Java Socket 类

2025年3月24日 | 阅读 6 分钟

Socket 类充当两台机器之间通信的端点。它实现了客户端套接字。

方法

方法	描述
bind(SocketAddress bindpoint)	此方法将给定的套接字绑定到指定的本地地址。
close()	此方法关闭套接字。
connect(SocketAddress endpoint) connect(SocketAddress endpoint, int timeout)	connect() 方法将此套接字连接到服务器。此方法以指定的超时值将此套接字连接到服务器。
getChannel()	它返回与此套接字关联的唯一 SocketChannel 对象。
getInetAddress()	它返回套接字连接到的地址。
getInputStream()	它返回指定套接字的输入流。
getKeepAlive()	此方法测试 SO_KEEPALIVE 选项是否已启用。
getLocalAddress()	它返回给定套接字所绑定的本地地址。
getLocalPort()	它获取指定套接字所绑定的本地端口号。
getLocalSocketAddress()	此方法获取此套接字所绑定的端点的地址。
getOOBInline()	此方法测试 SO_OOBINLINE 选项是否已启用。
getOutputStream()	此方法返回指定套接字的输出流。
getPort()	此方法返回套接字连接到的远程端口号。
getReceiveBufferSize()	它返回此 Socket 的 SO_RCVBUF 选项的值。
getRemoteSocketAddress()	此方法返回此套接字连接到的端点的地址，如果套接字未连接，则返回 null。
getReuseAddress()	它测试 SO_REUSEADDR 选项是否已启用。
getSendBufferSize()	此方法获取此 Socket 的 SO_SNDBUF 选项的值。
getSoLinger()	此方法返回 SO_LINGER 选项的设置。
getSoTimeout()	如果 SO_TIMEOUT 选项已启用，则返回其设置；否则，如果选项已禁用，则返回 0。
getTcpNoDelay()	此方法测试 TCP_NODELAY 选项是否已启用。
getTrafficClass()	此方法返回从此 Socket 发送的 IP 数据包的流量类别或服务类型。
isBound()	它返回此套接字的绑定状态。
isClosed()	此方法返回此套接字的关闭状态。
isConnected()	此方法返回套接字的连接状态。
isInputShutdown()	它返回套接字连接的读取部分是否已关闭。
isOutputShutdown()	它返回套接字连接的写入部分是否已关闭。
sendUrgentData(int data)	此方法将一个紧急数据字节发送到套接字。
setKeepAlive(boolean on)	此方法为此套接字启用或禁用 SO_KEEPALIVE 选项。
setOOBInline(boolean on)	此方法为此套接字启用或禁用 SO_OOBINLINE 选项。
setReceiveBufferSize(int size)	此方法将此 Socket 的 SO_RCVBUF 选项设置为指定值。
setReuseAddress(boolean on)	此方法为此套接字启用或禁用 SO_REUSEADDR 套接字选项。
setSendBufferSize(int size)	此方法将此 Socket 的 SO_SNDBUF 选项设置为指定值。
setSoLinger(boolean on, int linger)	它以指定的秒为单位启用或禁用 SO_LINGER 选项。
setSoTimeout(int timeout)	此方法以指定的毫秒数启用或禁用 SO_TIMEOUT 选项。
setTcpNoDelay(boolean on)	此方法为此套接字启用或禁用 TCP_NODELAY 选项。
setTrafficClass(int tc)	它返回从此 Socket 发送的 IP 数据包的流量类别或服务类型字节。
shutdownInput()	此方法将此套接字的输入流置于流的末尾。
shutdownOutput()	此方法禁用此套接字的输出流。
toString()	此方法将此套接字转换为 String。

示例 1

import java.io.IOException;
import java.net.*;
public class JavaSocketExample1  {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket();
        InetAddress inetAddress=InetAddress.getByName("localhost");
        //the port should be greater or equal to 0, else it will throw an error
        int port=1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //binding the  socket with the inetAddress and port number
        socket.bind(socketAddress);
        //connect() method connects the specified socket to the server
        socket.connect(socketAddress);
        //setSendBufferSize() sets the send buffer size or SO_SNDBUF option with the specified value
        socket.setSendBufferSize(67);
        //getSendBufferSize() method returns the buffer size(SO_SNDBUF) used by the platform for output
        System.out.println("Send Buffer size: "+socket.getSendBufferSize());
        //enabling the boolean value true
        boolean on=false;
        //setKeepAlive() method either enables or disables the SO_KEEPALIVE option
        socket.setKeepAlive(on);
        //getKeepAlive() returns  a boolean indicating whether SO_KEEPALIVE option is enabled or not
        if(socket.getKeepAlive()){
            System.out.println("SO_KEEPALIVE option is enabled");
        }
        else{
            System.out.println("SO_KEEPALIVE option is disabled");
        }
        //getRemoteSocketAddress() returns the address of the endpoint of the specified socket if the socket is connected
        System.out.println("Remote socket address: "+socket.getRemoteSocketAddress());
    }
 }

