springboot工程中json浅析

最新推荐文章于 2025-10-11 09:10:03 发布

原创最新推荐文章于 2025-10-11 09:10:03 发布 · 2.6k 阅读

5 ·

CC 4.0 BY-SA版权

文章标签：

#json #spring boot #java

springboot 专栏收录该内容

99 篇文章

订阅专栏

一、在java开发中常用的json解析方式有jackson、fastjson、gson、net.sf.json。
1、jackson
jackson为用来序列化和反序列化json的java的开源框架，spring mvc默认的json解析器就是jackson。

	<dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.13.1</version>
        </dependency>

	public static void main(String[] args) throws JsonProcessingException {
        String json1 = "{\"id\":1,\"name\":\"first\",\"stus\":[{\"id\":101,\"name\":\"刘一\",\"age\":16}]}";
        String json2 = "[\"北京\",\"天津\",\"杭州\"]";
        ObjectMapper objectMapper = new ObjectMapper();
        Grade grade = objectMapper.readValue(json1, Grade.class);
        System.out.println(grade);
        List<String> list = objectMapper.readValue(json2, new TypeReference<List<String>>() {});
        System.out.println(list);

        ArrayList<Student> students = new ArrayList<>();
        for (int i = 0; i < 3; i++) {
            students.add(new Student(100 + i, "大哥" + i, 1000 + i));

        }
        Grade grade2 = new Grade(22, "first", students);
        ObjectMapper objectMapper2 = new ObjectMapper();
        String json = objectMapper2.writeValueAsString(grade2);
        System.out.println(json);
    }

2、fastjson
fastjson是阿里系产品，效率最高。

		<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>

	public static void main(String[] args) {
        String json1 = "{'id':1,'name':'first','stus':[{'id':101,'name':'刘铭','age':16}]}";
        String json2 = "['北京','天津','杭州']";
        Grade grade = JSON.parseObject(json1, Grade.class);
        System.out.println(grade);
        List<String> list = JSON.parseArray(json2, String.class);
        System.out.println(list);

        ArrayList<Student> list2 = new ArrayList<>();
        for (int i = 1; i < 3; i++) {
            list2.add(new Student(101 + i, "大哥", 20 + i));
        }
        Grade grade2 = new Grade(100001, "first", list2);
        String json = JSON.toJSONString(grade);
        System.out.println(json);
    }

3、gson
gson是谷歌产品，也很好用

		<dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.9</version>
        </dependency>

	public static void main(String[] args) {
        String json1 = "{'id':1,'name':'first','stus':[{'id':101,'name':'刘一','age':16}]}";
        String json2 = "['北京','天津','杭州']";
        Gson gson = new Gson();
        Grade grade = gson.fromJson(json1, Grade.class);
        System.out.println(grade);
        ArrayList<String> list = gson.fromJson(json2, new TypeToken<ArrayList<String>>() {}.getType());
        System.out.println(list);

        ArrayList<Student> list2 = new ArrayList<>();
        for (int i = 1; i < 3; i++) {
            list2.add(new Student(101 + i, "大哥", 20 + i));
        }
        Grade grade2 = new Grade(100001, "first", list2);
        Gson gson2 = new Gson();
        String json = gson2.toJson(grade2);
        System.out.println(json);
    }

4、net.sf.json
json官方解析工具，最具有通用性。

		<dependency>
            <groupId>net.sf.json-lib</groupId>
            <artifactId>json-lib</artifactId>
            <version>2.4</version>
            <classifier>jdk15</classifier>
        </dependency>

	public static void main(String[] args) {
        String json = "{'id':1,'name':'first','stus':[{'id':101,'name':'刘一','age':16},{'id':102,'name':'刘二','age':23}]}";
        JSONObject jsonObject = JSONObject.fromObject(json);
        System.out.println(jsonObject);
        Map<String,Object> map = jsonObject;
        for (Map.Entry<String, Object> entry : map.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }

        Grade grade = new Grade();
        grade.setId(jsonObject.getInt("id"));
        grade.setName(jsonObject.getString("name"));
        ArrayList<Student> students = new ArrayList<>();
        grade.setStus(students);
        JSONArray stus = jsonObject.getJSONArray("stus");
        for (Object o : stus) {
            JSONObject jsonObject1 = JSONObject.fromObject(o);
            Student student = new Student(jsonObject1.getInt("id"), jsonObject1.getString("name"), jsonObject1.getInt("age"));
            grade.getStus().add(student);
        }
        System.out.println("grade: " + grade);

