debug小记

Java

copyProperties方法

• Spring的BeanUtils不会copy字段名相同但类型不同的属性

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 ex) {throw new FatalBeanException("Could not copy property '" + targetPd.getName() + "' from source to target", ex);}
}					

• apache的PropertyUtils::copyProperties若字段名相同但类型不同会抛java.lang.IllegalArgumentException异常
• apache的BeanUtils::copyProperties若字段名相同但类型不同会尝试转换类型后copy, Throws:ConversionException - if conversion cannot be performed successfully

// Convert the specified value to the required type and store it
if (index >= 0) {                    // Destination must be indexedvalue = convertForCopy(value, type.getComponentType());try {getPropertyUtils().setIndexedProperty(target, propName,index, value);} catch (final NoSuchMethodException e) {throw new InvocationTargetException(e, "Cannot set " + propName);}
}

String::substring(startIndex, endIndex) 方法的endIndex参数若大于字符串长度会直接抛异常, 而并非认为取剩余的所有字符

    public String substring(int beginIndex, int endIndex) {if (beginIndex < 0) {throw new StringIndexOutOfBoundsException(beginIndex);}if (endIndex > value.length) {throw new StringIndexOutOfBoundsException(endIndex);}int subLen = endIndex - beginIndex;if (subLen < 0) {throw new StringIndexOutOfBoundsException(subLen);}return ((beginIndex == 0) && (endIndex == value.length)) ? this: new String(value, beginIndex, subLen);}