[英]Android app to server Socket program not reading String from app
我有一个Android应用程序,它将使用以下代码将字符串发送到服务器:
package com.example.testapp;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
public class MainActivity extends Activity {
private Socket socket;
private static final int SERVERPORT = 5000;
private static final String SERVER_IP = "192.168.1.125";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new Thread(new ClientThread()).start();
}
public void onClick(View view) {
try {
EditText et = (EditText) findViewById(R.id.EditText01);
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);
socket = new Socket(serverAddr, SERVERPORT);
} catch (UnknownHostException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
}
在服务器端,我正在运行如下的java程序:
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.ClassNotFoundException;
import java.net.ServerSocket;
import java.net.Socket;
public class SocketServerExample {
//static ServerSocket variable
private static ServerSocket server;
//socket server port on which it will listen
private static int port = 5000;
public static void main(String args[]) throws IOException, ClassNotFoundException{
//create the socket server object
server = new ServerSocket(port);
//keep listens indefinitely until receives 'exit' call or program terminates
while(true){
System.out.println("Waiting for client request");
//creating socket and waiting for client connection
Socket socket = server.accept();
//read from socket to ObjectInputStream object
ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());
//convert ObjectInputStream object to String
String message = (String) ois.readObject();
System.out.println("Message Received: " + message);
//create ObjectOutputStream object
ObjectOutputStream oos = new ObjectOutputStream(socket.getOutputStream());
//write object to Socket
oos.writeObject("Hi Client "+message);
//close resources
ois.close();
oos.close();
socket.close();
//terminate the server if client sends exit request
if(message.equalsIgnoreCase("exit")) break;
}
System.out.println("Shutting down Socket server!!");
//close the ServerSocket object
server.close();
}
}
但它不是读取我从Android应用程序发送的字符串。 相反,当我从app提交时,java程序显示以下错误:
Exception in thread "main" java.io.StreamCorruptedException: invalid stream header: 54657374
at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:803)
at java.io.ObjectInputStream.<init>(ObjectInputStream.java:298)
at SocketServerExample.main(SocketServerExample.java:29)
我怎样才能解决这个问题。 我的错误在哪里? 它是在服务器端还是客户端? 请帮帮我们。
问题分析 :
您使用PrintWriter
从客户端发送,但您在服务器的接收端使用ObjectInputStream
。 这两个不兼容。
你必须一起使用一对Writer
和Reader
或一对ObjectOutputStream
和ObjectInputStream
,但你不能混用它们。
解决方案
我们将使用成对的Writer
和Reader
。 客户端已经使用了Writer
和Reader
,因此我们只需要更改服务器端。
在服务器端,使用BufferedReader
而不是ObjectInputStream
:
BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
reader.readLine();
此外,使用PrintWriter
而不是服务器端的ObjectOutputStream
发送回客户端:
PrintWriter writer = new PrintWriter(new BufferedWriter(
new OutputStreamWriter(socket.getOutputStream())),
true);
writer.println(str);
总而言之,服务器端看起来像这样:
import java.io.IOException;
import java.io.BufferedWriter;
import java.io.BufferedReader;
import java.io.OutputStreamWriter;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.lang.ClassNotFoundException;
import java.net.ServerSocket;
import java.net.Socket;
public class SocketServerExample {
//static ServerSocket variable
private static ServerSocket server;
//socket server port on which it will listen
private static int port = 5000;
public static void main(String args[]) throws IOException, ClassNotFoundException{
//create the socket server object
server = new ServerSocket(port);
//keep listens indefinitely until receives 'exit' call or program terminates
while(true){
System.out.println("Waiting for client request");
//creating socket and waiting for client connection
Socket socket = server.accept();
// //read from socket to ObjectInputStream object
// ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());
// //convert ObjectInputStream object to String
// String message = (String) ois.readObject();
// System.out.println("Message Received: " + message);
BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String message = reader.readLine();
System.out.println("Message Received: " + message);
// //create ObjectOutputStream object
// ObjectOutputStream oos = new ObjectOutputStream(socket.getOutputStream());
// //write object to Socket
// oos.writeObject("Hi Client "+message);
PrintWriter writer = new PrintWriter(new BufferedWriter(
new OutputStreamWriter(socket.getOutputStream())),
true);
writer.println("Hi Client "+message);
//close resources
reader.close();
writer.close();
socket.close();
//terminate the server if client sends exit request
if(message.equalsIgnoreCase("exit")) break;
}
System.out.println("Shutting down Socket server!!");
//close the ServerSocket object
server.close();
}
}
在客户端上使用此选项:
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
在服务器上使用它:
BufferedReader is = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
String message = is.readLine();
发送任何内容后使用flush()
。
out.println(str);
out.flush();
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