属性copy性能比较

两个bean之间有共同的属性，要实现相同属性间赋值，可以使用set，get，这种方法是最高效的。如果bean含有大量的属性，并且赋值，这样最写大量的get，set，代码不利于维护，PropertyUtils，BeanUtils，PropertyUtilsBean都提供了copyProperties方法，当然也可以自己通过反射来自己实现，各性能如下：

Student s1 = new Student();
		s1.setName("zhangsan");
		s1.setAge(26);
		s1.setBirthDay(new Date());
		Student s2 = new Student();
		long start = System.nanoTime();
		s2.setAge(s1.getAge());
		s2.setName(s1.getName());
		long end = System.nanoTime(); 
		System.out.println("set方法用时：" + (end - start));
		Student s3 = new Student();
		start = System.nanoTime();
		try{
			PropertyUtils.copyProperties(s3, s1);
		} catch (Exception e){
		}
		end = System.nanoTime();
		System.out.println("name=" + s3.getName() + ",age=" + s3.getAge() + ",date=" + s3.getBirthDay());
		System.out.println("propertyCopy方法用时：" + (end - start));  
		Student s4 = new Student();
		start = System.nanoTime();
		try{
			BeanUtils.copyProperties(s4, s1);     
		} catch (Exception e){
		}
		end = System.nanoTime();
		System.out.println("name=" + s4.getName() + ",age=" + s4.getAge() + ",date=" + s4.getBirthDay());    
		System.out.println("beanUtils方法用时：" + (end - start));   
		
		Student s5 = new Student();
		start = System.nanoTime();
		try{
			PropertyUtilsBean.class.newInstance().copyProperties(s5, s1);
		} catch (Exception e){
		}
		end = System.nanoTime();
		System.out.println("name=" + s5.getName() + ",age=" + s5.getAge() + ",date=" + s5.getBirthDay());       
		System.out.println("PropertyUtilsBean方法用时：" + (end - start));
		
		Student s6 = new Student();
		start = System.nanoTime();
		try{
			copyProperties(s6, s1);
		} catch (Exception e){
		}
		end = System.nanoTime();
		System.out.println("name=" + s6.getName() + ",age=" + s6.getAge() + ",date=" + s6.getBirthDay());       
		System.out.println("自己实现方法用时：" + (end - start));   

自己实现copy代码

public static Object copyProperties(Object dbInstance, Object bean) {
        Class klass = bean.getClass();
        Object obj = null;
        Method methods[] = klass.getMethods();
        for (int i = 0; i < methods.length; i++) {
            Method method = methods[i];
            String name = method.getName();
            String key = "";
            if (name.startsWith("get") && !name.equals("getClass")) {
                key = name.substring(3);
            } else {
                if (!name.startsWith("is")) {
                    continue;
                }
                key = name.substring(2);
            }
            try {
                obj = method.invoke(bean, new Object[]{});
            } catch (Exception e) {
            	e.printStackTrace();
            }
            if (obj != null
                    && !obj.getClass().getName().equals("java.util.HashSet")) {
                try {
                    for (int j = 0; j < methods.length; j++) {
                        if (!methods[j].getName().equals(
                                (new StringBuilder("set")).append(key)
                                        .toString())) {
                            continue;
                        }
                        Object objs[] = new Object[1];
                        objs[0] = obj;
                        methods[j].invoke(dbInstance, objs);
                        break;
                    }
                } catch (Exception e) {
                    key = name.substring(3);
                    for (int j = 0; j < methods.length; j++) {
                        if (!methods[j].getName().equals(
                                (new StringBuilder("set")).append(key)
                                        .toString())) {
                            continue;
                        }
                        Object objs[] = new Object[1];
                        objs[0] = obj;
                        try {
                            methods[j].invoke(dbInstance, objs);
                        } catch (Exception ex) {
                        	ex.printStackTrace();
                        }
                        break;
                    }
                }
            }
        }
        return dbInstance; 
    }

用时输出如下：

set方法用时：3642纳秒

INFO  2013-11-28 21:43:26,015 [main][] [cn.com.carsmart.util.configmanagement.ConfigUtil] - config reader type is set to default classpath loading way.
log4j:WARN unable to find the env.properties file
name=zhangsan,age=26,date=Thu Nov 28 21:43:25 CST 2013
propertyCopy方法用时：238577700纳秒
name=zhangsan,age=26,date=Thu Nov 28 21:43:25 CST 2013
beanUtils方法用时：792249纳秒
name=zhangsan,age=26,date=Thu Nov 28 21:43:25 CST 2013
PropertyUtilsBean方法用时：128124纳秒
name=zhangsan,age=26,date=Thu Nov 28 21:43:25 CST 2013

自己实现方法用时：60255纳秒

结论：对性能要求特别高的用set，get方法；只有简单属性的自己反射实现；对性能要求不太高，代码又便于维护的用PropertyUtilsBean的copyProperties方法。