拷貝對象工具類（對象指派）copyProperties——為null不複制

開發在中經常需要将一個對象的若幹個值指派給另外一個對象相對應的字段，且字段名是一樣的，如果一個一個取一個一個指派

太麻煩，使用​​

​org.springframework.beans.BeanUtils​

​的copyProperties方法，有個弊端就是會将null也複制過來

自己寫個工具類，繼承​

​org.springframework.beans.BeanUtils​

​

對該方法進行改造，如代碼中注釋部分

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);
        PropertyDescriptor[] var7 = targetPds;
        int var8 = targetPds.length;

        for (int var9 = 0; var9 < var8; ++var9) {
            PropertyDescriptor targetPd = var7[var9];
            Method writeMethod = targetPd.getWriteMethod();
            if (writeMethod != null) {
                PropertyDescriptor sourcePd = getPropertyDescriptor(source.getClass(), targetPd.getName());
                if (sourcePd != null) {
                    Method readMethod = sourcePd.getReadMethod();
                    if (readMethod != null && ClassUtils.isAssignable(writeMethod.getParameterTypes()[0], readMethod.getReturnType())) {
                        try {
                            if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers())) {
                                readMethod.setAccessible(true);
                            }
                            Object value = readMethod.invoke(source);
                            if (value != null) {//這裡判斷以下value是否為空
                                if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers())) {
                                    writeMethod.setAccessible(true);
                                }
                                writeMethod.invoke(target, value);
                            }
                        } catch (Throwable var15) {
                            throw new FatalBeanException("Could not copy property '" + targetPd.getName() + "' from source to target", var15);
                        }
                    }
                }
            }
        }
    }