java基础学习日志14

异常，和log4j（老司机）

public class SampleThrow {

    public static void main(String[] args) {
    	System.out.println("AAAAAAAAAAAAAAAAA");
    	try {
    		  int num = 0;
    		  if(num==0){
    			  num=1;
    		  }
    	      num = 10 / num; // 系统自动抛出异常
//    	      发生的异常类型与catch中异常的类型相同则可以被捕获
//    	      发生的异常类型是catch中异常的类型的子类也可以被捕获
//    	      如果try部分的代码没有发生错误，catch块的代码不会执行

		} catch (Exception e) {
			System.out.println("BBBBBBBBBBBBBBBBBBBBBBBB");
			e.printStackTrace();
		} 
    	
    }
}

/**
 * 检查型异常是在编译阶段直接报错的异常，必须要处理的异常
 * @author 
 * @date 2018年1月30日上午9:56:53
 */
public class SampleCheckException {
    public static void main(String[] args) {
        int num;
        // ArithmeticException属于非檢査型异常，可以不用try{}catch{}
//        num = test1(10, 2);
//        System.out.println(num);
//        num = test1(10, 0);
//        System.out.println(num);
//        try {
//            test2(10, 1); // IllegalAccessException属于檢査型异常
//        } catch (IllegalAccessException e) {
//            e.printStackTrace();
//        }
        
//在catch块中处理的异常是try语句快种异常的父类或者是该异常，不能是子类
        try {
            test3(10, 1); // test3抛出的是Exception，catch部分不能是IllegalAccessException
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static int test1(int num1, int num2) {

        if (num2 == 0) {
            // ArithmeticException繼承自RuntimeException
            throw new ArithmeticException("num is 0 err1");
        }

        return num1 / num2;
    }

    private static int test2(int num1, int num2) throws IllegalAccessException {

        if (num2 == 0) {
            // IllegalAccessException直接繼承自Exception
            throw new IllegalAccessException("num is 0 err2");
        }

        return num1 / num2;
    }

    private static int test3(int num1, int num2) throws Exception { // throws部分可以是父類

        if (num2 == 0) {
            // IllegalAccessException直接繼承自Exception
            throw new IllegalAccessException("num is 0 err3");
        }

        return num1 / num2;
    }
}

/**
 * 
 * @author 
 * @date 2018年1月30日上午10:03:50
 */
public class SampleExceptionMethod {
    public static void main(String[] args) {
        try {
            test(10, 0); // test3抛出的是Exception，catch部分不能是IllegalAccessException
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("------華麗的-----------------------分割線-----");
            System.out.println(e.getMessage());
            System.out.println("------華麗的-----------------------分割線-----");
            System.out.println(e.toString());
        }
    }

    private static int test(int num1, int num2) throws Exception { // throws部分可以是父類

        if (num2 == 0) {
            // IllegalAccessException直接繼承自Exception
            throw new IllegalAccessException("num is 0 这个是除数为0的异常");
        }

        return num1 / num2;
    }
}

public class SampleFinally {

    public static void main(String[] args) {
        // 未使用finally，如果希望不管是否發生异常，都要打印出“over”，需要在毎个地方加上打印語句
//        try {
//            test(-10);
//            System.out.println("OK");
//            System.out.println("over");
//        } catch (ArithmeticException e) {
//            System.out.println("err1");
//            System.out.println("over");
//        } catch (Exception e) {
//            System.out.println("err2");
//            System.out.println("over");
//        }

//        System.out.println("------華麗的-----------------------分割線-----");

        // 使用finally，只需要在finally块中加上打印語句即可
        try {
            test(10);
            System.out.println("OK");
            return ;
        } catch (ArithmeticException e) {
            System.out.println("err1");
        } catch (Exception e) {
            System.out.println("err2");
        } finally {
            System.out.println("over");
        }
    }

    private static void test(int num) {
        if (num <= 0) {
            throw new ArithmeticException("num is 0");
        }
    }
}

public class SampleException {
	private static org.apache.log4j.Logger logger1 = org.apache.log4j.Logger.getLogger("SampleException");
	private static org.apache.log4j.Logger logger = org.apache.log4j.Logger.getLogger("busi1");

