通过Java实现反向代理集群服务的平滑分配_Java教程

1.理解全过程

1.1.概述

需要具备的知识

Socket网络编程
反向代理的理解
平滑加权轮询算法的理解
线程池的理解

目的：实现Socket 集群服务的平滑加权轮询负载。

业务实现：客户端通过用户名来查询集群服务中的用户信息。

1.2.整个流程

客户端发起Socket请求给反向代理的Socket服务（客户端并不知道服务端是反向代理服务器）
反向代理服务器接收到Socket服务请求
线程池开启服务线程去处理请求
线程服务通过平滑加权轮询算法寻找当前权重最高的下游服务
通过负载均衡算法返回的服务节点信息来创建Socket请求
反向代理服务器使用客户端信息，发起Socket请求给下游服务
Socket集群服务节点收到Socket请求，查询用户信息，再将处理结果返回给反向代理服务器
反向代理服务器再将结果返回给客户端。

通过Java实现反向代理集群服务的平滑分配

几个细节点

使用反向代理服务，对客户端无感，客户端并不知道具体访问了哪个真实服务器；
反向代理服务器每次访问下游服务失败时，就会降低该下游服务器器的有效权重；每次访问下游服务成功时，就会提高该下游服务器的有效权重（不超过配置的权重值）；
平滑加权轮询算法会对宕机服务降权和提权，起到”剔除“宕机服务和缓冲恢复宕机服务的效果；
反向代理服务器重启后，所有配置恢复为配置参数；
反向代理服务器使用线程池发布Socket服务，支持多个客户端同时请求同时分发。

2.代码实现

2.1.节点类

用于保存服务节点相关信息

package com.yty.proxy.lba;


public class Node implements Comparable<Node>{
    private String ip;
    private Integer port;
    private final Integer weight;
    private Integer effectiveWeight;
    private Integer currentWeight;
    // 默认权重为：1
    public Node(String ip,Integer port){
        this(ip,port,1);
    }

    public Node(String ip,Integer port, Integer weight){
        this.ip = ip;
        this.port = port;
        this.weight = weight;
        this.effectiveWeight = weight;
        this.currentWeight = weight;
    }

    public String getIp() {
        return ip;
    }

    public void setIp(String ip) {
        this.ip = ip;
    }

    public Integer getPort() {
        return port;
    }

    public void setPort(Integer port) {
        this.port = port;
    }

    public Integer getWeight() {
        return weight;
    }

    public Integer getEffectiveWeight() {
        return effectiveWeight;
    }

    public void setEffectiveWeight(Integer effectiveWeight) {
        this.effectiveWeight = effectiveWeight;
    }

    public Integer getCurrentWeight() {
        return currentWeight;
    }

    public void setCurrentWeight(Integer currentWeight) {
        this.currentWeight = currentWeight;
    }
    // 每成功一次，恢复有效权重1，不超过配置的起始权重
    public void onInvokeSuccess(){
        if(effectiveWeight < weight) effectiveWeight++;
    }
    // 每失败一次，有效权重减少1，无底线的减少
    public void onInvokeFault(){
        effectiveWeight--;
    }

    @Override
    public int compareTo(Node node) {
        return currentWeight > node.currentWeight ? 1 : (currentWeight.equals(node.currentWeight) ? 0 : -1);
    }

    @Override
    public String toString() {
        return "Node{" +
                "ip="" + ip + """ +
                ", port=" + port +
                ", weight=" + weight +
                ", effectiveWeight=" + effectiveWeight +
                ", currentWeight=" + currentWeight +
                "}";
    }
}

