登陆拦截案例

登陆拦截器小案例，判断登陆的用户名及密码是否正确；：

1.创建一个maven项目，导入相关的坐标：

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.12.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.2</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
<!--插入tomcat7插件,内置tomcat-->
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.tomcat.maven</groupId>
            <artifactId>tomcat7-maven-plugin</artifactId>
            <version>2.2</version>
        </plugin>
    </plugins>
</build>

将打包方式设置为war:

    <packaging>war</packaging>

2.设置打包方式之后打开项目的模块设置，添加webapp和WEB-INF

在这里插入图片描述

得出项目结构：

在这里插入图片描述

3.在resources文件中添加配置文件spring-mvc.xml

4.在web.xml中加载spring-mvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.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">

<!--加载springmvc的配置文件-->
    <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:spring-mvc.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <!--过滤器：设置从浏览器过滤的数据，使用utf-8编码-->
    <filter>
        <filter-name>filter</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>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>filter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

5.添加页面index.jsp文件：

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<form action="/com/login" method="post">
    用户名：<input name="userName"><br>
    密码：<input name="passWorld"><br>
    <input type="submit" value="提交">
</form>
</body>
</html>

6.在main/java包下创建com包，在com包下创建controller包在controller包下创建loginController类

@Controller
@RequestMapping("/com")
public class loginController {

    @RequestMapping("/login")
    @ResponseBody
    public String login(String passWorld,String userName) {
        System.out.println(passWorld);
        System.out.println(userName);
        return "登陆成功";
    }
}

7.在spring-mvc.xml文件下配置注解扫描，和开启注解扫描

 <!--配置注解扫描-->
    <context:component-scan base-package="com"/>
    <!-- 开启注解支持 -->
    <mvc:annotation-driven>
        <mvc:message-converters>
            <!-- 配置编码字符集 -->
            <!-- 配置响应编码字符集 -->
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>text/html;charset=UTF-8</value>
                        <value>application/json;charset=UTF-8</value>
                        <value>text/plain;charset=UTF-8</value>
                        <value>application/xml;charset=UTF-8</value>
                    </list>
                </property>
            </bean>

<!--            &lt;!&ndash; 配置Jackson消息转换器 &ndash;&gt;-->
<!--            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">-->
<!--                <property name="objectMapper">-->
<!--                    <bean class="com.fasterxml.jackson.databind.ObjectMapper">-->
<!--                        &lt;!&ndash; 格式化日期 &ndash;&gt;-->
<!--                        <property name="dateFormat">-->
<!--                            <bean class="java.text.SimpleDateFormat">-->
<!--                                <constructor-arg type="java.lang.String" value="yyyy-MM-dd" />-->
<!--                            </bean>-->
<!--                        </property>-->
<!--                    </bean>-->
<!--                </property>-->
<!--            </bean>-->
        </mvc:message-converters>
    </mvc:annotation-driven>

8.在com/interceptor包下创建拦截器，

自定义拦截器有两种：

实现HandlerInterceptor接口
继承HandlerInterceptorAdapter类

这里我两种都用了：一种用来验证用户名，一种用来验证用户密码；

实现HandlerInterceptor接口：

public class MyIterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if ("123".equals(request.getParameter("passWorld"))){
            System.out.println("密码验证正确，放行2");
            return true;
        }
        return false;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("方法执行后2");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("页面渲染后2");
    }
}

继承HandlerInterceptorAdapter类：

public class MyIterceptor2 extends HandlerInterceptorAdapter {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if ("张三".equals(request.getParameter("userName"))){
            request.setAttribute("messege","登陆成功");
            System.out.println("姓名验证成功放行1");
            return true;
        }
        return false;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("方法执行后1");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("页面渲染后1");
    }
}

9.创建完拦截器之后再spring-mvc.xml文件中配置拦截配置

<mvc:interceptors>
    <mvc:interceptor>
        <mvc:mapping path="/**"/>
        <bean class="com.interceptor.MyIterceptor2"></bean>
    </mvc:interceptor>
    <mvc:interceptor>
        <mvc:mapping path="/**"/>
        <bean class="com.interceptor.MyIterceptor"></bean>
    </mvc:interceptor>
</mvc:interceptors>