在Spring中实现分布式 session管理
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本文主要是在Spring中实现分布式session，采用redis对session进行持久化管理，这样当应用部署的时候，不需要在Resin、Tomcat等容器里面进行分布式配置，方便加入新的节点服务器进行集群扩容，session不依赖各节点的服务器，可直接从redis获取。下面是功能的核心代码：
一、首先在web.xml里面配置
加入拦截器：
distributedSessionFilter
DistributedSessionFilter
key
xxxxxxxx
cacheBean
bean:redisPersistent//DistributedBaseInterFace，对应于此接口，进行session的持久化操作
cookieName
TESTSESSIONID
distributedSessionFilter
*.do
二、拦截器的实现，核心代码如下
主要有以下的几个类：
- DistributedSessionFilter，
- DistributedSessionManager，
- DistributedHttpSessionWrapper，
- DistributedHttpServletRequestWrapper
1、DistributedSessionFilter实现Filter：
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
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.HttpServletResponse;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
public class DistributedSessionFilter implements Filter {
private static final Logger log = LoggerFactory.getLogger(DistributedSessionFilter.class);
private String cookieName;
//主要是对session进行管理的操作
private DistributedSessionManager distributedSessionManager;
private String key;
}容器启动时候的初始化方法：
@Override
public void init(FilterConfig config) throws ServletException {
WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(config
.getServletContext());
String key = config.getInitParameter("key");
String cookieName = config.getInitParameter("cookieName");
String cacheBean = config.getInitParameter("cacheBean");
// 获取bean的名称，配置是"bean:"
String redisBeanStr = cacheBean.substring(5);
DistributedBaseInterFace distributedCache = (DistributedBaseInterFace) wac.getBean(redisBeanStr);
// 获取key，有2种配置方式,1对应为bean，格式为bean:key。2字符串
if (key.startsWith("bean:")) {
this.key = (String) wac.getBean(key.substring(5));
} else {
this.key = key;
}
this.cookieName = cookieName;
this.distributedSessionManager = DistributedSessionManager.getInstance(distributedCache);
//异常处理省略。。。
}进行实际的请求拦截：
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
throws ServletException, IOException {
DistributedHttpServletRequestWrapper distReq = null;
try {
//请求处理
distReq = createDistributedRequest(servletRequest, servletResponse);
filterChain.doFilter(distReq, servletResponse);
} catch (Throwable e) {
//省略。。。
} finally {
if (distReq != null) {
try {
//处理完成request后，处理session（主要是保存session会话）
dealSessionAfterRequest(distReq.getSession());
} catch (Throwable e2) {
//省略。。。
}
}
}
}
//分布式请求
private DistributedHttpServletRequestWrapper createDistributedRequest(ServletRequest servletRequest,
ServletResponse servletResponse) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
String userSid = CookieUtil.getCookie(cookieName, request);
String actualSid = distributedSessionManager.getActualSid(userSid, request, key);
if (StringUtil.isBlank(actualSid)) {
if (StringUtil.isNotBlank(userSid)) {
log.info("userSid[{}]验证不通过", userSid);
}
// 写cookie
String[] userSidArr = distributedSessionManager.createUserSid(request, key);
userSid = userSidArr[0];
CookieUtil.setCookie(cookieName, userSid, request, response);
actualSid = userSidArr[1];
}
actualSid = "sid:" + actualSid;
DistributedHttpSessionWrapper distSession = null;
try {
Map allAttribute = distributedSessionManager.getSession(actualSid, request.getSession()
.getMaxInactiveInterval());
distSession = new DistributedHttpSessionWrapper(actualSid, request.getSession(), allAttribute);
} catch (Throwable e) {
// 出错，删掉缓存数据
log.error(e.getMessage(), e);
Map allAttribute = new HashMap();
distSession = new DistributedHttpSessionWrapper(actualSid, request.getSession(), allAttribute);
distributedSessionManager.removeSession(distSession);
}
DistributedHttpServletRequestWrapper requestWrapper = new DistributedHttpServletRequestWrapper(request,
distSession);
return requestWrapper;
}
// request处理完时操作session
private void dealSessionAfterRequest(DistributedHttpSessionWrapper session) {
if (session == null) {
return;
}
if (session.changed) {
distributedSessionManager.saveSession(session);
} else if (session.invalidated) {
distributedSessionManager.removeSession(session);
} else {
distributedSessionManager.expire(session);
}
} 2、DistributedSessionManager，主要处理分布式session，核心代码：
class DistributedSessionManager {
protected static final Logger log = LoggerFactory.getLogger(DistributedSessionManager.class);
private static DistributedSessionManager instance = null;
//redis处理session的接口，自己根据情况实现
private DistributedBaseInterFace distributedBaseInterFace;
private static byte[] lock = new byte[1];
private DistributedSessionManager(DistributedBaseInterFace distributedBaseInterFace) {
this.distributedBaseInterFace = distributedBaseInterFace;
}
public static DistributedSessionManager getInstance(DistributedBaseInterFace redis) {
if (instance == null) {
synchronized (lock) {
if (instance == null) {
instance = new DistributedSessionManager(redis);
}
}
}
return instance;
}
//获取session
public Map getSession(String sid,int second) {
String json = this.distributedBaseInterFace.get(sid,second);
if (StringUtil.isNotBlank(json)) {
return JsonUtil.unserializeMap(json);
}
return new HashMap(1);
}
//保存session
public void saveSession(DistributedHttpSessionWrapper session) {
Map map=session.allAttribute;
if(MapUtil.isEmpty(map)){
return;
}
String json = JsonUtil.serializeMap(map);
this.distributedBaseInterFace.set(session.getId(), json, session.getMaxInactiveInterval());
}
//删除session
public void removeSession(DistributedHttpSessionWrapper session) {
distributedBaseInterFace.del(session.getId());
}
public void expire(DistributedHttpSessionWrapper session) {
distributedBaseInterFace.expire(session.getId(), session.getMaxInactiveInterval());
}
/**
* 创建cookie的sid
*/
public String[] createUserSid(HttpServletRequest request, String key) {
//...
