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spring MVC 登录拦截案列

2017-03-08 12:47 169 查看

//login.jsp 登录界面

其中的 name=“？？” 的属性值必须和model中User类的属性名称一致（表单里的属性个数可以少于User中的属个数），目的是spring的映射

<%@ page language="java" contentType="text/html; charset=UTF-8"

pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UT
4000
F-8">

<title>Insert title here</title>

</head>

<body>
<form action="login" method="post">

姓名： <input type="text" name="name" ><br/>

密码: <input type="password" name="age" ><br/>

<input type="submit" value="提交" >

</form>

</body>

</html>

//controller 类

  其中RequestMapping 必须在方法上写，类上面可写可不写。页面跳转的内容在本文后会有补充

package com.community.controller;

import java.io.IOException;

import javax.annotation.Resource;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import com.community.model.User;

import com.community.survice.UserService;

@Controller

public class LoginController {

@Resource
private UserService userService ;
@RequestMapping("/hello")
public void test(HttpServletResponse response) throws IOException{
response.getWriter().write("nihaos");
}

@RequestMapping("/login")
public String fun(HttpServletRequest request,User user){
boolean flag = userService.check(user);
if(flag ){
HttpSession session = request.getSession(true);
session.setAttribute("user", user.getName());
return "index" ;
}
return "redirect:login.jsp" ;
}

}

//interceptor 拦截器

  preHandle 方法如果返回的true ，则不拦截controller 的内容；如果为false ，则拦截内容如果想在这里跳转界面，必须在返回false之前

package com.community.interceptor;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import org.springframework.web.servlet.HandlerInterceptor;

import org.springframework.web.servlet.ModelAndView;

public class LoginInterceptor implements HandlerInterceptor {

/**
* 在Controller处理方法执行之后，在被渲染之前执行
* 关闭，释放，处理一些Controller执行中需要的资源
* */
@Override
public void afterCompletion(HttpServletRequest arg0,
HttpServletResponse arg1, Object arg2, Exception arg3)
throws Exception {

}

/**
* 在Controller处理方法执行之后，在被渲染之前执行
* 关闭，释放，处理一些Controller执行中需要的资源
* */
@Override
public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1,
Object arg2, ModelAndView arg3) throws Exception {

}

/**
* 在Controller的处理方法之前被执行
* 执行一些初始化，权限判断，日志等处理
* 如果返回false 将不会执行Controller中的处理方法
* */
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
Object arg2) throws Exception {
System.out.println("-----处理前-----");
HttpSession session = request.getSession();
Object obj = session.getAttribute("user");
boolean flag =false ;
if(obj != null){
return true;
}else{
//response.sendRedirect(request.getContextPath()+"/login.jsp");
request.getRequestDispatcher("/login.jsp").forward(request,response);
// return "forward:login.jsp";// 不可以，因为要返回boolean类型
return false ;
}
}

}

package com.community.model;

public class User {
String name;
int age;
public User() {}
public User(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}

}

//src 下的bean文件

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:context="http://www.springframework.org/schema/context"

xmlns:aop="http://www.springframework.org/schema/aop"

xmlns:mvc="http://www.springframework.org/schema/mvc"

xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd"> 
<context:component-scan base-package="com.community"/>


<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<mvc:exclude-mapping path="/login"/>
<bean class="com.community.interceptor.LoginInterceptor"></bean>
</mvc:interceptor>

</mvc:interceptors>



<bean id="stringConverter"
class="org.springframework.http.converter.StringHttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>text/plain;charset=UTF-8</value>
</list>
</property>
</bean>
<bean id="jsonConverter"
class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"></bean>
<bean
class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
<property name="messageConverters">
<list>
<ref bean="stringConverter" />
<ref bean="jsonConverter" />
</list>
</property>
</bean>


<mvc:annotation-driven />
<mvc:resources location="/js/" mapping="/js/**"/>


<bean id="viewResolver" class="org.springframework.web.servlet.view.UrlBasedViewResolver">

<property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
<property name="prefix" value="/WEB-INF/jsp/"/>
<property name="suffix" value=".jsp"/>
</bean>

</beans>

这个小项目的要注意的事项以及流程整理：

login.jsp---------(interceptor)------------controller-----------index,jsp（一般情况下放在WEB-INF 下，为了是不让别人直接访问。）

login.jsp 跳转到controller ，进行登录，在controller中验证用户名和密码的准确性，正确跳转到主页index.jsp

-----------------------------------------------------------------------------------------------controller 中的跳转---------------------------------------------------------------------

方式一：通过ServletAPI对象来实现

1.   @RequestMapping("/redirect")
publicvoidredirectJump(HttpServletRequestrequest,
HttpServletResponse response)throwsException {
response.sendRedirect(request.getContextPath()+"/jsp/JSPRedirect.jsp");
}
2.   @RequestMapping("/forward")
publicvoidforwardJump(HttpServletRequestrequest,
HttpServletResponse response)throwsException {
request.getRequestDispatcher("/jsp/JSPForward.jsp").forward(request,response);

c1b3
}

方式二：通过springmvc实现转发和重定向
（需要在bean 中配置渲染器；

<beanid="viewResolver"class="org.springframework.web.servlet.view.UrlBasedViewResolver">

<propertyname="viewClass"value="org.springframework.web.servlet.view.JstlView"/>

<propertyname="prefix"value="/WEB-INF/jsp/"/>

<propertyname="suffix"value=".jsp"/>

</bean> ）

1.@RequestMapping("/mvcdefault")

publicString mvcDefaultJump(HttpServletRequest request,

HttpServletResponseresponse)throws Exception {

return"index"; //直接跳转到项目的/WEB-INF/jsp/index.jsp

}

2.@RequestMapping("/mvcforward")

publicString mvcForwardJump(HttpServletRequest request,

HttpServletResponseresponse)throws Exception {

System.out.println("/mvcforward");

return"forward:index.jsp"; //forward 表示直接跳转到项目下，（和WEB-INF平级)然后查找index.jsp

}

3.@RequestMapping("/mvcredirect")

publicString mvcRedirectJump(HttpServletRequest request,

HttpServletResponseresponse)throws Exception {

System.out.println("/mvcredirect");

return"redirect:index.jsp";

}

-----------------------------------------------------------------web.xml----------------------------------------------------------------------
--------

<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:mvc.xml</param-value>

    </init-param>

   <load-on-startup>1</load-on-startup><!–服务启动就加载-->

</servlet>

<servlet-mapping>

    <servlet-name>springmvc</servlet-name>

    <url-pattern>/</url-pattern>

</servlet-mapping>

<context:component-scanbase-package="com"></context:component-scan>

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