com.eva.properties.Proxy Maven / Gradle / Ivy
/*
* $Id: Proxy.java 109 2007-03-24 14:55:03Z max $
*
* Copyright (c) 2006-2007 Maximilian Antoni. All rights reserved.
*
* This software is licensed as described in the file LICENSE.txt, which you
* should have received as part of this distribution. The terms are also
* available at http://www.maxantoni.de/projects/eva-properties/license.txt.
*/
package com.eva.properties;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.logging.Level;
/**
* is a proxy for another properties file referenced by a path.
*
* @author Max Antoni
* @version $Revision: 109 $
*/
public class Proxy implements Replaceable {
/**
* interface for internal delegate types used to resolve the object behind
* the proxy.
*/
private static interface Type {
/**
* resolves the object behind the proxy.
*
* @param inParent the parent properties to use.
* @param inContext the current context.
* @return the resolved object.
*/
Object resolve(Properties inParent, Context inContext);
/**
* returns the null object to use while resolving the
* actual object.
*
* @return the null object.
*/
Object getNullObject();
}
/**
* delegate to resolve another properties object from a path.
*/
private static class TypePath implements Type {
/**
* the path to the external properties file.
*/
private String path;
/**
* creates a new delegate with the given path.
*
* @param inPath the path.
*/
TypePath(String inPath) {
path = inPath;
}
/*
* @see com.eva.properties.Proxy.Type#resolve(
* com.eva.properties.Properties, com.eva.properties.Context)
*/
public Object resolve(Properties inParent, Context inContext) {
String replacedPath = Replacer.replace(path, inContext);
if(replacedPath == null) {
return Null.INSTANCE;
}
DataSource dataSource;
try {
dataSource = new DataSource((ClassLoader) inContext
.lookup("classloader"), replacedPath);
}
catch(FileNotFoundException e) {
/*
* This might happen a couple of times when a switch is
* processed.
*/
Log.instance().log(Level.FINE, "PropertiesProxy.fileNotFound",
replacedPath);
return Null.INSTANCE;
}
if(Log.instance().isLoggable(Level.CONFIG)) {
Log.instance().log(Level.CONFIG,
"PropertiesProxy.readingProperties",
dataSource.toString());
}
try {
// It is okay to pass null as the parent here:
return PropertiesParser.read(inParent, dataSource);
}
catch(IOException e) {
throw new PropertiesException(
"IOException while reading super properties "
+ replacedPath + ": " + e.getMessage());
}
catch(PropertiesException e) {
throw new PropertiesException(
"PropertiesException while reading super properties "
+ replacedPath + ": " + e.getMessage());
}
}
/*
* @see java.lang.Object#toString()
*/
public String toString() {
return "&\"" + path + "\"";
}
/*
* @see com.eva.properties.Proxy.Type#getNullObject()
*/
public Object getNullObject() {
return NoProperties.INSTANCE;
}
}
/**
* delegate to resolve objects from a replaceable.
*/
private static class TypeReplaceable implements Type {
/**
* the replaceable that provides the object.
*/
private Replaceable replaceable;
/**
* creates a delegate with the given replaceable.
*
* @param inReplaceable the replaceable.
*/
TypeReplaceable(Replaceable inReplaceable) {
replaceable = inReplaceable;
}
/*
* @see com.eva.properties.Proxy.Type#resolve(
* com.eva.properties.Properties, com.eva.properties.Context)
*/
public Object resolve(Properties inParent, Context inContext) {
return replaceable.replace(inContext);
}
/*
* @see java.lang.Object#toString()
*/
public String toString() {
return "&" + replaceable.toString();
}
/*
* @see com.eva.properties.Proxy.Type#getNullObject()
*/
public Object getNullObject() {
return Null.INSTANCE;
}
}
/**
* the replaced object. This is null if
* {@link #replace(Context)} was not yet called.
*/
private Object object;
/**
* the parent properties to use. Can be null.
*/
private Properties parent;
/**
* the delegate to use to resolve the object behind this proxy.
*/
private Type type;
/**
* creates a proxy with a path.
*
* @param inPath the path.
* @throws NullPointerException if the path is null.
*/
public Proxy(String inPath) {
if(inPath == null) {
throw new NullPointerException("Path cannot be null.");
}
if("".equals(inPath)) {
throw new IllegalArgumentException("Path cannot be empty.");
}
type = new TypePath(inPath);
}
/**
* creates a proxy with a parent properties object and a replaceable.
* @param inParent the parent properties.
* @param inReplaceable the replaceable.
* @throws NullPointerException if the replaceable is null.
*/
Proxy(Properties inParent, Replaceable inReplaceable) {
if(inReplaceable == null) {
throw new NullPointerException("Replaceable cannot be null.");
}
parent = inParent;
type = new TypeReplaceable(inReplaceable);
}
/**
* creates a proxy with a parent properties object and a path.
*
* @param inParent the parent properties.
* @param inPath the path.
* @throws NullPointerException if the path is null.
*/
Proxy(Properties inParent, String inPath) {
this(inPath);
parent = inParent;
}
/**
* creates a proxy with parent properties and a type.
*
* @param inParent the parent properties.
* @param inType the type.
*/
private Proxy(Properties inParent, Type inType) {
this(inType);
parent = inParent;
}
/**
* creates a proxy with the given type.
*
* @param inType the type.
*/
private Proxy(Type inType) {
type = inType;
}
/*
* @see com.eva.properties.Replaceable#copy(com.eva.properties.Properties)
*/
public Replaceable copy(Properties inParent) {
Proxy proxy = new Proxy(inParent, type);
if(object != null) {
if(object instanceof Replaceable) {
proxy.object = ((Replaceable) object).copy(inParent);
}
else {
proxy.object = object;
}
}
return proxy;
}
/*
* @see com.eva.properties.Replaceable#replace(com.eva.properties.Context)
*/
public Object replace(Context inContext) throws PropertiesException {
if(object == null) {
/*
* For a path, set object to NoProperties.INSTANCE to avoid
* recursive call when a proxy is used for "super". If something
* needs to be replaced inside the super reference a recursive call
* would be the consequence.
* For a references, use Null.INSTANCE:
*/
object = type.getNullObject();
object = type.resolve(parent, inContext);
}
return object;
}
/*
* @see java.lang.Object#toString()
*/
public String toString() {
return type.toString();
}
/*
* @see com.eva.properties.Replaceable#toString(java.lang.StringBuffer,
* java.lang.String)
*/
public void write(Writer inoutWriter) {
inoutWriter.append(type.toString());
inoutWriter.append("\n");
}
/**
* sets the parent properties for this proxy.
*
* @param inParent the parent properties.
*/
void setParent(Properties inParent) {
parent = inParent;
}
}
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