StandardLocation.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package javax.tools;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import javax.tools.JavaFileManager.Location;

/**
 * Standard locations of file objects.
 *
 * @author Peter von der Ahé
 * @since 1.6
 */
// 标准路径
public enum StandardLocation implements Location {
    
    /**
     * Location of new source files.
     */
    SOURCE_OUTPUT,  // 注解处理器生成的源码存放路径，支持自定义
    
    /**
     * Location of new class files.
     */
    CLASS_OUTPUT,   // 默认在项目的class文件输出目录
    
    /**
     * Location of new native header files.
     *
     * @since 1.8
     */
    NATIVE_HEADER_OUTPUT,
    
    /**
     * Location to search for existing source files.
     */
    SOURCE_PATH,
    
    /**
     * Location to search for user class files.
     */
    CLASS_PATH,
    
    /**
     * Location to search for annotation processors.
     */
    ANNOTATION_PROCESSOR_PATH,
    
    /**
     * Location to search for modules containing annotation processors.
     *
     * @spec JPMS
     * @since 9
     */
    ANNOTATION_PROCESSOR_MODULE_PATH,
    
    /**
     * Location to search for platform classes.  Sometimes called
     * the boot class path.
     */
    PLATFORM_CLASS_PATH,
    
    /**
     * Location to search for the source code of modules.
     *
     * @spec JPMS
     * @since 9
     */
    MODULE_SOURCE_PATH,
    
    /**
     * Location to search for upgradeable system modules.
     *
     * @spec JPMS
     * @since 9
     */
    UPGRADE_MODULE_PATH,
    
    /**
     * Location to search for system modules.
     *
     * @spec JPMS
     * @since 9
     */
    SYSTEM_MODULES,
    
    /**
     * Location to search for precompiled user modules.
     *
     * @spec JPMS
     * @since 9
     */
    MODULE_PATH,
    
    /**
     * Location to search for module patches.
     *
     * @spec JPMS
     * @since 9
     */
    PATCH_MODULE_PATH;
    
    //where
    private static final ConcurrentMap<String, Location> locations = new ConcurrentHashMap<>();
    
    /**
     * Returns a location object with the given name.  The following
     * property must hold: {@code locationFor(x) ==
     * locationFor(y)} if and only if {@code x.equals(y)}.
     * The returned location will be an output location if and only if
     * name ends with {@code "_OUTPUT"}. It will be considered to
     * be a module-oriented location if the name contains the word
     * {@code "MODULE"}.
     *
     * @param name a name
     *
     * @return a location
     *
     * @revised 9
     * @spec JPMS
     */
    public static Location locationFor(final String name) {
        if(locations.isEmpty()) {
            // can't use valueOf which throws IllegalArgumentException
            for(Location location : values()) {
                locations.putIfAbsent(location.getName(), location);
            }
        }
        
        name.getClass(); /* null-check */
        
        locations.putIfAbsent(name, new Location() {
            @Override
            public String getName() {
                return name;
            }
            
            @Override
            public boolean isOutputLocation() {
                return name.endsWith("_OUTPUT");
            }
        });
        
        return locations.get(name);
    }
    
    // 位置名称
    @Override
    public String getName() {
        return name();
    }
    
    // 是否为输出位置
    @Override
    public boolean isOutputLocation() {
        switch(this) {
            case CLASS_OUTPUT:
            case SOURCE_OUTPUT:
            case NATIVE_HEADER_OUTPUT:
                return true;
            default:
                return false;
        }
    }
    
    /**
     * {@inheritDoc}
     *
     * @since 9
     */
    @Override
    public boolean isModuleOrientedLocation() {
        switch(this) {
            case MODULE_SOURCE_PATH:
            case ANNOTATION_PROCESSOR_MODULE_PATH:
            case UPGRADE_MODULE_PATH:
            case SYSTEM_MODULES:
            case MODULE_PATH:
            case PATCH_MODULE_PATH:
                return true;
            default:
                return false;
        }
    }
}