redis实现跨服务器session共享

古城微笑少年丶 2022-08-21 13:43 249阅读 0赞

一般我们在做服务器集群的时候，都会配置nginx反向代理服务器。但是问题来了，多个服务器之间的session怎么共享的呢？

我在这里用的是redis，实现思路：

1.自己定义一个sessionId生成策略，在session.setAttribute操作的时候，生成一个CSESSIONID并写回服务器；

2.定义filter拦截请求，扩展HttpServletRequest，代理session实现类，扩展setAttribute方法和getAttribute方法；

3.每次请求更新cookie的生命周期和redis中键的生命周期，我这里设置的是30分钟。

我的代码并不优雅，也没有进行扩展，下面贴出我的实现：

1.简单的redis实现:

实际开发请与spring整合并配置连接池

package com.tanlei.utils;
    
    import java.util.UUID;
    
    import javax.servlet.http.Cookie;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class CookieUtil {
    
    	/** 设置session的过期时间*/
    	public static Integer KEY_EXPIRE_TIME = 30 * 60;
    
    	/**
    	 * 获取JessionId
    	 * @param request
    	 * @return
    	 */
    	public static String getJsessionId(HttpServletRequest request) {
    		Cookie[] cookies = request.getCookies();
    		// 从Cookie数据中遍历查找 并取CSESSIONID
    		if (null != cookies && cookies.length > 0) {
    			for (Cookie cookie : cookies) {
    				if ("CSESSIONID".equals(cookie.getName())) {
    					// 有 直接返回
    					return cookie.getValue();
    				}
    			}
    		}
    		return null;
    	}
    
    	public static String addCookie(HttpServletRequest request, HttpServletResponse response, Integer KEY_EXPIRE_TIME) {
    		String csessionId = getJsessionId(request);
    		if (csessionId == null || "".equals(csessionId)) {
    			csessionId = UUID.randomUUID().toString().replaceAll("-", "").toUpperCase();
    		}
    		Cookie cookie = new Cookie("CSESSIONID", csessionId);
    		cookie.setPath("/");
    		cookie.setMaxAge(KEY_EXPIRE_TIME);
    		response.addCookie(cookie);
    		return csessionId;
    	}
    }

package com.tanlei.utils;
    
    import redis.clients.jedis.Jedis;
    
    public class JedisProvider {  
    	  
        private static Jedis jedis;  
        public static Jedis getJedis() {  
            jedis = new Jedis("127.0.0.1", 6379);  
            return jedis;  
        }  
    
    }

package com.tanlei.filter;
    
    import java.io.IOException;
    import java.lang.reflect.InvocationHandler;
    import java.lang.reflect.Method;
    import java.lang.reflect.Proxy;
    import javax.servlet.Filter;
    import javax.servlet.FilterChain;
    import javax.servlet.FilterConfig;
    import javax.servlet.ServletException;
    import javax.servlet.ServletRequest;
    import javax.servlet.ServletResponse;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletRequestWrapper;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    import com.tanlei.bean.SerializeUtil;
    import com.tanlei.utils.CookieUtil;
    import com.tanlei.utils.JedisProvider;
    
    import redis.clients.jedis.Jedis;
    
    public class SessionFilter implements Filter {
    
    	private Jedis jedis = JedisProvider.getJedis();
    
    	public void init(FilterConfig filterConfig) throws ServletException {
    
    	}
    
    	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
    			throws IOException, ServletException {
    		// 当session不为空的时候，要刷新cookie存活周期和redis中键的存活日期
    		String csessionId = CookieUtil.getJsessionId((HttpServletRequest) request);
    		if (csessionId != null && !"".equals(csessionId)) {
    			jedis.expire(csessionId.getBytes(), CookieUtil.KEY_EXPIRE_TIME);
    			CookieUtil.addCookie((HttpServletRequest) request, (HttpServletResponse) response,
    					CookieUtil.KEY_EXPIRE_TIME);
    		}
    		chain.doFilter(new RemoteSessionRequest((HttpServletRequest) request, (HttpServletResponse) response),
    				response);
    	}
    
    	public void destroy() {
    
    	}
    
    }
    
    class RemoteSessionRequest extends HttpServletRequestWrapper {
    	private HttpServletRequest request;
    	private HttpServletResponse response;
    
    	public RemoteSessionRequest(HttpServletRequest request, HttpServletResponse response) {
    		super(request);
    		this.request = request;
    		this.response = response;
    	}
    
    	@Override
    	public HttpSession getSession() {
    		return RemoteSessionHandler.getInstance(super.getSession(), request, response);
    	}
    
    }
    
    class RemoteSessionHandler implements InvocationHandler {
    	private Jedis jedis = JedisProvider.getJedis();
    
    	private HttpSession session = null;
    	private HttpServletRequest request = null;
    	private HttpServletResponse response = null;
    
    	private RemoteSessionHandler(HttpSession httpSession, HttpServletRequest request, HttpServletResponse response) {
    		this.session = httpSession;
    		this.request = request;
    		this.response = response;
    	};
    
    	public static HttpSession getInstance(HttpSession httpSession, HttpServletRequest request,
    			HttpServletResponse response) {
    		InvocationHandler handler = new RemoteSessionHandler(httpSession, request, response);
    		return (HttpSession) Proxy.newProxyInstance(httpSession.getClass().getClassLoader(),
    				httpSession.getClass().getInterfaces(), handler);
    	}
    
