Java.util.zip Compressed Packaging File Summary Two: Zip decompression technology

First, brief

Decompression technology and compression technology just the opposite, the decompression technology to use the class: by the Zipinputstream through the Read method to extract data, and the need to set up redundancy check code through Checkedinputstream, such as:

New Checkedinputstream ( new          fileinputstream(new  CRC32 ());     New Zipinputstream (CIS);  

It is important to note that when building an extract file, you need to consider the automatic creation of the directory, where the parent directory is created recursively by layer, as follows:

Create a directory when the parent directory does not exist! 
Privatestaticvoid  fileprober (File dirfile) {      = dirfile.getparentfile ();       if (! parentfile.exists ()) {            //  recursive search for parent directory           fileprober (parentfile);         Parentfile.mkdir ();      }  }  

When compressing, we add a file as a compressed add-on (zipentry) to the compressed package, extracting a single compressed item from the compressed package, as follows:

Private Static voidDecompress (File destfile, Zipinputstream zis) throws Exception {ZipEntry entry=NULL;  while((Entry = Zis.getnextentry ())! =NULL) {            //fileString dir = destfile.getpath () + File.separator +Entry.getname (); File Dirfile=NewFile (dir); //file CheckFileprober (Dirfile); if(Entry.isdirectory ()) {dirfile.mkdirs (); } Else{decompressfile (dirfile, ZiS);      } zis.closeentry (); }  }

The most core of the decompression implementation, in fact, is very similar to the compression implementation, the code is as follows:

/** * File Uncompressed * * @param destfile * target file * @param zis * zipinputstream * @throws Exception */  Private Static voidDecompressfile (File destfile, Zipinputstream zis) throws Exception {Bufferedoutputstream Bos=NewBufferedoutputstream (NewFileOutputStream (destfile)); intcount; byteData[] =New byte[BUFFER];  while(count = zis.read (data,0, BUFFER))! =-1) {bos.write (data,0, Count);  } bos.close (); } 

A complete example:

Package Com.joyplus.test;import Java.io.BufferedOutputStream;  Import Java.io.File;  Import Java.io.FileInputStream;  Import Java.io.FileOutputStream;  Import java.util.zip.CRC32;  Import Java.util.zip.CheckedInputStream;  Import Java.util.zip.ZipEntry;  Import Java.util.zip.ZipInputStream;      /** * * @author * */public class ZipFiletest2 {public static final String EXT = ". zip";      private static final String Base_dir = "";      private static final String PATH = File.separator;        private static final int BUFFER = 1024; /** * File Uncompressed * * @param srcpath * source file path * * @throws Exception */Publ            IC static void Decompress (String Srcpath) throws Exception {file Srcfile = new File (Srcpath);      Decompress (srcfile); }/** * Unzip * * @param srcfile * @throws Exception * * public static void decompress ( File srcfile) throws Exception {String BasePath = srcfile.getparent ();      Decompress (Srcfile, basepath); */** * Unzip * * @param srcfile * @param destfile * @throws Exception */Public static void decompress (file srcfile, file destfile) throws Exception {checkedinputstream cis = new Checkedinpu            TStream (New FileInputStream (Srcfile), New CRC32 ());            Zipinputstream ZiS = new Zipinputstream (CIS);            Decompress (DestFile, ZiS);        Zis.close (); */** * Unzip * * @param srcfile * @param destpath * @throws Exception */Public static void Decompress (File srcfile, String destpath) throws Exception {Decompress (srcfile, new Fil        E (destpath));            /** * File Extract * * @param srcpath * source file path * @param destpath * Destination file path * @throws Exception */public static void decompress (string srcpath, string destpath) t HroWS Exception {file Srcfile = new File (Srcpath);      Decompress (Srcfile, destpath); /** * File Extract * * @param destfile * target file * @param zis * Zipin              Putstream * @throws Exception */private static void decompress (File destfile, Zipinputstream zis)          Throws Exception {ZipEntry entry = null; while ((entry = Zis.getnextentry ()) = null) {//file String dir = destfile.getpath () + file.se                Parator + entry.getname ();                File Dirfile = new file (dir);                Document Inspection Fileprober (dirfile);              if (Entry.isdirectory ()) {dirfile.mkdirs ();              } else {decompressfile (dirfile, ZiS);          } zis.closeentry ();      }}/** * file Probe * * * * When the parent directory does not exist, create a directory! * * * @param dirfile */Private Static void Fileprober (file dirfile) {File Parentfile = Dirfile.getparentfile ();                if (!parentfile.exists ()) {//recursive search for parent directory Fileprober (Parentfile);          Parentfile.mkdir ();            }}/** * File uncompressed * * @param destfile * target file * @param zis * Zipinputstream * @throws Exception */private static void Decompressfile (File destfile, Zipinputstream Z IS) throws Exception {bufferedoutputstream bos = new Bufferedoutputstream (New F            Ileoutputstream (DestFile));          int count;          byte data[] = new Byte[buffer];          while ((count = zis.read (data, 0, BUFFER))! =-1) {bos.write (data, 0, count);      } bos.close (); } public static void Main (string[] args) {//extract to the specified directory try {zipfiletest2.decompress ("D:\\sumzip\\co.zip", "D: \\log ");} catch (Exception e) {//TODO Auto-generated catch Blocke.printstacktrace ();} }}

　　

Reference article: http://snowolf.iteye.com/blog/642492

Java.util.zip Compressed Packaging File Summary Two: Zip decompression technology