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2008年9月 (9)

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void f();{

Cleaner cleaner=new Cleaner();;

try

{

Connection conn =

;

cleaner.add(conn);;

Statement stmt = conn.createStatement();;

cleaner.add(stmt );;

ResultSet rset =

;

cleaner.add(rset );;

//using ResultSet

cleaner.clean();//close rset

}

catch(Exception e);

{

throw new RuntimeException("",e);;

}

finally

{

cleaner.cleanAll();;

}

import java.io.InputStream;

import java.lang.reflect.Method;

import java.net.Socket;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.Statement;

import java.util.HashMap;

import java.util.Iterator;

import java.util.Map;

import java.util.Stack;

/**

* @author pufan

*

*/

public final class Cleaner

{

public static interface CleanListener

{

void catchClean(Object obj, Throwable t);;

}

private final static CleanListener NONE_LISTENER = new CleanListener();

{

public void catchClean(Object obj, Throwable t);

{

}

};

private final static Map map = new HashMap();

{

put(Connection.class, "close");;

put(Statement.class, "close");;

put(PreparedStatement.class, "close");;

put(ResultSet.class, "close");;

put(InputStream.class, "close");;

put(Socket.class, "close");;

}

};

private final Stack garbageContainer = new Stack();;

public void add(Object garbage);

{

add(garbage, NONE_LISTENER);;

}

public void add(Object garbage, CleanListener listener);

{

garbageContainer.add(new Garbage(garbage, listener););;

}

public void clean();

{

if (garbageContainer.size(); > 0);

try

{

doClean();;

}

catch (Throwable e);

{

throwThrowable(e);;

}

private void doClean(); throws Throwable

{

Garbage garbage = (Garbage); garbageContainer.pop();;

garbage.clean();;

}

public void cleanAll();

{

Throwable throwable = null;

while (garbageContainer.size(); > 0);

try

{

doClean();;

}

catch (Throwable t);

{

if (throwable == null);

throwable = t;

}

throwThrowable(throwable);;

}

private void throwThrowable(Throwable throwable);

{

if (throwable == null);

return;

if (throwable instanceof Error);

throw (Error); throwable;

else

throw new RuntimeException("error in closing garbage!", throwable);;

}

private static Method getMethod(Object obj);

{

Class clazz = obj.getClass();;

String methodName = getMethodName(clazz);;

try

{

return clazz.getMethod(methodName, new Class[0]);;

}

catch (Exception e);

{

throw new RuntimeException("can't find close method by " + obj, e);;

}

private static String getMethodName(Class clazz);

{

for (Iterator it = map.keySet();.iterator();; it.hasNext();; );

{

Class c = (Class); it.next();;

if (c.isAssignableFrom(clazz););

return (String); map.get(c);;

}

return null;

}

private static class Garbage

{

Object obj;

Method method;

CleanListener listener;

Garbage(Object obj, CleanListener listener);

{

method = getMethod(obj);;

this.obj = obj;

this.listener = listener;

}

void clean(); throws Throwable

{

try

{

method.invoke(obj, new Object[0]);;

}

catch (Throwable t);

{

listener.catchClean(obj, t);;

throw t;

}

posted on 2009-01-10 10:01 賀挺閱讀(178) 評論(0) 編輯收藏

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