com.facebook.buck.java.abi.ZipWalker.java Source code

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Here is the source code for com.facebook.buck.java.abi.ZipWalker.java

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/*
 * Copyright 2014-present Facebook, Inc.
 *
 * 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.facebook.buck.java.abi;

import com.google.common.base.Preconditions;
import com.google.common.collect.Sets;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Set;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipInputStream;

/**
 * A {@link Walker} which iterates over entries of a ZIP file in sorted (name) order.
 */
class ZipWalker implements Walker {
    private final Path zipFile;

    public ZipWalker(Path path) {
        this.zipFile = Preconditions.checkNotNull(path);
    }

    @Override
    public void walk(FileAction onFile) throws IOException {
        Set<String> names = Sets.newTreeSet();

        // Get the set of all names and sort them, so that we get a deterministic iteration order.
        try (FileInputStream fis = new FileInputStream(zipFile.toFile());
                BufferedInputStream bis = new BufferedInputStream(fis);
                ZipInputStream zis = new ZipInputStream(bis)) {
            for (ZipEntry entry = zis.getNextEntry(); entry != null; entry = zis.getNextEntry()) {
                if (entry.isDirectory()) {
                    continue;
                }
                names.add(entry.getName());
            }
        }

        // Iterate over the file entries, calling the action on each one.
        if (!names.isEmpty()) {
            try (ZipFile zip = new ZipFile(zipFile.toFile())) {
                for (String name : names) {
                    try (InputStream is = zip.getInputStream(zip.getEntry(name))) {
                        onFile.visit(Paths.get(name), is);
                    }
                }
            }
        }
    }
}