SpringMVC jackson的使用(json对象的使用)

json

• 前后端沟通的桥梁
• 就是键值对

Jackson的使用

• 导入maven依赖

<dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.12.2</version>
</dependency>

• 配置spring.xml,防止乱码

<?xml version="1.0" encoding="GBK"?>
<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 http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">

       <context:component-scan base-package="com.MVC.controller"/>
    <mvc:annotation-driven>
        <mvc:message-converters>
            <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>
    <mvc:default-servlet-handler/>
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="resourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

• 使用方法

@Controller
public class JacksonTest {
    @RequestMapping("/json")
    @ResponseBody//它就不会走视图解析器，会直接返回一个字符串
    public String Jackson() throws JsonProcessingException {
        People people = new People(1,"清风","新疆维吾尔自治区，哈萨克自治县");
        ObjectMapper objectMapper = new ObjectMapper();
        String str = objectMapper.writeValueAsString(people);
        return str;
    }
    @RequestMapping("/json2")
    @ResponseBody//它就不会走视图解析器，会直接返回一个字符串
    public String Jackson2() throws JsonProcessingException {//返回集合
        List<People> peopleList = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            peopleList.add(new People(i,"清风"+i+"号","新疆维吾尔自治区，哈萨克自治县"));
        }
        ObjectMapper objectMapper = new ObjectMapper();
        return objectMapper.writeValueAsString(peopleList);
    }
    @RequestMapping("/json3")
    @ResponseBody//它就不会走视图解析器，会直接返回一个字符串
    public String Jackson3() throws JsonProcessingException {//返回人可以认识的时间
        String time=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS").format(new Date());
        ObjectMapper objectMapper = new ObjectMapper();
        return objectMapper.writeValueAsString(time);
    }

}

fastJson的使用

• 导入maven依赖

<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.75</version>
</dependency>

• 使用方法

@Controller
public class JacksonTest {
    @RequestMapping("/Fjson4")
    @ResponseBody//它就不会走视图解析器，会直接返回一个字符串
    public String Jackson4() throws JsonProcessingException {
        List<People> peopleList = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            peopleList.add(new People(i,"清风"+i+"号","新疆维吾尔自治区，哈萨克自治县"));
        }
        return JSON.toJSONString(peopleList);
    }
}