2.2.代理配置类

一般都是放在配置文件中配置，然后读取指定key的配置文件信息来完成配置。模拟为了简单就直接写代码里了。

package com.yty.proxy;

import com.yty.proxy.lba.Node;

import java.util.ArrayList;
import java.util.List;

public class ProxyConfig {

    private static List<Node> nodes = new ArrayList<>();
    // 在配置文件中读取：节点集合信息。如果在同一台服务器测试，那就将ip配成一样
    static {
        nodes.add(new Node("192.168.233.100",8001,2));
        nodes.add(new Node("127.0.0.1",8002,5));
        nodes.add(new Node("127.0.0.1",8003,3));
    }
    public static List<Node> getProxyConfig(){
        return nodes;
    }
}

2.3.负载均衡算法接口

package com.yty.proxy.lba;

public interface Robin {

    Node selectNode();
}

2.4.平滑加权轮询算法

详细介绍可以阅读前两篇负载均衡算法的文章

package com.yty.proxy.lba;

import com.yty.proxy.ProxyConfig;
import java.util.List;

/**
 * 加权轮询算法：平滑加权轮询算法
 */
public class WeightedRoundRobin implements Robin {

    private static List<Node> nodes;
    // 读取配置信息
    static {
        nodes = ProxyConfig.getProxyConfig();
    }
    /**
     * 按照当前权重（currentWeight）最大值获取IP
     * @return Node
     */
    public Node selectNode(){
        if (nodes ==null || nodes.size()<=0) return null;
        if (nodes.size() == 1)  return nodes.get(0);

        // 权重之和
        Integer totalWeight = 0;
        for(Node node : nodes){
            totalWeight += node.getEffectiveWeight();
        }

        synchronized (nodes){
            // 选出当前权重最大的节点
            Node nodeOfMaxWeight = null;
            for (Node node : nodes) {
                if (nodeOfMaxWeight == null)
                    nodeOfMaxWeight = node;
                else
                    nodeOfMaxWeight = nodeOfMaxWeight.compareTo(node) > 0 ? nodeOfMaxWeight : node;
            }
            // 平滑负载均衡
            nodeOfMaxWeight.setCurrentWeight(nodeOfMaxWeight.getCurrentWeight() - totalWeight);
            nodes.forEach(node -> node.setCurrentWeight(node.getCurrentWeight()+node.getEffectiveWeight()));
            return nodeOfMaxWeight;
        }
    }

}

2.5.代理服务线程类

用于处理代理服务请求的线程类，不同请求创建不同线程来处理

package com.yty.proxy;

import java.io.*;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class ProxyServerThread implements Runnable {
    private Socket proxySocket;
    private OutputStream proxyOut;
    private InputStream proxyIn;
    private Socket socket;
    private OutputStream serverOut;
    private InputStream serverIn;
    public ProxyServerThread(Socket proxySocket) throws IOException {
        this.proxySocket = proxySocket;
        this.proxySocket.setSoTimeout(6000);
        this.proxyOut = proxySocket.getOutputStream();
        this.proxyIn = proxySocket.getInputStream();
    }

    @Override
    public void run() {
        try {
            this.proxyService();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            this.close();
        }
    }

    private void proxyService() throws IOException {
        // 代理接收客户端请求
        byte[] proxyDataBytes =null;
        proxyDataBytes = getData(proxyIn);
        System.out.println("代理收到请求数据："+new String(proxyDataBytes));
        if (proxyDataBytes == null){
            proxyOut.write("请求内容异常".getBytes());
        }

        byte[] serverData = this.dispatcherService(proxyDataBytes);

        // 代理响应客户端
        assert serverData != null;
        proxyOut.write(serverData);
        proxySocket.shutdownOutput();
        System.out.println("代理响应客户端数据："+new String(proxyDataBytes));
    }

    private byte[] dispatcherService(byte[] proxyDataBytes){
        // 选择节点：发送请求和接收响应信息
        Robin wrr = new WeightedRoundRobin();
        Node node = wrr.selectNode();
        byte[] serverData = null;
        try {
            this.socket = new Socket(node.getIp(), node.getPort());
            socket.setSoTimeout(6000);
            serverIn = socket.getInputStream();
            serverOut= socket.getOutputStream();
            serverOut.write(proxyDataBytes);
            socket.shutdownOutput();
            serverData = getData(serverIn);
            System.out.println("真实服务端响应数据："+ new String(serverData));
            node.onInvokeSuccess();//提权
        } catch (IOException e) {
            node.onInvokeFault();//降权
            serverData = "代理的下游服务器异常".getBytes();
        }
        System.out.println("负载均衡到：" + node);
        return serverData;
    }

