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使用ThreadLocal共享HttpSession

2016年06月15日技术, 默认暂无评论阅读 5,824 次

之前在使用.NET进行Web开发时，可以通过HttpContext.User在应用的任何层面获取当前登录的用户信息，而在使用Java进行Web开发时，最开始接触的就是SpringMVC，可是看到的都是形如下面的代码去获取Session中的用户信息。

public ModelAndView getTest(HttpServletRequest request, HttpServletResponse response){
String userId = request.getSession().getAttribute("user").toString();
}

上面的代码没什么错误，只是看起来很别扭。最开始我以为没什么比较简单的办法来进行封装，直到前些日子开发权限管理系统的时候在这里卡壳了，逼着我去翻阅资料解决这个问题，于是找了几个开源的项目看了看源码，在搜索引擎上大海捞了个针，最后发现其实Java是有解决办法的，只不过需要自己封装一下，同样可以达到.NET下的那种效果。

首先，需要一个封装类。

import javax.servlet.ServletContext;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.HashMap;
import java.util.Map;
public class HttpContext {
private HttpServletRequest request;
private HttpServletResponse response;
private final static ThreadLocal<HttpContext> contextContainer = new ThreadLocal<HttpContext>();
/**
* 初始化
*/
public static HttpContext begin(HttpServletRequest req, HttpServletResponse res) {
HttpContext context = new HttpContext();
context.request = req;
context.response = res;
contextContainer.set(context);
return context;
}
public static HttpContext get(){
return contextContainer.get();
}
/**
* 销毁
*/
public void end() {
this.request = null;
this.response = null;
contextContainer.remove();
}
public ServletContext getContext() {
return this.request.getServletContext();
}
public HttpSession getSession() {
return this.request.getSession(false);
}
public HttpServletRequest getRequest() {
return this.request;
}
public HttpServletResponse getResponse() {
return this.response;
}
public Map<String, Cookie> getCookies() {
Map<String, Cookie> map = new HashMap<String, Cookie>();
Cookie[] cookies = this.request.getCookies();
if(cookies != null)
for(Cookie ck : cookies) {
map.put(ck.getName(), ck);
}
return map;
}
}

然后，需要一个Filter。

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* HttpContext全局过滤器
*/
public class ContextFilter implements Filter{
public void init(FilterConfig filterConfig) throws ServletException {
}
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest)servletRequest;
HttpServletResponse res = (HttpServletResponse)servletResponse;
HttpContext.begin(req, res);
filterChain.doFilter(servletRequest, servletResponse);
}
public void destroy() {
HttpContext.get().end();
}
}