java - 创建一个简单的 Hello world Android 客户端-服务器程序

Question

为了简单起见，我想做的就是从 Android 模拟器向 Eclipse 上的 Java 控制台服务器发送一条消息，其中包含一个简单的字符串，然后我希望服务器用另一个字符串进行回复。当然;我将连接到主机 10.0.2.2 并使用任何开放端口(在我的例子中为 4000)。每次我单击模拟器上的连接按钮时，服务器都会收到“已连接”消息，但我找不到传递数据包或消息的方法。

如果您想阅读一些代码，这是我的(我认为是)对于简单任务来说太长的代码。

客户端 包 com.example.clienttest;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {

    Thread m_objThreadClient;
    Socket clientSocket;
    TextView serverMessage;
    EditText clientMessage;
    String sIn, sOut;
    ObjectOutputStream oos;
    ObjectInputStream ois;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        serverMessage = (TextView) findViewById(R.id.textView1);
        clientMessage = (EditText) findViewById(R.id.editText1);

    }


    public void Start(View view) throws IOException{
        final String Text;
        String send = " ";
        Text = clientMessage.getText().toString();
        m_objThreadClient = new Thread( new Runnable(){
            public void run()
            {
                try {
                    clientSocket = new Socket("10.0.2.2", 4000);
                    oos = new ObjectOutputStream (clientSocket.getOutputStream());
                    oos.writeObject(Text);
                    oos.flush();

                } catch (IOException e) {
                    serverMessage.setText(e.getMessage());
                }

            }
        });
        serverMessage.setText(send);

        m_objThreadClient.start();

    }

}

和服务器

import java.net.ServerSocket;
import java.net.Socket;

import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.PrintWriter;

import java.util.Hashtable;

public class Server2 {

    @SuppressWarnings("resource")
    public static void main (String[] args) throws IOException {

        ServerSocket server = null;  
        try {
            server = new ServerSocket(4000); 
        } catch (IOException e) {
            System.err.println("Could not start up on: " + "4000" + "Maby server is already open? Or a portforwording messup?");
            System.err.println(e);
            System.exit(1);
        }

        Socket client = null;
        while(true) {
            try {
                client = server.accept();
                System.out.print("connected");
            } catch (IOException e) {
                System.err.println("Accept failed.");
                System.err.println(e);
            }

            Thread t = new Thread(new ClientConn(client));
            t.start();
        }
    }
}


class ClientConn implements Runnable {
    private Socket client;
    ObjectInputStream ois;
    ObjectOutputStream oos;

    ClientConn(Socket client) {
        this.client = client;
        try {
            ois = new ObjectInputStream(client.getInputStream());
            String Recv;
            Recv = ois.readLine();

            oos = new ObjectOutputStream(client.getOutputStream());
            oos.writeChars("Welcome");
            oos.flush();

            oos.close();

        } catch (IOException e) {
            System.err.println(e);
            return;
        }
    }

    public void run() {
        String msg, response;
        try {
            System.out.print("checking");
            while ((msg = ois.readLine()) != null) {
                System.out.print(msg);
            }
        } catch (IOException e) {
            System.err.println(e);
        }
    }

    public void sendMsg(String msg) throws IOException {
        oos.writeChars(msg);
    }
}

谢谢~

Answer 1

一些可能或可能无法解决问题的想法:

ObjectInputStream 的 readLine() 方法已弃用。尝试使用 DataInputStream 代替。类似于:

try {
        outToClient = new DataOutputStream(socket.getOutputStream());
        inFromClient = new DataInputStream(socket.getInputStream());
} catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
}

然后:

inFromClient.readLine();

请注意，读取的行将继续读取，直到遇到换行符“\n”。因此 readLine() 将阻塞，直到读取换行符。

尝试这些方法，看看是否有帮助

编辑:看来 DataInputStream 的 readLine() 也已被弃用，但还有其他几种方法应该可以使用。例如readUTF()