Snappy压缩 | 易学教程

package demo02.action;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Date;

import org.apache.commons.codec.CharEncoding;
import org.xerial.snappy.Snappy;

/**
* 使用snappy压缩算法压缩文件
* @author gujie
*
*/
public class SnappyUtil {

   public static void main(String[] args) throws IOException {
       long time1 = new Date().getTime();
       //输入文件
       File fileread = new File("D:\\Users\\gujie\\Desktop\\js\\46818_19279_4547_50.json");
       //压缩后文件
       File fileWrite = new File("D:\\Users\\gujie\\Desktop\\js\\snappytest.snappy");

       String charEncoding = CharEncoding.ISO_8859_1;//只能是ISO_8859_1，由byte[]的编码决定

       //读取文件
       String readFile = readFile(fileread, charEncoding);
       System.out.println("read during(" + (new Date().getTime() - time1) + ")");

       //压缩内容
       long time2 = new Date().getTime();
       byte[] compressHtml = compressHtml(readFile);
       System.out.println("snappy during(" + (new Date().getTime() - time2) + ")");

       //存储压缩内容
       time2 = new Date().getTime();
       writeFile(fileWrite, compressHtml, charEncoding);
       System.out.println("snappy save during(" + (new Date().getTime() - time2) + ")");

       //读取压缩文件
       long time3 = new Date().getTime();
       String snappyStr = readFile(fileWrite,charEncoding);
       System.out.println("read snappy during(" + (new Date().getTime() - time3) + ")");

       //解压压缩文件内容
       long time4 = new Date().getTime();
       String decompressHtml = decompressHtml(snappyStr.getBytes(charEncoding));
//       System.out.println("dec file:"+decompressHtml);
       System.out.println("decode snappy during(" + (new Date().getTime() - time4) + ")");

       //查看压缩比
       long totalSpaceBefore = fileread.length();
       long totalSpaceAfter = fileWrite.length();
       System.out.println("压缩前：" + totalSpaceBefore + "\t压缩后:" + totalSpaceAfter + "\t压缩比："
               + totalSpaceAfter * 1.0 / totalSpaceBefore);
   }

   /**
   * 写文件接口
   * @param file
   * @param bytes
   * @param encodeing
   * @throws IOException
   */
   public static void writeFile(File file, byte[] bytes, String encodeing) throws IOException {
       OutputStreamWriter op = new OutputStreamWriter(new FileOutputStream(file), encodeing);
       op.append(new String(bytes,encodeing));
       op.flush();
       op.close();
   }

   /**
   * 读文件接口
   * @param file
   * @param encodeing
   * @return
   */
   public static String readFile(File file, String encodeing) {
       StringBuilder stringBuffer = new StringBuilder();
       try {
           byte [] fileBytes = Files.readAllBytes(Paths.get(file.getPath()));
           return new String(fileBytes,encodeing);
       } catch (IOException e) {
           e.printStackTrace();
       }

       return stringBuffer.toString();
   }

   /**
   * 压缩字符串
   * @param html
   * @return
   */
   public static byte[] compressHtml(String html) {
       try {
           return Snappy.compress(html.getBytes("UTF-8"));
       } catch (IOException e) {
           e.printStackTrace();
           return null;
       }
   }

   /**
   * 解压字节数组
   * @param bytes
   * @return
   */
   public static String decompressHtml(byte[] bytes) {
       try {
           return new String(Snappy.uncompress(bytes));
       } catch (IOException e) {
           e.printStackTrace();
           return null;
       }
   }
}

来源：博客园

作者：Giles_Gu

链接：https://www.cnblogs.com/blueshy/p/11586357.html

标签

snappy

string

date