打包Zip文件下载

• 项目里要把当个文件单个打包下载，找了个资料，备份

public synchronized static ByteArrayOutputStream zip(Map<String, byte[]> map)

           throws IOException {


       ByteArrayOutputStream baos = new ByteArrayOutputStream();

       ZipOutputStream zos = new ZipOutputStream(baos);

       ZipEntry zipEntry;


       for (String key : map.keySet()) {


           zipEntry = new ZipEntry(key);

           zipEntry.setSize(map.get(key).length);

           zipEntry.setTime(System.currentTimeMillis());


           zos.putNextEntry(zipEntry);

           zos.write(map.get(key));

           zos.flush();

       }


       zos.close();

       return baos;

    }

 

 

1.     ZipEntry：This class is used to represent a ZIP file entry.
2.     ZipFile：This class is used to read entries from a zip file.
3.     ZipInputStream：This class implements an input stream filter for reading files in the ZIP file format.
4.     ZipOutputStream：This class implements an output stream filter for writing files in the ZIP file format.

 

现在我们了解一下读写Zip文件的基本流程。当解压时，从该Zip文件输入流中读取出ZipEntry，然后根据ZipEntry的信息，读取对应文件的相应字节。代码实现如下：

 

public synchronized static Map<String, byte[]> unZip(InputStream is)

           throws IOException {

 

       Map<String, byte[]> result = new HashMap<String, byte[]>();

      

       byte[] buf;

       ZipInputStream zis = new ZipInputStream(is);

       ZipEntry zipEntry = zis.getNextEntry();

 

       while (zipEntry != null) {

 

           if (zipEntry.isDirectory()) {

 

              zipEntry = zis.getNextEntry();

              continue;

           } else {

 

              buf = new byte[(int) zipEntry.getSize()];

              zis.read(buf, 0, (int) zipEntry.getSize());

               result.put(zipEntry.getName(), buf);

 

              zipEntry = zis.getNextEntry();

           }

       }

 

       return result;

}

 

 

压缩操作与解压操作差不多，先将文件字节流组装成ZipEntry，然后把ZipEntry加入到输出流中即可。代码实现如下：

 

 

 

    至此，使用上面的两个方法就能完成基本的 Zip 文件压缩和解压缩处理了；该方法只适合处理 Zip 格式的文件，对于 GZip 格式的文件，我相信你也能轻松搞定了：）。