    private byte[] getData(InputStream in) throws IOException {
        List<Byte> byteList = new ArrayList<>();
        int temp = -1;
        while (true) {
            temp = in.read();
            if (temp != -1)
                byteList.add((byte) temp);
            else
                break;
        }
        byte[] bytes = new byte[byteList.size()];
        for (int i=0;i<byteList.size();i++){
            bytes[i]=byteList.get(i);
        }
        return bytes;
    }

    private void close() {
        try {
            if (proxySocket!=null){
                proxySocket.shutdownInput();
                proxySocket.close();
            }
            if (socket!=null){
                socket.shutdownInput();
                socket.close();
            }
        }catch (IOException e){
            e.printStackTrace();
            System.out.println("代理服务关闭socket资源异常");
        }
    }
}

2.6.代理服务类

通过线程池来管理代理服务线程，不同的请求分发到不同线程处理。这里用的是newCachedThreadPool 线程池。

代理服务器在本地启动。这里也可以新建一个类来启动服务，这样可以启动多个代理服务，这里为了简单就直接在本类的main方法启动。可以对比后面的业务服务类，业务服务类就是这么起的，因为要放到不同的服务器启动业务服务。

package com.yty.proxy;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class ProxyServer {
    private final Integer port;
    private ServerSocket serverSocket;
    public ProxyServer(Integer port) {
        this.port = port;
    }

    public void start(){
        ExecutorService threadPool = Executors.newCachedThreadPool();
        try {
            serverSocket = new ServerSocket(port);
            while (true){
                Socket socket = serverSocket.accept();
                threadPool.execute(new ProxyServerThread(socket));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }


    public static void main(String[] args) {
        Integer proxyPort=8000;
        ProxyServer proxyServer = new ProxyServer(proxyPort);
        System.out.println("开启代理服务……");
        proxyServer.start();
    }
}

2.7.业务实体类

package com.yty.proxy.server;

public class MyUser {
    private String name;
    private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public MyUser(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public MyUser() {
    }

    @Override
    public String toString() {
        return "{" +"name="" + name + """ + ", age=" + age + "}";
    }
}

2.8.业务类

处理具体业务的类，通过用户名称简单获取信息

package com.yty.proxy.server;

import java.util.ArrayList;
import java.util.List;

public class MyUserService {
    private static List<MyUser> list = new ArrayList<>();

    static{
        list.add(new MyUser("张三",18));
        list.add(new MyUser("张三丰",38));
        list.add(new MyUser("小白",18));
    }
    public MyUser findByUsername(String username){
        for (MyUser user:list){
            if (user.getName().equals(username)){
                return user;
            }
        }
        return null;
    }
}

2.9.业务服务线程类

用于处理业务服务请求的线程类，不同请求创建不同线程来处理

package com.yty.proxy.server;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class SocketServerThread implements Runnable {
    private Socket socket;
    private OutputStream serverOut;
    private InputStream serverIn;
    public SocketServerThread(Socket socket) throws IOException {
        this.socket = socket;
        socket.setSoTimeout(6000);
        this.serverOut = socket.getOutputStream();
        this.serverIn = socket.getInputStream();
    }

    @Override
    public void run() {
        try {
            this.service();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            this.close();
        }
    }
    private void service() throws IOException {
        // 接收客户端请求
        byte[] dataBytes =null;
        dataBytes = getData(serverIn);
        if (dataBytes == null){
            serverOut.write("请求内容异常".getBytes());
        }
        String username = new String(dataBytes);
        System.out.println("收到请求数据："+username);

