//下载apk程序代码

 protected File downLoadFile(String httpUrl) {

                 // TODO Auto-generated method stub

                 final String fileName = "updata.apk";

                 File tmpFile = new File("/sdcard/update");

                 if (!tmpFile.exists()) {

                         tmpFile.mkdir();

                 }

                 final File file = new File("/sdcard/update/" + fileName);

                try {

                         URL url = new URL(httpUrl);

                         try {

                                 HttpURLConnection conn = (HttpURLConnection) url

                                                 .openConnection();

                                 InputStream is = conn.getInputStream();

                                 FileOutputStream fos = new FileOutputStream(file);

                                 byte[] buf = new byte[256];

                                 conn.connect();

                                 double count = 0;

                                 if (conn.getResponseCode() >= 400) {

                                         Toast.makeText(Main.this, "连接超时", Toast.LENGTH_SHORT)

                                                         .show();

                                 } else {

                                         while (count <= 100) {

                                                 if (is != null) {

                                                         int numRead = is.read(buf);

                                                         if (numRead <= 0) {

                                                                 break;

                                                         } else {

                                                                 fos.write(buf, 0, numRead);

                                                         }

                                                } else {

                                                         break;

                                                 }

                                        }

                                 }

                                conn.disconnect();

                                 fos.close();

                                 is.close();

                         } catch (IOException e) {

                                 // TODO Auto-generated catch block

                                e.printStackTrace();

                         }

                 } catch (MalformedURLException e) {

                         // TODO Auto-generated catch block

                        e.printStackTrace();

                 }

                return file;

         }

 //打开APK程序代码

private void openFile(File file) {

                 // TODO Auto-generated method stub

                 Log.e("OpenFile", file.getName());

                 Intent intent = new Intent();

                 intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

                 intent.setAction(android.content.Intent.ACTION_VIEW);

                 intent.setDataAndType(Uri.fromFile(file),

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

                 startActivity(intent);

         }