没有输出json字符串

相关代码：

Controller代码：
@Controller
@RequestMapping("/restful")
public class RestfulController {
 @GetMapping("/person")
    public Person findByPersonId(Integer id){
        Person p = new Person();
        if(id==1){
            p.setName("lily");
            p.setAge(23);
        }else if(id == 2){
            p.setName("smith");
            p.setAge(22);
        }
        return p;
    }
}

pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ypy</groupId>
    <artifactId>restful</artifactId>
    <version>1.0-SNAPSHOT</version>
    <!--引入阿里云镜像-->
    <repositories>
        <repository>
            <id>aliyun</id>
            <name>aliyun</name>
            <url>https://maven.aliyun.com/repository/public</url>
        </repository>
    </repositories>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.3.4</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.9.10</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.10.8</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.9.10</version>
        </dependency>
    </dependencies>
</project>

web.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_3_1.xsd"
         version="3.1">
    <!--将请求使用DispatcherServlet分发-->
    <servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicaitonContext.xml</param-value>
    </init-param>
</servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <!--防止中文乱码-->
    <filter>
        <filter-name>characterFilter</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>characterFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

        <servlet-mapping>
            <servlet-name>default</servlet-name>
            <url-pattern>*.js</url-pattern>
        </servlet-mapping>
        <servlet-mapping>
            <servlet-name>default</servlet-name>
            <url-pattern>*.css</url-pattern>
        </servlet-mapping>

    <!--扩展put、delete对前台传来的数据进行获取，否则获取不到-->
    <filter>
        <filter-name>formContentFilter</filter-name>
        <filter-class>org.springframework.web.filter.FormContentFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>formContentFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>​
​
​
applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        https://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
    <!--扫描包中的注解-->
    <context:component-scan base-package="com.ypy.restful"/>
    <!--开启注解，并且配置响应的字符集编码格式UTF-8-->
    <mvc:annotation-driven>
        <mvc:message-converters>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>text/html;charset=utf-8</value>
                        <value>application/json;charset=utf-8</value>
                    </list>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>
    <!--将静态资源排除在外-->
    <mvc:default-servlet-handler/>

</beans>

问题描述：

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