1.导入maven依赖，导入后记得到lib包下查看是否添加成功：

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.10.0</version>
</dependency>

2.直接在Controller中使用@ResponseBody标签会使返回的字符串不走视图解析器，直接在页面返回结果，@RestController标签使整个类下的方法都不走视图解析器，直接在页面返回结果：

//转换JSON数据
@RequestMapping("/json1")
@ResponseBody
public String json1() throws JsonProcessingException {
    User user = new User("2022","吴清风","男");
    ObjectMapper mapper = new ObjectMapper();
    String str = mapper.writeValueAsString(user);
    return str;
}

JSON乱码问题解决：

<!--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>

在spring配置文件中配置