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adding zipentry and zipoutputstream classes
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Chris Jordan
200
classpath/java/util/zip/ZipOutputStream.java
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200
classpath/java/util/zip/ZipOutputStream.java
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package java.util.zip;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.io.UnsupportedEncodingException;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.zip.CRC32;
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import java.util.zip.DeflaterOutputStream;
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import java.util.zip.Deflater;
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import java.io.BufferedOutputStream;
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/**
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* An as simple as possible implementation of ZipOutputStream
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* Compression method defaults to DEFLATE
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* All hardcoded defaults match the defaults for openJDK,
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* including PKZip version, bit flags set, compression level, etc
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*
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* @author ReadyTalk Summer 2013 Intern Team
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*/
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public class ZipOutputStream extends DeflaterOutputStream {
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private static final int SIGNATURE = 0x04034b50;
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private static final short VERSION = 0x0014;
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private static final short BITFLAG = 0x0008;
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private static final short METHOD = 0x0008;
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private static final int CENTRAL_FILE_HEADER = 0x02014b50;
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private static final int DATA_DESCRIPTER_HEADER = 0x08074b50;
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private static final int END_OF_CENTRAL_DIRECTORY_SIG = 0x06054b50;
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private static final int DEFAULT_LEVEL = 6;
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private final OutputStream out;
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private DeflaterOutputStream deflaterStream;
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private Deflater deflater;
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private List<ZipEntry> entries;
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private CRC32 crc = new CRC32();
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private ZipEntry currentEntry;
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private int bytesWritten;
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private int sizeOfCentralDirectory;
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private byte[] buffer;
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public ZipOutputStream(OutputStream outStream, int bufferSize) {
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super(outStream);
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out = outStream;
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bytesWritten = 0;
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sizeOfCentralDirectory = 0;
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entries = new ArrayList<ZipEntry>();
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buffer = new byte[bufferSize];
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deflater = new Deflater(DEFAULT_LEVEL, true);
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}
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public ZipOutputStream(OutputStream outStream) {
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this(outStream, 4 * 1024);
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}
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public void putNextEntry(ZipEntry e) throws IOException {
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e.offset = bytesWritten;
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currentEntry = e;
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entries.add(e);
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writeLocalHeader(e);
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}
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public void closeEntry() throws IOException {
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deflater.finish();
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while (!deflater.finished()) {
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deflate();
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}
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deflater.dispose();
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deflater.reset();
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currentEntry.crc = (int) crc.getValue();
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crc.reset();
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writeDataDescriptor(currentEntry);
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}
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private void writeLocalHeader(ZipEntry e) throws IOException {
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writeFourBytes(SIGNATURE); // local header signature
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writeTwoBytes(VERSION); // version used
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writeTwoBytes(BITFLAG); // flags
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writeTwoBytes(METHOD); // compression method
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writeTwoBytes(e.modTime); // last modified time
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writeTwoBytes(e.modDate); // last modified date
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writeFourBytes(0); // CRC is 0 for local header
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// with default flag settings, the compressed and uncompressed size
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// is written here as 0 and written correctly in the data descripter
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writeFourBytes(0); // compressed size
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writeFourBytes(0); // uncompressed size
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writeTwoBytes(e.name.length()); // length of file name
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// extra field length, in this implementation extra field in not used
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writeTwoBytes(0);
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// write file name, return the number of bytes written
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int len = writeVariableByteLength(e.getName());
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bytesWritten += 30 + len;
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}
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private void writeDataDescriptor(ZipEntry currentEntry) throws IOException {
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writeFourBytes(DATA_DESCRIPTER_HEADER); // data descripter header
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writeFourBytes(currentEntry.crc); // crc value
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writeFourBytes(currentEntry.compSize); // compressed size
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writeFourBytes(currentEntry.uncompSize); // uncompressed size
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bytesWritten += 16;
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}
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public void write(byte[] b, int offset, int length) throws IOException {
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currentEntry.uncompSize += length;
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crc.update(b, offset, length);
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currentEntry.crc = (int) crc.getValue();
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deflater.setInput(b, offset, length);
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while (deflater.getRemaining() > 0)
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deflate();
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}
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public void write(int b) throws IOException {
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byte[] buf = new byte[1];
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buf[0] = (byte)(b & 0xff);
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write(buf, 0, 1);
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}
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private void deflate() throws IOException {
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int len = deflater.deflate(buffer, 0, buffer.length);
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currentEntry.compSize += len;
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bytesWritten += len;
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if (len > 0)
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out.write(buffer, 0 , len);
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}
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private void writeCentralDirectoryHeader(ZipEntry e) throws IOException {
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writeFourBytes(CENTRAL_FILE_HEADER); // central directory header signature
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writeTwoBytes(VERSION); // version made by
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writeTwoBytes(VERSION); // version needed
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writeTwoBytes(BITFLAG); // flags
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writeTwoBytes(METHOD); // compression method
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writeTwoBytes(e.modTime); // last mod time
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writeTwoBytes(e.modDate); // last mod date
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writeFourBytes(e.crc); // crc
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writeFourBytes(e.compSize); // compressed size
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writeFourBytes(e.uncompSize); // uncompressed size
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writeTwoBytes(e.getName().length()); // file name length
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// the following 5 fields are all 0 for a simple default compression
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writeTwoBytes(0); // extra field length (not used)
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writeTwoBytes(0); // comment length (not used)
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writeTwoBytes(0); // disk number start
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writeTwoBytes(0); // internal file attribute
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writeFourBytes(0); // external file attribute
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writeFourBytes((int) e.offset); // relative offset of local header
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int len = writeVariableByteLength(e.getName());
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bytesWritten += 46 + len;
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sizeOfCentralDirectory += 46 + len;
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}
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private void writeEndofCentralDirectory(int offset) throws IOException {
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short numEntries = (short) entries.size();
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writeFourBytes(END_OF_CENTRAL_DIRECTORY_SIG); // end of central directory signature
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writeTwoBytes(0); // disk number
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writeTwoBytes(0); // disk number where central dir starts
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writeTwoBytes(numEntries); // number of entries on this disk
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writeTwoBytes(numEntries); // number of entries in central dir
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writeFourBytes(sizeOfCentralDirectory); // length of central directory
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writeFourBytes(offset); // offset of central directory
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writeTwoBytes(0); // length of added comments (not used)
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bytesWritten += 22;
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}
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public void close() throws IOException {
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int centralDirOffset = bytesWritten;
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for (ZipEntry e : entries)
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writeCentralDirectoryHeader(e);
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writeEndofCentralDirectory(centralDirOffset);
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}
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private void writeTwoBytes(int bytes) throws IOException {
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out.write(bytes & 0xff);
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out.write((bytes >> 8) & 0xff);
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}
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private void writeFourBytes(int bytes) throws IOException {
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out.write(bytes & 0xff);
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out.write((bytes >> 8) & 0xff);
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out.write((bytes >> 16) & 0xff);
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out.write((bytes >> 24) & 0xff);
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}
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private int writeVariableByteLength(String text) throws IOException {
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byte[] bytes = text.getBytes("UTF-8");
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out.write(bytes, 0, bytes.length);
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return bytes.length;
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}
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}
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