java 字符串压缩之Snappy

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Snappy 是一个 C++ 的用来压缩和解压缩的开发包。其目标不是最大限度压缩或者兼容其他压缩格式，而是旨在提供高速压缩速度和合理的压缩率。

引入maven

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<dependency>
 <groupId>org.xerial.snappy</groupId>
 <artifactId>snappy-java</artifactId>
 <version>1.1.4</version>
</dependency>

将字符串压缩成byte数组

使用iso8859-1编码（具体编码可以视具体字符串而定）。

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public static String compress(String info) throws IOException {
  return Snappy.compress(info, "ISO-8859-1");
}

将byte数组解码成字符串

使用iso8859-1编码（具体编码可以视具体字符串而定）。

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public static String uncompress(byte[] info) throws IOException {
  return Snappy.uncompressString(info, "ISO-8859-1");
}

二进制转字符串

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public static String byteTohex(byte[] b) {
  String hs = "";
  String stmp = "";
  for (int n = 0; n < b.length; n++) {
    stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
    if (stmp.length() == 1) {
      hs = hs + "0" + stmp;
    } else {
      hs = hs + stmp;
    }
  }
  return hs;
}

字符串转二进制

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public static byte[] hexTobyte(String str) {
  if (str == null) {
    return null;
  }
  str = str.trim();
  int len = str.length();
    if (len == 0 || len % 2 == 1) {
      return null;
    }
    byte[] b = new byte[len / 2];
    try {
      for (int i = 0; i < str.length(); i += 2) {
        b[i / 2] = (byte) Integer.decode("0x" + str.substring(i, i + 2)).intValue();
    }
    return b;
  } catch (Exception e) {
    return null;
  }
}

完整的SnappyUtil.java

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import java.io.IOException;
import org.xerial.snappy.Snappy;

public class SnappyUtil {

  public static String compress(String info) throws IOException {
    return byteTohex(Snappy.compress(info, "ISO-8859-1"));
  }

  public static String uncompress(String info) throws IOException {
    return Snappy.uncompressString(hexTobyte(info), "ISO-8859-1");
  }

  private static String byteTohex(byte[] b) {
    String hs = "";
    String stmp = "";
    for (int n = 0; n < b.length; n++) {
      stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
      if (stmp.length() == 1) {
        hs = hs + "0" + stmp;
      } else {
        hs = hs + stmp;
      }
    }
    return hs;
  }

  private static byte[] hexTobyte(String str) {
    if (str == null) {
      return null;
    }
    str = str.trim();
    int len = str.length();
    if (len == 0 || len % 2 == 1) {
      return null;
    }
    byte[] b = new byte[len / 2];
    try {
      for (int i = 0; i < str.length(); i += 2) {
        b[i / 2] = (byte) Integer.decode("0x" + str.substring(i, i + 2)).intValue();
      }
      return b;
    } catch (Exception e) {
      return null;
    }
  }
}