参考视频:【狂神说Java】SpringMVC最新教程IDEA版通俗易懂 点击观看
文章目录
什么是JSON
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type = "text/javascript">
//编写一个JS对象
var user = {
name: "张三",
age: 18,
sex: "男"
};
console.log(user);
//将JS对象转换为JSON字符串
var json = JSON.stringify(user);
console.log(json);
//将JSON字符串转换为JS对象
var js = JSON.parse(json);
console.log(js);
</script>
</head>
<body>
</body>
</html>

Jackson使用
导包
xml
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.21.1</version>
</dependency>
web.xml
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">
<!--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>
springmvc-servlet.xml
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
https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<context:component-scan base-package="com.findx.controller"/>
<mvc:default-servlet-handler />
<mvc:annotation-driven />
<!-- 视图解析器 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
id="internalResourceViewResolver">
<!-- 前缀 -->
<property name="prefix" value="/WEB-INF/jsp/" />
<!-- 后缀 -->
<property name="suffix" value=".jsp" />
</bean>
</beans>
User的实体类
java
package com.findx.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;
@Override
public String toString() {
return "User{" +
"name='" + name + '\'' +
", age=" + age +
", sex='" + sex + '\'' +
'}';
}
}
UserController测试
java
package com.findx.controller;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.findx.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 = "/json1",produces = "application/json;charset=utf-8")
@ResponseBody//不会去走视图解析器会直接返回字符串
public String json1() throws JsonProcessingException {
//jackson(ObjectMapper)
ObjectMapper mapper = new ObjectMapper();
//创建一个User对象
User user = new User("findx",17,"男");
String json = mapper.writeValueAsString(user);
return json;
}
}

乱码统一解决
java
package com.findx.controller;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.findx.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 = "/json1",produces = "application/json;charset=utf-8")
@RequestMapping("/json1")
@ResponseBody//不会去走视图解析器会直接返回字符串
public String json1() throws JsonProcessingException {
//jackson(ObjectMapper)
ObjectMapper mapper = new ObjectMapper();
//创建一个User对象
User user = new User("findx",17,"男");
String json = mapper.writeValueAsString(user);
return json;
}
}
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
https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<context:component-scan base-package="com.findx.controller"/>
<mvc:default-servlet-handler />
<mvc:annotation-driven />
<!--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>
<!-- 视图解析器 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
id="internalResourceViewResolver">
<!-- 前缀 -->
<property name="prefix" value="/WEB-INF/jsp/" />
<!-- 后缀 -->
<property name="suffix" value=".jsp" />
</bean>
</beans>


返回json字符串统一解决
在类上直接使用 @RestController类中所有的方法都只会返回json字符串,不用给每一个方法都添加@ResponseBody
java
package com.findx.controller;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.findx.pojo.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
//@Controller
@RestController
public class UserController {
// @RequestMapping(value = "/json1",produces = "application/json;charset=utf-8")
// @ResponseBody//不会去走视图解析器会直接返回字符串
@RequestMapping("/json1")
public String json1() throws JsonProcessingException {
//jackson(ObjectMapper)
ObjectMapper mapper = new ObjectMapper();
//创建一个User对象
User user = new User("findx",17,"男");
String json = mapper.writeValueAsString(user);
return json;
}
}
FastJson
导包
xml
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.83</version>
</dependency>
java
package com.findx.controller;
import com.alibaba.fastjson.JSON;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.findx.pojo.User;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.ArrayList;
import java.util.List;
@RestController
public class UserController {
@RequestMapping("/json2")
public String json2() throws JsonProcessingException {
List<User> userList = new ArrayList<>();
User user1 = new User("findx1",17,"男");
User user2 = new User("findx2",18,"女");
User user3 = new User("findx3",19,"男");
User user4 = new User("findx4",20,"女");
userList.add(user1);
userList.add(user2);
userList.add(user3);
userList.add(user4);
return JSON.toJSONString(userList);
}
}
