JSON数据的几种解析方式_constructparametrictype

作者：我家自动化 | 2024-04-02 10:16:17

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constructparametrictype

对于简单的json字符串或者数组数据，可以用：JsonObject和JsonArray。

使用以上两种方式解析json均需要依赖json-lib.jar开发包使用依赖包。

1、如果只是一条简单的json数据，可以直接用JsonObject即可

使用JsonObject解析只有一条数据的json是非常方便的例如："{\"name\":\"zhangsan\",\"password\":\"zhangsan123\",\"email\":\"10371443@qq.com\"}"

public static void main(String[] args) {
String jsonString ="{\"name\":\"zhangsan\",\"password\":\"zhangsan123\",\"email\":\"10371443@qq.com\"}";
JSONObject json = JSONObject.fromObject(jsonString);
User user = new User();
user.setName(json.getString("name"));
user.setPassword(json.getString("password"));
user.setEmail(json.getString("email"));
System.out.println(user.toString());
}

2、如果是数组数据的json,用JsonArray比较合适

使用JsonArray解析数组数据的json是非常方便的例如："[{\"name\":\"zhangsan\",\"password\":\"zhangsan123\",\"email\":\"10371443@qq.com\"},{\"name\":\"lisi\",\"password\":\"lisi123\",\"email\":\"1435123@qq.com\"}]"

String json = "[{\"name\":\"zhangsan\",\"password\":\"zhangsan123\",\"email\":\"10371443@qq.com\"},{\"name\":\"lisi\",\"password\":\"lisi123\",\"email\":\"1435123@qq.com\"}]";
JSONArray jsonArray = JSONArray.fromObject(json);
ArrayList<User> users = new ArrayList<User>();
for (int i = 0; i < jsonArray.size(); i++) {
User userM = new User();
user.setName(jsonArray.getJSONObject(i).getString("name"));
user.setpassword(jsonArray.getJSONObject(i).getString("password"));
user.setEmail(jsonArray.getJSONObject(i).getString("email"));
users.add(user);
}
for (User user : users) {
System.out.println(user.toString());
}

3、对于复杂的json数据，需要借助jackson框架，先泛型转化，再readValue

Jackson处理一般的JavaBean和Json之间的转换只要使用ObjectMapper 对象的readValue和writeValueAsString两个方法就能实现。但是如果要转换复杂类型Collection如 List<YourBean>，那么就需要先反序列化复杂类型为泛型的Collection Type。

如果是ArrayList<YourBean>那么使用ObjectMapper 的getTypeFactory().constructParametricType(collectionClass, elementClasses);

如果是HashMap<String,YourBean>那么ObjectMapper

的getTypeFactory().constructParametricType(HashMap.class,String.class, YourBean.class);

实例简介一：

 
 jackjson 和 java对象的转化，先泛型化再readValue 

 
 String TaskStr =  
 getTaskListFile 
 (task,id, 
 false 
 ); 

 
 // 
 DeserializationFeature. 
 FAIL_ON_UNKNOWN_PROPERTIES 
 ,  
 false 
 ，避免在转化为class对象时，没有关联的 

 
 //属性匹配而报异常 

 
 objectMapper 
 .configure(DeserializationFeature. 
 FAIL_ON_UNKNOWN_PROPERTIES 
 ,  
 false 
 ); 

 
 //将TaskDO对象泛型化list---List<TaskDO> 

 
 JavaType TaskDOType =  
 objectMapper 
 .getTypeFactory().constructParametricType(ArrayList. 
 class 
 , TaskDO. 
 class 
 ); 

 
 //将List<TaskDO>泛型化Response<List<TaskDO>> 

 
 JavaType responseType =  
 objectMapper 
 .getTypeFactory().constructParametricType(Response. 
 class 
 , TaskDOType); 

 
 //最后将字符串，按Response<List<TaskDO>>这个类型，给转化 

 
 //成Response<List<TaskDO>> 

 
 Response<List<TaskDO>> response = (Response<List<TaskDO>>)  
 objectMapper 
 .readValue(TaskStr, responseType); 

