JAVA 实现TCP请求转发

背景：前端时间做了关于区块链项目，需要遍历区块，由于有端口限制，故不能直接访问，于是就写下了这个转发工具。 Nginx 同样能完成此项工作，但我选择了JAVA。

ForwardMsg 类为转发实体信息

import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.URLDecoder;
import java.net.UnknownHostException;
import java.util.HashMap;
import java.util.Map;
import java.util.Vector;
import java.util.regex.Matcher;
import java.util.regex.Pattern;/*** @Computer XYSM* @Program: cmd* @Package: com.hsy.cmd* @Description* @Author System* @CreateTime 2021-01-19 09:50* @Version 1.0.0*/
public class Forward {public static void main(String[] args) {ForwardMsg cmd  = new ForwardMsg(10253, 36253, "127.0.0.1", "CMD 客户端");new Thread(() -> new Forward().accept(cmd)).start();new Thread(() -> new MessageListener().listening()).start();}/** 转发实例 */private ForwardMsg msg;private void accept(ForwardMsg forwardMsg){try {System.out.println(forwardMsg.toString());this.msg = forwardMsg;ServerSocket server = new ServerSocket(forwardMsg.localPort);while (true){Socket socket;try{socket = server.accept();long ts = System.currentTimeMillis();for (Connect c : MessageListener.vector) {if (ts - c.timestamp > 30000){close(c);}else {break;}}MessageListener.vector.add(new Connect(socket, this.msg));}catch(Exception e){e.printStackTrace();}}} catch (IOException e) {}}public static void close(Closeable  ... closeables){for (Closeable closeable : closeables) {try{closeable.close();}catch(Exception e){}}}}class MessageListener{public MessageListener() {super();}public static volatile Vector<Connect> vector = new Vector<Connect>();public void listening(){System.out.println("消息队列工作中。。。。");while (true){if (vector.size() == 0){continue;}Connect pack = vector.remove(0);new Thread(()->{try{System.out.println(pack.toString());/* 转发请求流 */this.forwardStream(pack);/* 转发响应流 */this.transferTo(pack.target, pack.source);}catch(Exception e){e.printStackTrace();}finally {Forward.close(pack);}}).start();}}public void transferTo(Socket source, Socket target){try{byte[] buffer = new byte[512];int read;InputStream  is = source.getInputStream();OutputStream os = target.getOutputStream();while ((read = is.read(buffer)) >= 0) {os.write(buffer, 0, read);if (read < buffer.length){break;}}}catch(Exception e){}}private void forwardStream(Connect connect){try{/* 读取头部 */HttpReader httpReader = new HttpReader(connect.source);if (connect.target == null){httpReader.setConnect(connect);}else {httpReader.setTargetHost(connect.target.getRemoteSocketAddress().toString().substring(1));}/* 解析body */httpReader.parseBody();/* 转发报文 */connect.target.getOutputStream().write(httpReader.getSource().getBytes());}catch(Exception e){e.printStackTrace();System.out.println("write error");}}
}class Connect implements Closeable{public  long  timestamp;public Socket source;public Socket target;public Connect(Socket source, ForwardMsg msg) throws IOException {this.timestamp  = System.currentTimeMillis();this.source     = source;this.target     = msg.targetUri == null ? null : new Socket(msg.targetUri, msg.targetPort);}@Overridepublic void close() throws IOException {if (this.target != null){this.target.close();}if (this.source != null){this.source.close();}}@Overridepublic String toString() {return "请求转发: " + source.toString() + " --> " + (target == null ? "请求指定" : target.toString());}
}class ForwardMsg{public int localPort;public int targetPort;public String targetUri;public String title;public ForwardMsg(int localPort, int targetPort, String targetUri) {this.localPort  = localPort;this.targetPort = targetPort;this.targetUri  = targetUri;}public ForwardMsg(int localPort, int targetPort, String targetUri, String title) {this.localPort  = localPort;this.targetPort = targetPort;this.targetUri  = targetUri;this.title      = title;}@Overridepublic String toString() {return this.title + ":  " + this.localPort + " -> [" + this.targetUri + ":" + this.targetPort + ']';}
