Json字符串转换为Java对象和应用(使用fastjson工具类)
记录：468
场景：把Json字符串转换为Java对象。Java对象属性包括String、List、Map等类型。
版本：JDK 1.8,Spring Boot 2.6.3,fastjson-2.0.33。
JSON：JavaScript Object Notation(JavaScript 对象表示法)。
JSON语法规则：数据由名称/值对组成。数据由逗号","分隔。使用斜杆\来转义字符。大括号{}保存对象。中括号[]保存数组(或者List类型)，数组可以包含多个对象。
1.JSON字符串转换为JSONObject
1.1JSON字符串
{
"cityDescribe": "宁波是港口城市",
"cityId": 2023062802,
"cityName": "宁波",
"updateTime": "2023-07-16 13:15:40"
}1.2转换代码
public static void f1() {
String jsonStr = "{\n" +
" \"cityDescribe\": \"宁波是港口城市\",\n" +
" \"cityId\": 2023062802,\n" +
" \"cityName\": \"宁波\",\n" +
" \"updateTime\": \"2023-07-16 13:15:40\"\n" +
"}";
System.out.println("====================f1====================");
JSONObject obj = JSON.parseObject(jsonStr);
System.out.println(obj.get("cityId"));
System.out.println(obj.get("cityName"));
System.out.println(obj.get("cityDescribe"));
System.out.println(obj.get("updateTime"));
}2.JSON字符串转换为CityDto
2.1JSON字符串
{
"cityDescribe": "宁波是港口城市",
"cityId": 2023062802,
"cityName": "宁波",
"updateTime": "2023-07-16 13:15:40"
}2.2转换代码
public static void f2() {
String jsonStr = "{\n" +
" \"cityDescribe\": \"宁波是港口城市\",\n" +
" \"cityId\": 2023062802,\n" +
" \"cityName\": \"宁波\",\n" +
" \"updateTime\": \"2023-07-16 13:15:40\"\n" +
"}";
System.out.println("====================f2====================");
CityDto cityDto = JSON.parseObject(jsonStr, CityDto.class);
System.out.println(cityDto.getCityId());
System.out.println(cityDto.getCityName());
System.out.println(cityDto.getCityDescribe());
System.out.println(cityDto.getUpdateTime());
}2.3实体对象
@Data
@Builder
public class CityDto implements Serializable {
private Long cityId;
private String cityName;
private String cityDescribe;
private String updateTime;
}3.JSON字符串转换为CityObjectDto,对象属性中是一个对象
3.1JSON字符串
{
"cityObj": {
"cityName": "宁波",
"updateTime": "2023-07-16 13:15:40",
"cityId": 2023062802,
"cityDescribe": "宁波是港口城市"
}
}3.2转换代码
public static void f3() {
String jsonStr = "{\n" +
" \"cityObj\": {\n" +
" \t\"cityName\": \"宁波\",\n" +
" \t\"updateTime\": \"2023-07-16 13:15:40\",\n" +
" \t\"cityId\": 2023062802,\n" +
" \t\"cityDescribe\": \"宁波是港口城市\"\n" +
" }\n" +
"}";
System.out.println("====================f3====================");
CityObjectDto cityDto = JSON.parseObject(jsonStr, CityObjectDto.class);
System.out.println(cityDto.getCityObj().getCityId());
System.out.println(cityDto.getCityObj().getCityName());
System.out.println(cityDto.getCityObj().getCityDescribe());
System.out.println(cityDto.getCityObj().getCityDescribe());
}3.3实体对象
@Data
@Builder
public class CityObjectDto implements Serializable {
private CityDto cityObj;
}4.JSON字符串转换为Map
4.1JSON字符串
{
"cityDescribe": "宁波是港口城市",
"cityId": 2023062802,
"cityName": "宁波",
"updateTime": "2023-07-16 13:15:40"
}4.2转换代码
public static void f4() {
String jsonStr = "{\n" +
" \"cityDescribe\": \"宁波是港口城市\",\n" +
" \"cityId\": 2023062802,\n" +
" \"cityName\": \"宁波\",\n" +
" \"updateTime\": \"2023-07-16 13:15:40\"\n" +
"}";
System.out.println("====================f4====================");
Map mapObj = JSON.parseObject(jsonStr, Map.class);
System.out.println(mapObj.get("cityId"));
System.out.println(mapObj.get("cityName"));
System.out.println(mapObj.get("cityDescribe"));
