编写自己的Exception

在实际的工作中，通常需要定义自己功能模块相关的异常，下面一个实例可以实现定义自己的异常：

1.定义一个异常码抽象类作为基类

public abstract class BaseExceptionCode {
   private String errorMessage ;
   private int errorCode ;
   private final BaseExceptionCode display ;
   
   public BaseExceptionCode(String errorMessage,int errorCode){
	   this.errorMessage = errorMessage;
	   this.errorCode = errorCode ;
	   this.display = this ;
   }
   
   public BaseExceptionCode(int errorCode,String errorMessage){
	   this.errorCode = errorCode ;
	   this.errorMessage = errorMessage ;
	   this.display = this ;
   }
   
   public String getErrorMessage(){
	   return errorMessage ;
   }
   
   public int getErrorCode(){
	   return errorCode ;
   }
   
   public BaseExceptionCode getDisplay(){
	   return display ;
   }
}

2.定义自己的异常码

public class MyExceptionCode extends BaseExceptionCode{
    protected MyExceptionCode(String errorMessage,int errorCode){
    	super(errorMessage,errorCode);
    }
    
    protected MyExceptionCode(int errorCode,String errorMessage){
    	super(errorCode,errorMessage);
    }
    
    public static final MyExceptionCode E_PARAM_IS_NULL_A = new MyExceptionCode(ConstantWithExceptionMsg.E_PARAM_NULL,ConstantWithExceptionCode.E_PARAM_CODE);
    
    public static final MyExceptionCode E_PARAM_IS_NULL_B = new MyExceptionCode(ConstantWithExceptionCode.E_PARAM_CODE,ConstantWithExceptionMsg.E_PARAM_NULL);
}

3.定义自己的异常码集合（常量）

/**
 * 异常码集合
 */
public class ConstantWithExceptionCode {
    public static final int E_PARAM_CODE = 100001 ;
}

4.定义自己的异常信息集合（常量）

/**
 * 异常信息
 */
public class ConstantWithExceptionMsg {
    public static final String E_PARAM_NULL = "参数为空" ;
}

5.定义自己的异常

public class MyException extends RuntimeException{
	private static final long serialVersionUID = -1933116620478022916L;
	
	private String errorMessage ; //异常信息
	private MyExceptionCode errorCode ; //异常码
	
	public MyException(MyExceptionCode errorCode){
		super(errorCode.getErrorMessage());
		this.errorCode = errorCode ;
		this.errorMessage = errorCode.getErrorMessage();
	}
	
	public MyException(String errorMessage,MyExceptionCode errorCode){
		super(errorMessage);
		this.errorMessage = errorMessage ;
		this.errorCode = errorCode ;
	}
	
	public MyException(MyExceptionCode errorCode,String errorMessage){
		super(errorMessage);
		this.errorCode = errorCode;
		this.errorMessage = errorMessage;
	}
	
	
	public String getErrorMessage(){
		return errorMessage ;
	}
	
	public MyExceptionCode getErrorCode(){
		return errorCode ;
	}

}

6.测试自己的异常

public class MyExceptionTest {
   public static void main(String[] args){
	   try{
		   test("","");
	   }catch(MyException e){
		   System.out.println(e);
		   throw e ;
	   }
	   
   }
   
   private static void test(String str1,String str2) throws MyException{
	   if("".equals(str1) || str1 == null || "".equals(str2) || str2 == null ){
		   throw new MyException(MyExceptionCode.E_PARAM_IS_NULL_A);
	   }else{
		   return ;
	   }
   }
}

7.测试结果

com.zh.exception.MyException: 参数为空

Exception in thread "main" com.zh.exception.MyException: 参数为空

at com.zh.exception.MyExceptionTest.test(MyExceptionTest.java:16)

at com.zh.exception.MyExceptionTest.main(MyExceptionTest.java:6)