Java实现端口映射/转发
20190630 14：57更新
添加了一个功能 检查当前连接状态 同时发现清除超时连接忘了加定时器 现在清除超时连接可以正常工作了
1 import java.io.IOException;
2 import java.io.InputStream;
3 import java.io.OutputStream;
4 import java.net.ServerSocket;
5 import java.net.Socket;
6 import java.text.SimpleDateFormat;
7 import java.util.*;
8
9 public class SimpleForward implements Runnable {
10 // 服务器
11 private ServerSocket server;
12 // 监听本地端口
13 private int localPort = 1080;
14 // 目标主机地址
15 private String remoteHostAddr = "0.0.0.0";
16 // 目标主机端口
17 private int remoteHostPort = 8388;
18 // 设置超时时间 30s
19 private static int TIMEOUT = 30;
20 // 客户端列表 用于删除失效连接和超时连接
21 private static HashMap<Socket, Date> clientList = new HashMap<>();
22
23 public static void main(String[] args) throws IOException {
24 // new SimpleForward();
25 new SimpleForward(1234, "127.0.0.1", 1080);
26 }
27
28 public SimpleForward() throws IOException {
29 run();
30 }
31
32 public SimpleForward(int localPort, String remoteHostAddr, int remoteHostPort) throws IOException {
33 this.localPort = localPort;
34 this.remoteHostAddr = remoteHostAddr;
35 this.remoteHostPort = remoteHostPort;
36 run();
37 }
38
39 @Override
40 public void run() {
41 try {
42 this.server = new ServerSocket(this.localPort);
43 System.out.println("服务器开启成功");
44 System.out.println("监听端口 : " + this.localPort);
45 } catch (IOException e) {
46 System.out.println("服务器开启失败");
47 System.out.println(e.getMessage());
48 System.out.println("退出运行");
49 return;
50 }
51 // 自动清除失效连接和超时连接
52 new Thread(new Terminal()).start();
53 new Thread(new AutoDestroy()).start();
54 while (true) {
55 Socket socket = null;
56 Socket remoteHost = null;
57 try {
58 socket = server.accept();
59 // 接收到请求就把socket扔进map,value为刷新时间
60 clientList.put(socket, new Date());
61 String address = socket.getRemoteSocketAddress().toString();
62 System.out.println("新连接 ： " + address);
63 // 建立与目标主机的连接
64 remoteHost = new Socket(this.remoteHostAddr, this.remoteHostPort);
65 System.out.println("连接地址 : " + this.remoteHostAddr + ":" + this.remoteHostPort);
66 // 端口转发
67 new Thread(new Switch(socket, remoteHost, remoteHost.getInputStream(), socket.getOutputStream())).start();
68 new Thread(new Switch(socket, remoteHost, socket.getInputStream(), remoteHost.getOutputStream())).start();
69 } catch (IOException e) {
70 System.out.println("连接异常");
71 System.out.println(e.getMessage());
72 close(socket);
73 close(remoteHost);
74 }
75 }
76 }
77
78 private void close(Socket socket) {
79 try {
80 if (socket != null) {
81 socket.close();
82 }
83 } catch (IOException e) {
84 e.printStackTrace();
85 }
86 }
87
88 // 用于端口转发
89 private class Switch implements Runnable {
90 private Socket host;
91 private Socket remoteHost;
92 private InputStream in;
93 private OutputStream out;
94
95 Switch(Socket host, Socket remoteHost, InputStream in, OutputStream out) {
96 this.host = host;
97 this.remoteHost = remoteHost;
98 this.in = in;
99 this.out = out;
100 }
101
102 @Override
103 public void run() {
104 int length = 0;
105 byte[] buffer = new byte[1024];
106 try {
107 while (!host.isClosed() && (length = in.read(buffer)) > -1) {
108 clientList.put(host, new Date());
109 out.write(buffer, 0, length);
110 }
111 } catch (IOException e) {
112 System.out.println("连接关闭");
113 } finally {
114 close(host);
115 close(remoteHost);
116 }
117 }
118 }
119
120 // 用于清除失效连接和超时连接
121 private class AutoDestroy implements Runnable {
122
123 @Override
124 public void run() {
125 Timer timer = new Timer();
126 timer.schedule(new TimerTask() {
127 @Override
128 public void run() {
129 List<Socket> list = new LinkedList<>();
130 System.out.println("开始扫描失效与超时连接");
131 Date start = new Date();
132 for (Socket socket : clientList.keySet()) {
133 Date lastTime = clientList.get(socket);
134 long time = new Date().getTime() - lastTime.getTime();
135 if (socket.isClosed() || time / 1000 >= TIMEOUT) {
136 list.add(socket);
137 }
138 }
139 System.out.println("找到" + list.size() + "个,用时 : " + (new Date().getTime() - start.getTime()) + "毫秒");
140 System.out.println("开始清除失效与超时连接");
141 for (Socket socket : list) {
142 try {
143 clientList.remove(socket);
144 socket.close();
145 } catch (IOException e) {
146 e.printStackTrace();
147 }
148 }
149 System.out.println("当前连接数 : " + clientList.size());
150 }
151 }, 30 * 1000, 30 * 1000);
152 }
153 }
154
155 private class Terminal implements Runnable {
156 private ReaderUtil reader = new ReaderUtil();
157 private String format = "yyyy-MM-dd HH:mm:ss";
158 private SimpleDateFormat dateFormat = new SimpleDateFormat(format);
159
160 @Override
161 public void run() {
162 while (!server.isClosed()) {
163 System.out.print("请输入命令 : ");
164 String cmd = reader.readKB();
165 handler(cmd);
166 }
167 }
168
169 private void handler(String cmd) {
170 switch (cmd) {
171 case "status":
172 System.out.println("当前时间 : " + dateFormat.format(new Date()));
173 System.out.println("总连接数 : " + clientList.size());
174 for (Socket socket : clientList.keySet()) {
175 long time = new Date().getTime() - clientList.get(socket).getTime();
176 System.out.println("<" + socket.getRemoteSocketAddress().toString() + "> " + time / 1000);
177 }
178 break;
179 }
180 }
181 }
182 }ReaderUtil这个东西是我自己写的从键盘读一行的工具类 没啥东西 你们需要自己写
