[Java知识库]简单使用springmvc

springmvc

一、springmvc入门

1.导入依赖

<dependencies>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.1.9.RELEASE</version>
</dependency>
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>servlet-api</artifactId>
    <version>2.5</version>
</dependency>
<dependency>
    <groupId>javax.servlet.jsp</groupId>
    <artifactId>jsp-api</artifactId>
    <version>2.2</version>
</dependency>
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
    <version>1.2</version>
</dependency>
</dependencies>
<build>
    <resources>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>false</filtering>
        </resource>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>false</filtering>
        </resource>
    </resources>
</build>

<properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
</properties>

2.配置文件

2.1.springmvc.xml

<?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
       http://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
       http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!--自动扫描包，让指定包下的注解生效，由IOC容器统一管理-->
    <context:component-scan base-package="com.drl.controller"/>
    <!--让SpringMvc不处理静态资源-->
    <mvc:default-servlet-handler/>
    <mvc:annotation-driven/>
    <!--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>
<!--解决json 乱码配置-->
<mvc:annotation-driven>
    <mvc:message-converters register-defaults="true">
        <bean class="org.springframework.http.converter.StringHttpMessageConverter">
            <constructor-arg value="UTF-8"/>
        </bean>
        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <property name="objectMapper">
                <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                    <property name="failOnEmptyBeans" value="false"/>
                </bean>
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>
</beans>

2.2.web.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">
    
    <servlet>
        <servlet-name>SpringMvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <!--本地的配置文件-->
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:springmvc-servlet.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>
    <!--2. 配置Springmvc的乱码过滤器-->
<filter>
    <filter-name>encoding</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>encoding</filter-name>
    <!--若为"/"不能过滤jsp文件，"/*"则都可以过滤-->
    <url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>

3.测试

? Hellocontroller

@Controller
public class HelloController {

    @RequestMapping("/hello")
    public String hello(Model model) {
        //封装数据
        model.addAttribute("msg","Hello,SpringMVCAnnotation!");
        return "hello";
    }
}

二、注解

1.@Controller

? @Controller放在类名上面，将类注册在bean内，相当于spring里的@Component。

2.@RequestMapping

? @RequestMapping可以放在类上，也可以放在方法上，作为项目的地址url

2.1@GetMapping

? 浏览器发起get请求。

2.2@PostMapping

? 浏览器发起post请求。

2.3@ResponseBody

? 在类和方法上均可使用，使用之后不会走视图解析器，直接会返回字符串，示例如下：

? controller层

@RequestMapping("/test")
public @ResponseBody String test(){
    String hello="hello";
    return hello;
}

? 结果如下：

三、Json

? 使用json如下

? controller

@RequestMapping("/json2")
@ResponseBody
public String json2() throws JsonProcessingException {

    ObjectMapper mapper=new ObjectMapper();
    LinkedList<User> list= new LinkedList<User>();
    User user1=new User("张三","男",19);
    User user2=new User("李四","男",20);
    User user3=new User("王五","男",21);
    User user4=new User("赵六","男",22);
    list.add(user1);
    list.add(user2);
    list.add(user3);
    list.add(user4);
    String str = mapper.writeValueAsString(list);
    return str;
}

? 结果