//此处用的包是

package org.springframework.beans;

 public static void copyProperties(Object source, Object target) throws BeansException {
        copyProperties(source, target, (Class)null, (String[])null);
    }

业务代码简要

Optional<Record> record = RecordDao.findByIdAndState(id,0);

Output output= new Output();

BeanUtils.copyProperties(record,output);

 

在对PO和Dto使用copyPeoperties中出现了目标对象为null的问题，源码

  private static void copyProperties(Object source, Object target, @Nullable Class<?> editable, @Nullable String... ignoreProperties) throws BeansException {
        Assert.notNull(source, "Source must not be null");
        Assert.notNull(target, "Target must not be null");
        Class<?> actualEditable = target.getClass();
        if (editable != null) {
            if (!editable.isInstance(target)) {
                throw new IllegalArgumentException("Target class [" + target.getClass().getName() + "] not assignable to Editable class [" + editable.getName() + "]");
            }

            actualEditable = editable;
        }

        PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable);
        List<String> ignoreList = ignoreProperties != null ? Arrays.asList(ignoreProperties) : null;
        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 && (ignoreList == null || !ignoreList.contains(targetPd.getName()))) {
                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 (!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);
                        }
                    }
                }
            }
        }

    }

 @Nullable
    public static PropertyDescriptor getPropertyDescriptor(Class<?> clazz, String propertyName) throws BeansException {
        CachedIntrospectionResults cr = CachedIntrospectionResults.forClass(clazz);
        return cr.getPropertyDescriptor(propertyName);
    }

　发现问题在于自己从数据库查出的record 在getPropertyDescriptor方法的clazz<>为Optional 导致copyProperties方法中的sourcePd 一直为null 无法进行值复制，从hibernate接口Optinal<Record>更改返回类型 为Record 问题结决

一开始还找了半天lombok的问题 直接debug源码就好^_^