Android 在线升级APK

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

Dialog dialog = new AlertDialog.Builder(Cockhorse.this)
.setTitle("系统更新")
.setMessage("发现新版本，请更新！")
// 设置内容
.setPositiveButton("确定",// 设置确定按钮
new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog,
int which) {
pBar = new ProgressDialog(Cockhorse.this);
pBar.setTitle("正在下载");
pBar.setMessage("请稍候…");
pBar.setProgressStyle(ProgressDialog.STYLE_SPINNER);
downFile("http://192.168.1.103:80/gzzd/androidapk/飞哥.apk");
}
})
.setNegativeButton("取消", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
// 点击"取消"按钮之后退出程序

}
}).create();// 创建
// 显示对话框
dialog.show();
// new Thread(new MyThread()).start();
}

void downFile(final String url) {
pBar.show();
new Thread() {
public void run() {
HttpClient client = new DefaultHttpClient();
// params[0]代表连接的url
HttpGet get = new HttpGet(url);
HttpResponse response;
try {
response = client.execute(get);
HttpEntity entity = response.getEntity();
long length = entity.getContentLength();
InputStream is = entity.getContent();
FileOutputStream fileOutputStream = null;
if (is != null) {

File file = new File(
Environment.getExternalStorageDirectory(),
"Cockhorse.apk");
fileOutputStream = new FileOutputStream(file);

byte[] buf = new byte[1024];
int ch = -1;
int count = 0;
while ((ch = is.read(buf)) != -1) {

fileOutputStream.write(buf, 0, ch);
count += ch;
if (length > 0) {

}
}
}
fileOutputStream.flush();
if (fileOutputStream != null) {
fileOutputStream.close();
}
down();
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}.start();
}

void down() {
handler.post(new Runnable() {
public void run() {
pBar.cancel();
update();
}
});
}

void update() {
Intent intent = new Intent(Intent.ACTION_VIEW);
// intent.setDataAndType(Uri.fromFile(new
// File("/sdcard/Feige.apk")),
// "http://192.168.1.103:80/gzzd/androidapk/Feige.apk");
intent.setDataAndType(Uri.fromFile(new File("/sdcard/飞哥.apk")),
"application/vnd.android.package-archive");
startActivity(intent);
}

//注意：APK必须通过数字签名才可以