目标

实现 Json 字符串和类的相互转换

开发环境

使用 fastjson，gson

pom.xml 引用

<properties>
    <fastjson.version>1.2.38</fastjson.version>
    <gson.version>2.8.5</gson.version>
</properties>
<dependencies>
    <!--Fastjson是一个Java语言编写的高性能功能完善的JSON库。它采用一种“假定有序快速匹配”的算法，把JSON Parse的性能提升到极致，是目前Java语言中最快的JSON库-->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>${fastjson.version}</version>
    </dependency>    
        <!-- 用于日志切面中，以 json 格式打印出入参（本来使用阿里的 FASTJSON, 但是对于文件上传的接口，打印参数会报错，换为 Gson） -->
     <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>${gson.version}</version>
    </dependency>
</dependencies>
</dependencies>

代码

1.测试类

package com.test.invoice.data;
import com.alibaba.fastjson.annotation.JSONField;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
import lombok.experimental.Accessors;
/**
 * TRbtTestData 参数类
 *
 * @author:
 * @version:
 * @date: 2019-08-09 08:57
 */
@Data
@Accessors(chain = true) //@Accessors 注解用来配置lombok如何产生和显示getters和setters的方法。
public class TRbtTestData {
    @ApiModelProperty("id")
    @JSONField(name = "id")
    private String id;
    @ApiModelProperty("名称")
    @JSONField(name = "name")
    private String name;
    @ApiModelProperty("版本号")
    @JSONField(name = "version")
    private String version;
}

2.转换代码

/**
 * ClassToJson
 * @param data TRbtTestData
 * @param convertType 1:使用 GSON 转换，2:使用 alibaba.fastjson 转换
 * @return JsonString
 */
@PostMapping("/Test/ClassToJson")
@ApiOperation(value = "类转 Json",httpMethod = "POST",response = ResponseVO.class,notes="类转 Json")
public ResponseVO ClassToJson(@RequestBody TRbtTestData data,@RequestParam(value="convertType",required = true) String convertType)
{
    ResponseVO responseVO = new ResponseVO<String>();
    if (convertType.equals("1")){
        GsonBuilder builder = new GsonBuilder();
        Gson gson = builder.create();
        responseVO.setData(gson.toJson(data));
    }else if (convertType.equals("2")){
        responseVO.setData(JSON.toJSONString(data));
    }
    responseVO.setCode(ResponseCode.OK.value());
    return responseVO;
}
/**
 *  JsonToClass
 * @param data String
 * @param convertType 1:使用 GSON 转换，2:使用 alibaba.fastjson 转换
 * @return Class
 */
@PostMapping("/Test/JsonToClass")
@ApiOperation(value = "Json 转类",httpMethod = "POST",response = ResponseVO.class,notes="Json 转类")
public ResponseVO JsonToClass(@RequestBody String data,@RequestParam(value = "convertType",required = true) String convertType){
    ResponseVO responseVO = new ResponseVO<TRbtTestData>();
    if (convertType.equals("1")){
        GsonBuilder builder = new GsonBuilder();
        Gson gson = builder.create();
        responseVO.setData(gson.fromJson(data,TRbtTestData.class));
    }else if (convertType.equals("2")){
        responseVO.setData(JSON.parseObject(data,TRbtTestData.class));
    }
    responseVO.setCode(ResponseCode.OK.value());
    return responseVO;
}

测试

1.类转 Json

2.Json 转换为类

扩展-Json 转 List 对象

String jsonStr = configService.get("bg_list").getSysValue();
List<ListVO> listData =   JSON.parseArray(jsonStr,ListVO.class);

获取 Json 字符串中指定的属性值

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.JSONPath;
public static void main(String[] args){
    String data_toKenCompanyInfoVo="{\"accountNo\":\"000001\",\"openId\":\"000002\"}";
    JSONObject jsonObject = JSON.parseObject(data_toKenCompanyInfoVo);
    String accountNo = JSONPath.eval(jsonObject,"$.accountNo").toString();
    String openId = JSONPath.eval(jsonObject,"openId").toString();
    log.info("accountNo："+accountNo);
    log.info("openId："+openId);
}

输出

accountNo：000001
openId：000002

使用 ObjectMapper

//对象转json字符串
public static String convertToJson(Object obj, boolean enableNull) {
    ObjectMapper mapperJson = new ObjectMapper();
    //mapperJson.setSerializationInclusion(JsonInclude.Include.NON_NULL);
    //mapperJson.setSerializationInclusion(JsonInclude.Include.NON_DEFAULT);
    if (!enableNull) {
        mapperJson.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
    }
    SerializationConfig config = mapperJson.getSerializationConfig().without(
            MapperFeature.AUTO_DETECT_CREATORS,
            MapperFeature.AUTO_DETECT_SETTERS,
            MapperFeature.AUTO_DETECT_GETTERS,
            MapperFeature.AUTO_DETECT_IS_GETTERS);
    mapperJson.setConfig(config);
    mapperJson.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);
    String dataJson = null;
    try {
        dataJson = mapperJson.writeValueAsString(obj);
    } catch (JsonProcessingException e) {
        e.printStackTrace();
    }
    return dataJson;
}
//json 转对象
public static <T> T convertToObject(String json, TypeReference<T> typeRef, boolean isHaveTime) {
    T t = null;
    try {
        ObjectMapper objectMapper = new ObjectMapper();
        String pattern = "yyyy/MM/dd";
        if (isHaveTime) {
            pattern = "yyyy/MM/dd HH:mm:ss";
        }
        objectMapper.setDateFormat(new SimpleDateFormat(pattern));
        //解决反序列化时json字段比实体字段多的问题
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        //忽略大小写
        objectMapper.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true);
        t = objectMapper.readValue(json, typeRef);
    } catch (Exception e) {
        log.error("convertToObject >>> deserialize fail:", e);
    }
    return t;
}
@Data
public static class Student{
    private Integer id;
    private String name;
}
public static void main(String[] args) {
    try{
        Student student = new Student();
        student.setId(1);
        student.setName("name-1");
        String json = convertToJson(student,false);
        System.out.println(json);
        Student student1 = convertToObject(json, new TypeReference<Student>() {},true);
        System.out.println(student1.getId());
        System.out.println(student1.getName());
    }catch(Exception e){}
}

输出

{"id":1,"name":"name-1"}
1
name-1