SpringMVC学习笔记（一）-优快云博客

本文链接：https://blog.youkuaiyun.com/sonpam/article/details/103624674

本文详细介绍了SpringMVC框架的基本配置与使用方法，包括依赖管理、前端控制器配置、视图解析器设置、注解驱动等核心概念，同时深入探讨了请求参数绑定机制及常用注解的应用，为初学者提供了全面的SpringMVC实践指南。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

SpringMVC入门案例

pom.xml

  <dependencies>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>3.0</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.2</version>
    </dependency>
  </dependencies>

web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  
  <!--配置前端控制器对象-->
  <servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
  
</web-app>

springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        https://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">
    <!--配置Spring创建容器时要扫描的包-->
    <context:component-scan base-package="com.how2java"></context:component-scan>
    
    <!--配置视图解析器对象-->
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/pages/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>
    
    <!--开启SpringMVC注解的支持-->
    <mvc:annotation-driven conversion-service="conversionService"></mvc:annotation-driven>
</beans>

index.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/12/21
  Time: 13:51
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h3>入门</h3>
    <a href="request/hello">hello</a>
    <a href="request/testRequestMapping">testRequestMapping</a>
</body>
</html>

HelloController.java

package com.how2java.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

/**
 * 控制器
 */
@Controller
@RequestMapping(path = "/request")//用于表示具体的某个模块
public class HelloController {

    @RequestMapping(path = "/hello")
    public String sayHello() {
        System.out.println("Hello SpringMVC!");
        return "success";
    }

    /**
     * 请求映射：
     *     作用：建立请求url和处理请求方法之间的对应关系。
     *     属性：
     *         path指定该方法的请求路径。
     *         value作用与path相同。
     *         method指定该方法的请求方式，取值为枚举类型。
     *         params指定限制请求参数的条件，支持简单的表达式，要求请求参数的key和value必须与配置相同。
     *         headers指定限制请求消息头的条件。
     * @return
     */
    @RequestMapping(value = "/testRequestMapping", method = {RequestMethod.GET}, params = "username=root$password=admin", headers = {"Accept"})
    public String testRequestMapping() {
        System.out.println("测试RequestMapping注解。。。");
        return "success";
    }
}

success.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/12/19
  Time: 22:10
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h3>入门成功</h3>
</body>
</html>

在这里插入图片描述

请求参数的绑定

pom.xml

  <dependencies>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>3.0</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.2</version>
    </dependency>
  </dependencies>

web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>

  <!--配置字符编码过滤器-->
  <filter>
    <filter-name>characterEncodingFilter</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>characterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

  <!--配置前端控制器对象-->
  <servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
  
</web-app>

springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        https://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">
    <!--配置Spring创建容器时要扫描的包-->
    <context:component-scan base-package="com.how2java"></context:component-scan>

    <!--配置视图解析器对象-->
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/pages/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

    <!--配置自定义类型转换器-->
    <bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
        <property name="converters">
            <set>
                <bean id="stringToDateConverter" class="com.how2java.utils.StringToDateConverter"></bean>
            </set>
        </property>
    </bean>

    <!--开启SpringMVC注解的支持-->
    <mvc:annotation-driven conversion-service="conversionService"></mvc:annotation-driven>
</beans>

params.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/12/22
  Time: 22:26
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <%--基本类型和String类型--%>
    <a href="request/testString?username=新垣结衣&password=12345">请求参数的绑定</a>
    
    <%--JavaBean类型--%>
    <form action="request/testAccount" method="post">
    账户ID：<input type="text" name="id"/><br>
    账户名称：<input type="text" name="name"/><br>
    账户金额：<input type="text" name="money"/><br>
    用户姓名：<input type="text" name="user.username"/><br>
    用户年龄：<input type="text" name="user.age"/><br>
    <input type="submit" value="提交">
    </form>
    
    <%--类型转化器--%>
    <form action="request/testUser" method="post">
    用户名称：<input type="text" name="username"/><br>
    用户年龄：<input type="text" name="age"/><br>
    用户生日：<input type="text" name="birthday"/><br>
    <input type="submit" value="提交">
    </form>
    
    <%--获取Servlet原生的API--%>
    <a href="request/testServlet">获取Servlet原生的API</a>
</body>
</html>

success.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/12/21
  Time: 14:15
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h3>success</h3>
</body>
</html>

ParamsController.java

package com.how2java.controller;

import com.how2java.domain.Account;
import com.how2java.domain.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

/**
 * 请求参数的绑定：
 *     绑定要求：
 *         ①表单提交的数据都是键值对，如username=root&password=admin。
 *         ②表单提交的name与控制器类属性名称或方法参数名称一致。
 *     绑定机制：
 *         SpringMVC框架将表单传过来的值赋值给控制器方法的对应参数。
 *     支持的数据类型：
 *         ①基本类型和String类型：表单提交的name与方法参数名称相同。
 *         ②JavaBean类型（实体类）：表单提交的name与控制器类的属性或引用类型的属性相同。
 *         ③集合类型。
 *
 */
@Controller("paramsController")
@RequestMapping("/request")
public class ParamsController {

