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个人笔记SpringMVC

news 2025/8/20 9:55:34

SpringMVC

1.

1.新建一个Maven-webapp项目

2.导入依赖pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>SpringMVC</artifactId><packaging>pom</packaging><modules><module>SpringMVC01-hellomvc</module></modules><version>1.0-SNAPSHOT</version><name>SpringMVC Maven Webapp</name><url>http://maven.apache.org</url><dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>3.8.1</version><scope>test</scope></dependency>
​<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java --><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.33</version></dependency>
​<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.19</version></dependency>
​<!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc --><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>6.2.9</version></dependency>
​<!-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc --><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>6.2.9</version></dependency>
​<!-- https://mvnrepository.com/artifact/org.aspectj/aspectjweaver --><dependency><groupId>org.aspectj</groupId><artifactId>aspectjweaver</artifactId><version>1.9.24</version></dependency>
​<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis-spring --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>3.0.5</version></dependency>
​<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok --><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.38</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.13.2</version><scope>test</scope></dependency>
​<dependency><groupId>jakarta.servlet</groupId><artifactId>jakarta.servlet-api</artifactId><version>6.0.0</version></dependency>
​
​</dependencies><build><resources><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>true</filtering></resource><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>true</filtering></resource></resources></build>
</project>
​

3.检查项目结构/工件/WEB-INF/lib里有没有导入依赖包

4.给webapp/WEB-INF/web.xml里替换了

<?xml version="1.0" encoding="UTF-8"?>
<web-appxmlns="https://jakarta.ee/xml/ns/jakartaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee
https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"version="6.0"><display-name>Welcome to Tomcat</display-name><description>Welcome to Tomcat</description>
</web-app>

5.在webapp/WEB-INF/jsp里写个test.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body>
<h2>Hello World!111111111111111</h2>
</body>
</html>
​

6.在web.xml里配置DIspatchServlet

注意点： / 和 /*不一样

  • /：只匹配所有的请求，不会去匹配jsp页面

  • /*：匹配所有的请求，包括jsp页面

<?xml version="1.0" encoding="UTF-8"?>
<web-appxmlns="https://jakarta.ee/xml/ns/jakartaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee
https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"version="6.0"><display-name>Welcome to Tomcat</display-name><description>Welcome to Tomcat</description>
​
<!--  配置DispatchServlet，这是SpringMVC的核心，请求分发器，前端控制器--><servlet><servlet-name>springmvc</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!--    DispatchServlet要绑定Spring-mvc的配置文件--><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:springmvc-servlet.xml</param-value></init-param>
<!--    启动级别：1--><load-on-startup>1</load-on-startup></servlet>
​<servlet-mapping><servlet-name>springmvc</servlet-name><url-pattern>/</url-pattern></servlet-mapping>
</web-app>

7.SpringMVC的核心三要素：

  • 处理器映射器

  • 处理器适配器

  • 视图解析器

在springmvc-servlet.xml中配置核心三要素

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beanshttps://www.springframework.org/schema/beans/spring-beans.xsd">
​
<!--    处理器映射器--><bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
<!--    处理器适配器--><bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
<!--    视图解析器--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
<!--        前缀   prefix后缀   suffix
--><property name="prefix" value="WEB-INF/jsp/"/><property name="suffix" value=".jsp"/></bean>
​
</beans>

8.写业务代码HelloController

package com.lyj.controller;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;
public class HelloController implements Controller {@Overridepublic ModelAndView handleRequest(jakarta.servlet.http.HttpServletRequest request, jakarta.servlet.http.HttpServletResponse response) throws Exception {ModelAndView mv = new ModelAndView();//业务代码String result = "Hello World!";mv.addObject("msg", result);//视图跳转mv.setViewName("test");return mv;}
}
​

9.回到springmvc-servlet.xml

BeanNameUrlHandlerMapping处理器有个特性，它会根据bean的名字来找，所有需要写个bean

BeanNameUrlHandlerMapping根据输入(http://localhost:8080/hello)的url(/hello)去匹配bean的id寻找controller

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beanshttps://www.springframework.org/schema/beans/spring-beans.xsd">
​<!--    处理器映射器--><bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/><!--    处理器适配器--><bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/><!--    视图解析器--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver"><!--        前缀   prefix后缀   suffix--><property name="prefix" value="WEB-INF/jsp/"/><property name="suffix" value=".jsp"/></bean>
<!--    BeanNameUrlHandlerMapping  bean--><bean id="/hello" class="com.lyj.controller.HelloController"/>
​
</beans>