}class HttpReader{private static final char   SPACE = ' ';private static final String BLANK = "";private static final String CONTENT_LENGTH = "content-length";private static final String NEW_LINE = "\r\n";private static final String HEAD_SEPARATOR = ": ";/** 原始字符串 */private StringBuilder source = new StringBuilder(512);/** 请求头部 */private Map<String,Object> hearders = new HashMap<>(10);/** 请求参数 */private StringBuilder body = new StringBuilder();/** 请求输入流 */private BufferedReader reader;/** 已读取数据长度 */private int readLength = 0;/** 请求方式 */private String method;/** URI */private String uri;/** 版本 */private String version;/** URL中的目标地址 */private Connect connect;/** target host */private String targetHost;public HttpReader(InputStream inputStream) {this.reader = new BufferedReader(new InputStreamReader(inputStream));}public HttpReader(Socket socket) throws IOException {this(socket.getInputStream());}private String readLine() {try {String line = this.reader.readLine();if (line == null){return BLANK;}this.source.append(line).append(NEW_LINE);this.readLength += line.getBytes().length + 2;return line;} catch (IOException e) {throw new RuntimeException("HTTP parse error");}}public static final Pattern ISSUED_DATA  = Pattern.compile("issuedUri=[^&]+");private void parseProtocol(){String line = null;while (line == null){line = this.readLine();}int size = line.length(), i = -1, lastBeginIndex = 0, time = 0;String value;while (++ i < size){if (line.charAt(i) == SPACE) {value = line.substring(lastBeginIndex, i);lastBeginIndex = i + 1;if (time == 0){time ++;this.method = value;}else if (time == 1){this.uri = value;this.version = line.substring(lastBeginIndex);}}}/* 从请求端读取目标地址 */if (this.connect != null){Matcher matcher = ISSUED_DATA.matcher(this.uri);if (matcher.find()) {try {String sourceUri = matcher.group(0);this.uri = this.uri.replace(sourceUri, BLANK);if (this.uri.charAt(this.uri.length() - 1) == '?'){this.uri = this.uri.substring(0, this.uri.length() - 1);}String ip;int port;String uri = URLDecoder.decode(sourceUri.substring(10), "utf-8");int index;if ((index = uri.indexOf(":")) > -1 && index < uri.length()){ip = uri.substring(0, index);port = Integer.parseInt(uri.substring(index + 1));this.targetHost = ip + ':' + port;}else {port = 80;ip = uri;this.targetHost = ip;}this.connect.target = new Socket(ip, port);this.source.delete(0, this.source.length()).append(this.method + " " + this.uri + " " +this.version + NEW_LINE);} catch (UnsupportedEncodingException e) {e.printStackTrace();} catch (UnknownHostException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}}}private int parseHearders(){String line;int index;while (true){line = this.readLine();index = line.indexOf(HEAD_SEPARATOR);if (index > -1){String key      = line.substring(0, index).toLowerCase(), value    = line.substring(index + 2);if (key.equals("host")){int start = this.source.indexOf(value);this.source.replace(start, start + value.length(), this.targetHost);}this.hearders.put(key, value);}if (line.length() == 0){break;}}return this.hearders.size();}/*** PC* @title       content-type 长度，为字节长度， 注意* @description* @params*    @param* @since        - 2021/3/15 11:53* @throws* @return      Result<>** * * * * T * I * M * E * * * * ** 创建及修改内容* @author      KB* @createTime  2021/3/15 11:53* @editor      KB* @updateDesc  原著* @updateTime  2021/3/15 11:53*/public int parseBody(){this.parseProtocol();this.parseHearders();Object l = this.hearders.get(CONTENT_LENGTH);int readSize = 0, contentSize = l == null ? 0 : Integer.parseInt(l.toString());if (contentSize == 0){return 0;}char[] c = new char[contentSize % 512 + 1];int length;try{while ((length = this.reader.read(c)) > -1){body.append(c, 0, length);source.append(c, 0, length);readSize += length;//todo 中文字符长度 ！= 字节长度， 因为是char数组，若统计，相对麻烦， 可以使用 new String(c, 0, length).getBytes().length()this.readLength += length;if (readSize >= contentSize || length < c.length){break;}}}catch(Exception e){e.printStackTrace();}return readSize;}public String getSource() {return source.toString();}public int getBodyByteSize() {return Integer.parseInt(this.hearders.get(CONTENT_LENGTH).toString());}public BufferedReader getReader() {return reader;}public int getReadLength() {return readLength;}public void setConnect(Connect connect) {this.connect = connect;}public void setTargetHost(String targetHost) {this.targetHost = targetHost;}
}

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