什么是JSON

MegaDataFlowers2026-04-02 17:35

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 复制代码 
<!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 复制代码 
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.21.1</version>
</dependency>

web.xml

xml 复制代码 
<?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 复制代码 
<?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 复制代码 
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 复制代码 
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 复制代码 
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 复制代码 
<?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 复制代码 
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 复制代码 
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.83</version>
</dependency>
java 复制代码 
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);
    }
}
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