2.使用注解开发SpringMVC

1.导包

2.web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-appxmlns="https://jakarta.ee/xml/ns/jakartaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee
https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"version="6.0"><display-name>Welcome to Tomcat</display-name><description>Welcome to Tomcat</description>
​<!--  配置DispatchServlet，这是SpringMVC的核心，请求分发器，前端控制器--><servlet><servlet-name>springmvc</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><!--    DispatchServlet要绑定Spring-mvc的配置文件--><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:springmvc-servlet.xml</param-value></init-param><!--    启动级别：1--><load-on-startup>1</load-on-startup></servlet>
​
​<servlet-mapping><servlet-name>springmvc</servlet-name><url-pattern>/</url-pattern></servlet-mapping>
</web-app>

3.配置springmvc-servlet.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/beanshttps://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttps://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/mvchttps://www.springframework.org/schema/mvc/spring-mvc.xsd">
​
​
<!--    自动扫描包，让指定报下的注解生效，由IOC容器统一管理--><context:component-scan base-package="com.lyj.controller"/>
​
<!--    过滤：让SpringMVC不处理静态资源--><mvc:default-servlet-handler/>
<!--    支持mvc注解驱动-->
<!--    在spring中一般采用@RequestMapping注解来完成映射关系-->
<!--    要使注解生效-->
<!--    必须想上下文中注册DefaultAnnotationHandlerMapping-->
<!--    和一个AnnotationMethodHandlerAdapter实例-->
<!--    这两个实例分别在类级别和方法级别处理-->
<!--    而annotation-driver配置帮助我们自动完成上述两个实例的注入-->
​
​<!--    视图解析器--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver"><!--        前缀   prefix后缀   suffix--><property name="prefix" value="WEB-INF/jsp/"/><property name="suffix" value=".jsp"/></bean>
​
​
</beans>
​
​

4.HelloController

package com.lyj.controller;
​
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
​
@Controller
public class HelloController {@RequestMapping("/hello")public String hello(Model model){//封装数据model.addAttribute("msg","hello,controller");
​return "hello";//会被视图解析器处理}
​
}
​

3.RestFul

3.1

1.配置web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-appxmlns="https://jakarta.ee/xml/ns/jakartaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee
https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"version="6.0"><display-name>Welcome to Tomcat</display-name><description>Welcome to Tomcat</description>
​<!--  配置DispatchServlet，这是SpringMVC的核心，请求分发器，前端控制器--><servlet><servlet-name>springmvc</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><!--    DispatchServlet要绑定Spring-mvc的配置文件--><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:springmvc-servlet.xml</param-value></init-param><!--    启动级别：1--><load-on-startup>1</load-on-startup></servlet>
​
​<servlet-mapping><servlet-name>springmvc</servlet-name><url-pattern>/</url-pattern></servlet-mapping>
</web-app>

2.配置springmvc-servlet.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/beanshttps://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttps://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/mvchttps://www.springframework.org/schema/mvc/spring-mvc.xsd">
​
​
<!--    自动扫描包，让指定报下的注解生效，由IOC容器统一管理--><context:component-scan base-package="com.lyj.controller"/>
​
<!--    过滤：让SpringMVC不处理静态资源--><mvc:default-servlet-handler/>
​<mvc:annotation-driven/>
<!--    支持mvc注解驱动-->
<!--    在spring中一般采用@RequestMapping注解来完成映射关系-->
<!--    要使注解生效-->
<!--    必须想上下文中注册DefaultAnnotationHandlerMapping-->
<!--    和一个AnnotationMethodHandlerAdapter实例-->
<!--    这两个实例分别在类级别和方法级别处理-->
<!--    而annotation-driver配置帮助我们自动完成上述两个实例的注入-->
​
​<!--    视图解析器--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver"><!--        前缀   prefix后缀   suffix--><property name="prefix" value="/WEB-INF/jsp/"/><property name="suffix" value=".jsp"/></bean>
​
​
</beans>
​
​

3.实现Controller接口，ControllerTest1

package com.lyj.controller;
​
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;
​
public class ControllerTest1 implements Controller {@Overridepublic ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {ModelAndView mv = new ModelAndView();mv.addObject("msg","ControllerTest1");mv.setViewName("test");return mv;}
}
​

