Java压缩技术（一） ZLib

有关ZLib可参见官方主页 http://www.zlib.net/
ZLib可以简单的理解为压缩/解压缩算法，它与ZIP、RAR等归档算法有所不同，与bzip2比较接近。

压缩工具代码如下：

Java代码

1. /**  
2.  * 2009-9-9  
3.  */  
4. package org.zlex.commons.io;   
5.   
6. import java.io.ByteArrayOutputStream;   
7. import java.io.IOException;   
8. import java.io.InputStream;   
9. import java.io.OutputStream;   
10. import java.util.zip.Deflater;   
11. import java.util.zip.DeflaterOutputStream;   
12. import java.util.zip.Inflater;   
13. import java.util.zip.InflaterInputStream;   
14.   
15. /**  
16.  * ZLib压缩工具  
17.  *   
18.  * @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a>  
19.  * @version 1.0  
20.  * @since 1.0  
21.  */  
22. public abstract class ZLibUtils {   
23.   
24.     /**  
25.      * 压缩  
26.      *   
27.      * @param data  
28.      *            待压缩数据  
29.      * @return byte[] 压缩后的数据  
30.      */  
31.     public static byte[] compress(byte[] data) {   
32.         byte[] output = new byte[0];   
33.   
34.         Deflater compresser = new Deflater();   
35.   
36.         compresser.reset();   
37.         compresser.setInput(data);   
38.         compresser.finish();   
39.         ByteArrayOutputStream bos = new ByteArrayOutputStream(data.length);   
40.         try {   
41.             byte[] buf = new byte[1024];   
42.             while (!compresser.finished()) {   
43.                 int i = compresser.deflate(buf);   
44.                 bos.write(buf, 0, i);   
45.             }   
46.             output = bos.toByteArray();   
47.         } catch (Exception e) {   
48.             output = data;   
49.             e.printStackTrace();   
50.         } finally {   
51.             try {   
52.                 bos.close();   
53.             } catch (IOException e) {   
54.                 e.printStackTrace();   
55.             }   
56.         }   
57.         compresser.end();   
58.         return output;   
59.     }   
60.   
61.     /**  
62.      * 压缩  
63.      *   
64.      * @param data  
65.      *            待压缩数据  
66.      *   
67.      * @param os  
68.      *            输出流  
69.      */  
70.     public static void compress(byte[] data, OutputStream os) {   
71.         DeflaterOutputStream dos = new DeflaterOutputStream(os);   
72.   
73.         try {   
74.             dos.write(data, 0, data.length);   
75.   
76.             dos.finish();   
77.   
78.             dos.flush();   
79.         } catch (IOException e) {   
80.             e.printStackTrace();   
81.         }   
82.     }   
83.   
84.     /**  
85.      * 解压缩  
86.      *   
87.      * @param data  
88.      *            待压缩的数据  
89.      * @return byte[] 解压缩后的数据  
90.      */  
91.     public static byte[] decompress(byte[] data) {   
92.         byte[] output = new byte[0];   
93.   
94.         Inflater decompresser = new Inflater();   
95.         decompresser.reset();   
96.         decompresser.setInput(data);   
97.   
98.         ByteArrayOutputStream o = new ByteArrayOutputStream(data.length);   
99.         try {   
100.             byte[] buf = new byte[1024];   
101.             while (!decompresser.finished()) {   
102.                 int i = decompresser.inflate(buf);   
103.                 o.write(buf, 0, i);   
104.             }   
105.             output = o.toByteArray();   
106.         } catch (Exception e) {   
107.             output = data;   
108.             e.printStackTrace();   
109.         } finally {   
110.             try {   
111.                 o.close();   
112.             } catch (IOException e) {   
113.                 e.printStackTrace();   
114.             }   
115.         }   
116.   
117.         decompresser.end();   
118.         return output;   
119.     }   
120.   
121.     /**  
122.      * 解压缩  
123.      *   
124.      * @param is  
125.      *            输入流  
126.      * @return byte[] 解压缩后的数据  
127.      */  
128.     public static byte[] decompress(InputStream is) {   
129.         InflaterInputStream iis = new InflaterInputStream(is);   
130.         ByteArrayOutputStream o = new ByteArrayOutputStream(1024);   
131.         try {   
132.             int i = 1024;   
133.             byte[] buf = new byte[i];   
134.   
135.             while ((i = iis.read(buf, 0, i)) > 0) {   
136.                 o.write(buf, 0, i);   
137.             }   
138.   
139.         } catch (IOException e) {   
140.             e.printStackTrace();   
141.         }   
142.         return o.toByteArray();   
143.     }   
144. }  