    	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    		if ("setAttribute".equals(method.getName())) {
    			String csessionId = CookieUtil.getJsessionId(request);
    			if (csessionId == null || "".equals(csessionId)) {
    				csessionId = CookieUtil.addCookie(request, response, CookieUtil.KEY_EXPIRE_TIME);
    				request.setAttribute("csessionId", csessionId); //1.ask:为什么这里会在request域里面set一次?因为session的一次连续的setAttribute和getAttribute，cookie的值并没有写入，会取不到
    				String keyStr = args[0].toString();
    				Object obj = args[1]; //获取对象
    				jedis.hset(csessionId.getBytes(), keyStr.getBytes(), SerializeUtil.serialize(obj)); //向jedis写入对象
    			}
    		} else if ("getAttribute".equals(method.getName())) {
    			String csessionId = CookieUtil.getJsessionId(request);
    			if("".equals(csessionId) || null == csessionId) { //1.answer:所以这里在cookie中取不到的时候，再从request域里面取
    				csessionId = (String) request.getAttribute("csessionId");
    			}
    			if("".equals(csessionId) || null == csessionId) { //为什么需要双次判断，这是因为在第三方jar包或servlet or jsp包中默认有些试用session的情况
    				return null;
    			}
    			String keyStr = args[0].toString();
    			byte[] bytes = jedis.hget(csessionId.getBytes(), keyStr.getBytes()); //从jedis取出二进制对象
    			Object obj = SerializeUtil.unserialize(bytes);
    			return obj; //反系列化
    		} //按需求覆盖其他session的方法
    		return method.invoke(session, args);
    	}
    }

package com.tanlei.controller;
    
    import java.io.IOException;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    
    import com.tanlei.bean.User;
    
    
    public class SessionSetServlet extends HttpServlet {
    	private static final long serialVersionUID = 1L;
    
        public SessionSetServlet() {
        }
    
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            HttpSession session= request.getSession();  
            System.out.println("xxxxxxxxxxxxxxxxxxxx");
            session.setAttribute("user", new User(1, "ttttttttt66666666"));  //session中放入值
            request.getRequestDispatcher("index.jsp").forward(request, response);  
    	}
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		doGet(request, response);
    	}
    
    }

package com.tanlei.bean;
    
    import java.io.Serializable;
    
    /**
     * 我这里要求所有的对象必须实现系列化接口，也是一个弊端
     * @author t6
     *
     */
    public class User implements Serializable{
    
    	private Integer id;
    	private String userName;
    
    	public Integer getId() {
    		return id;
    	}
    
    	public void setId(Integer id) {
    		this.id = id;
    	}
    
    	public String getUserName() {
    		return userName;
    	}
    
    	public User(Integer id, String userName) {
    		super();
    		this.id = id;
    		this.userName = userName;
    	}
    
    	public void setUserName(String userName) {
    		this.userName = userName;
    	}
    
    }

package com.tanlei.bean;
    
    import java.io.ByteArrayInputStream;
    import java.io.ByteArrayOutputStream;
    import java.io.ObjectInputStream;
    import java.io.ObjectOutputStream;
    
    public class SerializeUtil {
    	public static byte[] serialize(Object object) {
    		ObjectOutputStream oos = null;
    		ByteArrayOutputStream baos = null;
    		try {
    			// 序列化
    			baos = new ByteArrayOutputStream();
    			oos = new ObjectOutputStream(baos);
    			oos.writeObject(object);
    			byte[] bytes = baos.toByteArray();
    			return bytes;
    		} catch (Exception e) {
    
    		}
    		return null;
    	}
    
    	public static Object unserialize(byte[] bytes) {
    		ByteArrayInputStream bais = null;
    		try {
    			// 反序列化
    			bais = new ByteArrayInputStream(bytes);
    			ObjectInputStream ois = new ObjectInputStream(bais);
    			return ois.readObject();
    		} catch (Exception e) {
    
    		}
    		return null;
    	}
    	
    	public static void main(String[] args) {
    		byte[] b = serialize("xxxxxxxxx");
    		System.out.println(unserialize(b));
    	}
    }

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    	<groupId>com.tanlei</groupId>
    	<artifactId>testsession1</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<packaging>war</packaging>
    	<name>testsession1</name>
    	<description>测试session</description>
    	<dependencies>
    		<dependency>
    			<groupId>javax.servlet</groupId>
    			<artifactId>servlet-api</artifactId>
    			<version>2.5</version>
    			<scope>provided</scope>
    		</dependency>
    		<dependency>
    			<groupId>javax.servlet.jsp</groupId>
    			<artifactId>jsp-api</artifactId>
    			<version>2.1</version>
    			<scope>provided</scope>
    		</dependency>
    		<dependency>
    			<groupId>redis.clients</groupId>
    			<artifactId>jedis</artifactId>
    			<version>2.7.2</version>
    		</dependency>
    		<dependency>
    			<groupId>commons-logging</groupId>
    			<artifactId>commons-logging</artifactId>
    			<version>1.1.3</version>
    		</dependency>
    	</dependencies>
    </project>