = functions.getHttpResponse(

urlApi + "base.asp", "getVer");

System.out.println("newString--->"+newVerString);

Log.d("StartPage", "Check Server.");

if (newVerString != null)

{

ArrayList listVerStrings = functions.splitString(newVerString);

//得到当前版本号

int curVersion = functions.getAppVersionName(getApplicationContext());

Log.d("StartPage", listVerStrings.get(0));

// Check New Version

if (curVersion < Integer.parseInt(listVerStrings.get(0)))

{

Log.d("StartPage", "find new version.");

try

{

URL Url = new URL(listVerStrings.get(1));

URLConnection conn = Url.openConnection();

conn.connect();

InputStream is = conn.getInputStream();

int fileSize = conn.getContentLength();//获取文件长度

Log.d("StartPage", "new version download start ("

+ String.valueOf(fileSize) + ")...");

msg = new Message();

msg.what = UPDATE_NEWVER;

msg.arg1 = fileSize;

handler.sendMessage(msg);

if (fileSize <= 0)return;

FileOutputStream FOS = new FileOutputStream(strSDPath

+ "/cawords.apk");

byte buf[] = new byte[1024];

int downLoadFilePosition = 0;

int numread;

while ((numread = is.read(buf)) != -1)

{

FOS.write(buf, 0, numread);

downLoadFilePosition += numread;

Log.d("StartPage", "new version downloading ("

+ String.valueOf(downLoadFilePosition)

+ ")...");

msg = new Message();

msg.what = UPDATE_DOWNLOAD;

msg.arg1 = downLoadFilePosition;

handler.sendMessage(msg);

}

Log.d("StartPage", "New Version Downloaded.");

Intent intent = new Intent();

// 安装程序

intent.setDataAndType(

Uri.fromFile(new File(strSDPath

+ "/com.quannaojiaoyu.cadict.apk")),

"application/vnd.android.package-archive");

startActivity(intent);

Log.d("StartPage", "New Version Installed.");

finish();

System.exit(0);

} catch (Exception ex)

{

如何得到当前版本号：

public static int getAppVersionName(Context context) {   int versionName = -1;   try   {    PackageManager pm = context.getPackageManager();    PackageInfo pi = pm.getPackageInfo(context.getPackageName(), 0);    versionName = pi.versionCode;    Log.d("versionName ", versionName +"");   } catch (Exception e)   {    Log.e("GET VER", "Exception", e);   }   return versionName; }