springmvc07 json的使用

JSON（JavaScript Object Notation, JS对象简谱）是一种轻量级的数据交换格式。采用完全独立于编程语言的文本格式来存储和表示数据。简洁和清晰的层次结构使得 JSON 成为理想的数据交换语言。易于人阅读和编写，同时也易于机器解析和生成，并有效地提升网络传输效率。

DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Titletitle>
    <script type="text/javascript">
      var user= {
          name:"xxx",
          age:3,
          sex:"男"
      }
      //将js对象转换为json字符串
      var json = JSON.stringify(user)
      //将json字符串转换为js对象
      var user2= JSON.parse(json)
      console.log(json)
      console.log("=======================")
      console.log(user2)
    script>
head>
<body>

body>
html>
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在这里插入图片描述

Jackson使用

1.导入Jackson依赖

<dependency>
            <groupId>com.fasterxml.jackson.coregroupId>
            <artifactId>jackson-databindartifactId>
            <version>2.13.4.2version>
        dependency>
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2.配置json乱码问题


    <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>
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3.编写User类

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    public String name;
    public int age;
    public String sex;
}
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4.编写UserController类

@RestController //和下面的@ResponseBody一个效果
//@Controller
public class UserController {
    //@RequestMapping中有一个produces = "application/json;charset=utf-8" 处理json乱码问题
    @RequestMapping(value = "/j1")
    //@ResponseBody//不走视图解析器，只返回字符串
    public String json1() throws JsonProcessingException {
        //jackson中有一个对象叫ObjectMapper
        ObjectMapper mapper = new ObjectMapper();
       	User user = new User("xxx",24,"男");
        String s = mapper.writeValueAsString(user);
        return s;
    }
    @RequestMapping(value = "/j2")
    public String json2() throws JsonProcessingException {
        //jackson中有一个对象叫ObjectMapper
        ObjectMapper mapper = new ObjectMapper();
        List<User> list  = new ArrayList<>();
        User user1 = new User("xxx",24,"男");
        User user2 = new User("xxx",24,"男");
        User user3 = new User("xxx",24,"男");
        User user4 = new User("xxx",24,"男");
        User user5 = new User("xxx",24,"男");
        list.add(user1);
        list.add(user2);
        list.add(user3);
        list.add(user4);
        list.add(user5);
        String s = mapper.writeValueAsString(list);
        return s;
    }
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返回json字符串形式
在这里插入图片描述

在页面以json字符串输出时间（两种方式）

    @RequestMapping(value = "/j3")
    public String json3() throws JsonProcessingException {
        //jackson中有一个对象叫ObjectMapper
        ObjectMapper mapper = new ObjectMapper();
        //ObjectMapper,时间解析后的默认格式为时间戳Timestamp 1970.1.1开始
        Date date = new Date();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        return mapper.writeValueAsString(sdf.format(date));
    }
    @RequestMapping(value = "/j4")
    public String json4() throws JsonProcessingException {
        //jackson中有一个对象叫ObjectMapper
        ObjectMapper mapper = new ObjectMapper();
        //关闭默认的时间戳格式
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        mapper.setDateFormat(sdf);
        Date date = new Date();
        return mapper.writeValueAsString(date);
    }
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提取重复的操作制作工具类

public class JsonUtils {
	//方法重载，直接使用已经写好的方法，第二个参数可以提供一下空字符串返回
    public static String getJson(Object object) throws JsonProcessingException {
        return getJson(object,"");
    }
    public static String getJson(Object object,String dateFormat) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);
        SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
        mapper.setDateFormat(sdf);
        return mapper.writeValueAsString(object);
    }
}
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/j4代码就可以精简成下述/j5

@RequestMapping(value = "/j5")
    public String json5() throws JsonProcessingException {
        Date date = new Date();
        return JsonUtils.getJson(date,"yyyy-MM-dd HH:mm:ss");
    }
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/j1代码就可以精简成下述

   @RequestMapping(value = "/j1")
    public String json1() throws JsonProcessingException {
        return JsonUtils.getJson(new User("xxx",24,"男"));
    }
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Fastjson使用

1.导入Fastjson依赖

<dependency>
            <groupId>com.alibabagroupId>
            <artifactId>fastjsonartifactId>
            <version>2.0.16version>
        dependency>
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2.使用Fastjson

@RequestMapping(value = "/j6")
    public String json6() throws JsonProcessingException {
        List<User> list  = new ArrayList<>();
        User user1 = new User("姚秉文",24,"男");
        User user2 = new User("姚秉文",24,"男");
        User user3 = new User("姚秉文",24,"男");
        User user4 = new User("姚秉文",24,"男");
        User user5 = new User("姚秉文",24,"男");
        list.add(user1);
        list.add(user2);
        list.add(user3);
        list.add(user4);
        list.add(user5);
        return JSON.toJSONString(list);
    }
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使用JSON.方法直接进行使用

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原文地址：https://blog.csdn.net/hl12138/article/details/127553986