【复制对象 null的字段不进行不覆盖-重写copy方法】

Dear 丶 2023-09-28 10:51 125阅读 0赞

/**
         * 重写copy方法  null的字段不进行不覆盖
         *
         * @param source
         * @param target
         * @throws BeansException
         */
        public static void copyProperties(Object source, Object target) throws BeansException {
        
            Assert.notNull(source, "Source must not be null");
            Assert.notNull(target, "Target must not be null");
            Class<?> actualEditable = target.getClass();
            PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable);
            for (PropertyDescriptor targetPd : targetPds) {
        
                if (targetPd.getWriteMethod() != null) {
        
                    PropertyDescriptor sourcePd = getPropertyDescriptor(source.getClass(), targetPd.getName());
                    if (sourcePd != null && sourcePd.getReadMethod() != null) {
        
                        try {
        
                            Method readMethod = sourcePd.getReadMethod();
                            if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers())) {
        
                                readMethod.setAccessible(true);
                            }
                            Object value = readMethod.invoke(source);
                            // 这里判断以下value是否为空 也可以加些其他处理
                            if (value != null) {
        
                                Method writeMethod = targetPd.getWriteMethod();
                                if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers())) {
        
                                    writeMethod.setAccessible(true);
                                }
                                writeMethod.invoke(target, value);
                            }
                        } catch (Throwable ex) {
        
                            throw new FatalBeanException("Could not copy properties from source to target", ex);
                        }
                    }
                }
            }
        }

方法测试：

public static void main(String[] args) throws NoSuchFieldException {
        
            User user = new User();
            user.setName("dsadsa");
            User newUser = new User();
            newUser.setId(44);
            copyProperties(newUser, user);
            System.out.println(user);
        }

打印结果：

user.id=44,user.name=dsadsa,user.age=null