Java的Jackson库中复杂对象集合的几种简单转换

话不多说，请看代码：

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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