利用反射手写对象属性复制

Posted 2022-05-11 野生java研究僧

因为在工作中经常用到 BeanUtils.copyProperties(userInfo, userInfoVO); 所以就想着试试看自己的反射水平怎么样？能不能自己也写个一样的功能？所以我就写了个如下方法，虽然在很多方面还需要优化，但是基本功能是实现了的。

public class BeanCopyTest 

    @Test
    public void beanCopyProperties()   
        UserInfo userInfo = new UserInfo("admin", "123", 20, "admin@qqcom");
        UserInfoVO beanCopy = beanCopyProperty(userInfo, UserInfoVO.class);
        System.out.println(userInfo);
        // toString无法显示 如果是public的可以进行显示
        System.out.println(beanCopy);
        System.out.println(beanCopy.getAge()+","+beanCopy.getName()+","+beanCopy.getPassword()+","+beanCopy.getEmail());

    

    @Test
    public void copyProperties()
        UserInfo userInfo = new UserInfo("admin", "123", 20, "admin@qqcom");

        UserInfoVO userInfoVO = new UserInfoVO();
        BeanUtils.copyProperties(userInfo, userInfoVO);
        System.out.println(userInfoVO.getAge() + "," + userInfoVO.getName() + "," + userInfoVO.getPassword() + "," + userInfoVO.getEmail());
    

    /***
     * <p>
     * beanCopyProperty ：将源对象的属性复制到指定类型对象上，支持【直接继承】的方式，允许父类用private修饰
     * 需要注意的是，父类用private修饰的成员变量，子类无法在toString中访问，所有会导致赋值成功，但是toString无法打印
     * </p >
     * @param source 源对象
     * @param targetClazz 目标类class
     * @return T
     * @author compass
     * @date 2022/5/10 22:17
     * @since 1.0.0
     **/
    public static <T> T beanCopyProperty(Object source, Class<T> targetClazz)   
        if (source == null || targetClazz == null)
            throw  new IllegalArgumentException("source or targetClazz is Not Null");
        
        Field[] sourceFields = source.getClass().getDeclaredFields();
        Class<?> sourceClass = source.getClass();
        Object resultInstance = null;
        try 
            resultInstance = targetClazz.newInstance();
         catch (InstantiationException e) 
            e.printStackTrace();
         catch (IllegalAccessException e) 
            e.printStackTrace();
        
        List<Object> targetFiledNameList = new ArrayList<>();

        // 获取父类属性名称
        if (!(targetClazz.getSuperclass() == Object.class)) 
            Field[] targetParentFields = targetClazz.getSuperclass().getDeclaredFields();
            for (Field targetParentField : targetParentFields) 
                targetFiledNameList.add(targetParentField.getName());
            
        

        // 获取当前类属性名称
        Field[] targetFieldArr = targetClazz.getDeclaredFields();
        for (Field targetField : targetFieldArr) 
            if (!(targetFiledNameList.contains(targetField.getName())))
                targetFiledNameList.add(targetField.getName());
        

        // 根据来源对象属性给目标对象属性赋值
        for (int i = 0; i < sourceFields.length; i++) 
            try 
                // 获取原本字段的value
                String sourceFieldName = sourceFields[i].getName();
                Field sourceField = sourceClass.getDeclaredField(sourceFieldName);
                sourceField.setAccessible(true);
                Object currentFiledValue = sourceField.get(source);

                // 根据属性名称给目标对象设置值
                Field targetField = null;
                if (targetFiledNameList.contains(sourceFieldName)) 
                    if (!(targetClazz.getSuperclass() == Object.class)) 
                        targetField = targetClazz.getSuperclass().getDeclaredField(sourceFieldName);
                     else 
                        targetField = targetClazz.getDeclaredField(sourceFieldName);
                    

                    targetField.setAccessible(true);
                    targetField.set(resultInstance, currentFiledValue);
                
             catch (Exception e) 
                e.printStackTrace();
            
        
        return (T) resultInstance;