java 对象之间属性值复制

Java对象之间属性值复制在许多开源框架中也有实现，在这里介绍下自己的实现、apache commons-beanutils、spring三种方式实现。

1 自己实现。采用反射，通过源对象getter 方法获取属性值，并通过目标对象的setter方法设置到目标对象中去。没有考虑太多性能，如果需要批量或者经常性执行该操作，建议不采用此种实现。下面给出源码：

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print?

1. /** 
2.      * 利用反射实现对象之间属性复制 
3.      * @param from 
4.      * @param to 
5.      */  
6.     public static void copyProperties(Object from, Object to) throws Exception {  
7.         copyPropertiesExclude(from, to, null);  
8.     }  
9.       
10.     /** 
11.      * 复制对象属性 
12.      * @param from 
13.      * @param to 
14.      * @param excludsArray 排除属性列表 
15.      * @throws Exception 
16.      */  
17.     @SuppressWarnings("unchecked")  
18.     public static void copyPropertiesExclude(Object from, Object to, String[] excludsArray) throws Exception {  
19.         List<String> excludesList = null;  
20.         if(excludsArray != null && excludsArray.length > 0) {  
21.             excludesList = Arrays.asList(excludsArray); //构造列表对象  
22.         }  
23.         Method[] fromMethods = from.getClass().getDeclaredMethods();  
24.         Method[] toMethods = to.getClass().getDeclaredMethods();  
25.         Method fromMethod = null, toMethod = null;  
26.         String fromMethodName = null, toMethodName = null;  
27.         for (int i = 0; i < fromMethods.length; i++) {  
28.             fromMethod = fromMethods[i];  
29.             fromMethodName = fromMethod.getName();  
30.             if (!fromMethodName.contains("get"))  
31.                 continue;  
32.             //排除列表检测  
33.             if(excludesList != null && excludesList.contains(fromMethodName.substring(3).toLowerCase())) {  
34.                 continue;  
35.             }  
36.             toMethodName = "set" + fromMethodName.substring(3);  
37.             toMethod = findMethodByName(toMethods, toMethodName);  
38.             if (toMethod == null)  
39.                 continue;  
40.             Object value = fromMethod.invoke(from, new Object[0]);  
41.             if(value == null)  
42.                 continue;  
43.             //集合类判空处理  
44.             if(value instanceof Collection) {  
45.                 Collection newValue = (Collection)value;  
46.                 if(newValue.size() <= 0)  
47.                     continue;  
48.             }  
49.             toMethod.invoke(to, new Object[] {value});  
50.         }  
51.     }  
52.       
53.     /** 
54.      * 对象属性值复制，仅复制指定名称的属性值 
55.      * @param from 
56.      * @param to 
57.      * @param includsArray 
58.      * @throws Exception 
59.      */  
60.     @SuppressWarnings("unchecked")  
61.     public static void copyPropertiesInclude(Object from, Object to, String[] includsArray) throws Exception {  
62.         List<String> includesList = null;  
63.         if(includsArray != null && includsArray.length > 0) {  
64.             includesList = Arrays.asList(includsArray); //构造列表对象  
65.         } else {  
66.             return;  
67.         }  
68.         Method[] fromMethods = from.getClass().getDeclaredMethods();  
69.         Method[] toMethods = to.getClass().getDeclaredMethods();  
70.         Method fromMethod = null, toMethod = null;  
71.         String fromMethodName = null, toMethodName = null;  
72.         for (int i = 0; i < fromMethods.length; i++) {  
73.             fromMethod = fromMethods[i];  
74.             fromMethodName = fromMethod.getName();  
75.             if (!fromMethodName.contains("get"))  
76.                 continue;  
77.             //排除列表检测  
78.             String str = fromMethodName.substring(3);  
79.             if(!includesList.contains(str.substring(0,1).toLowerCase() + str.substring(1))) {  
80.                 continue;  
81.             }  
82.             toMethodName = "set" + fromMethodName.substring(3);  
83.             toMethod = findMethodByName(toMethods, toMethodName);  
84.             if (toMethod == null)  
85.                 continue;  
86.             Object value = fromMethod.invoke(from, new Object[0]);  
87.             if(value == null)  
88.                 continue;  
89.             //集合类判空处理  
90.             if(value instanceof Collection) {  
91.                 Collection newValue = (Collection)value;  
92.                 if(newValue.size() <= 0)  
93.                     continue;  
94.             }  
95.             toMethod.invoke(to, new Object[] {value});  
96.         }  
97.     }  
98.       
99.       
100.   
101.     /** 
102.      * 从方法数组中获取指定名称的方法 
103.      *  
104.      * @param methods 
105.      * @param name 
106.      * @return 
107.      */  
108.     public static Method findMethodByName(Method[] methods, String name) {  
109.         for (int j = 0; j < methods.length; j++) {  
110.             if (methods[j].getName().equals(name))  
111.                 return methods[j];  
112.         }  
113.         return null;  
114.     }  

