JDK 中压缩和好压缩

JDK 中压缩和解压缩
package cn.tang.zip;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.util.Enumeration;import java.util.zip.ZipEntry;import java.util.zip.ZipFile;import java.util.zip.ZipOutputStream;public class MyZipUtil {public void unzip(File zipFile, File unzipFolder) throws IOException {if (!unzipFolder.exists()) {unzipFolder.mkdir();}ZipFile zip = new ZipFile(zipFile);unzip(zip, unzipFolder.getAbsolutePath());zip.close();}private void unzip(ZipFile zipFile, String parentDir) throws IOException {Enumeration<? extends ZipEntry> entries = zipFile.entries();byte[] buffer = new byte[128];while (entries.hasMoreElements()) {ZipEntry entry = entries.nextElement();String entryName = entry.getName();File f = new File(parentDir + File.separator + entryName);System.out.println(f.getAbsolutePath());if (entry.isDirectory()||entryName.endsWith("\")||entryName.endsWith(File.separator)) {if (!f.exists()) {f.mkdir();}} else {if (!f.exists())f.createNewFile();OutputStream os = new BufferedOutputStream(new FileOutputStream(f));InputStream is = zipFile.getInputStream(entry);int count = -1;while ((count=is.read(buffer)) != -1) {os.write(buffer, 0, count);}os.close();is.close();}}}public void zip(File sourceFile, File zipFile) throws IOException {FileOutputStream fos = new FileOutputStream(zipFile);ZipOutputStream out = new ZipOutputStream(new BufferedOutputStream(fos));zip(sourceFile, out, "");out.close();}private void zip(File sourceFile, ZipOutputStream out, String parentDir) throws IOException {if (sourceFile == null || !sourceFile.exists())throw new FileNotFoundException();String currentPath = parentDir + sourceFile.getName();if (sourceFile.isDirectory()) {ZipEntry entry = new ZipEntry(currentPath + File.separator);out.putNextEntry(entry);for (File temp : sourceFile.listFiles()) {zip(temp, out, currentPath + File.separator);}} else {ZipEntry entry = new ZipEntry(currentPath);out.putNextEntry(entry);byte[] buffer = new byte[128];FileInputStream fis = new FileInputStream(sourceFile);BufferedInputStream bis = new BufferedInputStream(fis);int count = 0;while ((count = bis.read(buffer)) != -1) {out.write(buffer, 0, count);}bis.close();}}}

?这里有点要注意的是，ZipEntry.isDirectory()方法，如果你在linux平台基本没有问题，但是如果在windows平台可能不好用。看看源码就知道了

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 public boolean isDirectory()    {        return name.endsWith("/");    }

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?2.对流进行压缩和解压

JDK中提供了一下几个类来帮助我们对输入输出流进行解压和压缩

public class InflaterInputStream extends FilterInputStreampublic class InflaterOutputStream extends FilterOutputStreampublic class DeflaterInputStream extends FilterInputStreampublic class DeflaterOutputStream extends FilterOutputStream//看看他们的继承关系public class DeflaterInputStream extends FilterInputStreampublic class FilterInputStream extends InputStream//看构造方法 public DeflaterInputStream(InputStream inputstream)    {        this(inputstream, new Deflater());        usesDefaultDeflater = true;    }protected FilterInputStream(InputStream inputstream)    {        in = inputstream;    }//装饰着模式，不用说都知道怎么用

?这里要注意的是，reset 和mark方法不能用，源代码为证

  public synchronized void mark(int i)    {    }    public synchronized void reset()        throws IOException    {        throw new IOException("mark/reset not supported");    }

?最近看hadoop 源码的时候发现它实现了这个方法，刚兴趣的同学可以看看

org.apache.hadoop.io.compress.zlib.ZlibCompressor这个类

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