“项目中经常要用到Bean之间的属性复制，本文主要介绍了几种常见的Bean拷贝工具以及几种在Bean拷贝过程中根据需要实现Bean字段类型转换的方法。”
项目中经常要用到Bean之间的属性复制，如果自己使用 set 方法逐个设值，不仅运行效率低，如果用到的地方很多，代码维护也很困难。实际上，已经有很多可以完成 Bean 属性复制的工具。本文就来重点讨论一下。本文主要包括以下内容:
- 选择哪个框架的Bean工具效率最高
- 封装springBean工具自定义copyBeanProperties实现Bean拷贝
- apacheBean工具实现时间类字段向字符串字段拷贝
- apacheBean工具自定义Converter实现Bean拷贝
哪个BeanUtils效率最高
当前有很多用于Bean拷贝的BeanBeanUtisl工具类，常见的主要有
- Spring BeanUtils
- Cglib BeanCopier
- Apache BeanUtils
- Apache PropertyUtils
class BeanUtilsTestDemo {
public static void main(String[] args)
throws InvocationTargetException, IllegalAccessException, NoSuchMethodException {
Person person = Person.builder().id("123456789").name("zhang san").age(18).dept("cloud bu").build();
StringUtils.printHr();
cglibBeanCopier(person, 100);
cglibBeanCopier(person, 1000);
cglibBeanCopier(person, 10000);
cglibBeanCopier(person, 100000);
cglibBeanCopier(person, 1000000);
StringUtils.printHr();
apachePropertyUtils(person, 100);
apachePropertyUtils(person, 1000);
apachePropertyUtils(person, 10000);
apachePropertyUtils(person, 100000);
apachePropertyUtils(person, 1000000);
StringUtils.printHr();
apacheBeanUtils(person, 100);
apacheBeanUtils(person, 1000);
apacheBeanUtils(person, 10000);
apacheBeanUtils(person, 100000);
apacheBeanUtils(person, 1000000);
StringUtils.printHr();
springBeanUtils(person, 100);
springBeanUtils(person, 1000);
springBeanUtils(person, 10000);
springBeanUtils(person, 100000);
springBeanUtils(person, 1000000);
}
public static void cglibBeanCopier(Person person, int times) {
StopTimer stopwatch = new StopTimer();
stopwatch.start();
for (int i = 0; i times; i++) {
PersonCopy personCopy = new PersonCopy();
BeanCopier copier = BeanCopier.create(Person.class, PersonCopy.class, false);
copier.copy(person, personCopy, null);
}
stopwatch.stop();
System.out.println("cglibBeanCopier cost :" + stopwatch.getTotalTimeMillis());
}
public static void apachePropertyUtils(Person person, int times)
throws InvocationTargetException, IllegalAccessException, NoSuchMethodException {
StopTimer stopwatch = new StopTimer();
stopwatch.start();
for (int i = 0; i times; i++) {
PersonCopy personCopy = new PersonCopy();
PropertyUtils.copyProperties(personCopy, person);
}
stopwatch.stop();
System.out.println("apachePropertyUtils cost :" + stopwatch.getTotalTimeMillis());
}
public static void apacheBeanUtils(Person person, int times)
throws InvocationTargetException, IllegalAccessException {
StopTimer stopwatch = new StopTimer();
stopwatch.start();
for (int i = 0; i times; i++) {
PersonCopy personCopy = new PersonCopy();
BeanUtils.copyProperties(personCopy, person);
}
stopwatch.stop();
System.out.println("apacheBeanUtils cost :" + stopwatch.getTotalTimeMillis());
}
public static void springBeanUtils(Person person, int times) {
StopTimer stopwatch = new StopTimer();
stopwatch.start();
for (int i = 0; i times; i++) {
PersonCopy personCopy = new PersonCopy();
org.springframework.beans.BeanUtils.copyProperties(person, personCopy);
}
stopwatch.stop();
System.out.println("springBeanUtils cost :" + stopwatch.getTotalTimeMillis());
}
}
2c4g配置下，对 bean 做 100,1000,10000,100000,,1000000 次复制，耗费时间如下
---------------------
cglibBeanCopier cost :90
cglibBeanCopier cost :5
cglibBeanCopier cost :15
cglibBeanCopier cost :48
cglibBeanCopier cost :51
---------------------
apachePropertyUtils cost :414
apachePropertyUtils cost :88
apachePropertyUtils cost :431
apachePropertyUtils cost :2719
apachePropertyUtils cost :27991
---------------------
apacheBeanUtils cost :3
apacheBeanUtils cost :27
apacheBeanUtils cost :268
apacheBeanUtils cost :2698
apacheBeanUtils cost :28819
---------------------
springBeanUtils cost :47
springBeanUtils cost :0
springBeanUtils cost :0
springBeanUtils cost :15
springBeanUtils cost :47
结论:
从测试结果看，如果效率上考虑，应尽量使用 springBeanUtils 和 cglibBeanCopier, 避免使用 apachePropertyUtils 和 apacheBeanUtils。
封装springBean工具自定义copyBeanProperties实现Bean拷贝
对于 org.springframework.beans.copyProperties 未实现的功能可以自定义copyBeanProperties方法完成属性赋值，如使用自定义方式完成 java.sql.Timestamp向字符串转换.