/** * 利用反射实现对象之间属性复制 * @param from * @param to */public static void copyProperties(Object from, Object to) throws Exception {copyPropertiesExclude(from, to, null);}/** * 复制对象属性 * @param from * @param to * @param excludsArray 排除属性列表 * @throws Exception */@SuppressWarnings("unchecked")public static void copyPropertiesExclude(Object from, Object to, String[] excludsArray) throws Exception {List<String> excludesList = null;if(excludsArray != null && excludsArray.length > 0) {excludesList = Arrays.asList(excludsArray);//构造列表对象}Method[] fromMethods = from.getClass().getDeclaredMethods();Method[] toMethods = to.getClass().getDeclaredMethods();Method fromMethod = null, toMethod = null;String fromMethodName = null, toMethodName = null;for (int i = 0; i < fromMethods.length; i++) {fromMethod = fromMethods[i];fromMethodName = fromMethod.getName();if (!fromMethodName.contains("get"))continue;//排除列表检测if(excludesList != null && excludesList.contains(fromMethodName.substring(3).toLowerCase())) {continue;}toMethodName = "set" + fromMethodName.substring(3);toMethod = findMethodByName(toMethods, toMethodName);if (toMethod == null)continue;Object value = fromMethod.invoke(from, new Object[0]);if(value == null)continue;//集合类判空处理if(value instanceof Collection) {Collection newValue = (Collection)value;if(newValue.size() <= 0)continue;}toMethod.invoke(to, new Object[] {value});}}/** * 对象属性值复制，仅复制指定名称的属性值 * @param from * @param to * @param includsArray * @throws Exception */@SuppressWarnings("unchecked")public static void copyPropertiesInclude(Object from, Object to, String[] includsArray) throws Exception {List<String> includesList = null;if(includsArray != null && includsArray.length > 0) {includesList = Arrays.asList(includsArray);//构造列表对象} else {return;}Method[] fromMethods = from.getClass().getDeclaredMethods();Method[] toMethods = to.getClass().getDeclaredMethods();Method fromMethod = null, toMethod = null;String fromMethodName = null, toMethodName = null;for (int i = 0; i < fromMethods.length; i++) {fromMethod = fromMethods[i];fromMethodName = fromMethod.getName();if (!fromMethodName.contains("get"))continue;//排除列表检测String str = fromMethodName.substring(3);if(!includesList.contains(str.substring(0,1).toLowerCase() + str.substring(1))) {continue;}toMethodName = "set" + fromMethodName.substring(3);toMethod = findMethodByName(toMethods, toMethodName);if (toMethod == null)continue;Object value = fromMethod.invoke(from, new Object[0]);if(value == null)continue;//集合类判空处理if(value instanceof Collection) {Collection newValue = (Collection)value;if(newValue.size() <= 0)continue;}toMethod.invoke(to, new Object[] {value});}}/** * 从方法数组中获取指定名称的方法 *  * @param methods * @param name * @return */public static Method findMethodByName(Method[] methods, String name) {for (int j = 0; j < methods.length; j++) {if (methods[j].getName().equals(name))return methods[j];}return null;}