        // 具体业务代码
        MyUserService myUserService = new MyUserService();
        MyUser user = myUserService.findByUsername(new String(dataBytes));
        String serverData = "没有查询到用户" + username + "的数据";
        if(user!=null){
            serverData = user.toString();
            serverOut.write(user.toString().getBytes());
        }
        System.out.println("响应客户端数据：" + serverData);
    }

    private byte[] getData(InputStream in) throws IOException {
        List<Byte> byteList = new ArrayList<>();
        int temp = -1;
        while (true) {
            temp = in.read();
            if (temp != -1)
                byteList.add((byte) temp);
            else
                break;
        }
        byte[] bytes = new byte[byteList.size()];
        for (int i=0;i<byteList.size();i++){
            bytes[i]=byteList.get(i);
        }
        return bytes;
    }

    private void close() {
        try {
            if (socket!=null){
                socket.shutdownInput();
                socket.shutdownOutput();
                socket.close();
            }
        }catch (IOException e){
            e.printStackTrace();
            System.out.println("服务关闭socket资源异常");
        }
    }
}

2.10.业务服务类

通过线程池来管理业务服务线程，不同的请求分发到不同线程处理。这里用的也是newCachedThreadPool 线程池。

package com.yty.proxy.server;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class SocketServer {
    private final Integer port;
    private ServerSocket serverSocket;
    private Integer threads = 3;


    public SocketServer(Integer port) {
        this.port = port;
    }

    public void start(){
        ExecutorService threadPool = Executors.newFixedThreadPool(threads);
        try {
            serverSocket = new ServerSocket(port);
            while (true){
                Socket socket = serverSocket.accept();
                threadPool.execute(new SocketServerThread(socket));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

}

2.11.启动三个业务服务(服务集群)

本次测试是分在两台服务器测试，1台【192.168.233.100】、另外都是本地【127.0.0.1】。如果觉得麻烦，那就都配成本地【127.0.0.1】，然后起服务都在本地起。

服务1：在IP为192.168.233.100 的服务器启动

package com.yty.proxy.test;
import com.yty.proxy.server.SocketServer;
public class StartServer1 {
    public static void main(String[] args) {
        System.out.println("开启后端服务8001……");
        new SocketServer(8001).start();
    }
}

服务2：在本地服务器启动

package com.yty.proxy.test;
import com.yty.proxy.server.SocketServer;
public class StartServer2 {
    public static void main(String[] args) {
        System.out.println("开启后端服务8002……");
        new SocketServer(8002).start();
    }
}

服务3：在本地服务器启动

package com.yty.proxy.test;
import com.yty.proxy.server.SocketServer;
public class StartServer3 {
    public static void main(String[] args) {
        System.out.println("开启后端服务8003……");
        new SocketServer(8003).start();
    }
}

2.12.客户端

package com.yty.proxy.test;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class Client {
    public static void main(String[] args) throws IOException {
        String ip = "127.0.0.1";
        int port = 8000;
        Socket socket = new Socket(ip, port);
        socket.setSoTimeout(6000);
        OutputStream out = socket.getOutputStream();
        InputStream in = socket.getInputStream();
        // 发送数据
        out.write("小白".getBytes());
        out.flush();
        socket.shutdownOutput();
        // 读取数据
        byte[] data = new Client().getData(in);
        System.out.println("响应数据："+new String(data));
        out.close();
    }

    private byte[] getData(InputStream in) throws IOException {
        BufferedInputStream bin = new BufferedInputStream(in);
        List<Byte> byteList = new ArrayList<>();
        while (true) {
            int temp = bin.read();
            if (temp != -1)
                byteList.add((byte) temp);
            else
                break;
        }
        byte[] bytes = new byte[byteList.size()];
        for (int i=0;i<byteList.size();i++){
            bytes[i]=byteList.get(i);
        }
        return bytes;
    }
}