com.gitee.starblues.loader.jar.CentralDirectoryParser Maven / Gradle / Ivy
/*
* Copyright 2012-2021 the original author or authors.
* Copy from spring-boot-loader
*
* 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
*
* https://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.gitee.starblues.loader.jar;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/**
* Parses the central directory from a JAR file.
*
* @author Phillip Webb
* @author Andy Wilkinson
* @see CentralDirectoryVisitor
*/
public class CentralDirectoryParser {
private static final int CENTRAL_DIRECTORY_HEADER_BASE_SIZE = 46;
private final List visitors = new ArrayList<>();
T addVisitor(T visitor) {
this.visitors.add(visitor);
return visitor;
}
/**
* Parse the source data, triggering {@link CentralDirectoryVisitor visitors}.
* @param data the source data
* @param skipPrefixBytes if prefix bytes should be skipped
* @return the actual archive data without any prefix bytes
* @throws IOException on error
*/
RandomAccessData parse(RandomAccessData data, boolean skipPrefixBytes) throws IOException {
CentralDirectoryEndRecord endRecord = new CentralDirectoryEndRecord(data);
if (skipPrefixBytes) {
data = getArchiveData(endRecord, data);
}
RandomAccessData centralDirectoryData = endRecord.getCentralDirectory(data);
visitStart(endRecord, centralDirectoryData);
parseEntries(endRecord, centralDirectoryData);
visitEnd();
return data;
}
private void parseEntries(CentralDirectoryEndRecord endRecord, RandomAccessData centralDirectoryData)
throws IOException {
byte[] bytes = centralDirectoryData.read(0, centralDirectoryData.getSize());
CentralDirectoryFileHeader fileHeader = new CentralDirectoryFileHeader();
int dataOffset = 0;
for (int i = 0; i < endRecord.getNumberOfRecords(); i++) {
fileHeader.load(bytes, dataOffset, null, 0, null);
visitFileHeader(dataOffset, fileHeader);
dataOffset += CENTRAL_DIRECTORY_HEADER_BASE_SIZE + fileHeader.getName().length()
+ fileHeader.getComment().length() + fileHeader.getExtra().length;
}
}
private RandomAccessData getArchiveData(CentralDirectoryEndRecord endRecord, RandomAccessData data) {
long offset = endRecord.getStartOfArchive(data);
if (offset == 0) {
return data;
}
return data.getSubsection(offset, data.getSize() - offset);
}
private void visitStart(CentralDirectoryEndRecord endRecord, RandomAccessData centralDirectoryData) {
for (CentralDirectoryVisitor visitor : this.visitors) {
visitor.visitStart(endRecord, centralDirectoryData);
}
}
private void visitFileHeader(int dataOffset, CentralDirectoryFileHeader fileHeader) {
for (CentralDirectoryVisitor visitor : this.visitors) {
visitor.visitFileHeader(fileHeader, dataOffset);
}
}
private void visitEnd() {
for (CentralDirectoryVisitor visitor : this.visitors) {
visitor.visitEnd();
}
}
}