/**
* Bean 复制属性值
*
* @param source 源对象：属性值的来源
* @param target 目标对象：被赋值的对象
* @throws ReflectiveOperationException 反射异常
*/
public static void copyBeanProperties(Object source, Object target) throws ReflectiveOperationException {
BeanUtils.copyProperties(source, target);
Class classtyType = source.getClass();
Field[] fields = classtyType.getDeclaredFields();
for (Field field : fields) {
if (field.getType().equals(Timestamp.class)) {
field.setAccessible(true);
Object value = field.get(source);
if (value != null) {
long stampValue = ((Timestamp) value).getTime();
Field f = target.getClass().getDeclaredField(field.getName());
f.setAccessible(true);
f.set(target, String.valueOf(stampValue));
}
}
}
}
测试代码
/**
* 基于 springBeanUtils 改造的 Bean 工具
*
* @throws ReflectiveOperationException
*/
private static void surperSpringBeanUtilTest() throws ReflectiveOperationException {
//springBeanUtils
Address1 addr3 = new Address1("beijing", new Date(1596470797498L));
Address2 addr4 = new Address2();
BeanUtil.copyBeanProperties(addr3, addr4);//addr3 是 target , addr2 是source
System.out.println(addr3);
System.out.println(addr4);
}
结果
Person{id='12', name='WangZhi', age=19, dept='TEG', birthday='20010804130907'}
PersonCopy{id='12', name='WangZhi', age=19, dept='TEG', birthday=Sat Aug 04 13:09:07 CST 2001}
apacheBean工具实现时间类字段向字符串字段拷贝
org.springframework.beans.copyProperties 使用 SqlDateConverter 实现时间类字段向字符串字段拷贝
测试代码
/**
* 基于 apacheBean 工具从 Date 字段的Bean复制到 String 字段的Bean
*
* @throws InvocationTargetException
* @throws IllegalAccessException
*/
private static void apacheBeanCopyFromDate2String() throws InvocationTargetException, IllegalAccessException {
// apacheBeanUtils
Address1 addr1 = new Address1("wuhan", new Date(1596470787498L));
Address2 addr2 = new Address2();
ConvertUtils.register(new SqlDateConverter(), String.class);
//addr1 是 source , addr2 是 target
org.apache.commons.beanutils.BeanUtils.copyProperties(addr2, addr1);
System.out.println(addr1);
System.out.println(addr2);
//springBeanUtils
Address1 addr3 = new Address1("beijing", new Date(1596470797498L));
Address2 addr4 = new Address2();
//addr3 是 target , addr2 是source
org.springframework.beans.BeanUtils.copyProperties(addr3, addr4);
System.out.println(addr3);
System.out.println(addr4);
}
结果
Address1{city='wuhan', createAt=2020-08-04}
Address2{city='wuhan', createAt='2020-08-04'}
Address1{city='beijing', createAt=2020-08-04}
Address2{city='beijing', createAt='null'}
apacheBean工具自定义Converter实现Bean拷贝
当遇到 springframework Bean工具实现的功能不满足需求时，使用反射方式在 springframework Bean工具外面封装了一层，而对 apacheBean工具可以直接扩展其功能，使用起来更方便。
具体方式为 使用 org.apache.commons.beanutils.BeanUtils.copyProperties 自定义的Converter类进行类型转换。
CustomerDateConverter.java
import java.text.ParseException;
import java.text.SimpleDateFormat;
import org.apache.commons.beanutils.Converter;
public class CustomerDateConverter implements Converter {
//根据传来的时间字符串格式：例如：20130224201210
private final static SimpleDateFormat DATE_FORMATE_SHOW = new SimpleDateFormat("yyyyMMddHHmmss");
public Object convert(Class type, Object value){
if (type.equals(java.util.Date.class) ) {
try {
return DATE_FORMATE_SHOW.parse(value.toString());
} catch (ParseException e) {
e.printStackTrace();
}
}
return null;
}
}
测试代码
/**
* 基于 apacheBean 工具从 String 字段的Bean复制到 Date 字段的Bean
* @throws InvocationTargetException
* @throws IllegalAccessException
*/
private static void apacheBeanCopyFromString2Date() throws InvocationTargetException, IllegalAccessException {
Person p1 = new Person("12", "WangZhi", 19, "TEG", "20010804130907");
PersonCopy p2 = new PersonCopy();
CustomerDateConverter dateConverter = new CustomerDateConverter();
ConvertUtils.register(dateConverter, java.util.Date.class);
org.apache.commons.beanutils.BeanUtils.copyProperties(p2, p1);
System.out.println(p1);
System.out.println(p2);
}
结果
Person{id='12', name='WangZhi', age=19, dept='TEG', birthday='20010804130907'}
PersonCopy{id='12', name='WangZhi', age=19, dept='TEG', birthday=Sat Aug 04 13:09:07 CST 2001}
总结
本文主要介绍了几种常见的Bean拷贝工具: Spring BeanUtils、Cglib BeanCopier、Apache BeanUtils、Apache PropertyUtils。通过示例实验发现，springBeanUtils 和 cglibBeanCopier 的效率更高，因此如果要拷贝的Bean数量较多，应首先考虑这两个工具。
另外本文也介绍了几种在Bean拷贝过程中根据需要实现Bean字段类型转换的方法，尤其是封装springBean工具自定义copyBeanProperties实现Bean拷贝 和 使用apacheBean工具自定义Converter实现Bean拷贝两种方法在实际开发中十分有用。
本文代码: https://gitee.com/sifangcloud/mavensample/blob/master/src/main/java/dev/utils/demos/BeanUtilsTestDemo.java
参考资料
[1]org.apache.commons.beanutils.BeanUtils 使用自定义的Converter类进行类型转换: https://blog.csdn.net/imonHu/article/details/77772745
org.springframework.beans.BeanUtils 与 org.apache.commons.beanutils.BeanUtils 使用对比: http://www.manongzj.com/blog/3-ouxecnltwenfrgs.html
end
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