4.写一下webapp/WEb-INF/jsp/test.jsp

​
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body>
${msg}
​
</body>
</html>
​

5.在springmvc-servlet .xml中注册请求的bean:name对应的请求路径,class对应处理请求的类

<bean name="/t3" class="com.lyj.controller.ControllerTest1"/>
<?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/beanshttps://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttps://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/mvchttps://www.springframework.org/schema/mvc/spring-mvc.xsd">
​
​
<!--    自动扫描包，让指定报下的注解生效，由IOC容器统一管理--><context:component-scan base-package="com.lyj.controller"/>
​
<!--    过滤：让SpringMVC不处理静态资源--><mvc:default-servlet-handler/>
​<mvc:annotation-driven/>
<!--    支持mvc注解驱动-->
<!--    在spring中一般采用@RequestMapping注解来完成映射关系-->
<!--    要使注解生效-->
<!--    必须想上下文中注册DefaultAnnotationHandlerMapping-->
<!--    和一个AnnotationMethodHandlerAdapter实例-->
<!--    这两个实例分别在类级别和方法级别处理-->
<!--    而annotation-driver配置帮助我们自动完成上述两个实例的注入-->
​
​<!--    视图解析器--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver"><!--        前缀   prefix后缀   suffix--><property name="prefix" value="/WEB-INF/jsp/"/><property name="suffix" value=".jsp"/></bean>
​<bean name="/t3" class="com.lyj.controller.ControllerTest1"/>
​
</beans>
​
​

6.测试ControllerTest2

package com.lyj.controller;
​
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
​
@Controller
public class ControllerTest2 {
​@RequestMapping("/t2")public String test1(Model model){model.addAttribute("msg","ControllerTest2");return "test";}@RequestMapping("/t3")public String test2(Model model){model.addAttribute("msg","ControllerTest3");return "test";}
}
​

3.2

1.新建一个类RestFulController

有两种访问路径

  • 访问路径1：http://localhost:8080/add?a=1&b=2

  • 访问路径2：http://localhost:8080/add/a/b

2.访问路径1,RestFulController

package com.lyj.controller;
​
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
​
@Controller
public class RestFulController {
​// 访问路径：http://localhost:8080/add?a=1&b=2@RequestMapping("/add")public String test(@RequestParam("a") int a,  // 显式指定参数名为"a"@RequestParam("b") int b,  // 显式指定参数名为"b"Model model ){int res = a + b;model.addAttribute("msg", "结果是" + res);return "test";}
​
​
}
​

3.访问路径2：在SpringMVC中可以使用@PathVariable注解，让方法参数的值对用绑定到一个URL模板变量上

package com.lyj.controller;
​
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
​
@Controller
public class RestFulController {
​
​
​@RequestMapping("/add/{a}/{b}")public String test(@PathVariable("a") int a,  // 显式指定参数名为"a"@PathVariable("b") int b,  // 显式指定参数名为"b"Model model ){int res = a + b;model.addAttribute("msg", "结果是" + res);return "test";}
}
​

想要指定的方式请求：

1：

2：

@getMapping
@PostMapping
@PutMapping
@DeleteMapping
@PatchMapping

4.转发和重定向

4.1

在没有配置视图解析器的情况要要实现转发和重定向

4.2

在有配置视图解析器的情况要要实现转发和重定向

image-20250814201949313

5.接收请求参数及数据回显

1.实体类 pojo/User

package com.lyj.pojo;
​
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
​
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {private int id;private String name;private int age;
}
​

2.UserController

t1是@ResquestParam

t2是使用User对象，如果使用对象，前端传递的参数名必须和对象名一致

package com.lyj.controller;
​
import com.lyj.pojo.User;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
​
@Controller
@RequestMapping("/user")
public class UserController {
​@GetMapping("/t1")public String test1(//请求方式http://localhost:8080/t3/user/t1?name=1111@RequestParam("name") String name,  // 显式绑定请求参数 "name"Model model) {System.out.println("接收到前端的参数为：" + name);model.addAttribute("msg", name); // 传递到前端视图return "test"; // 跳转至 test.jsp 或其他视图}
​@GetMapping("/t2")public String test2(User user, Model model){//http://localhost:8080/t3/user/t2?id=888&name=1111&age=321System.out.println(user);return "test";}
}//请求方式http://localhost:8080/t3/user/t1?name=1111
​

