java Exception

1.Exception家谱

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?? Exception继承Throwable基类，而Throwable类现实了Serializable接口，即Throwable自身以及它的子类都是可序列化的。

?? (1)Throwable类

??????? 主要成员变量：

??????? detailMessage:String???????????????????????? 用于描述异常信息

??????? cause:Throwable?????????????????????????????? 指向引起本异常的上一个异常，作用于组成异常链，

?????????????????????????????????????????????????????????????????? 可命名为”原因异常“

??????? stackTrace:StackTraceElement[] ????? 异常栈信息，就是一个StackTraceElement的数组，

?????????????????????????????????????????????????????????????????? StackTraceElement见下面类介绍

??????? 主要成员方法：

??????? printStackTrace():void??????????????????????? 输出异常信息。首先打印本异常类全路径、detailMessage，

?????????????????????????????????????????????????????????????????? 和异常栈信息，再指向cause，递归输出整个异常链的信息

???????????????????????????

?? (2)Exception类

?????? Exception类没什么可说的，就定义了多个不同类型的构造方法，每个构造方法，都调用基类Throwable

?????? 的相应构造方法。

??

?? (3)StackTraceElement类

?????? 主要成员变量：

?????? declaringClass:String??????????????????????????? 发生异常的类全路径名

?????? methodName:String????????????????????????????? 发生异常的类方法名

?????? fileName:String???????????????????????????????????? 发生异常的类文件名

?????? lineNumber:int????????????????????????????????????? 发生的异常在类代码的第几行

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?? 下面贴上类图，如下：

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2.模范SQLException写的异常类

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package com.wind.DbTec.sqlpkg;

import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;

/**
 * 模范SQLException实现 探究Iterable接口的实现，链表的实现
 * 
 * @author zhouyanjun
 * @version 1.0 2014-12-9
 */
public class MyException extends Exception implements Iterable<Throwable> {

	public MyException(Throwable throwable) {
		super(throwable);
	}

	/**
	 * 设置下一个相关异常
	 * 
	 * @param ex
	 */
	public void setNextException(MyException ex) {
		MyException current = this;
		for (;;) {
			MyException next = current.next;
			if (next != null) {
				current = next;
				continue;
			}
			if (nextUpdater.compareAndSet(current, null, ex)) {
				return;
			}
			current = current.next;
		}
	}

	/**
	 * 异常迭代方法，用于遍历异常，实现了Iterable迭代器的类，可以在foreach语句下遍历
	 */
	public Iterator<Throwable> iterator() {
		return new Iterator<Throwable>() {
			MyException nextException = MyException.this;
			Throwable cause = null;

			public boolean hasNext() {
				if (nextException != null || cause != null) {
					return true;
				}
				return false;
			}

			public Throwable next() {
				Throwable throwable = null;
				if (cause == null && nextException != null) {
					throwable = nextException;
					cause = nextException.getCause();
					nextException = nextException.getNextException();
				} else if (cause != null) {
					throwable = cause;
					cause = cause.getCause();
				} else {
					throw new NoSuchElementException();
				}
				return throwable;
			}

			public void remove() {
				throw new UnsupportedOperationException();
			}
		};
	}

	/**
	 * public Iterator<Throwable> iterator() { return new Iterator<Throwable>()
	 * { MyException firstException = MyException.this; MyException
	 * nextException = firstException.getNextException(); Throwable cause =
	 * firstException.getCause();
	 * 
	 * public boolean hasNext() { if (firstException != null || nextException !=
	 * null || cause != null) { return true; } return false; }
	 * 
	 * public Throwable next() { Throwable throwable = null; if (firstException
	 * != null) { throwable = firstException; firstException = null; } else if
	 * (cause != null) { throwable = cause; cause = cause.getCause(); } else if
	 * (nextException != null) { throwable = nextException; cause =
	 * next.getCause(); nextException = nextException.getNextException(); } else
	 * throw new NoSuchElementException(); return throwable; }
	 * 
	 * public void remove() { throw new UnsupportedOperationException(); } }; }
	 **/

	private MyException getNextException() {
		return (next);
	}

	private volatile MyException next; // 下一个异常，用于实现链表

	private static final long serialVersionUID = 7376914647474065999L;

	private static final AtomicReferenceFieldUpdater<MyException, MyException> nextUpdater = AtomicReferenceFieldUpdater
		.newUpdater(MyException.class, MyException.class, "next"); // 原子对象字段更新器，对Volatile变量进行值更新

	public static void main(String[] args) {
		NoSuchElementException noSEleException = new NoSuchElementException();
		UnsupportedOperationException unSuOperaException = new UnsupportedOperationException();
		MyException head = new MyException(noSEleException);
		MyException one = new MyException(unSuOperaException);
		head.setNextException(one);
		for (Throwable throwable : head) {
			throwable.printStackTrace();
		}
	}
}

???

?? (1) MyException继承Exception，实现了自己的异常类。

?? (2)另外MyException定义了一个next成员变量，指向下一个MyException类型的异常，以实现链表。MyEx- ception还实现了Iterable接口，用于迭代遍历链表。

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java Exception

原文：http://unnkoel.iteye.com/blog/2165129