如何自定义异常类



在B站学习java写的代码

代码如下
MyException类
package com.day0203_2;
/*
 * 如何自定义异常类
 * 1.继承与现有的异常结构：RuntimeException、Exception
 * 2.提供全局常量：serialVersionUID
 * 3.提供重载的构造器
 * 
 * 
 * 
 * 
 */
public class MyException extends RuntimeException{

	static final long serialVersionUID = -3387516993124229999L;
	
	public MyException() {
		
	}
	
	public MyException(String msg) {
		super(msg);
	}
	
	
}


StudentTest类
package com.day0203_2;
/*
 * 关于异常对象的产生： 1 系统自动生成的异常对象
 * 					   2 手动的生成一个异常对象，并抛出（throw）
 */

public class StudentTest {
	
	public static void main(String[] args) {
		try {
			Student s=new Student();
			s.regist(-1001);
			System.out.println(s);
		} catch (Exception e) {
//			e.printStackTrace();
			System.out.println(e.getMessage());
		}
	}

}

class Student{
	
	int id;
	
	public void regist(int id) throws Exception {
		if (id>0) {
			this.id=id;
		}else {
//			System.out.println("您输入的数据非法！");
			//手动的抛出异常对象
//			throw new RuntimeException("您输入的数据非法！");
//			throw new Exception("您输入的数据非法！");
			throw new MyException("不能输入负数");
		}
	}

	@Override
	public String toString() {
		return "Student [id=" + id + "]";
	}
	
	
}

package com.cdzyjsxy.javase.exception;

import com.sun.org.apache.xpath.internal.SourceTree;
import com.sun.org.apache.xpath.internal.objects.XObject;
import com.sun.xml.internal.ws.addressing.WsaActionUtil;

/**
 * @author FL
 * @date 2020/6/17
 **/
public class MyStack {

    private Object [] elements;
    private int index;

    public MyStack(){
        this.elements = new Object[10];
        this.index = -1;
    }
    /**
     * 亚栈方法
        * @param object
        * @return void
        * @author FanLin
        * @date 2020/6/17 9:44
    */
    public void push(Object object) throws MyStackOperationException {
        if (index>=elements.length-1){
//            System.out.println("占已满，亚栈失败");
//            return;
       //创建异常对象
       //     MyStackOperationException e = new MyStackOperationException("栈已满，压栈失败");
       //手动抛出异常
       //     throw e;
       //合并上述两行代码
            throw new MyStackOperationException("栈已满，压栈失败");
        }
        index++;
        elements[index] = object;
        System.out.println("亚栈"+object+"元素成功，栈针指向"+index);
    }
    /**
     * 弹栈方法
        * @param
        * @return void
        * @author FanLin
        * @date 2020/6/17 9:50
    */
    public void pop() throws MyStackOperationException {
        if (index<0){
//            System.out.println("弹栈失败，栈已空");
//            return;
//           创建异常对象
//         MyStackOperationException e =   new MyStackOperationException("弹栈失败，栈已空");
//           手动抛出异常
//         throw e;
     //合并上述两行代码
            throw new MyStackOperationException("弹栈失败，栈已空");

        }
        System.out.println("弹栈"+elements[index]+"元素成功");
        index--;
        System.out.println("栈针指向"+index);
    }

    public Object[] getElements() {
        return elements;
    }

    public void setElements(Object[] elements) {
        this.elements = elements;
    }

    public int getIndex() {
        return index;
    }

    public void setIndex(int index) {
        this.index = index;
    }
}


package com.cdzyjsxy.javase.exception;

/**
 * @author FL
 * @date 2020/6/17
 **/
//栈操作异常:自定义异常
public class MyStackOperationException extends Exception {
    public MyStackOperationException() {
        super();
    }

    public MyStackOperationException(String message) {
        super(message);
    }
}


package com.cdzyjsxy.javase.exception;

/**
 * @author FL
 * @date 2020/6/17
 **/
//测试改过后的程序
public class Exception05 {
    public static void main(String[] args) {
       //创建对象
        MyStack myStack = new MyStack();
        //压栈
        try {
            myStack.push(new Object());
            myStack.push(new Object());
            myStack.push(new Object());
            myStack.push(new Object());
            myStack.push(new Object());
            myStack.push(new Object());
            myStack.push(new Object());
            myStack.push(new Object());
            myStack.push(new Object());
            myStack.push(new Object());
            //压栈失败
            myStack.push(new Object());
            myStack.push(new Object());

        } catch (MyStackOperationException e) {
            e.printStackTrace();
            System.out.println("shibai");
        }
        //弹栈
        try {
            myStack.pop();
            myStack.pop();
            myStack.pop();
            myStack.pop();
            myStack.pop();
            myStack.pop();
            myStack.pop();
            myStack.pop();
            myStack.pop();
            myStack.pop();
            //此处就应该弹栈失败
            myStack.pop();

        } catch (MyStackOperationException e) {
            e.printStackTrace();
            System.out.println("shibai");
        }
    }
}


 

定义异常类

public class BusinessException extends Exception {

    private static final long serialVersionUID = -928281303665542095L;

    private String errCode;
    private String errMsg;
    private String message;
    
    public String getErrCode() {
        return errCode;
    }


    public void setErrCode(String errCode) {
        this.errCode = errCode;
    }


    public String getErrMsg() {
        return errMsg;
    }


    public void setErrMsg(String errMsg) {
        this.errMsg = errMsg;
    }
    

    public void setMessage(String message) {
        this.message = message;
    }


    public BusinessException() {
        super();
    }


    public BusinessException(String message, Throwable cause, boolean enableSuppression,
            boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
    }


    public BusinessException(String message, Throwable cause) {
        super(message, cause);
    }


    public BusinessException(String message) {
        super(message);
        setMessage(message);
    }


    public BusinessException(Throwable cause) {
        super(cause);
    }

    @Override
    public String getMessage() {
        return message;
    }


    @Override
    public String toString() {
        return BusinessException.class.getCanonicalName() + message;
    }

}

tp5实现自定义异常类：



 

1.在applocation 下新建 Exception  文件夹，用来放自定义的异常类，

2.在Exception 建立Exception .php类，引入think\exception\handle;

                think\exception\handle 是系统的异常处理类，handle是处理异常的，render是显示异常处理的界面，

              所以要重写此方法。

 



 

json中的$data不存在，页面一定会报错

报错结果如下：