输出

Send Buffer size: 67
SO_KEEPALIVE option is disabled
Remote socket address: localhost/127.0.0.1:1085

示例 2

import java.io.IOException;
import java.net.*;
public class JavaSocketExample2  {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket();
        InetAddress inetAddress=InetAddress.getByName("localhost");
        //the port should be greater or equal to 0, else it will throw an error
        int port=1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //binding the  socket with the inetAddress and port number
        socket.bind(socketAddress);
        //connect() method connects the specified socket to the server
        socket.connect(socketAddress);
        //enabling the SO_LINGER option
        boolean on=true;
        //setting the integer value for timeout
        int timeout=90;
        socket.setSoLinger(on,timeout);
        //getSoLinger() method returns the setting if the SO_Linger option is set
        System.out.println("Send Buffer size: "+socket.getSoLinger());
        //integer timeout value
        socket.setSoTimeout(timeout);
        //getSoTimeout() method returns the setting for SO_TIMEOUT option
        System.out.println("Timeout value: "+socket.getSoTimeout());
        //setTcpNoDelay() method enables or disables the SO_TIMEOUT option
        socket.setTcpNoDelay(on);
        //getTcpNoDelay() returns the setting for SO_TIMEOUT option
        System.out.println("SO_TIMEOUT option is enabled: "+socket.getTcpNoDelay());
        //setKeepAlive() method either enables or disables the SO_KEEPALIVE option
        socket.setKeepAlive(on);
        //getKeepAlive() returns  a boolean indicating whether SO_KEEPALIVE option is enabled or not
        System.out.println("SO_KEEPALIVE is enabled: "+socket.getKeepAlive());
        //getLocalSocketAddress() returns the address of the endpoint to which this socket is bound
        System.out.println("Local socket address: "+socket.getLocalSocketAddress());
    }
 }

输出

Send Buffer size: 90
Timeout value: 90
SO_TIMEOUT option is enabled: true
SO_KEEPALIVE is enabled: true
Local socket address: /127.0.0.1:1085

示例 3

import java.io.IOException;
import java.net.*;
public class JavaSocketExample3  {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket();
        InetAddress inetAddress=InetAddress.getByName("localhost");
        //the port should be greater or equal to 0, else it will throw an error
        int port=1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //binding the  socket with the inetAddress and port number
        socket.bind(socketAddress);
        //connect() method connects the specified socket to the server
        socket.connect(socketAddress);
        //The getInetAddress() returns the Inet Address for this socket
        System.out.println("Inet address: "+socket.getInetAddress());
        //setting the buffer size with the help of setReceiveBufferSize() method
        socket.setReceiveBufferSize(10);
        //getReceiveBufferSize() method returns the buffer size for this socket
        System.out.println("Buffer size: "+socket.getReceiveBufferSize());
        //setReuseAddress() method enables or disables the SO_REUSEADDR option
        socket.setReuseAddress(true);
        //getReuseAddress() method returns boolean value 'true' if SO_REUSEADDR option is enabled else it return false
        System.out.println("SO_REUSEADDR option is enabled: "+socket.getReuseAddress());
        //closing the socket will have no effect it will continue to return the same binding state
        socket.close();
        //isClosed() method returns whether the socket is closed or not
        System.out.println("The socket is closed: "+socket.isClosed());
        //The toString() method returns the string representation for the given socket.
        socket.toString();
        //it will return the connecting port and binding address
        System.out.println(socket);
    }
 }

输出

Inet address: localhost/127.0.0.1
Buffer size: 10
SO_REUSEADDR option is enabled: true
The socket is closed: true
Socket[addr=localhost/127.0.0.1,port=1085,localport=1085]

示例 4

import java.io.DataOutputStream;
import java.io.IOException;
import java.net.*;
public class JavaSocketExample4  {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket();
        InetAddress inetAddress=InetAddress.getByName("localhost");
        //the port should be greater or equal to 0, else it will throw an error
        int port=1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //binding the  socket with the inetAddress and port number
        socket.bind(socketAddress);
        //connect() method connects the specified socket to the server
        socket.connect(socketAddress);
        //The isConnected() method returns the connected state for this socket
        System.out.println("The socket is connected: "+socket.isConnected());
        //The isBound() states whether this socket is bounded or not
        System.out.println("The socket is binded: "+socket.isBound());
        //The getLocalPort() method returns the port number for this socket.
        System.out.println("Local Port: "+socket.getLocalPort());
        //getOutputStream() returns an output stream for writing bytes to this socket.
        DataOutputStream  outputStream=new DataOutputStream(socket.getOutputStream());
        System.out.println("Output Stream: "+outputStream);
    }
 }

输出

The socket is connected: true
The socket is binded: true
Local Port: 1085
Output Stream: java.io.DataOutputStream@1540e19d

下一主题Java Socket 类

Java Socket 类

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示例 2

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