6.JSON讲解

1.jackson 依赖包

<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.19.2</version>
</dependency>

2.web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-appxmlns="https://jakarta.ee/xml/ns/jakartaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee
https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"version="6.0"><display-name>Welcome to Tomcat</display-name><description>Welcome to Tomcat</description>
​<!--1.注册servlet--><servlet><servlet-name>SpringMVC</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><!--通过初始化参数指定SpringMVC配置文件的位置，进行关联--><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:springmvc-servlet.xml</param-value></init-param><!-- 启动顺序，数字越小，启动越早 --><load-on-startup>1</load-on-startup></servlet>
​<!--所有请求都会被springmvc拦截--><servlet-mapping><servlet-name>SpringMVC</servlet-name><url-pattern>/</url-pattern></servlet-mapping>
​<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><url-pattern>/</url-pattern></filter-mapping>
</web-app>

3.springmvc-servlet.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/beanshttps://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttps://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/mvchttps://www.springframework.org/schema/mvc/spring-mvc.xsd">
​
​<!--    自动扫描包，让指定报下的注解生效，由IOC容器统一管理--><context:component-scan base-package="com.lyj.controller"/>
​<!--    过滤：让SpringMVC不处理静态资源--><mvc:default-servlet-handler/>
​<mvc:annotation-driven/><!--    支持mvc注解驱动--><!--    在spring中一般采用@RequestMapping注解来完成映射关系--><!--    要使注解生效--><!--    必须想上下文中注册DefaultAnnotationHandlerMapping--><!--    和一个AnnotationMethodHandlerAdapter实例--><!--    这两个实例分别在类级别和方法级别处理--><!--    而annotation-driver配置帮助我们自动完成上述两个实例的注入-->
​
​<!--    视图解析器--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver"><!--        前缀   prefix后缀   suffix--><property name="prefix" value="/WEB-INF/jsp/"/><property name="suffix" value=".jsp"/></bean>
​​
</beans>
​
​

4.webapp/WEB-INF/jsp

5.pojo/User

package com.lyj.pojo;
​
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
​
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
​private String name;private int age;private String sex;
}
​

6.UserControllre

package com.lyj.controller;
​
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.lyj.pojo.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
​
@Controller
public class UserController {@RequestMapping(value = "/j1",produces ="application/json;charset=utf-8" )@ResponseBodypublic String json1() throws JsonProcessingException {ObjectMapper mapper = new ObjectMapper();
​User user = new User("名字",20,"男");
​String str = mapper.writeValueAsString(user);return str;}
}
​

@Controller和@RestController

@Controller 走视图解析器

@RestController 直接返回字符串

@ResponseBody 是配合@Controller使用的

乱码问题

注意：乱码问题解决：

@RequestMapping(value = "/j1",produces ="application/json;charset=utf-8" )

上述方法需要频繁添加，所以在springmvc-servlet.xml 里添加 mvc:annotation-driven/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/beanshttps://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttps://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/mvchttps://www.springframework.org/schema/mvc/spring-mvc.xsd">
​
​<!--    自动扫描包，让指定报下的注解生效，由IOC容器统一管理--><context:component-scan base-package="com.lyj.controller"/>
​
<!--    解决JSON乱码问题配置--><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>
​
​<!--    过滤：让SpringMVC不处理静态资源--><mvc:default-servlet-handler/>
​
<!--    <mvc:annotation-driven/>--><!--    支持mvc注解驱动--><!--    在spring中一般采用@RequestMapping注解来完成映射关系--><!--    要使注解生效--><!--    必须想上下文中注册DefaultAnnotationHandlerMapping--><!--    和一个AnnotationMethodHandlerAdapter实例--><!--    这两个实例分别在类级别和方法级别处理--><!--    而annotation-driver配置帮助我们自动完成上述两个实例的注入-->
​
​<!--    视图解析器--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver"><!--        前缀   prefix后缀   suffix--><property name="prefix" value="/WEB-INF/jsp/"/><property name="suffix" value=".jsp"/></bean>
​
​
​
</beans>
​
​

7.fastjson

<!-- https://mvnrepository.com/artifact/com.alibaba.fastjson2/fastjson2 -->
<dependency><groupId>com.alibaba.fastjson2</groupId><artifactId>fastjson2</artifactId><version>2.0.57</version>
</dependency>
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