System.out.println(mapObj.get("updateTime"));
}5.JSON字符串转换为CityMapDto,对象属性是一个Map类型
5.1JSON字符串
{
"cityMap": {
"cityName": "宁波",
"updateTime": "2023-07-16 13:15:40",
"cityId": 2023062802,
"cityDescribe": "宁波是港口城市"
}
}5.2转换代码
public static void f5() {
String jsonStr = "{\n" +
" \"cityMap\": {\n" +
" \t\"cityName\": \"宁波\",\n" +
" \t\"updateTime\": \"2023-07-16 13:15:40\",\n" +
" \t\"cityId\": 2023062802,\n" +
" \t\"cityDescribe\": \"宁波是港口城市\"\n" +
" }\n" +
"}";
System.out.println("====================f5====================");
CityMapDto cityMapDto = JSON.parseObject(jsonStr, CityMapDto.class);
System.out.println(cityMapDto.getCityMap().get("cityId"));
System.out.println(cityMapDto.getCityMap().get("cityName"));
System.out.println(cityMapDto.getCityMap().get("cityDescribe"));
System.out.println(cityMapDto.getCityMap().get("updateTime"));
}5.3实体对象
@Data
@Builder
public class CityMapDto implements Serializable {
private Map cityMap;
} 6.JSON字符串转换为List
6.1JSON字符串
[{
"cityDescribe": "杭州是互联网城市",
"cityId": 2023062801,
"cityName": "杭州",
"updateTime": "2023-07-16 13:15:40"
}, {
"cityDescribe": "宁波是港口城市",
"cityId": 2023062802,
"cityName": "宁波",
"updateTime": "2023-07-16 13:15:40"
}]6.2转换代码
public static void f6() {
String jsonStr = "[{\n" +
"\t\"cityDescribe\": \"杭州是互联网城市\",\n" +
"\t\"cityId\": 2023062801,\n" +
"\t\"cityName\": \"杭州\",\n" +
"\t\"updateTime\": \"2023-07-16 13:15:40\"\n" +
"}, {\n" +
"\t\"cityDescribe\": \"宁波是港口城市\",\n" +
"\t\"cityId\": 2023062802,\n" +
"\t\"cityName\": \"宁波\",\n" +
"\t\"updateTime\": \"2023-07-16 13:15:40\"\n" +
"}]";
System.out.println("====================f6====================");
List cityList = JSON.parseArray(jsonStr, CityDto.class);
cityList.forEach((cityDto) -> {
System.out.println(cityDto.getCityId());
System.out.println(cityDto.getCityName());
System.out.println(cityDto.getCityDescribe());
System.out.println(cityDto.getUpdateTime());
}
);
} 7.JSON字符串转换为CityListDto,对象属性是一个List类型
7.1JSON字符串
{
"cityList": [{
"cityDescribe": "杭州是互联网城市",
"cityId": 2023062801,
"cityName": "杭州",
"updateTime": "2023-07-16 13:15:40"
}, {
"cityDescribe": "宁波是港口城市",
"cityId": 2023062802,
"cityName": "宁波",
"updateTime": "2023-07-16 13:15:40"
}]
}7.2转换代码
public static void f7() {
String jsonStr = "{\n" +
"\t\"cityList\": [{\n" +
"\t\t\"cityDescribe\": \"杭州是互联网城市\",\n" +
"\t\t\"cityId\": 2023062801,\n" +
"\t\t\"cityName\": \"杭州\",\n" +
"\t\t\"updateTime\": \"2023-07-16 13:15:40\"\n" +
"\t}, {\n" +
"\t\t\"cityDescribe\": \"宁波是港口城市\",\n" +
"\t\t\"cityId\": 2023062802,\n" +
"\t\t\"cityName\": \"宁波\",\n" +
"\t\t\"updateTime\": \"2023-07-16 13:15:40\"\n" +
"\t}]\n" +
"}";
System.out.println("====================f7====================");
CityListDto cityListDto = JSON.parseObject(jsonStr, CityListDto.class);
List cityList = JSON.parseArray(cityListDto.getCityList().toString(), CityDto.class);
cityList.forEach((cityDto) -> {
System.out.println(cityDto.getCityId());
System.out.println(cityDto.getCityName());
System.out.println(cityDto.getCityDescribe());
System.out.println(cityDto.getUpdateTime());
}
);
} 7.3实体对象
@Data
@Builder
public class CityListDto implements Serializable {
private List cityList;
}8.复杂的JSON字符串转换为ProvinceDto,在对象中包含对象和List类型
8.1JSON字符串
{
"provinceName": "浙江省",