    /**
     * 基本数据类型和String类型的请求参数绑定
     * @param username
     * @param password
     * @return
     */
    @RequestMapping("/testString")
    public String testString(String username, String password) {
        System.out.println("String类型的请求参数绑定。。。");
        System.out.println("用户名："+username);
        System.out.println("密码："+password);
        return "success";
    }

    /**
     * JavaBean类型的请求参数绑定
     */
    @RequestMapping("/testAccount")
    public String testAccount(Account account) {
        System.out.println("JavaBean类型的请求参数绑定。。。");
        System.out.println(account);
        return "success";
    }

    /**
     * 自定义类型转换器
     * @param user
     * @return
     */
    @RequestMapping("/testUser")
    public String testUser(User user) {
        System.out.println("自定义类型转换器。。。");
        System.out.println(user);
        return "success";
    }

    /**
     * 获取Servlet原生的API
     * @param request
     * @return
     */
    @RequestMapping("/testServlet")
    public String testServlet(HttpServletRequest request) {
        System.out.println("获取Servlet原生的API。。。");
        System.out.println(request);
        HttpSession session = request.getSession();
        System.out.println(session);
        ServletContext context = session.getServletContext();
        System.out.println(context);
        return "success";
    }

}

Account.java

package com.how2java.domain;

import java.io.Serializable;

public class Account implements Serializable{

    private Integer id;
    private String name;
    private Float money;

    private User user;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Float getMoney() {
        return money;
    }

    public void setMoney(Float money) {
        this.money = money;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", money=" + money +
                ", user=" + user +
                '}';
    }

}

User.java

package com.how2java.domain;

import java.io.Serializable;
import java.util.Date;

public class User implements Serializable{

    private String username;
    private Integer age;
    private Date birthday;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "User{" +
                "username='" + username + '\'' +
                ", age=" + age +
                ", birthday=" + birthday +
                '}';
    }

}

StringToDateConverter.java

package com.how2java.utils;

import org.springframework.core.convert.converter.Converter;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

public class StringToDateConverter implements Converter<String, Date> {

    /**
     * 字符串转日期
     * @param s
     * @return
     */
    @Override
    public Date convert(String s) {
        if(s==null) {
            throw new RuntimeException("请传入数据");
        }
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        try {
            return df.parse(s);
        } catch (Exception e) {
            throw new RuntimeException("类型转换异常");
        }
    }

}

常用注解

pom.xml

  <dependencies>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>3.0</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.2</version>
    </dependency>
  </dependencies>

web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>

  <!--配置字符编码过滤器-->
  <filter>
    <filter-name>characterEncodingFilter</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>characterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

  <!--配置前端控制器对象-->
  <servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
  
</web-app>

springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        https://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">
    <!--配置Spring创建容器时要扫描的包-->
    <context:component-scan base-package="com.how2java"></context:component-scan>

    <!--配置视图解析器对象-->
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/pages/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

    <!--开启SpringMVC注解的支持-->
    <mvc:annotation-driven></mvc:annotation-driven>
</beans>

User.java

package com.how2java.domain;

import java.io.Serializable;
import java.util.Date;

public class User implements Serializable{

    private String username;
    private Integer age;
    private Date birthday;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "User{" +
                "username='" + username + '\'' +
                ", age=" + age +
                ", birthday=" + birthday +
                '}';
    }

}

annotation.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/12/22
  Time: 18:56
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <%--RequestParam--%>
    <a href="request/testRequestParam?name=新垣结衣">testRequestParam</a>

    <br>

    <%--RequestBody--%>
    <form action="request/testRequestBody" method="post">
        用户姓名：<input type="text" name="username"/><br>
        用户年龄：<input type="text" name="age"/><br>
        <input type="submit" value="提交">
    </form>

    <%--PathVariable--%>
    <a href="request/testPathVariable/10">testPathVariable</a>

    <br>

    <%--RequestHeader--%>
    <a href="request/testRequestHeader">testRequestHeader</a>

    <br>

    <%--CookieValue--%>
    <a href="request/testCookieValue">testCookieValue</a>

    <br>

    <%--ModelAttribute--%>
    <form action="request/testModelAttribute" method="post">
        用户姓名：<input type="text" name="username"/><br>
        用户年龄：<input type="text" name="age"/><br>
        <input type="submit" value="提交">
    </form>

    <br>

    <%--testSessionAttributes--%>
    <a href="request/testSessionAttributes">testSessionAttributes</a>
    <a href="request/getSessionAttributes">getSessionAttributes</a>
    <a href="request/deleteSessionAttributes">deleteSessionAttributes</a>

    <<br>

</body>
</html>

success.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/12/21
  Time: 14:15
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h3>success</h3>
    <%--EL表达式的域对象--%>
    ${requestScope.msg}
    ${sessionScope}
</body>
</html>

