其实具体多大压缩率要看源文件的内容，一般来说重复的单词越多，压缩率越高。
下面是把/usr/share/dict/words压缩的测试程序
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.zip.GZIPOutputStream;
import org.apache.commons.codec.binary.Base64;
public class GzipBase64Tests {
public static void main(String[] args) throws Exception {
File input = new File("/Users/matianyi/input.txt");
File output = new File("/Users/matianyi/output.txt");
if (!input.exists()) {
System.out.println("input file not exists!");
return;
}
if (output.exists()) {
output.delete();
}
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
GZIPOutputStream gout = new GZIPOutputStream(buffer);
FileInputStream in = new FileInputStream(input);
long t1 = System.currentTimeMillis();
byte[] buf = new byte[1024];
int total=0;
int rd;
while ((rd = in.read(buf)) != -1) {
total += rd;
gout.write(buf,0, rd);
}
gout.close();
in.close();
byte[] result = buffer.toByteArray();
long t2 = System.currentTimeMillis();
String base64 = Base64.encodeBase64String(result);
long t3 = System.currentTimeMillis();
System.out.printf("raw %d -> gzip %d -> base64 %d, time1 %dms, time2 %dms", total, result.length, base64.length(), t2-t1, t3-t2);
}
}
输出为： raw 2493109 -> gzip 753932 -> base64 1005244, time1 225ms, time2 43ms
压缩了50%。
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