wiki实战所会考察的面试题

第三章

请说明resource注解和Autowired区别

可以参考这篇文章
@Autowired和@Resource的区别

beanUtils

你还在用BeanUtils进行对象属性拷贝？

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;
        }

      //获取属性描述符
        PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable);
        //无需copy的属性
        List 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];
            //获取目标类的写方法
            Method writeMethod = targetPd.getWriteMethod();
            if (writeMethod != null && (ignoreList == null || !ignoreList.contains(targetPd.getName()))) {
            //从source的get拿到值set到target中
                PropertyDescriptor sourcePd = getPropertyDescriptor(source.getClass(), targetPd.getName());
                if (sourcePd != null) {
                    Method readMethod = sourcePd.getReadMethod();
                    if (readMethod != null) {
                        ResolvableType sourceResolvableType = ResolvableType.forMethodReturnType(readMethod);
                        ResolvableType targetResolvableType = ResolvableType.forMethodParameter(writeMethod, 0);
                        if (targetResolvableType.isAssignableFrom(sourceResolvableType)) {
                            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 var17) {
                                throw new FatalBeanException("Could not copy property '" + targetPd.getName() + "' from source to target", var17);
                            }
                        }
                    }
                }
            }
        }

    }