AnnotationController.java

package com.how2java.controller;

import com.how2java.domain.User;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.bind.support.SessionStatus;

import java.util.Date;
import java.util.Map;

@Controller("annotationController")
@RequestMapping("/request")
@SessionAttributes(value = {"msg"})//将msg=新垣结衣存入session域对象中
public class AnnotationController {

    /**
     * RequestParam:
     *     作用：将请求中指定名称的参数赋值给控制器中方法参数。
     *     属性：value指定请求参数名称。required表示是否必须提供此参数，默认true。
     * @param username
     * @return
     */
    @RequestMapping("/testRequestParam")
    public String testRequestParam(@RequestParam(name = "name") String username) {
        System.out.println("RequestParam注解测试。。。");
        System.out.println(username);
        return "success";
    }

    /**
     * RequestBody:
     *     作用：获取请求体内容。直接使用得到key=value&key=value...结构的数据。get请求方式不适用。
     *     属性：required表示是否必须有请求体，默认true。当取值true时，get请求方式会报错；当取值false时，get请求方式得到null。
     * @param body
     * @return
     */
    @RequestMapping("/testRequestBody")
    public String testRequestBody(@RequestBody String body) {
        System.out.println("RequestBody注解测试。。。");
        System.out.println(body);
        return "success";
    }

    /**
     * restful风格：通过请求方式和占位符选择要执行的方法。
     * PathVariable：
     *     作用：获取占位符数字。
     *     属性：name指定占位符中的数字。
     * @param id
     * @return
     */
    @RequestMapping("/testPathVariable/{aid}")
    public String testPathVariable(@PathVariable(name = "aid") String id) {
        System.out.println("PathVariable注解测试。。。");
        System.out.println(id);
        return "success";
    }

    /**
     * RequestHeader:
     *     作用：获取请求头内容。
     *     属性：name或value指定请求头内容。
     * @param header
     * @return
     */
    @RequestMapping("/testRequestHeader")
    public String testRequestHeader(@RequestHeader(value = "Accept") String header) {
        System.out.println("RequestHeader注解测试。。。");
        System.out.println(header);
        return "success";
    }

    /**
     * CookieValue:
     *     作用：获取JSESSIONID。
     *     属性：name或value指定JSESSIONID内容。
     * @param cookieValue
     * @return
     */
    @RequestMapping("/testCookieValue")
    public String testCookieValue(@CookieValue(value = "JSESSIONID") String cookieValue) {
        System.out.println("CookieValue注解测试。。。");
        System.out.println(cookieValue);
        return "success";
    }

    /**
     * ModelAttribute:
     *     作用：表示当前方法会在控制器方法执行之前执行。可以修饰没有返回值的方法，也可以修饰有返回值的方法。
     *     属性：value指定请求数据的key。key可以是pojo的属性名称，也可以是map结构的key。
     *     应用场景：当表单提交的数据不是完整的实体类数据时，保证没有提交的数据字段使用数据库对象的原有数据。
     * @return
     */
    @RequestMapping("/testModelAttribute")
    public String testModelAttribute(@ModelAttribute(value = "新垣结衣") User user) {
        System.out.println("CookieValue注解测试。。。");
        System.out.println(user);
        return "success";
    }

    /**
     * ①有返回值的方法演示
     */
//    @ModelAttribute
//    public User showUser1(String username) {
//        System.out.println("showUser1方法执行了。。。");
//        //模拟用户查询数据
//        User user = new User();
//        user.setUsername(username);
//        user.setAge(20);
//        user.setBirthday(new Date());
//        return user;
//    }

    /**
     * ②没有返回值的方法演示
     */
    @ModelAttribute
    public void showUser2(String username, Map<String, User> map) {
        System.out.println("showUser2方法执行了。。。");
        //模拟用户查询数据
        User user = new User();
        user.setUsername(username);
        user.setAge(20);
        user.setBirthday(new Date());
        map.put("新垣结衣", user);
    }

    /**
     * SessionAttributes:
     *     作用：用于多次执行控制器方法间的参数共享。
     *     属性：value指定存入的属性名称，type指定存入的数据类型。
     * @return
     */
    @RequestMapping("/testSessionAttributes")
    public String testSessionAttributes(Model model) {
        System.out.println("SessionAttributes注解测试。。。");
        //存入request域对象中
        model.addAttribute("msg", "新垣结衣");
        return "success";
    }

    @RequestMapping("/getSessionAttributes")
    public String getSessionAttributes(ModelMap modelMap) {
        System.out.println("getSessionAttributes注解测试。。。");
        //获取session域中的信息
        String msg = (String) modelMap.get("msg");
        System.out.println(msg);
        return "success";
    }

    @RequestMapping("/deleteSessionAttributes")
    public String deleteSessionAttributes(SessionStatus status) {
        System.out.println("deleteSessionAttributes注解测试。。。");
        //清空session域中的信息
        status.setComplete();
        return "success";
    }
}