Java【BeanUtils】Map与Bean的映射

Apache BeanUtils

• 深拷贝与浅拷贝
• Apache BeanUtils常用的三个方法
  • copyProperties(Object to, Object from):void
  • deacribe(Object bean):Map
  • populate(Object bean, Map):void

一&＃xff1a;深拷贝与浅拷贝

相关文章&＃xff1a;Java - 【序列化】序列化与克隆

测试用例&＃xff1a;

import java.io.*;public class Test {public static void main(String[] args) throws CloneNotSupportedException, IOException, ClassNotFoundException {String name &＃61; "小明";String gender &＃61; "男";int age &＃61; 10;String[] cards &＃61; new String[]{"建设银行","中国银行"};Person p1 &＃61; new Person(name,gender,age,cards);Person p2 &＃61; (Person) p1.clone();System.out.println(p1);System.out.println(p2);age &＃61; 20;System.out.println(p1);System.out.println(p2);name &＃61; "大明";System.out.println(p1);System.out.println(p2);cards[0] &＃61; null;System.out.println(p1);System.out.println(p2);/* 深克隆 */Person p3 &＃61; (Person) deepClone(p1);System.out.println(p3);cards[0] &＃61; "建设银行";System.out.println(p3);}/*** 深克隆测试方法* &＃64;param from* &＃64;return 克隆出的新对象* &＃64;throws IOException* &＃64;throws ClassNotFoundException*/public static Object deepClone(Object from) throws IOException, ClassNotFoundException {ByteArrayOutputStream baos &＃61; new ByteArrayOutputStream();ObjectOutputStream oos &＃61; new ObjectOutputStream(baos);oos.writeObject(from);ByteArrayInputStream bais &＃61; new ByteArrayInputStream(baos.toByteArray());ObjectInputStream ois &＃61; new ObjectInputStream(bais);return ois.readObject();}
}


二&＃xff1a;Apache BeanUtils常用的三个方法

• copyProperties(Object to, Object from):void
  • property 属性n
• describe(Object bean):Map
  • describe 描述vt
• populate(Object bean, Map):void
  • populate : 填充vt

→ 附加 : BeanUtils中的copyProperties(Object to, Object from) 是浅拷贝&＃xff0c;但是和一般使用clone()造成的浅克隆有部分差异&＃xff1b;

• copyProperties() 浅克隆会对数组进行完整克隆&＃xff0c;但是引用类型不进行克隆&＃xff1b;
• clone() 浅克隆不会对数组进行克隆&＃xff0c;同时也不会对引用类型进行克隆。
  

Test.java

import org.apache.commons.beanutils.BeanUtils;import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.Map;public class Test {public static void main(String[] args) throws InvocationTargetException, IllegalAccessException, NoSuchMethodException {// 1. 获取一个MapMap<String,Object> map &＃61; new HashMap<>();map.put("name","小明");map.put("GenDer","男");map.put("age",18);String[] hobby &＃61; {"篮球", "足球", "羽毛球"};map.put("hobby",hobby);// 2. 将map映射到JavaBean中: populate(Object bean, Map):void// 2.1 映射默认忽略大小写// 2.2 只对map中匹配的键值完成映射&＃xff0c;否则填充nullUser user1 &＃61; new User();BeanUtils.populate(user1,map);System.out.println(user1);// 3. 将JavaBean映射到map中: deacribe(Object bean):Map// 3.1 注意这里的Map, 键值的类型都是String&＃xff0c;这可能直接导致Bean中的数组出现转换异常的问题Map<String,String> map1 &＃61; BeanUtils.describe(user1);System.out.println(map1);// 4. JavaBean的拷贝: copyProperties(Object to, Object from):void ---->>>> 浅拷贝Temp temp &＃61; new Temp();temp.setTemp1(new Temp1("temp1-hello"));user1.setTemp(temp);User user2 &＃61; new User();BeanUtils.copyProperties(user2,user1);System.out.println(user2);hobby[1] &＃61; "???";temp.setA("AAA");temp.setTemp1(new Temp1("temp1_world"));System.out.println(user2);}
}


User.java

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.RequiredArgsConstructor;&＃64;Data
&＃64;RequiredArgsConstructor
&＃64;AllArgsConstructor
public class User {private String name;private String gender;private Integer age;private String[] hobby;private Temp temp;
}


Temp.java

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.RequiredArgsConstructor;&＃64;Data
&＃64;RequiredArgsConstructor
&＃64;AllArgsConstructor
public class Temp {private String a;private String b;private Temp1 temp1;
}


Temp1.java

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.RequiredArgsConstructor;&＃64;Data
&＃64;RequiredArgsConstructor
&＃64;AllArgsConstructor
public class Temp1 {private String temp1Value;
}