简介
SpringMVC的处理器拦截器类似于Servlet开发中的过滤器Filter,用于对处理器进行预处理和后处理。开发者可以自己定义一些拦截器来实现特定的功能。
过滤器
servlet规范中的一部分，任何java web工程都可以使用 在url-pattern中配置了/*之后，可以对所有要访问的资源进行拦截拦截器
拦截器是SpringMVC框架自己的，只有使用了SpringMVC框架的工程才能使用 拦截器只会拦截访问的控制器方法， 如果访问的是jsp/html/css/image/js是不会进行拦截的过滤器与拦截器的区别：
拦截器是AOP思想的具体应用。
拦截器初体验
1.新建一个项目，添加web支持，在IDEA导入该项目依赖的lib包。
2.配置web.xml
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<? xml version = "1.0" encoding = "UTF-8" ?> < web-app xmlns = "http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi = "http://HdhCmsTestw3.org/2001/XMLSchema-instance" xsi:schemaLocation = "http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version = "4.0" > < servlet > < servlet-name >springmvc</ servlet-name > < servlet-class >org.springframework.web.servlet.DispatcherServlet</ servlet-class > < init-param > < param-name >contextConfigLocation</ param-name > < param-value >classpath:springmvc-servlet.xml</ param-value > </ init-param > < load-on-startup >1</ load-on-startup > </ servlet > < servlet-mapping > < servlet-name >springmvc</ servlet-name > < url-pattern >/</ url-pattern > </ servlet-mapping >
< filter > < filter-name >encoding</ filter-name > < filter-class >org.springframework.web.filter.CharacterEncodingFilter</ filter-class > < init-param > < param-name >encoding</ param-name > < param-value >UTF-8</ param-value > </ init-param > </ filter > < filter-mapping > < filter-name >encoding</ filter-name > < url-pattern >/*</ url-pattern > </ filter-mapping >
</ web-app > |
3.配置springmvc-servlet.xml
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<? xml version = "1.0" encoding = "UTF-8" ?> < beans xmlns = "http://HdhCmsTestspringframework.org/schema/beans" xmlns:xsi = "http://HdhCmsTestw3.org/2001/XMLSchema-instance" xmlns:context = "http://HdhCmsTestspringframework.org/schema/context" xmlns:mvc = "http://HdhCmsTestspringframework.org/schema/mvc" xsi:schemaLocation="http://HdhCmsTestspringframework.org/schema/beans http://HdhCmsTestspringframework.org/schema/beans/spring-beans.xsd http://HdhCmsTestspringframework.org/schema/context http://HdhCmsTestspringframework.org/schema/context/spring-context.xsd http://HdhCmsTestspringframework.org/schema/mvc http://HdhCmsTestspringframework.org/schema/mvc/spring-mvc.xsd"> <!-- 扫描指定包，让指定包下的注解生效 --> < context:component-scan base-package = "controller" /> < mvc:annotation-driven />
<!-- JSON解决乱码--> < mvc:annotation-driven > < mvc:message-converters register-defaults = "true" > < bean class = "org.springframework.http.converter.StringHttpMessageConverter" > < constructor-arg value = "UTF-8" /> </ bean > < bean class = "org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" > < property name = "objectMapper" > < bean class = "org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean" > < property name = "failOnEmptyBeans" value = "false" /> </ bean > </ property > </ bean > </ mvc:message-converters > </ mvc:annotation-driven >
<!-- 视图解析器 --> < bean class = "org.springframework.web.servlet.view.InternalResourceViewResolver" id = "internalResourceViewResolver" > < property name = "prefix" value = "/WEB-INF/jsp/" /> < property name = "suffix" value = ".jsp" /> </ bean >
</ beans > |
4.编写自定义的拦截器。（实现HandlerInterceptor接口）
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package interceptor;
import org.springframework.web.servlet.HandlerInterceptor; import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;
public class MyInterceptor implements HandlerInterceptor {
//在请求处理的方法之前执行 //如果返回true执行下一个拦截器 //如果返回false就不执行下一个拦截器 public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println( "------------处理前------------" ); return true ; } //在请求处理方法执行之后执行 public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println( "------------处理后------------" ); } //在dispatcherServlet处理后执行,做清理工作. public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { System.out.println( "------------清理------------" ); } } |
事实上，只要重写preHandle方法就可以。
5.在springmvc-servlet.xml文件中配置拦截器
