我对android和java编程很陌生。我正在编写服务器客户端连接。我的电脑是服务器，我的安卓智能手机是客户端。服务器工作得很好。我可以从客户端向服务器发送消息，但不能从服务器向客户端发送消息。当我这样做时，客户端会自行粉碎并关闭。我真的希望任何人都可以帮助我解决我的大问题。
这是我的活动：
package com.example.sercerclient2zweidreidrei;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MyActivity extends Activity {
Button btn;
EditText textOut;
TextView textIn;
TextView problems;
Button send;
private TCPClient myTcpClient;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final EditText editText = (EditText) findViewById(R.id.editText);
final TextView textIn = (TextView) findViewById(R.id.textin);
Button send = (Button)findViewById(R.id.send_button);
// connect to the server
new connectTask().execute("");
send.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String message = editText.getText().toString();
//sends the message to the server
if (myTcpClient != null) {
myTcpClient.sendMessage(message);
}
}
});
}
public class connectTask extends AsyncTask<String,String,TCPClient> {
@Override
protected TCPClient doInBackground(String... message) {
//we create a TCPClient object and
myTcpClient = new TCPClient(new TCPClient.OnMessageReceived() {
@Override
//here the messageReceived method is implemented
public void messageReceived(String message) {
//this method calls the onProgressUpdate
publishProgress(message);
}
});
myTcpClient.run();
return null;
}
@Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
//in the arrayList we don't add the message received from server
//here i try to write the incomming message into a textVie
textIn.setText(values[0]);
}
}
}
这是我的 TCPClient 类：
package com.example.sercerclient2zweidreidrei;
import android.util.Log;
import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
public class TCPClient {
private String serverMessage;
public static final String SERVERIP = "192.168.2.107"; //your computer IP address
public static final int SERVERPORT = 4444;
private OnMessageReceived mMessageListener = null;
private boolean mRun = false;
PrintWriter out;
BufferedReader in;
/**
* constructor of the class. OnMessageReceived listens for the messages
* received from server
*/
public TCPClient(OnMessageReceived listener) {
mMessageListener = listener;
}
/**
* Sends the message entered by client to the server
* @param message text entered by client
*/
public void sendMessage(String message){
if (out != null && !out.checkError()) {
out.println(message);
out.flush();
}
}
public void stopClient() {
mRun = false;
}
public void run() {
mRun = true;
try {
// here you must put your computer's IP address.
InetAddress serverAddr = InetAddress.getByName(SERVERIP);
Log.e("TCP Client", "C: Connecting...");
//create a socket to make the connection with the server
Socket socket = new Socket(serverAddr, SERVERPORT);
try {
//send the message to the server
out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
Log.e("TCP Client", "C: Sent.");
Log.e("TCP Client", "C:Done.");
//receive the message which the server sends back
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
//in this while the client listens for the messages send by the server
while (mRun) {
serverMessage = in.readLine();
if (serverMessage != null && mMessageListener != null) {
//call the method messageReceived from MyActivity class
mMessageListener.messageReceived(serverMessage);
}
serverMessage = null;
}
Log.e("RESPONSE FROM SERVER", "S: Received Message: '" + serverMessage + "'");
} catch (Exception e) {
Log.e("TCP", "S: Error", e);
} finally {
//the socket must be closed. It is not possible to reconnect to this socket
//after it is closed, which means a new socket instance has to be created.
socket.close();
}
} catch (Exception e) {
Log.e("TCP", "C:Error", e);
}
}
/*
* Declare the interface. The method messageReceived(String message must be
* implemented in the MyActivity class at on asynckTask doInBackground
*/
public interface OnMessageReceived {
public void messageReceived(String message);
}
}
最后在这里你可以看到我的 main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MyActivity" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="@string/Textausgabe" />
<EditText
android:id="@+id/editText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/textView1"
android:layout_marginTop="34dp"
android:ems="10" >
<requestFocus />
</EditText>
<Button
android:id="@+id/send_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignRight="@+id/textView1"
android:layout_below="@+id/editText"
android:layout_marginTop="26dp"
android:text="@string/Senden" />
<TextView
android:id="@+id/textin"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:text="@string/EinkommenderText"
android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>
这是我的 LogCat：
12-30 16:36:37.340: I/dalvikvm(548): threadid=3: 对信号 3 做出反应
12-30 16:36:37.560: I/dalvikvm(548): 将堆栈跟踪写入“/data/anr/traces.txt”
12-30 16:36:37.740: I/dalvikvm(548): threadid=3: 对信号 3 做出反应
12-30 16:36:37.790: I/dalvikvm(548): 将堆栈跟踪写入“/data/anr/traces.txt”
12-30 16:36:38.350：D/gralloc_goldfish(548)：没有检测到 GPU 仿真的仿真器。
12-30 16:36:38.630: I/dalvikvm(548): threadid=3: 对信号 3 做出反应
12-30 16:36:38.650: I/dalvikvm(548): 将堆栈跟踪写入“/data/anr/traces.txt”
12-30 16:36:39.721：E/TCP 客户端（548）：C：正在连接...
12-30 16:36:39.981：E/TCP 客户端（548）：C：已发送。
12-30 16:36:39.990：E/TCP 客户端（548）：C：完成。
12-30 16:38:59.034: D/AndroidRuntime(548): 关闭虚拟机
12-30 16:38:59.034: W/dalvikvm(548): threadid=1: 线程以未捕获的异常退出 (group=0x409c01f8)
12-30 16:38:59.051：E/AndroidRuntime(548)：致命异常：主要
12-30 16:38:59.051: E/AndroidRuntime(548): java.lang.NullPointerException
12-30 16:38:59.051: E/AndroidRuntime(548): 在 com.example.sercerclient2zweidreidrei.MyActivity$connectTask.onProgressUpdate(MyActivity.java:72)
12-30 16:38:59.051: E/AndroidRuntime(548): at com.example.sercerclient2zweidreidrei.MyActivity$connectTask.onProgressUpdate(MyActivity.java:1)
12-30 16:38:59.051: E/AndroidRuntime(548): 在 android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:618)
12-30 16:38:59.051: E/AndroidRuntime(548): 在 android.os.Handler.dispatchMessage(Handler.java:99)
12-30 16:38:59.051: E/AndroidRuntime(548): 在 android.os.Looper.loop(Looper.java:137)
12-30 16:38:59.051: E/AndroidRuntime(548): 在 android.app.ActivityThread.main(ActivityThread.java:4424)
12-30 16:38:59.051: E/AndroidRuntime(548): 在 java.lang.reflect.Method.invokeNative(Native Method)
12-30 16:38:59.051: E/AndroidRuntime(548): 在 java.lang.reflect.Method.invoke(Method.java:511)
12-30 16:38:59.051: E/AndroidRuntime(548): 在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-30 16:38:59.051: E/AndroidRuntime(548): 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-30 16:38:59.051: E/AndroidRuntime(548): at dalvik.system.NativeStart.main(Native Method)
12-30 16:38:59.752: I/dalvikvm(548): threadid=3: 对信号 3 做出反应
12-30 16:38:59.900: I/dalvikvm(548): 将堆栈跟踪写入“/data/anr/traces.txt”
我希望你能找到我的错误。