SpringMVC入门使用注解

SpringMVC使用注解开发

需要知道的几个注解

• @Controller : 表示这是一个组件（Controller） 注册到spring容器中，他还有几个相似的注解（@Service @Component @Repository）都表示是一个组件
• @RequestMapping : 获取所有请求
• @GetMapping： 获取Get请求
• @PostMapping：获取Post请求

下面就以一个Hello 程序例子来入门注解开发

1. 第一步 检查包是否导入 需要的依赖如下

<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.13.2</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.3.6</version>
</dependency>
<!-- https://mvnrepository.com/artifact/javax.servlet/servlet-api -->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>servlet-api</artifactId>
    <version>2.5</version>
    <scope>provided</scope>
</dependency>


<!-- https://mvnrepository.com/artifact/javax.servlet.jsp/jsp-api -->
<dependency>
    <groupId>javax.servlet.jsp</groupId>
    <artifactId>jsp-api</artifactId>
    <version>2.2</version>
    <scope>provided</scope>
</dependency>

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
    <version>1.2</version>
</dependency>

2. 第二步 在web.xml文件中配置DispatcherServlet

<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-config.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>

3. 第三步 配置我们的springMVC配置

<?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:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/mvc
        https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!-- 扫描包 该包下的注解生效-->
    <context:component-scan base-package="com.yxx.controller"/>
    <!-- 开启注解驱动
    并且 这个会为我们自动配置映射器和适配器
    RequestMappingHandlerMapping和RequestMappingHandlerAdapter
    -->
    <mvc:annotation-driven/>

    <!--配置视图解析器 -->
    <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. 第四步 写Controller

@Controller
public class MyController {

    @RequestMapping("/hello")
    public String hello(Model model){
        model.addAttribute("msg","Hello!!!!");
        return "hello";//  /WEB-INF/jsp/hello.jsp
    }
}

注意的点：使用注解 ，我们需要扫描使用注解类的包即要在springMVC的配置文件中如下配置

<!-- 扫描包 该包下的注解生效-->
<context:component-scan base-package="com.yxx.controller"/>