在我的安卓应用程序中，我想连续读取传入的数据（使用Telnet协议）。我能够读取一行（然后应用程序在空闲状态下运行），我想知道如何创建一个简单的无尽主循环。
我认为围绕这一行放置一个循环是有意义的：
telnetThread.start();
我已经尝试实现一个循环器，但没有任何成功。
这是我的代码：
package com.example.clienttel;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.Log;
import org.apache.commons.net.telnet.TelnetClient;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
public class MainActivity extends ActionBarActivity {
// Variables
public final String ADDRESS = "194.66.82.11";
public final int PORT = 50100;
public String NMEA = null;
public final String TAG = "TestApp";
public boolean first = true;
public MyTelnetClass mtc;
public Thread telnetThread;
// Handler in mainthread
Handler handler = new Handler() {
public void handleMessage(Message msg) {
String dataString = "";
Bundle bundle = msg.getData();
Log.d("handleMessage", bundle.toString());
if (bundle.containsKey("outgoingString")) {
dataString = bundle.getString("outgoingString");
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
createThread();
}
private void createThread() {
final Runnable runnable = new Runnable() {
public void run() {
try {
mtc = new MyTelnetClass();
mtc.mhandler = handler;
mtc.run();
Bundle b = new Bundle();
b.putString("TCPThread", "visible");
Message m = handler.obtainMessage();
m.setData(b);
handler.sendMessage(m);
} catch (Exception e) {
Log.e("createTCPThread", "exception: " + e.getMessage());
Bundle b = new Bundle();
b.putString("TCPThread", "unvisible");
Message m = handler.obtainMessage();
m.setData(b);
handler.sendMessage(m);
}
}
};
// create the thread needed and run it, LOOP HERE?
telnetThread = new Thread(runnable);
telnetThread.start();
}
// catch NMEA-sentences and send them using mhandler
class MyTelnetClass {
public Handler mhandler = null;
public void run() {
TelnetClient telnet = new TelnetClient();
Log.i(TAG, "telnetThread active");
if (first) {
// Connect To Server in 1st Iteration
try {
telnet.connect(ADDRESS, PORT);
} catch (IOException e) {
e.printStackTrace();
}
first = false;
}
// Process NMEA-sentences
InputStream inStream = telnet.getInputStream();
BufferedReader r = new BufferedReader(new InputStreamReader(inStream));
try {
NMEA = r.readLine();
} catch (IOException e) {
e.printStackTrace();
}
// Handler in MyTelnetClass to send back
Bundle b = new Bundle();
b.putString("outgoingString", NMEA);
Message m = mhandler.obtainMessage();
m.setData(b);
mhandler.sendMessage(m);
}
}
}
处理这个问题的有效方法是什么？
编辑：
我将循环器放在 run（） 周围，但它只执行一次（我不确定循环是否可以这样工作）：
public void run() {
try {
Looper.prepare(); // HERE...
Log.d(TAG,"executing run");
mtc = new MyTelnetClass();
mtc.mhandler = handler;
mtc.run();
Bundle b = new Bundle();
b.putString("TCPThread", "visible");
Message m = handler.obtainMessage();
m.setData(b);
handler.sendMessage(m);
Looper.loop(); // ...AND HERE
} catch (Exception e) {
Log.e("createTCPThread", "exception: " + e.getMessage());
Bundle b = new Bundle();
b.putString("TCPThread", "unvisible");
Message m = handler.obtainMessage();
m.setData(b);
handler.sendMessage(m);
}
}
您已经创建了一个线程，这是您的开始，但它将运行一次。如果你想让他循环运行，你需要放循环。循环需要在run()方法中，从开始到结束，或者
如果你写一个你推荐的循环，这将是浪费时间（/memory）并且无效，它会一遍又一遍地创建相同的线程。如果你在telnetThread.start();的地方做，它会导致大量的线程，它们都会在大约相同的时间内运行。
如果您在 run() 函数中执行此操作，它将无限次运行（除非您有条件），并且仅在循环的最后一次运行结束后运行。
请尝试以下代码：
{
new Thread () {
public void run() {
Message msg = Message.obtain();
msg.what=1;
try {
openTelnetConnection(url, mmsgH);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace(); }
}
}.start();
}
private void openTelnetConnection(String urlStr, Handler mhandler) throws IOException {
ProtocolConnection protConn = null;
String line = null;
try {
// Get your CONNECTION
BufferedReader is =
new BufferedReader(new InputStreamReader(protConn.getInputStream()));
while ((line = is.readLine( )) != null) {
Message msg = Message.obtain();
msg.what=1;
msg.obj=line;
mhandler.sendMessage(msg);
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch( SocketTimeoutException e){
e.printStackTrace();
} catch (IOException e) {
Log.d(TAG, "IOERR " +e);
e.printStackTrace();
Message msg = Message.obtain();
msg.what=2;
BufferedInputStream in = new BufferedInputStream(httpConn.getErrorStream());
line =new String(readStream(in));
msg.obj=line;
mhandler.sendMessage(msg);
}
finally {protConn.disconnect();}
}
正如@ChrisStratton和@amitfarag所说，一个简单的while()循环正是我所需要的。在我的情况下不需要活套：
while (true) {
try {
mtc = new MyTelnetClass();
mtc.mhandler = handler;
mtc.run();
Bundle b = new Bundle();
b.putString("TCPThread", "visible");
Message m = handler.obtainMessage();
m.setData(b);
handler.sendMessage(m);
} catch (Exception e) {
Log.e("createTCPThread", "exception: " + e.getMessage());
Bundle b = new Bundle();
b.putString("TCPThread", "unvisible");
Message m = handler.obtainMessage();
m.setData(b);
handler.sendMessage(m);
e.printStackTrace();
}