MemFileSystemRegistry.java

/*
 * Copyright 2010, Mysema Ltd
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.mysema.codegen;

import java.lang.ref.WeakReference;
import java.net.URL;
import java.util.Map;
import java.util.WeakHashMap;

import javax.tools.JavaFileManager;

/**
 * @author tiwe
 * 
 */
public final class MemFileSystemRegistry {

    public static final MemFileSystemRegistry DEFAULT = new MemFileSystemRegistry();

    private final Map<JavaFileManager, String> jfm2prefix = new WeakHashMap<JavaFileManager, String>();

    private Map<String, WeakReference<JavaFileManager>> prefix2jfm = new WeakHashMap<String, WeakReference<JavaFileManager>>();

    private final String protocolName;

    private int sequence = 0;

    private MemFileSystemRegistry() {
        String pkgName = MemFileSystemRegistry.class.getPackage().getName();
        protocolName = pkgName.substring(pkgName.lastIndexOf('.') + 1);
        String pkgs = System.getProperty("java.protocol.handler.pkgs");
        String parentPackage = pkgName.substring(0, pkgName.lastIndexOf('.'));
        pkgs = pkgs == null ? parentPackage : pkgs + "|" + parentPackage;
        System.setProperty("java.protocol.handler.pkgs", pkgs);
    }

    public JavaFileManager getFileSystem(URL url) {
        String prefix = url.getProtocol() + "://" + url.getHost() + "/";
        if (prefix2jfm.containsKey(prefix)) {
            return prefix2jfm.get(prefix).get();
        } else {
            return null;
        }
    }

    public String getUrlPrefix(JavaFileManager jfm) {
        if (jfm2prefix.containsKey(jfm)) {
            return jfm2prefix.get(jfm);
        } else {
            String result = protocolName + "://jfm" + (sequence++) + "/";
            jfm2prefix.put(jfm, result);
            prefix2jfm.put(result, new WeakReference<JavaFileManager>(jfm));
            return result;
        }
    }

}