java对象属性复制

经常我们需要将两个java对象的属性进行复制，spring框架已经给我们提供了很好的工具：org.springframework.beans.BeanUtils

复制属性我们就用里面的copyProperties(Object source,Object target)

下面我们分析一下源代码：

值得注意的是，在使用这个工具类的时候，如果两个对象某个属性名字一样，但类型不一样，就会报错，如下：

package com.creditease.mobile.utils;

import org.springframework.beans.BeanUtils;

class A{
	private int aaa;
	private Integer bbb;
	private int ccc;
	public int getAaa() {
		return aaa;
	}

	public void setAaa(int aaa) {
		this.aaa = aaa;
	}

	public Integer getBbb() {
		return bbb;
	}

	public void setBbb(Integer bbb) {
		this.bbb = bbb;
	}

	public int getCcc() {
		return ccc;
	}

	public void setCcc(int ccc) {
		this.ccc = ccc;
	}
	
}
class B{
	private int aaa;
	private Integer bbb;
	private String ccc;
	public int getAaa() {
		return aaa;
	}

	public void setAaa(int aaa) {
		this.aaa = aaa;
	}

	public Integer getBbb() {
		return bbb;
	}

	public void setBbb(Integer bbb) {
		this.bbb = bbb;
	}

	public String getCcc() {
		return ccc;
	}

	public void setCcc(String ccc) {
		this.ccc = ccc;
	}
	
}
public class AAAAAA {
	public static void main(String[] args) {
		A a = new A();
		a.setAaa(12);
		a.setBbb(24);
		a.setCcc(123);
		B b = new B();
		BeanUtils.copyProperties(a, b);
		System.out.println(a.getAaa()+","+b.getAaa());
		System.out.println(a.getBbb()+","+b.getBbb());
		System.out.println(a.getCcc()+","+b.getCcc());
		
	}
}

执行结果：

Exception in thread "main" org.springframework.beans.FatalBeanException: Could not copy properties from source to target; nested exception is java.lang.IllegalArgumentException: argument type mismatch
	at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:621)
	at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:531)
	at com.creditease.mobile.utils.AAAAAA.main(AAAAAA.java:70)
Caused by: java.lang.IllegalArgumentException: argument type mismatch
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:618)
	... 2 more

这里我们尝试将A对象中int类型的ccc字段复制给B对象中String类型的ccc字段，就会报type mismatch，这一点在使用的时候要特别留意。