实例详解二：

package com;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.List;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
/**
* jackson 复杂对象集合的几种简单转换
* @author lenovo
*
* @param <T>
*/
public class Main<T>
{
 static ObjectMapper mapper = new ObjectMapper();

 public static void main(String[] args) throws JsonParseException,
 JsonMappingException, IOException
 {

 String josn = "{\"UserID\":1,\"LoginName\":\"唐工\",\"Truename\":\"超级\",\"Nickname\":null,\"LoginPwd\":\"E10ADC3949BA59ABBE56E057F20F883E\",\"QQ\":\"\",\"Phone\":\"\",\"Email\":null,\"Remark\":\"\",\"Account_Non_Locked\":0,\"Telelephone\":null,\"IsDelete\":0}";
 User u = mapper.readValue(josn, User.class);
 // User u=new Main<User>().jsonStreamConverObject(josn, User.class);
 System.out.println("转对象:" + u);

 // 转集合
 String josn2 = "[{\"UserID\":1,\"LoginName\":\"唐工\",\"Truename\":\"超级\",\"Nickname\":null,\"LoginPwd\":\"E10ADC3949BA59ABBE56E057F20F883E\",\"QQ\":\"\",\"Phone\":\"\",\"Email\":null,\"Remark\":\"\",\"Account_Non_Locked\":0,\"Telelephone\":null,\"IsDelete\":0}]";
 JavaType javaType = mapper.getTypeFactory().constructParametricType(
 List.class, User.class);
 List<User> me = mapper.readValue(josn2, javaType);
 System.out.println("转集合me:" + me);

 // 对象里有集合转换
 String josn3 = "{\"UserID\":1,\"LoginName\":\"唐工\",\"Truename\":\"超级\",\"Nickname\":null,\"LoginPwd\":\"E10ADC3949BA59ABBE56E057F20F883E\",\"QQ\":\"\",\"Phone\":\"\",\"Email\":null,\"Remark\":\"\",\"Account_Non_Locked\":0,\"Telelephone\":null,\"IsDelete\":0,\"RoleList\":[{\"Roleid\":0,\"Name\":\"超级管理员\",\"Show_Name\":\"超级管理员\",\"Remark\":null,\"Type\":1}]}";

 User u3 = mapper.readValue(josn3, User.class); // 简单方式
 // User u3=new Main<User>().jsonConverObject(josn3, User.class); 流方式
 System.out.println("转对象里有集合u3:" + u3);

 // 集合对象集合转换
 String josn4 = "[{\"UserID\":1,\"LoginName\":\"唐工\",\"Truename\":\"超级\",\"Nickname\":null,\"LoginPwd\":\"E10ADC3949BA59ABBE56E057F20F883E\",\"QQ\":\"\",\"Phone\":\"\",\"Email\":null,\"Remark\":\"\",\"Account_Non_Locked\":0,\"Telelephone\":null,\"IsDelete\":0,\"RoleList\":[{\"Roleid\":0,\"Name\":\"超级管理员\",\"Show_Name\":\"超级管理员\",\"Remark\":null,\"Type\":1}]},{\"UserID\":2,\"LoginName\":\"唐工\",\"Truename\":\"超级\",\"Nickname\":null,\"LoginPwd\":\"E10ADC3949BA59ABBE56E057F20F883E\",\"QQ\":\"\",\"Phone\":\"\",\"Email\":null,\"Remark\":\"\",\"Account_Non_Locked\":0,\"Telelephone\":null,\"IsDelete\":0,\"RoleList\":[{\"Roleid\":0,\"Name\":\"超级管理员\",\"Show_Name\":\"超级管理员\",\"Remark\":null,\"Type\":1}]}]";
 JavaType javaType4 = mapper.getTypeFactory().constructParametricType(
 List.class, User.class);
 List<User> list = mapper.readValue(josn4, javaType4);
 System.out.println("集合里是对象对象里有集合转换:" + list);

 }

 /***
 * 转对象
 * @param josn
 * @param clz
 * @return
 */
 public T jsonStreamConverObject(String josn, Class<T> clz)
 {

