Spring MVC day01 请求参数问题及常用注解

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文章目录

一、Spring MVC基本概念

1-1 Spring MVC的优势

1-2 SpringMVC 和 Struts2 的优略分析

二、 SpringMVC 的入门

2-1 SpringMVC 的入门案例

  • 创建WEB工程，引入开发的jar包
<properties>
        <spring.version>5.0.2.RELEASE</spring.version>
    </properties>

    <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>2.5</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
  • 配置web.xml配置文件
    <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>
        <!-- 配置servlet启动时加载对象 -->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
  • 编写springmvc.xml的配置文件
<?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 http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    <!--配置Spring配置容器时要扫描的包-->
    <context:component-scan base-package="com.qgc"></context:component-scan>
    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/pages/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
    <!--Spring开启注解-->
    <mvc:annotation-driven></mvc:annotation-driven>
</beans>
  • 编写HelloController控制器类
@Controller
public class HelloController 
    @RequestMapping(path = "/hello")
    public String sayHello()
        System.out.println("Spring配置成功");
        return "success";

2-2 入门程序执行流程

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2-3 入门案例中涉及的组件

  • DispatcherServlet：前端控制器
  • HandlerMapping：处理器映射器
  • Handler：处理器
  • HandlAdapter：处理器适配器
  • View Resolver：视图解析器
  • View：视图

2-4 <mvc:annotation-driven>说明

        <!-- 上面的标签相当于 如下配置-->
        <!-- Begin -->
        <!-- HandlerMapping --> 
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"></bean> 
<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"></bean>
        <!-- HandlerAdapter --> 
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"></bean> 
<bean class="org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter"></bean> 
<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"></bean>
        <!-- HadnlerExceptionResolvers --> 
<bean class="org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver"></bean>
<bean class="org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver"></bean> 
<bean class="org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver"></bean>
        <!-- End -->

2-5 RequestMapping 注解

  • RequestMapping可以放在类上，下面代码访问路径就为：项目名称/user/hello
@Controller
@RequestMapping(path = "/user")
public class HelloController 
    @RequestMapping(path = "/hello")
    public String sayHello()
        System.out.println("Spring配置成功");
        return "success";
  • RequestMapping的属性
三、请求参数

3-1 基本类型参数

直接在controller类上加上参数即可，要求此参数与前端传过来的参数名称一致

 @RequestMapping(path = "/hello")
    public String getParam(String username)
        System.out.println("用户名"+username);
        return "success";

3-2 POJO 类型参数

直接写上实体类即可

    @RequestMapping(path = "/form")
    public String getParams(Account account)
        System.out.println(account);
        return "success";

3-3 解决POST提交乱码问题

在web.xml中加入以下代码即可

    <!--配置解决乱码的过滤器-->
    <filter>
        <filter-name>characterEncodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <!-- 指定字符集 -->
        <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>

3-4 给集合属性数据封装

JSP页面编写方式：list[0].属性或者是map[key属性].value属性

3-5 自定义类型转换器

  • 写一个自定义类型转换器实现Converter接口
public class StringToDate implements Converter<String, Date> 
    /**
     * 自定义类型转换器
     *
     * @param source 传入的参数
     * @return
     */
    @Override
    public Date convert(String source) 
        if (source == null) 
            throw new RuntimeException("参数不能为空");
        
        try 
            DateFormat df = new SimpleDateFormat("yyyy-MM-dd"); // 解析字符串
            Date date = df.parse(source);
            return date;
         catch (Exception e) 
            throw new RuntimeException("类型转换错误");
  • 注册自定义类型转换器，在springmvc.xml配置文件中编写配置
<!--配置自定义转换器-->
    <bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
        <property name="converters">
            <set>
                <bean class="cn.itcast.utils.StringToDateConverter"/>
            </set>
        </property>
    </bean>
    <!--Spring开启注解-->
    <mvc:annotation-driven conversion-service="conversionService"></mvc:annotation-driven>

3-6 获取Servlet原生api

@RequestMapping("/testServletAPI")
public String testServletAPI(HttpServletRequest request,
HttpServletResponse response,
HttpSession session) 
System.out.println(request);
System.out.println(response);
System.out.println(session);
四、 常用注解

4-1 RequestParam

例：

//将前端的name值传给username
@RequestMapping("/useRequestParam")
public String useRequestParam(@RequestParam("name") String username)

4-2 RequestBody

例：

@RequestMapping("/useRequestBody")
public String useRequestBody(@RequestBody(required=false) String body)

4-3 PathVaribale

例：

@RequestMapping("/usePathVariable/id")
public String usePathVariable(@PathVariable("id") Integer id)

4-4 RequestHeader（不常用）

例：

@RequestMapping("/useRequestHeader")
public String useRequestHeader(@RequestHeader(value="Accept-Language",required=false)String requestHeader)

4-5 CookieValue(不常用)

@RequestMapping("/useCookieValue")
public String useCookieValue(@CookieValue(value="JSESSIONID",required=false) String cookieValue)

4-6 ModelAttribute

  • 方式一：在方法名上加ModelAttribute
    @RequestMapping(path = "/test2")
    public String saveUser(User user)
        System.out.println(user);
        return "success";
    
    @ModelAttribute
    public User modelAttribute(String uname)
        User user = new User();
        user.setAge(99);
        user.setBirthday(new Date());
        user.setUname(uname);
        return user;
  • 方式二：不适用返回值
    @RequestMapping(path = "/test3")
    public String saveUser1(@ModelAttribute User user)
        System.out.println(user);
        return "success";
    
    @ModelAttribute
    public void modelAttribute(String uname, Map<String,User> map)
        User user = new User();
        user.setAge(99);
        user.setBirthday(new Date());
        user.setUname(uname);
        map.put("abc",user);

4-7 SessionAttribute

例：
前端页面

    <a href="user/setSessionAttribute">设置值</a>
    <a href="user/getSessionAttribute">取出值</a>
    <a href="user/delSessionAttribute">删除值</a>

后端

@SessionAttributes(value="abc",types = String.class)
public class HelloController 
    @RequestMapping("/setSessionAttribute")
    public String setSessionAttribute(Model model)
        model.addAttribute("abc","123e");
        return "success";
    
    @RequestMapping("/getSessionAttribute")
    public String getSessionAttribute(ModelMap modelMap)
        Object o = modelMap.get("abc");
        System.out.println(o);
        return "success";
    
    @RequestMapping("/delSessionAttribute")
    public String delSessionAttribute(SessionStatus status)
        status.setComplete();
        return "success";

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