這個也是一個工具類

場景：比如說我們需要在controller或者service或者dao層用到當前登陸人的信息。我們之前的做法，肯定是從session中取出來。然后哪里需要傳哪里。這樣很麻煩。這時候我們需要造一個工具類。目的是在任何地方都能獲取到當前登陸人的信息。

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在這里我們要用到一個對象??ThreadLocal? 這個對象 這個類相當于一個map，但是這個類的key是當前的進程。所以說，一個這樣類只能放一個對象。這里要注意一下。

為什么要用這樣的一個類呢？因為這個類的特性，每個進程的是完全隔離的，避免高并發情況下發生一些錯誤（我也不知道啥錯誤，反正就是防止高并發，這個坑回來再填！！！ToDo~~）

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1.RequestHolder.java
package com.mmall.common;import com.mmall.model.SysUser;import javax.servlet.http.HttpServletRequest;public class RequestHolder {private static final ThreadLocal<SysUser> userHolder = new ThreadLocal<SysUser>();private static final ThreadLocal<HttpServletRequest> requestHolder = new ThreadLocal<HttpServletRequest>();public static void add(SysUser sysUser) {userHolder.set(sysUser);}public static void add(HttpServletRequest request) {requestHolder.set(request);}public static SysUser getCurrentUser() {return userHolder.get();}public static HttpServletRequest getCurrentRequest() {return requestHolder.get();}public static void remove() {userHolder.remove();requestHolder.remove();} } View Code

說明：這里new了兩個這樣的類，一個放當前對象，一個放當前request，然后自定義add方法，還有一個remove方法，因為在每次請求完之后，要把ThreadLocal 里面的數據移除掉

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?2. 然后寫一個filter過濾器。攔截所有的請求。沒有登錄直接返回登錄頁面，登錄了就從session中獲取當前對象，然后add進去

LoginFilter.java

package com.mmall.filter;import com.mmall.common.RequestHolder; import com.mmall.model.SysUser; import lombok.extern.slf4j.Slf4j;import javax.servlet.*; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException;/*** Created by 敲代碼的卡卡羅特* on 2018/3/28 23:49.*/ @Slf4j public class LoginFilter implements Filter {@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {HttpServletRequest req = (HttpServletRequest) servletRequest;HttpServletResponse resp = (HttpServletResponse) servletResponse;SysUser sysUser = (SysUser)req.getSession().getAttribute("user");if (sysUser == null) {String path = "/signin.jsp";resp.sendRedirect(path);return;}RequestHolder.add(sysUser);RequestHolder.add(req);filterChain.doFilter(servletRequest, servletResponse);return;}@Overridepublic void destroy() {} } View Code

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3.每次請求結束清除當前數據? ?如何知道每次當前請求結束 請看我這一篇博客

HttpInterceptor.java package com.mmall.common;import com.mmall.util.JsonMapper; import lombok.extern.slf4j.Slf4j; import org.springframework.web.servlet.ModelAndView; import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.util.Map;@Slf4j public class HttpInterceptor extends HandlerInterceptorAdapter {private static final String START_TIME = "requestStartTime";@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {String url = request.getRequestURI().toString();Map parameterMap = request.getParameterMap();log.info("request start. url:{}, params:{}", url, JsonMapper.obj2String(parameterMap));long start = System.currentTimeMillis();request.setAttribute(START_TIME, start);return true;}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {String url = request.getRequestURI().toString();long start = (Long) request.getAttribute(START_TIME);long end = System.currentTimeMillis();log.info("request finished. url:{}, cost:{}", url, end - start);}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {String url = request.getRequestURI().toString();long start = (Long) request.getAttribute(START_TIME);long end = System.currentTimeMillis();log.info("request completed. url:{}, cost:{}", url, end - start);removeThreadLocalInfo();}public void removeThreadLocalInfo() {RequestHolder.remove();;}} View Code

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4.在web.xml中配置過濾器

<filter><filter-name>loginFilter</filter-name><filter-class>com.mmall.filter.LoginFilter</filter-class> </filter> <filter-mapping><filter-name>loginFilter</filter-name><url-pattern>/sys/*</url-pattern><url-pattern>/admin/*</url-pattern> </filter-mapping>

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轉載于:https://www.cnblogs.com/coder-lzh/p/8667394.html

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