        JSONObject jsonObject2 = new JSONObject();
        jsonObject2.put("id", 100);
        jsonObject2.put("name", "大哥");
        jsonObject2.put("age", 30);
        JSONObject jsonObject3 = new JSONObject();
        jsonObject3.put("id", 102);
        jsonObject3.put("name", "二哥");
        jsonObject3.put("age", 10);
        JSONArray jsonArray = new JSONArray();
        jsonArray.add(jsonObject2);
        jsonArray.add(jsonObject3);
        System.out.println("jsonArray: " + jsonArray);
    }

二、在springboot开发中返回json的方式有jackson、gson、fastjson。
json是目前主流的前后端数据传输方式，轻量级的数据交换格式。
1、jackson
springboot工程添加web依赖时默认提供了jackson组件，不需添加额外的依赖。
在这里插入图片描述
实例

public class UserVO extends BaseVO {

    private static final long serialVersionUID = 1L;

    private long id;
    private String userName;
    private String name;
    ...
    @JsonFormat(pattern = "yyyy-MM-dd hh:mm:ss", timezone = "GMT+8")
    private Date createTime;
    ...
}

在实体类的属性上添加 @JsonFormat 注解可以实现时间类型的自定义格式。

	@RequestMapping(value = "/getUserPage", method = RequestMethod.POST)
    public Object getUserPage(@RequestBody  UserDTO params) throws ParamException {
        ...
        PageData<List<UserVO>> result = ***;
        return ResponseData.ok(result, "查询成功！");
    }

JSON的解析离不开 HttpMessageConvert接口，HttpMessageConvert是一个消息转换工具，主要有两方面的功能：将服务端返回的对象序列化成JSON字符串；将前端传来的JSON字符串反序列化成Java对象。
自定义MappingJackson2HttpMessageConverter类，删除 @JsonFormat注解，新建一个配置类

@Configuration
public class WebMVCConfig {
 
    @Bean
    MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter(){
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd"));
        converter.setObjectMapper(objectMapper);
        return converter;
    }
}

或自定义ObjectMapper类

@Configuration
public class WebMVCConfig {
 
    @Bean
    ObjectMapper objectMapper(){
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd"));
        return objectMapper;
    }
}

两种自定义的作用的是一样的。
2、gson
gson也在springboot工程中提供了自动化配置的，需要去掉spring-boot-starter-json依赖，然后引入gson依赖。

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-json</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
 
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
        </dependency>

自定义GsonHttpMessageConverter类

@Configuration
public class WebMVCConfig {
 
    @Bean
    GsonHttpMessageConverter gsonHttpMessageConverter(){
        GsonHttpMessageConverter converter=new GsonHttpMessageConverter();
        converter.setGson(new GsonBuilder().setDateFormat("yyyy-MM-dd").create());
        return converter;
    }
}

或自定义Gson类

@Configuration
public class WebMVCConfig {
 
    @Bean
    Gson gson() {
        return new GsonBuilder().setDateFormat("yyyy-MM-dd").create();
    }
}

3、fastjson
fastjson是阿里系的开源框架，需要引入第三方的依赖。

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-json</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
 
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.74</version>
        </dependency>

因为 SpringBoot没有提供相关的自动化配置类，所以我们需要手动创建 FastJson的消息转换工具类。

@Configuration
public class WebMVCConfig {
 
    @Bean
    FastJsonHttpMessageConverter fastJsonHttpMessageConverter() {
        FastJsonHttpMessageConverter converter = new FastJsonHttpMessageConverter();
        FastJsonConfig config = new FastJsonConfig();
        config.setDateFormat("yyyy-MM-dd HH:mm:ss");
        config.setCharset(Charset.forName("UTF-8"));
        config.setSerializerFeatures(
                SerializerFeature.WriteClassName,
                SerializerFeature.WriteMapNullValue,
                SerializerFeature.PrettyFormat,
                SerializerFeature.WriteNullListAsEmpty,
                SerializerFeature.WriteNullStringAsEmpty
        );
        converter.setFastJsonConfig(config);
        return converter;
    }
}

注意，不同的json解析组件对数据的处理是不一样的，如null或空值或时间的显示处理。