}
public String getActualSid(String userSid, HttpServletRequest request, String key) {
//...
}
}3、DistributedHttpSessionWrapper 实现了 HttpSession，进行分布式session包装，核心代码：
public class DistributedHttpSessionWrapper implements HttpSession {
private HttpSession orgiSession;
private String sid;
boolean changed = false;
boolean invalidated = false;
Map allAttribute;
public DistributedHttpSessionWrapper(String sid, HttpSession session, Map allAttribute) {
this.orgiSession = session;
this.sid = sid;
this.allAttribute = allAttribute;
}
@Override
public String getId() {
return this.sid;
}
@Override
public void setAttribute(String name, Object value) {
changed = true;
allAttribute.put(name, value);
}
@Override
public Object getAttribute(String name) {
return allAttribute.get(name);
}
@Override
public Enumeration getAttributeNames() {
Set set = allAttribute.keySet();
Iterator iterator = set.iterator();
return new MyEnumeration(iterator);
}
private class MyEnumeration implements Enumeration {
Iterator iterator;
public MyEnumeration(Iterator iterator) {
super();
this.iterator = iterator;
}
@Override
public boolean hasMoreElements() {
return iterator.hasNext();
}
@Override
public T nextElement() {
return iterator.next();
}
}
@Override
public void invalidate() {
this.invalidated = true;
}
@Override
public void removeAttribute(String name) {
changed = true;
allAttribute.remove(name);
}
@Override
public long getCreationTime() {
return orgiSession.getCreationTime();
}
@Override
public long getLastAccessedTime() {
return orgiSession.getLastAccessedTime();
}
@Override
public int getMaxInactiveInterval() {
return orgiSession.getMaxInactiveInterval();
}
@Override
public ServletContext getServletContext() {
return orgiSession.getServletContext();
}
@Override
public Object getValue(String arg0) {
return orgiSession.getValue(arg0);
}
@Override
public String[] getValueNames() {
return orgiSession.getValueNames();
}
@Override
public boolean isNew() {
return orgiSession.isNew();
}
@Override
public void putValue(String arg0, Object arg1) {
orgiSession.putValue(arg0, arg1);
}
@Override
public void removeValue(String arg0) {
orgiSession.removeValue(arg0);
}
@Override
public void setMaxInactiveInterval(int arg0) {
orgiSession.setMaxInactiveInterval(arg0);
}
@Override
public HttpSessionContext getSessionContext() {
return orgiSession.getSessionContext();
}
4、DistributedHttpServletRequestWrapper 实现了 HttpServletRequestWrapper，包装处理过的session和原始request，核心代码：
public class DistributedHttpServletRequestWrapper extends javax.servlet.http.HttpServletRequestWrapper {
private HttpServletRequest orgiRequest;
private DistributedHttpSessionWrapper session;
public DistributedHttpServletRequestWrapper(HttpServletRequest request, DistributedHttpSessionWrapper session) {
super(request);
if (session == null){
//异常处理。。
}
if (request == null){
//异常处理。。
}
this.orgiRequest = request;
this.session = session;
}
public DistributedHttpSessionWrapper getSession(boolean create) {
orgiRequest.getSession(create);
return session;
}
public DistributedHttpSessionWrapper getSession() {
return session;
}
}
5、另外，定义DistributedBaseInterFace接口，用来处理session入redis进行持久化操作：
public interface DistributedBaseInterFace {
/**
* 根据key获取缓存数据
* @param key
* @param seconds
*/
public String get(String key,int seconds);
/**
* 更新缓存数据
* @param key
* @param json
* @param seconds
*/
public void set(String key, String json,int seconds);
/**
* 删除缓存
* @param key
*/
public void del(String key);
/**
* 设置过期数据
* @param key
* @param seconds
*/
public void expire(String key,int seconds);
注：本文只是在Spring中采用redis的方式对session进行管理，还有其他诸多的实现方式，比如在容器里面配置等，设计路由算法让session依赖于集群中的各个节点服务器，，，，，，但redis这种方式在实际应用中还是比较广泛的，LZ公司主要就是采用此方式。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持创新互联。
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