Springmvc中jackson

1.导入json依赖

<dependency>
  <groupId>org.projectlombok</groupId>
  <artifactId>lombok</artifactId>
  <version>1.18.8</version>
  <scope>provided</scope>
</dependency>

2.在springmvc.xm配置解决json乱码问题

  <!--json乱码问题解决-->
    <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>

3.将JavaBean对象转换为json字符串输出到前端

@Controller
public class UserController {
    @RequestMapping("/t")
    @ResponseBody//加了这个注解以后就不会再走视图解析器，直接返回一个字符串
    public String json1() throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        //创建一个对象
        User user = new User("张三",3,"男");
        //将user对象转换为json格式,返回给前端
        return objectMapper.writeValueAsString(user);
    }

    @RequestMapping("/t1")
    @ResponseBody
    public String json2() throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        List<User> userList = new ArrayList<User>();
        User user1 = new User("张三",3,"男");
        User user2 = new User("张三",4,"男");
        User user3 = new User("张三",5,"男");
        User user4 = new User("张三",6,"男");

        userList.add(user1);
        userList.add(user2);
        userList.add(user3);
        userList.add(user4);
        return objectMapper.writeValueAsString(userList);
    }
}