com.github.jasmo.util.ClassPath.java Source code

Introduction

Here is the source code for com.github.jasmo.util.ClassPath.java

Source

/*
 * Copyright  2017 Caleb Whiting <caleb.andrew.whiting@gmail.com>
 * This work is free. You can redistribute it and/or modify it under the
 * terms of the Do What The Fuck You Want To Public License, Version 2,
 * as published by Sam Hocevar. See the COPYING file for more details.
 */

package com.github.jasmo.util;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.objectweb.asm.*;
import org.objectweb.asm.tree.*;

import java.io.*;
import java.util.*;
import java.util.jar.*;
import java.util.stream.Stream;

/**
 * @author Caleb Whiting
 *
 * Loads/caches jar files found in java.class.path as {@link ClassNode} objects and stores them in a map for conveneience.
 */
public class ClassPath extends HashMap<String, ClassNode> {

    private static final Logger log = LogManager.getLogger("ClassPath");

    private static ClassPath instance;

    private ClassPath() {
        String[] classpath = System.getProperty("java.class.path").split(System.getProperty("path.separator"));
        Stream.of(classpath).filter(path -> path.endsWith(".jar")).forEach(this::append);
    }

    private void append(String jarPath) {
        log.debug("Loading library from classpath: {}", jarPath);
        try (JarFile jar = new JarFile(jarPath)) {
            Enumeration<JarEntry> entries = jar.entries();
            while (entries.hasMoreElements()) {
                JarEntry entry = entries.nextElement();
                try (InputStream in = jar.getInputStream(entry)) {
                    if (entry.getName().endsWith(".class")) {
                        byte[] bytes;
                        try (ByteArrayOutputStream tmp = new ByteArrayOutputStream()) {
                            byte[] buf = new byte[256];
                            for (int n; (n = in.read(buf)) != -1;) {
                                tmp.write(buf, 0, n);
                            }
                            bytes = tmp.toByteArray();
                        }
                        ClassNode c = new ClassNode();
                        ClassReader r = new ClassReader(bytes);
                        r.accept(c, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG);
                        put(c.name, c);
                    }
                }
            }
        } catch (IOException e) {
            log.error("An error occurred while reading jar file: {}", jarPath, e);
        }
    }

    public static ClassPath getInstance() {
        if (instance == null)
            instance = new ClassPath();
        return instance;
    }

}