如何在Android中通过Handler传递消息? [英] How can I pass message via Handler in Android?
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问题描述
我正在学习Android中的工作处理程序.我做了Android服务器和套接字类.当有人连接到服务器时，我想从套接字向mainactivity发送一些消息(即"New Connect").我不知道如何从套接字传递到mainactivity. (更多评论)
I'm learning how work handler in Android. I did Android server and socket class. I want send some message (i.e. "New Connect") from socket to mainactivity, when somebody connect to server. I can't figure out how to pass from socket to mainactivity. (More in comments)
HttpServerActivity.java
HttpServerActivity.java
public class HttpServerActivity extends Activity implements OnClickListener{
private SocketServer s;
private static final int READ_EXTERNAL_STORAGE = 1;
Button btn1, btn2;
// There I'm trying to send message to button, when somebody connected
Handler h = new Handler(){
@Override
public void handleMessage(Message msg){
super.handleMessage(msg);
String text = (String)msg.obj;
btn1.setText(text);
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_http_server);
Button btn1 = (Button)findViewById(R.id.button1);
Button btn2 = (Button)findViewById(R.id.button2);
btn1.setOnClickListener(this);
btn2.setOnClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.http_server, menu);
return true;
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.button1) {
int permissionCheck = ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);
if (permissionCheck != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(
this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, READ_EXTERNAL_STORAGE);
} else {
// I dont know figure out in this place
s = new SocketServer(h);
s.start();
}
}
if (v.getId() == R.id.button2) {
s.close();
try {
s.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch (requestCode) {
case READ_EXTERNAL_STORAGE:
if ((grantResults.length > 0) && (grantResults[0] == PackageManager.PERMISSION_GRANTED)) {
// I dont know figure out in this place
s = new SocketServer(h);
s.start();
}
break;
default:
break;
}
}
}
SocketServer.java
SocketServer.java
public class SocketServer extends Thread {
private final Handler mHandler;
public SocketServer(Handler handler)
{
mHandler = handler;
}
ServerSocket serverSocket;
public final int port = 12345;
boolean bRunning;
public void close() {
try {
serverSocket.close();
} catch (IOException e) {
Log.d("SERVER", "Error, probably interrupted in accept(), see log");
e.printStackTrace();
}
bRunning = false;
}
public Handler mHandler;
public void run() {
try {
Log.d("SERVER", "Creating Socket");
serverSocket = new ServerSocket(port);
bRunning = true;
while (bRunning) {
Log.d("SERVER", "Socket Waiting for connection");
Socket s = serverSocket.accept();
Log.d("SERVER", "Socket Accepted");
// trying to send some message
String[] messageString = new String[1];
Message message = Message.obtain();
messageString[0]="OK";
message.obj = messageString;
mHandler.sendMessage(message);
OutputStream o = s.getOutputStream();
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(o));
out.write("HTTP/1.0 200 OK\n" +
"Date: Fri, 31 Dec 1999 23:59:59 GMT\n" +
"Content-Type: text/html\n" +
"Content-Length: 1354\n" +
"\n" +
"<html>\n" +
"<body>\n" +
"<h1> Connected </h1>\n" +
"</body>\n" +
"</html>");
out.flush();
while (!((tmp = in.readLine()).isEmpty()))
{
Log.d("Header", tmp);
if (tmp.startsWith("GET"))
{
getRequest = tmp;
}
}
s.close();
Log.d("SERVER", "Socket Closed");
}
}
catch (IOException e) {
if (serverSocket != null && serverSocket.isClosed())
Log.d("SERVER", "Normal exit");
else {
Log.d("SERVER", "Error");
e.printStackTrace();
}
}
finally {
serverSocket = null;
bRunning = false;
}
}
}
推荐答案
这是几年前我参与的一个更大项目的样本.您将无法按原样运行，但是我认为您可以看到Service与Activity之间的通信是如何工作的.随时询问是否不清楚
This is a sample of a bigger project I was involved a few years ago. You will not be able to run as it is, but I think you can see how the communication between a Service and an Activity works. Feel free to ask if anything is not clear
服务
public class BluetoothService {
private final Handler mHandler;
public BluetoothService(Context context, Handler handler) {
mHandler = handler;
}
public synchronized void Connecting(...) {
...
Message MenssageToActivity = mHandler.obtainMessage(Cliente_Bluetooth.MESSAGE_HELLO);
Bundle bundle = new Bundle();
bundle.putString(BluetoothClient.DEVICE_NAME, " Gorkatan");
MensajeParaActivity.setData(bundle);
mHandler.sendMessage(MensajeParaActivity);
...
}
}
活动
public class BluetoothClient{
public static final int MESSAGE_HELLO = 1;
public static final int MESSAGE_BYE = 2;
@Override
protected void onCreate(Bundle savedInstanceState) {
mBluetoothService = new BluetoothService(this, mHandler);
}
private final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MESSAGE_HELLO:
String mName = null;
mName = msg.getData().getString(DEVICE_NAME);
Toast.makeText(getApplicationContext(), "Hello "+ mName, Toast.LENGTH_SHORT).show();
break;
case MESSAGE_BYE:
System.out.println("Bye!")
break;
}
这是整个项目(带有西班牙语的注释和变量名):
Here it is the whole project (which has got comments and variable names in Spanish):
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