"areaNumber": "330000",
"data": {
"dataFlag": "01",
"cityData": {
"dataList": [{
"cityDescribe": "杭州是互联网城市",
"cityId": 2023062801,
"cityName": "杭州",
"updateTime": "2023-07-16 13:15:40"
}, {
"cityDescribe": "宁波是港口城市",
"cityId": 2023062802,
"cityName": "宁波",
"updateTime": "2023-07-16 13:15:40"
}]
}
}
}8.2转换代码
public static void f8() {
String jsonStr = "{\n" +
"\t\"provinceName\": \"浙江省\",\n" +
"\t\"areaNumber\": \"330000\",\n" +
"\t\"data\": {\n" +
"\t\t\"dataFlag\": \"01\",\n" +
"\t\t\"cityData\": {\n" +
"\t\t\t\"dataList\": [{\n" +
"\t\t\t\t\"cityDescribe\": \"杭州是互联网城市\",\n" +
"\t\t\t\t\"cityId\": 2023062801,\n" +
"\t\t\t\t\"cityName\": \"杭州\",\n" +
"\t\t\t\t\"updateTime\": \"2023-07-16 13:15:40\"\n" +
"\t\t\t}, {\n" +
"\t\t\t\t\"cityDescribe\": \"宁波是港口城市\",\n" +
"\t\t\t\t\"cityId\": 2023062802,\n" +
"\t\t\t\t\"cityName\": \"宁波\",\n" +
"\t\t\t\t\"updateTime\": \"2023-07-16 13:15:40\"\n" +
"\t\t\t}]\n" +
"\t\t}\n" +
"\t}\n" +
"}";
System.out.println("====================f8====================");
//1.解析JSON字符串(嵌套JSON对象逐层解析)
ProvinceDto provinceDto = JSON.parseObject(jsonStr, ProvinceDto.class);
DataDto data = JSON.parseObject(provinceDto.getData().toString(), DataDto.class);
CityDataDto cityData = JSON.parseObject(data.getCityData().toString(), CityDataDto.class);
List dataList = JSON.parseArray(cityData.getDataList().toString(), CityDto.class);
//2.解析完成后转换为Java对象
CityDataDto cityDataResult = CityDataDto.builder()
.dataList(dataList)
.build();
DataDto dataResult = DataDto.builder()
.dataFlag(data.getDataFlag())
.cityData(cityDataResult)
.build();
ProvinceDto provinceDtoResult = ProvinceDto.builder()
.provinceName(provinceDto.getProvinceName())
.areaNumber(provinceDto.getAreaNumber())
.data(dataResult)
.build();
//3.使用Java对象
System.out.println(provinceDtoResult.getProvinceName());
System.out.println(provinceDtoResult.getAreaNumber());
DataDto dataDtoApp = (DataDto) provinceDtoResult.getData();
System.out.println(dataDtoApp.getDataFlag());
CityDataDto cityDataDtoApp = (CityDataDto) dataDtoApp.getCityData();
List dataListApp = (List) cityDataDtoApp.getDataList();
dataListApp.forEach((cityDto) -> {
System.out.println(cityDto.getCityId());
System.out.println(cityDto.getCityName());
System.out.println(cityDto.getCityDescribe());
System.out.println(cityDto.getUpdateTime());
}
);
} 8.3实体对象
8.3.1Java对象ProvinceDto
(1)示例代码
@Data
@Builder
public class ProvinceDto implements Serializable {
private String provinceName;
private String areaNumber;
private T data;
} (2)解析代码
ProvinceDto对象对应Json字符串的provinceName、areaNumber、data属性。
8.3.2Java对象DataDto
(1)示例代码
@Data
@Builder
public class DataDto implements Serializable {
private String dataFlag;
private T cityData;
} (2)解析代码
DataDto对象对应JSON字符串的data属性的dataFlag、cityData属性。
8.3.3Java对象CityDataDto
(1)示例代码
@Data
@Builder
public class CityDataDto implements Serializable {
private T dataList;
} (2)解析代码
CityDataDto对象对应JSON字符串的data属性的cityData属性的dataList属性。
8.3.4Java对象CityDto
(1)示例代码
@Data
@Builder
public class CityDto implements Serializable {
private Long cityId;
private String cityName;
private String cityDescribe;
private String updateTime;
}2)解析代码
CityDto 对象对应JSON字符串的data属性的cityData属性的dataList属性的List中的对象。
以上，感谢。
2023年7月16日