2 利用apache commons-beanutils的开源实现。

BeanUtils.copyProperties(dst, src)。方法能够将源对象和目标对象中相同名称的属性值复制过去。注意的是参数前面的是目标对象，后面是源对象。使用该方法需要注意：不能将入口方法与源对象、目标对象之一放在同一源文件之内，否者将没有任何效果。

PropertyUtils.copyProperties(dst, src)。功能与BeanUtils.copyProperties类似，只是在同属性名称的类型参数之间可以执行转换操作。

3 利用Spring实现属性之间的复制。spring内部自有实现方法，如果我们需要在外面采用spring的托管复制，需要修改spring的源码，将spring中的org.springframework.beans.CachedIntrospectionResults类的forClass、getPropertyDescriptor、getBeanInfo改为可见的后重新打包。然后将Spring中关于复制的代码提取出来，最后修改成代码如下：

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print?

1. /** 
2.      * 利用spring实现bean之间属性复制 
3.      * @param source 
4.      * @param target 
5.      */  
6.     @SuppressWarnings("unchecked")  
7.     public static void copyPropertiesBySpring(Object source, Object target) throws Exception {  
8.         Class actualEditable = target.getClass();  
9.         PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable);  
10.         for (int i = 0; i < targetPds.length; i++) {  
11.             PropertyDescriptor targetPd = targetPds[i];  
12.             if (targetPd.getWriteMethod() != null) {  
13.                 PropertyDescriptor sourcePd = getPropertyDescriptor(source  
14.                         .getClass(), targetPd.getName());  
15.                 if (sourcePd != null && sourcePd.getReadMethod() != null) {  
16.                     try {  
17.                         Method readMethod = sourcePd.getReadMethod();  
18.                         if (!Modifier.isPublic(readMethod.getDeclaringClass()  
19.                                 .getModifiers())) {  
20.                             readMethod.setAccessible(true);  
21.                         }  
22.                         Object value = readMethod.invoke(source, new Object[0]);  
23.                         if(value == null)  
24.                             continue;  
25.                         //集合类判空处理  
26.                         if(value instanceof Collection) {  
27. //                          Collection newValue = (Collection)value;  
28. //                          if(newValue.size() <= 0)  
29.                                 continue;  
30.                         }  
31.                         Method writeMethod = targetPd.getWriteMethod();  
32.                         if (!Modifier.isPublic(writeMethod.getDeclaringClass()  
33.                                 .getModifiers())) {  
34.                             writeMethod.setAccessible(true);  
35.                         }  
36.                         writeMethod.invoke(target, new Object[] { value });  
37.                     } catch (Throwable ex) {  
38.                     }  
39.                 }  
40.             }  
41.         }  
42.     }     
43.     /** 
44.      * 获取指定类指定名称的属性描述符 
45.      * @param clazz 
46.      * @param propertyName 
47.      * @return 
48.      * @throws BeansException 
49.      */  
50.     @SuppressWarnings("unchecked")  
51.     public static PropertyDescriptor getPropertyDescriptor(Class clazz,  
52.             String propertyName) throws BeansException {  
53.         CachedIntrospectionResults cr = CachedIntrospectionResults.forClass(clazz);  
54.         return cr.getPropertyDescriptor(propertyName);  
55.     }  
56.       
57.       
58.     /** 
59.      * 获取指定类得所有属性描述符 
60.      * @param clazz 
61.      * @return 
62.      * @throws BeansException 
63.      */  
64.     @SuppressWarnings("unchecked")  
65.     public static PropertyDescriptor[] getPropertyDescriptors(Class clazz) throws BeansException {  
66.         CachedIntrospectionResults cr = CachedIntrospectionResults.forClass(clazz);  
67.         return cr.getBeanInfo().getPropertyDescriptors();  
68.     }