costin 00/12/27 22:15:21
Added: src/share/org/apache/tomcat/util/hooks Hooks.java
Log:
First attempt to refactor hooks. Moving them in a util package is not a
bad idea ( and it's inspired by the new organization in 2.0 - I was
initially surprized to find ap_hook.h in apr-utils, but it's quite a generic
concept ).
The only disadvantage of using "generic" hooks is that a cast is
needed ( to BaseInterceptor ), but it gives a lot more flexibility.
I think there is a simple workaround for that.
Revision Changes Path
1.1 jakarta-tomcat/src/share/org/apache/tomcat/util/hooks/Hooks.java
Index: Hooks.java
===================================================================
/*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999 The Apache Software Foundation. All rights
* reserved.
*
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* modification, are permitted provided that the following conditions
* are met:
*
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* "This product includes software developed by the
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*
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*/
package org.apache.tomcat.util.hooks;
import org.apache.tomcat.util.*;
import java.io.*;
import java.net.*;
import java.util.*;
import java.lang.reflect.*;
/** Hooks support. Hooks implement a chain-of-command pattern, and
* are commonly used in most web servers as a mechanism of extensibility.
*
* This class doesn't deal with hook invocation - the program is expected
* to use interfaces or base classes with the hooks beeing methods that
* are invoked. Reflection-based invocation is very expensive and shouldn't
* be used.
*
* The Hooks class will provide support for registering and maintaining
* a list of modules implementing each hook.
*
* The module can be added automatically to the right lists by using
* introspection ( if the module implements a certain method, it'll
* be added to the chain for the hook with the same name ). It is also
* possible for a module to explicitely register hooks.
*
* This class is modeled after Apache2.0 hooks - most web servers are using
* this pattern, but so far A2.0 has the most flexible and powerfull
* implementation
*/
public class Hooks {
int hookCount;
String hookNames[];
Vector hooksV[];
Object hooks[][];
Vector allModulesV;
Object allModules[];
private static final int dL=0;
public Hooks(int hookCount ) {
this.hookCount=hookCount;
hooksV=new Vector[hookCount];
for( int i=0; i<hookCount ; i++ )
hooksV[i]=new Vector();
allModulesV=new Vector();
hookNames=new String[hookCount];
hooks=new Object[hookCount][];
}
public int registerHook( String name ) {
for( int i=0; i<hookNames.length; i++ ) {
if( hookNames[i]==null ) {
hookNames[i]=name;
return i;
}
}
throw new RuntimeException("Too many hooks");
}
public void registerHook( String name, int id ) {
hookNames[id]=name;
}
public String getHookName( int id ) {
return hookNames[id];
}
public int getHookId( String hookName ) {
for( int i=0; i< hookNames.length; i++ ) {
if( hookName.equals(hookNames[i]))
return i;
}
return -1;
}
/** Add the module to all the hook chains it's implements
* The hook name should match a method defined in the module
* ( not inherited - explicitely defined there )
*/
public void addModule( Object bi ) {
for( int i=0; i< hookNames.length ; i++ ) {
if( hasHook( bi, hookNames[i] )) {
if( dL > 0 ) debug( "Adding " + hookNames[i] + " " +bi );
hooksV[i].addElement( bi );
hooks[i]=null;
}
}
allModules=null;
allModulesV.addElement( bi );
}
public void removeModule( Object bi ) {
for( int i=0; i<hookNames.length; i++ ) {
if( hooksV[i].contains( bi )) {
hooksV[i].removeElement( bi );
hooks[i]=null;
}
}
allModulesV.removeElement( bi );
allModules=null;
}
Hooks localHooks;
public Object[] getModules( int type )
{
if( hooks[type] != null ) {
return hooks[type];
}
hooks[type]=new Object[hooksV[type].size()];
hooksV[type].copyInto( hooks[type] );
return hooks[type];
}
/** Get all interceptors
*/
public Object[] getModules()
{
if( allModules!=null ) {
return allModules;
}
allModules=new Object[allModulesV.size()];
allModulesV.copyInto( allModules );
return allModules;
}
private void debug(String s ) {
System.out.println("Hooks: " + s );
}
/** Test if the interceptor implements a particular
* method
*/
public static boolean hasHook( Object obj, String methodN ) {
try {
Method myMethods[]=obj.getClass().getMethods();
for( int i=0; i< myMethods.length; i++ ) {
if( methodN.equals ( myMethods[i].getName() )) {
// check if it's overriden
Class declaring=myMethods[i].getDeclaringClass();
Class parentOfDeclaring=declaring.getSuperclass();
// this works only if the base class doesn't extend
// another class.
// if the method is declared in a top level class
// like BaseInterceptor parent is Object, otherwise
// parent is BaseInterceptor or an intermediate class
if( ! "java.lang.Object".
equals(parentOfDeclaring.getName() )) {
return true;
}
}
}
} catch ( Exception ex ) {
ex.printStackTrace();
}
return false;
}
}
