springboot工程中json浅析_ldcaws_json springboot

网络投稿 02-07 1290

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。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。