java中TCP实现回显服务器及客户端

Java中TCP实现回显服务器及客户端的步骤如下：

1. 编写服务器端程序

服务器端需要完成以下任务：

1. 创建ServerSocket对象

ServerSocket serverSocket = new ServerSocket(8888);

1. 监听客户端的连接请求

Socket socket = serverSocket.accept();

1. 读取客户端发送的数据

InputStream inputStream = socket.getInputStream();
byte[] buffer = new byte[1024];
int len = inputStream.read(buffer);

1. 回显客户端发送的数据

OutputStream outputStream = socket.getOutputStream();
outputStream.write(buffer, 0, len);
outputStream.flush();

完整代码如下：

public class EchoServer {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(8888);
        System.out.println("EchoServer started.");

        Socket socket = serverSocket.accept();
        System.out.println("Accepted connection.");

        InputStream inputStream = socket.getInputStream();
        byte[] buffer = new byte[1024];
        int len = inputStream.read(buffer);
        System.out.println("Received message: " + new String(buffer, 0, len));

        OutputStream outputStream = socket.getOutputStream();
        outputStream.write(buffer, 0, len);
        outputStream.flush();

        System.out.println("EchoServer stopped.");
        socket.close();
        serverSocket.close();
    }
}

2. 编写客户端程序

客户端需要完成以下任务：

1. 创建Socket对象，连接服务器

Socket socket = new Socket("localhost", 8888);

1. 向服务器发送数据

OutputStream outputStream = socket.getOutputStream();
outputStream.write("Hello, EchoServer!".getBytes());
outputStream.flush();

1. 读取服务器回显的数据

InputStream inputStream = socket.getInputStream();
byte[] buffer = new byte[1024];
int len = inputStream.read(buffer);
System.out.println("Received message: " + new String(buffer, 0, len));

完整代码如下：

public class EchoClient {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket("localhost", 8888);

        OutputStream outputStream = socket.getOutputStream();
        outputStream.write("Hello, EchoServer!".getBytes());
        outputStream.flush();
        System.out.println("Sent message: Hello, EchoServer!");

        InputStream inputStream = socket.getInputStream();
        byte[] buffer = new byte[1024];
        int len = inputStream.read(buffer);
        System.out.println("Received message: " + new String(buffer, 0, len));

        socket.close();
    }
}

3. 示例说明

以下是一个简单的示例，演示了如何使用Java Socket API实现回显服务器：

// EchoServer.java
public class EchoServer {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(8888);
        System.out.println("EchoServer started.");

        Socket socket = serverSocket.accept();
        System.out.println("Accepted connection.");

        InputStream inputStream = socket.getInputStream();
        byte[] buffer = new byte[1024];
        int len = inputStream.read(buffer);
        System.out.println("Received message: " + new String(buffer, 0, len));

        OutputStream outputStream = socket.getOutputStream();
        outputStream.write(buffer, 0, len);
        outputStream.flush();

        System.out.println("EchoServer stopped.");
        socket.close();
        serverSocket.close();
    }
}

// EchoClient.java
public class EchoClient {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket("localhost", 8888);

        OutputStream outputStream = socket.getOutputStream();
        outputStream.write("Hello, EchoServer!".getBytes());
        outputStream.flush();
        System.out.println("Sent message: Hello, EchoServer!");

        InputStream inputStream = socket.getInputStream();
        byte[] buffer = new byte[1024];
        int len = inputStream.read(buffer);
        System.out.println("Received message: " + new String(buffer, 0, len));

        socket.close();
    }
}

运行服务器端程序后，控制台输出如下：

EchoServer started.
Accepted connection.
Received message: Hello, EchoServer!
EchoServer stopped.

运行客户端程序后，控制台输出如下：

Sent message: Hello, EchoServer!
Received message: Hello, EchoServer!

说明服务器端成功地回显了客户端发送的数据。