Jackson - 暮无雪代码博客

前置准备

1.导入依赖

　　　　　　<!-- jackson       -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.14.0</version>
        </dependency>

　　　　<!--fastJson  阿里开发的方便于  json与javaBean对象的转换    -->
　　　　　　<dependency>
   　　　　　　 <groupId>com.alibaba</groupId>
    　　　　　　<artifactId>fastjson</artifactId>
   　　　　　　 <version>1.2.60</version>
　　　　　　</dependency>

2.配置解决json乱码问题

<?xml version="1.0" encoding="UTF8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">

    <!-- 自动扫描包，并让下面的包注解生效   记得配置mvc和context的约束   -->
    <context:component-scan base-package="com.zxy.controller"/>

    <!--解决json 乱码配置-->
    <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>

</beans>

web.xml(配置MVC核心和乱码过滤)

<?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.配置DispatchServlet-->
    <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:springmvc-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <!-- 配置中文乱码过滤器 -->
    <filter>
        <filter-name>characterEncodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <!-- 初始化过滤器 -->
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>characterEncodingFilter</filter-name>
        <!-- 拦截所有请求 -->
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

UserController (使用书写原码的思想重载类避免重返书写重复代码)

package com.zxy.controller;

import com.alibaba.fastjson.JSON;
import com.zxy.pojo.User;
import com.zxy.utils.JsonUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.ArrayList;
import java.util.Date;

@RestController //此类下面的所有的返回值都是字符串
@Controller
public class UserController {

    @RequestMapping("/j1")
//    @ResponseBody  //有他就不会走视图解析器了，胡直接返回一个字符串  和  @RestController   二者有一个就可以
    public String json1() {

        ArrayList<User> userlist = new ArrayList<>();
        User user1 = new User("钟悉洋1",3,"男");
        User user2 = new User("钟悉洋2",3,"男");
        User user3 = new User("钟悉洋3",3,"男");
        User user4 = new User("钟悉洋4",3,"男");
        userlist.add(user1);
        userlist.add(user2);
        userlist.add(user3);
        userlist.add(user4);

        return JsonUtils.getJson(userlist);
    }

    @RequestMapping("/j2")
    public String json2() {

        Date date = new Date();
        //将实现过程代码分离
        return JsonUtils.getJson(date);
    }

    //使用阿里fastJson  需要导入fastjson的依赖
    @RequestMapping("/j3")
    public String json3() {

        ArrayList<User> userlist = new ArrayList<>();
        User user1 = new User("钟悉洋1",3,"男");
        User user2 = new User("钟悉洋2",3,"男");
        User user3 = new User("钟悉洋3",3,"男");
        User user4 = new User("钟悉洋4",3,"男");
        userlist.add(user1);
        userlist.add(user2);
        userlist.add(user3);
        userlist.add(user4);

        String string = JSON.toJSONString(userlist);
        return string;
    }
}

JsonUtils (使用书写原码的思想重载类避免重返书写重复代码)

package com.zxy.utils;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

import java.text.SimpleDateFormat;

public class JsonUtils {
    //重载的方法
    public static String getJson(Object object){
        return getJson(object,"yyyy-MM-dd HH:mm:ss");
    }

    public static String getJson(Object object,String dateFormat){
        ObjectMapper mapper = new ObjectMapper();
        //显示时间
        //不使用时间戳的方法
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);

        //自定义日期的格式
        SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);

        mapper.setDateFormat(sdf);
        try {
            return mapper.writeValueAsString(object);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return null;
    }
}

User

package com.zxy.pojo;
public class User {
    private String name;
    private int age;
    private String sex;

    public User() {
    }

    public User(String name, int age, String sex) {
        this.name = name;
        this.age = age;
        this.sex = sex;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                '}';
    }
}