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<!--关于拦截器的配置--> < mvc:interceptors > < mvc:interceptor > <!--/** 包括路径及其子路径--> <!--/admin/* 拦截的是/admin/add等等这种 , /admin/add/user不会被拦截--> <!--/admin/** 拦截的是/admin/下的所有--> < mvc:mapping path = "/**" /> <!--bean配置的就是拦截器--> < bean class = "interceptor.MyInterceptor" /> </ mvc:interceptor > </ mvc:interceptors > |
6.编写controller
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package controller;
import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController;
@RestController public class InterceptorController { @RequestMapping ( "/interceptor" ) public String test(){ System.out.println( "InterceptorController" ); return "ok" ; } } |
7.配置Tomcat，进行测试
初体验：自定义拦截器实现了HandlerInterceptor接口，重写了preHandle方法。在preHandle方法中，返回值决定了是否拦截，当返回值为true时，不拦截；反之则拦截。
8.结果：
返回值为true，拦截器不拦截，跳转 返回值为false，拦截器拦截，不跳转
拦截器再体验-登录验证
实现思路
有一个登陆页面，需要写一个controller访问页面。 登陆页面有一提交表单的动作。需要在controller中处理。判断用户名密码是否正确。如果正确，向session中写入用户信息。返回登陆成功。 拦截用户请求，判断用户是否登陆。如果用户已经登陆。放行， 如果用户未登陆，跳转到登陆页面登录界面
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<%@ page contentType= "text/html;charset=UTF-8" language= "java" %> <html> <head> <title>Title</title> </head>
<h1>登录页面</h1> <hr>
<body> <form action= "${pageContext.request.contextPath}/user/login" > 用户名：<input type= "text" name= "username" > <br> 密码：<input type= "password" name= "pwd" > <br> <input type= "submit" value= "提交" > </form> </body> </html> |
controller处理请求
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package controller;
import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpSession;
@Controller @RequestMapping ( "/user" ) public class UserController {
//跳转到登陆页面 @RequestMapping ( "/jumplogin" ) public String jumpLogin() throws Exception { return "login" ; }
//跳转到成功页面 @RequestMapping ( "/jumpSuccess" ) public String jumpSuccess() throws Exception { return "success" ; }
//登陆提交 @RequestMapping ( "/login" ) public String login(HttpSession session, String username, String pwd) throws Exception { // 向session记录用户身份信息 System.out.println( "接收前端===" +username); session.setAttribute( "user" , username); return "success" ; }
//退出登陆 @RequestMapping ( "logout" ) public String logout(HttpSession session) throws Exception { // session 过期 session.invalidate(); return "login" ; } } |
登录成功页面
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<%@ page contentType= "text/html;charset=UTF-8" language= "java" %> <html> <head> <title>Title</title> </head> <body>
<h1>登录成功页面</h1> <hr>
${user} <a href= "${pageContext.request.contextPath}/user/logout" >注销</a> </body> </html> |
index页面
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<%@ page contentType= "text/html;charset=UTF-8" language= "java" %> <html> <head> <title>$Title$</title> </head> <body> <h1>首页</h1> <hr> <%--登录--%> <a href= "${pageContext.request.contextPath}/user/jumplogin" >登录</a> <a href= "${pageContext.request.contextPath}/user/jumpSuccess" >成功页面</a> </body> </html> |
index页面
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<%@ page contentType="text/html;charset=UTF-8" language="java" %> < html > < head > < title >$Title$</ title > </ head > < body > < h1 >首页</ h1 > < hr > <%--登录--%> < a href = "${pageContext.request.contextPath}/user/jumplogin" >登录</ a > < a href = "${pageContext.request.contextPath}/user/jumpSuccess" >成功页面</ a > </ body > </ html > |
编写控制器
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package interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession;
public class LoginInterceptor implements HandlerInterceptor { public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { if (request.getRequestURI().contains( "login" )) { return true ; }
HttpSession session = request.getSession();
// 如果用户已登陆，不拦截 if (session.getAttribute( "user" ) != null ) { return true ; }
// 用户没有登陆，拦截，并跳转到登陆页面 request.getRequestDispatcher( "/WEB-INF/jsp/login.jsp" ).forward(request, response); return false ; } } |
在springmvc-servlet.xml配置拦截器
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< mvc:interceptor > < mvc:mapping path = "/**" /> < bean id = "loginInterceptor" class = "interceptor.LoginInterceptor" /> </ mvc:interceptor > |
配置Tomcat，测试。
结果：没有登录就无法直接访问登陆成功页面。
以上就是SpringMVC 中文乱码的解决方案的详细内容，更多关于SpringMVC 中文乱码的资料请关注其它相关文章！
原文链接：https://juejin.cn/post/6944667529717481485
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