Java example source code file (SmartFileManager.java)

This example Java source code file (SmartFileManager.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

fileobject, hashmap, hashset, ioexception, iterable, javafileobject, kind, listbuffer, net, network, override, set, smartfilemanager, string, stringbuilder, uri, util

The SmartFileManager.java Java example source code

/*
 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.tools.sjavac.comp;

import com.sun.tools.javac.util.ListBuffer;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.URI;
import java.util.Set;
import java.util.HashSet;
import java.util.Map;
import java.util.HashMap;
import javax.tools.*;
import javax.tools.JavaFileObject.Kind;

/**
 * Intercepts reads and writes to the file system to gather
 * information about what artifacts are generated.
 *
 * Traps writes to certain files, if the content written is identical
 * to the existing file.
 *
 * Can also blind out the filemanager from seeing certain files in the file system.
 * Necessary to prevent javac from seeing some sources where the source path points.
 *
 * <p>This is NOT part of any supported API.
 * If you write code that depends on this, you do so at your own
 * risk.  This code and its internal interfaces are subject to change
 * or deletion without notice.</b>

 */
public class SmartFileManager extends ForwardingJavaFileManager<JavaFileManager> {

    // Set of sources that can be seen by javac.
    Set<URI> visibleSources = new HashSet();
    // Map from modulename:packagename to artifacts.
    Map<String,Set packageArtifacts = new HashMap>();
    // Where to print informational messages.
    PrintWriter stdout;

    public SmartFileManager(JavaFileManager fileManager) {
        super(fileManager);
    }

    public void setVisibleSources(Set<URI> s) {
        visibleSources = s;
    }

    public void cleanArtifacts() {
        packageArtifacts = new HashMap<String,Set();
    }

    public void setLog(PrintWriter pw) {
        stdout = pw;
    }

    public Map<String,Set getPackageArtifacts() {
        return packageArtifacts;
    }

    @Override
    public Iterable<JavaFileObject> list(Location location,
                                         String packageName,
                                         Set<Kind> kinds,
                                         boolean recurse)
        throws IOException
    {
        // Acquire the list of files.
        Iterable<JavaFileObject> files = super.list(location, packageName, kinds, recurse);
        if (visibleSources.isEmpty()) {
            return files;
        }
        // Now filter!
        ListBuffer<JavaFileObject> filteredFiles = new ListBuffer();
        for (JavaFileObject f : files) {
            URI uri = f.toUri();
            String t = uri.toString();
            if (t.startsWith("jar:")
                || t.endsWith(".class")
                || visibleSources.contains(uri))
            {
                filteredFiles.add(f);
            }
        }
        return filteredFiles;
    }

    @Override
    public boolean hasLocation(Location location) {
        return super.hasLocation(location);
    }

    @Override
    public JavaFileObject getJavaFileForInput(Location location,
                                              String className,
                                              Kind kind)
        throws IOException
    {
        JavaFileObject file = super.getJavaFileForInput(location, className, kind);
        if (file == null || visibleSources.isEmpty()) {
            return file;
        }

        if (visibleSources.contains(file.toUri())) {
            return file;
        }
        return null;
    }

    @Override
    public JavaFileObject getJavaFileForOutput(Location location,
                                               String className,
                                               Kind kind,
                                               FileObject sibling)
        throws IOException
    {
        JavaFileObject file = super.getJavaFileForOutput(location, className, kind, sibling);
        if (file == null) return file;
        int dp = className.lastIndexOf('.');
        String pkg_name = "";
        if (dp != -1) {
            pkg_name = className.substring(0, dp);
        }
        // When modules are in use, then the mod_name might be something like "jdk_base"
        String mod_name = "";
        addArtifact(mod_name+":"+pkg_name, file.toUri());
        return file;
    }

    @Override
    public FileObject getFileForInput(Location location,
                                      String packageName,
                                      String relativeName)
        throws IOException
    {
        FileObject file =  super.getFileForInput(location, packageName, relativeName);
        if (file == null || visibleSources.isEmpty()) {
            return file;
        }

        if (visibleSources.contains(file.toUri())) {
            return file;
        }
        return null;
    }

    @Override
    public FileObject getFileForOutput(Location location,
                                       String packageName,
                                       String relativeName,
                                       FileObject sibling)
        throws IOException
    {
        FileObject file = super.getFileForOutput(location, packageName, relativeName, sibling);
        if (file == null) return file;
        if (location.equals(StandardLocation.NATIVE_HEADER_OUTPUT) &&
                file instanceof JavaFileObject) {
           file = new SmartFileObject((JavaFileObject)file, stdout);
           packageName = ":" + packageNameFromFileName(relativeName);
        }
        if (packageName.equals("")) {
            packageName = ":";
        }
        addArtifact(packageName, file.toUri());
        return file;
    }

    private String packageNameFromFileName(String fn) {
        StringBuilder sb = new StringBuilder();
        int p = fn.indexOf('_'), pp = 0;
        while (p != -1) {
            if (sb.length() > 0) sb.append('.');
            sb.append(fn.substring(pp,p));
            if (p == fn.length()-1) break;
            pp = p+1;
            p = fn.indexOf('_',pp);
        }
        return sb.toString();
    }

    @Override
    public void flush() throws IOException {
        super.flush();
    }

    @Override
    public void close() throws IOException {
        super.close();
    }

    void addArtifact(String pkgName, URI art) {
        Set<URI> s = packageArtifacts.get(pkgName);
        if (s == null) {
            s = new HashSet<URI>();
            packageArtifacts.put(pkgName, s);
        }
        s.add(art);
    }
}