 T t = null;
 // ObjectMapper jacksonMapper = new ObjectMapper();
 InputStreamReader in = new InputStreamReader(new ByteArrayInputStream(
 josn.getBytes()));
 BufferedReader streamReader = new BufferedReader(in);
 StringBuilder buff = new StringBuilder();
 String inputStr;
 try
 {
 while ((inputStr = streamReader.readLine()) != null)
 buff.append(inputStr);
 // ObjectMapper mapper = new ObjectMapper();
 t = mapper.readValue(buff.toString(), clz);

 } catch (IOException e)
 {

 e.printStackTrace();
 }

 return t;
 }

 /***
 * 转对象
 * @param josn
 * @param clz
 * @return
 */
 public T jsonConverObject(String josn, Class<T> clz)
 {

 T t = null;
 try
 {
 t = mapper.readValue(josn, clz);
 } catch (JsonParseException e)
 {
 e.printStackTrace();
 } catch (JsonMappingException e)
 {
 e.printStackTrace();
 } catch (IOException e)
 {
 e.printStackTrace();
 }

 return t;
 }

 /**
 * 转集合
 * @param josn
 * @param clz
 * @return
 */
 public List<T> jsonConverList(String josn, Class<T> clz)
 {

 List<T> me = null;
 try
 {
 // jacksonMapper
 // .disable(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES);
 // jacksonMapper.enableDefaultTyping();
 // jacksonMapper.setVisibility(JsonMethod.FIELD,JsonAutoDetect.Visibility.ANY);
 // jacksonMapper.configure(SerializationConfig.Feature.INDENT_OUTPUT,
 // false);//格式化
 // jacksonMapper.setSerializationInclusion(JsonSerialize.Inclusion.NON_NULL);
 // jacksonMapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS,
 // false);

 JavaType javaType = mapper.getTypeFactory()
 .constructParametricType(List.class, clz);// clz.selGenType().getClass()

 me = mapper.readValue(josn, javaType);
 } catch (JsonParseException e)
 {
 e.printStackTrace();
 } catch (JsonMappingException e)
 {
 e.printStackTrace();
 } catch (IOException e)
 {
 e.printStackTrace();
 }

 return me;
 }
}

/**
* output:
* 转对象:User [UserID=1, LoginName=唐工, Truename=超级, Nickname=null, LoginPwd=E10ADC3949BA59ABBE56E057F20F883E, QQ=, Phone=, Email=null, Remark=, Account_Non_Locked=0, Telelephone=null, Indate=null, IsDelete=0, RoleList=null]
* 转集合me:[User [UserID=1, LoginName=唐工, Truename=超级, Nickname=null, LoginPwd=E10ADC3949BA59ABBE56E057F20F883E, QQ=, Phone=, Email=null, Remark=, Account_Non_Locked=0, Telelephone=null, Indate=null, IsDelete=0, RoleList=null]]
* 转对象里有集合u3:User [UserID=1, LoginName=唐工, Truename=超级, Nickname=null, LoginPwd=E10ADC3949BA59ABBE56E057F20F883E, QQ=, Phone=, Email=null, Remark=, Account_Non_Locked=0, Telelephone=null, Indate=null, IsDelete=0, RoleList=[Role [Roleid=0, Name=超级管理员, Show_Name=超级管理员, Remark=null, Type=1]]]
* 集合里是对象对象里有集合转换:[User [UserID=1, LoginName=唐工, Truename=超级, Nickname=null, LoginPwd=E10ADC3949BA59ABBE56E057F20F883E, QQ=, Phone=, Email=null, Remark=, Account_Non_Locked=0, Telelephone=null, Indate=null, IsDelete=0, RoleList=[Role [Roleid=0, Name=超级管理员, Show_Name=超级管理员, Remark=null, Type=1]]], User [UserID=2, LoginName=唐工, Truename=超级, Nickname=null, LoginPwd=E10ADC3949BA59ABBE56E057F20F883E, QQ=, Phone=, Email=null, Remark=, Account_Non_Locked=0, Telelephone=null, Indate=null, IsDelete=0, RoleList=[Role [Roleid=0, Name=超级管理员, Show_Name=超级管理员, Remark=null, Type=1]]]]

* */

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