我正在为android创建一个基本测试应用程序，它可以连接到套接字服务器并发送和接收数据。我已经能够从客户端发送数据到服务器工作，但似乎有问题让Android接收数据。服务器工作，因为我已经能够使用外部应用程序测试它。
这是我的代码
package com.socket_sending_and_receving_test;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.BufferedReader;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Timer;
import java.util.TimerTask;
import android.os.Looper;
import android.os.Message;
import android.widget.Button;
import android.widget.TextView;
import android.os.Handler;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
public class Sending_And_Receiving extends Activity {
private Socket socket;
String message = "";
String mClientMsg;
TextView text;
final Handler myHandler = new Handler();
int count = 0;
public static String SERVERPORT;
public static int SERVERPORT2;
public static String SERVER_IP;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sending_and_receaving);
text = (TextView) findViewById(R.id.textView);
text.setText("0");
}
Handler myUpdateHandler = new Handler() {
public void handleMessage(Message msg) {
TextView tv = (TextView) findViewById(R.id.textView);
tv.setText(mClientMsg);
super.handleMessage(msg);
}
};
class CommsThread implements Runnable {
String st = null;
public void run() {
while (!Thread.currentThread().isInterrupted()) {
Message m = new Message();
{
BufferedReader input = null;
try {
InputStreamReader streamReader = new InputStreamReader(socket.getInputStream());
BufferedReader reader = new BufferedReader(streamReader);
st = reader.readLine();
mClientMsg = st;
myUpdateHandler.sendMessage(m);
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
public void connect(View view) {
EditText ip = (EditText) findViewById(R.id.ip);
EditText port = (EditText) findViewById(R.id.port);
SERVER_IP = ip.getText().toString();
SERVERPORT = port.getText().toString();
new Thread(new ClientThread()).start();
new Thread(new CommsThread()).start();
}
public void Disconnect(View view) {
try {
socket.shutdownInput();
socket.shutdownOutput();
} catch (IOException e) {
e.printStackTrace();
}
}
public void onClick(View view) {
try {
EditText et = (EditText) findViewById(R.id.ko);
String str = et.getText().toString();
PrintWriter out = new PrintWriter(new BufferedWriter(
new OutputStreamWriter(socket.getOutputStream())),
true
);
out.println(str);
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
class ClientThread implements Runnable {
@Override
public void run() {
try {
InetAddress serverAddr = InetAddress.getByName(SERVER_IP);
SERVERPORT2 = Integer.parseInt(SERVERPORT);
socket = new Socket(serverAddr, SERVERPORT2);
} catch (UnknownHostException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
}
连接完成后，应用程序崩溃。我不认为这是由于UI更新，但我认为这是由于接收数据。
这里是logcat
07-08 21:59:57.915 7041-7041/com.socket_sending_and_receving_test D/libEGL﹕ loaded /system/lib/egl/libEGL_mali.so
07-08 21:59:57.920 7041-7041/com.socket_sending_and_receving_test D/libEGL﹕ loaded /system/lib/egl/libGLESv1_CM_mali.so
07-08 21:59:57.925 7041-7041/com.socket_sending_and_receving_test D/libEGL﹕ loaded /system/lib/egl/libGLESv2_mali.so
07-08 21:59:57.930 7041-7041/com.socket_sending_and_receving_test D/﹕ Device driver API match
Device driver API version: 10
User space API version: 10
07-08 21:59:57.930 7041-7041/com.socket_sending_and_receving_test D/﹕ mali: REVISION=Linux-r2p4-02rel0 BUILD_DATE=Tue Oct 16 15:37:13 KST 2012
07-08 21:59:57.965 7041-7041/com.socket_sending_and_receving_test D/OpenGLRenderer﹕ Enabling debug mode 0
07-08 21:59:57.965 7041-7041/com.socket_sending_and_receving_test E/SensorManager﹕ thread start
07-08 21:59:57.970 7041-7041/com.socket_sending_and_receving_test D/SensorManager﹕ registerListener :: handle = 0 name= LSM330DLC 3-axis Accelerometer delay= 200000 Listener= android.view.OrientationEventListener$SensorEventListenerImpl@42b1cf38
07-08 21:59:58.080 7041-7041/com.socket_sending_and_receving_test E/SpannableStringBuilder﹕ SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
07-08 21:59:58.080 7041-7041/com.socket_sending_and_receving_test E/SpannableStringBuilder﹕ SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
07-08 22:00:03.235 7041-7193/com.socket_sending_and_receving_test W/dalvikvm﹕ threadid=13: thread exiting with uncaught exception (group=0x41e792a0)
07-08 22:00:03.240 7041-7193/com.socket_sending_and_receving_test E/AndroidRuntime﹕ FATAL EXCEPTION: Thread-2791
java.lang.NullPointerException
at com.socket_sending_and_receving_test.Sending_And_Receiving$CommsThread.run(Sending_And_Receiving.java:74)
at java.lang.Thread.run(Thread.java:856)
07-08 22:00:03.320 7041-7041/com.socket_sending_and_receving_test D/SensorManager﹕ unregisterListener:: Listener= android.view.OrientationEventListener$SensorEventListenerImpl@42b1cf38
07-08 22:00:03.320 7041-7041/com.socket_sending_and_receving_test D/Sensors﹕ Remain listener = Sending .. normal delay 200ms
07-08 22:00:03.320 7041-7041/com.socket_sending_and_receving_test I/Sensors﹕ sendDelay --- 200000000
07-08 22:00:03.320 7041-7041/com.socket_sending_and_receving_test D/SensorManager﹕ JNI - sendDelay
07-08 22:00:03.320 7041-7041/com.socket_sending_and_receving_test I/SensorManager﹕ Set normal delay = true
07-08 22:00:09.870 7041-7041/com.socket_sending_and_receving_test I/Choreographer﹕ Skipped 392 frames! The application may be doing too much work on its main thread.
07-08 22:00:11.680 7041-7193/com.socket_sending_and_receving_test I/Process﹕ Sending signal. PID: 7041 SIG: 9
非常感谢有关此问题的任何帮助
干杯：）
答案 0 :(得分：1)
您的套接字为NULL。这是因为竞争条件：
new Thread(new ClientThread()).start();
new Thread(new CommsThread()).start();
这两个线程都是在这里启动的，但是当CommsThread尝试使用它时，ClientThread将初始化套接字。但此时尚未初始化。
您可以在socket = ...之后立即调用CommsThread的run（），或者如果您确实需要第二个线程，请在那里启动它。
答案 1 :(得分：0)
在ClientThread完成连接之前，您的CommsThread正在运行。所以，＆＃39; socket＆＃39;仍然是空的，你得到一个NPE。
这些绝对没有理由成为两个不同的主题。合并它们，以便首先建立连接，然后开始I / O.使用两个线程来执行必须顺序的任务基本上是无用的。