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);
}
@Override
public void close() throws IOException {
if (this.target != null){
this.target.close();
}
if (this.source != null){
this.source.close();
}
}
@Override
public 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;
}
@Override
public 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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