	public static void main(String[] args) {
		int[] arr = { 1, 2 };
		try {
			arr[2] = 3;
			System.out.println("OK1");
		} catch (ArrayIndexOutOfBoundsException e) { // 只处理数组下标越界异常
			System.out.println("ERR1");
		}
		System.out.println("------華麗的-----------------------分割線-----");
		try {
			arr[1] = 3;
			System.out.println("OK2");
		} catch (Exception e) { // 使用Exception表示所有的异常都使用相同的方式處理
			System.out.println("ERR2");
		}
		SampleException se = new SampleException();
		se.testLog();
	}

	public void testLog() {

		logger1.info("默认输出路径");
		logger.info("自定义输出路径");
	}
}

/**
 * 
 * @author 
 * @date 2018年1月30日上午10:35:08
 */
class MyException extends Exception {
	private static org.apache.log4j.Logger logger1=org.apache.log4j.Logger.getLogger("MyException");
	private static org.apache.log4j.Logger logger=org.apache.log4j.Logger.getLogger("busi");
	private static final long serialVersionUID = -5171311572974280588L;

    public MyException() {
        super("MyException 出现异常errerr");
    }

    public MyException(String msg) {
        super(msg);
    }
    public void testLog(){
    	logger1.info("默认输出路径");
    	logger.info("自定义输出路径");
    	}
}

public class SampleExceptionEx {

    public static void f(int num) throws MyException {

        if (num < 0) {
            throw new MyException();
        }
    }

    public static void g(int num) throws MyException {
        if (num == 0) {
            throw new MyException("Throwing MyException from g()");
        }
    }
    public static void main(String[] args) {
//        try {
//            f(-1);
//        } catch (MyException e) {
//            System.out.println(e.getMessage());
//        }
//
//        System.out.println("------壺楉揑-----------------------暘妱慄-----");
//
//        try {
//            f(10);
//            g(0);
//        } catch (MyException e) {
//            System.out.println(e.getMessage());
//            e.printStackTrace();
//            System.out.println(e.toString());
//        }
    	
//    	try {
//			int arr[]=new int[2];
////			arr[2]=0;
//			arr=null;
//			System.out.println(arr[0]);
//		} catch (ArrayIndexOutOfBoundsException e) {
//			e.printStackTrace();
//		} catch(NullPointerException e1){
//			e1.printStackTrace();
//		}
    	MyException mye = new MyException();
    	mye.testLog();
    }
}

import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;

public class ExceptionDemo1 {
	public void run() {
		NullPointerException n = new NullPointerException();
		throw n;
	}

	public void run1() {
		// try {
		// System.out.println("AAAAAAAAAAAA");
		run();
		// } catch (Exception e) {
		// System.out.println("捕获该异常");
		// }

	}

	public void run2() {
		System.out.println("我要在Run2方法中处理异常");
		try {
			run1();
		} catch (Exception e) {
			e.printStackTrace();
			System.out.println("捕获该异常");
		}

	}

	public static void main(String[] args) {
		PropertyConfigurator.configure("log4j.properties");
		Logger logger = Logger.getLogger(ExceptionDemo1.class);
		logger.debug(" debug ");
		logger.error(" error ");
		ExceptionDemo1 ed = new ExceptionDemo1();
		ed.run2();
	}

}

public class SampleExceptionInclude {

	public static void main(String[] args) {
		try {
			test1(1);
			try {
				test2();
			} catch (Exception e) {
				System.out.println(e.getMessage());
			}

			// test2的异常處理完之后会运行以下的代碼
			test1(-1);

		} catch (ArithmeticException e) {
			System.out.println(e.getMessage());
		}

		System.out.println("------華麗的-----------------------分割線-----");

		try {
			test1(-1);
		} catch (ArithmeticException e) {
			System.out.println("test1 err");
			try {
				test2();
			} catch (Exception e1) {
				System.out.println(e.getMessage());
			}
		}

		System.out.println("------華麗的-----------------------分割線-----");

		try {
			test1(-1);
		} catch (ArithmeticException e) {
			System.out.println(e.getMessage());
		} finally {
			try {
				test2();
			} catch (Exception e) {
				System.out.println(e.getMessage());
			}
		}
	}

	private static void test1(int num) {
		if (num <= 0) {
			throw new ArithmeticException("num is 0 err1");
		}
	}

	private static void test2() throws Exception {
		throw new Exception("test2 err");
	}

}