异常处理规范

1、 Throwable是Java中所有错误和异常的超类。 error是所有错误的超类，这些错误并不意味着需要被应用程序所捕获。捕获Throwable或Error也将捕获OutOfMemoryError和InternalError，应用程序不应尝试恢复这些错误。只能捕获异常及其子类，文章最后贴上自定义的异常代码。

2、 定义时区分unchecked / checked 异常，避免直接抛出new RuntimeException()，更不允许抛出Exception或者Throwable，应使用有业务含义的自定义异常。末尾贴上自定义的异常处理代码。

3、 不同的一场类型会影响业务走向，所以我一般都是在service这一层统一处理收敛异常。但是在有事务的情况下，我是会将异常抛出到控制层做处理的，不然可能会影响事务的回滚。总结就是：存在事务，抛到控制层用aop作统一处理，如果不存在事务，统一在service层处理，这样方便一些。

4、异常分类：

Throwable

                  Error       

                  Exception

                          编译异常（受检异常），编译过程中可能发生的异常。

                                   IOException

                                   FileNotFoundException

                                   SQLException

                                   两种异常都是在运行时出错。

                          运行异常（非受检异常）RuntimeException，运行过程中发现问题。

                                   NullPointerException空指针异常

                                   IndexOutOfBoundsException下标越界

                                   ClassCastException类型转换

                                   NumberFormateException数字格式不正确

                                   ArithmeticException数学运算

5、自定义异常代码：

public class UserException extends RuntimeException{

         private String errorCode;

         private String errorMessage;

         private boolean forceCatch = false;

         public UserException(){

 

         }

         public UserException(String errorMessage){

                  super(errorMessage);

                  this.errorMessage = errorMessage;

         }

 

         public UserException(ResultEnum resultEnum){

                  super(resultEnum.getMessage());

                  this.errorCode = resultEnum.getCode();

                  this.errorMessage = resultEnum.getMessage();

         }

         public UserException(String errorCode,String errorMessage){

                  super(errorMessage);

                  this.errorCode = errorCode;

                  this.errorMessage = errorMessage;

         }

         public UserException(String errorMessage,Throwable throwable){

                  super(errorMessage,throwable);

                  this.errorMessage = errorMessage;

         }

         public UserException(String errorMessage,Throwable throwable,boolean forceCatch){

                  super(errorMessage,throwable);

                  this.errorMessage = errorMessage;

                  this.forceCatch = forceCatch;

         }

         public UserException(String errorCode,String errorMessage,Throwable throwable){

                  super(errorMessage,throwable);

                  this.errorCode = errorCode;

                  this.errorMessage = errorMessage;

         }

         public UserException(String errorCode,String errorMessage,Throwable throwable,boolean forceCatch){

                  super(errorMessage,throwable);

                  this.errorCode = errorCode;

                  this.errorMessage = errorMessage;

                  this.forceCatch = forceCatch;

         }

         public String getErrorCode() {

                  return errorCode;

         }

         public void setErrorCode(String errorCode) {

                  this.errorCode = errorCode;

         }

         public String getErrorMessage() {

                  return errorMessage;

         }

         public void setErrorMessage(String errorMessage) {

                  this.errorMessage = errorMessage;

         }

         public boolean isForceCatch() {

                  return forceCatch;

         }

         public void setForceCatch(boolean forceCatch) {

                  this.forceCatch = forceCatch;

         }

 

}