/** * 2009-9-9 */package org.zlex.commons.io;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.util.zip.Deflater;import java.util.zip.DeflaterOutputStream;import java.util.zip.Inflater;import java.util.zip.InflaterInputStream;/** * ZLib压缩工具 *  * @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a> * @version 1.0 * @since 1.0 */public abstract class ZLibUtils {/** * 压缩 *  * @param data *            待压缩数据 * @return byte[] 压缩后的数据 */public static byte[] compress(byte[] data) {byte[] output = new byte[0];Deflater compresser = new Deflater();compresser.reset();compresser.setInput(data);compresser.finish();ByteArrayOutputStream bos = new ByteArrayOutputStream(data.length);try {byte[] buf = new byte[1024];while (!compresser.finished()) {int i = compresser.deflate(buf);bos.write(buf, 0, i);}output = bos.toByteArray();} catch (Exception e) {output = data;e.printStackTrace();} finally {try {bos.close();} catch (IOException e) {e.printStackTrace();}}compresser.end();return output;}/** * 压缩 *  * @param data *            待压缩数据 *  * @param os *            输出流 */public static void compress(byte[] data, OutputStream os) {DeflaterOutputStream dos = new DeflaterOutputStream(os);try {dos.write(data, 0, data.length);dos.finish();dos.flush();} catch (IOException e) {e.printStackTrace();}}/** * 解压缩 *  * @param data *            待压缩的数据 * @return byte[] 解压缩后的数据 */public static byte[] decompress(byte[] data) {byte[] output = new byte[0];Inflater decompresser = new Inflater();decompresser.reset();decompresser.setInput(data);ByteArrayOutputStream o = new ByteArrayOutputStream(data.length);try {byte[] buf = new byte[1024];while (!decompresser.finished()) {int i = decompresser.inflate(buf);o.write(buf, 0, i);}output = o.toByteArray();} catch (Exception e) {output = data;e.printStackTrace();} finally {try {o.close();} catch (IOException e) {e.printStackTrace();}}decompresser.end();return output;}/** * 解压缩 *  * @param is *            输入流 * @return byte[] 解压缩后的数据 */public static byte[] decompress(InputStream is) {InflaterInputStream iis = new InflaterInputStream(is);ByteArrayOutputStream o = new ByteArrayOutputStream(1024);try {int i = 1024;byte[] buf = new byte[i];while ((i = iis.read(buf, 0, i)) > 0) {o.write(buf, 0, i);}} catch (IOException e) {e.printStackTrace();}return o.toByteArray();}}

测试用例代码如下：

Java代码

1. /**  
2.  * 2009-9-9  
3.  */  
4. package org.zlex.commons.io;   
5.   
6. import static org.junit.Assert.*;   
7.   
8. import java.io.File;   
9. import java.io.FileInputStream;   
10. import java.io.FileOutputStream;   
11.   
12. import org.junit.Test;   
13.   
14. /**  
15.  * ZLib压缩测试用例  
16.  *   
17.  * @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a>  
18.  * @version 1.0  
19.  * @since 1.0  
20.  */  
21. public class ZLibUtilsTest {   
22.   
23.     @Test  
24.     public final void testBytes() {   
25.         System.err.println("字节压缩／解压缩测试");   
26.         String inputStr = "snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org";   
27.         System.err.println("输入字符串:\t" + inputStr);   
28.         byte[] input = inputStr.getBytes();   
29.         System.err.println("输入字节长度:\t" + input.length);   
30.   
31.         byte[] data = ZLibUtils.compress(input);   
32.         System.err.println("压缩后字节长度:\t" + data.length);   
33.   
34.         byte[] output = ZLibUtils.decompress(data);   
35.         System.err.println("解压缩后字节长度:\t" + output.length);   
36.         String outputStr = new String(output);   
37.         System.err.println("输出字符串:\t" + outputStr);   
38.   
39.         assertEquals(inputStr, outputStr);   
40.     }   
41.   
42.     @Test  
43.     public final void testFile() {   
44.         String filename = "zlib";   
45.         File file = new File(filename);   
46.         System.err.println("文件压缩／解压缩测试");   
47.         String inputStr = "snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org";   
48.         System.err.println("输入字符串:\t" + inputStr);   
49.         byte[] input = inputStr.getBytes();   
50.         System.err.println("输入字节长度:\t" + input.length);   
51.   
52.         try {   
53.   
54.             FileOutputStream fos = new FileOutputStream(file);   
55.             ZLibUtils.compress(input, fos);   
56.             fos.close();   
57.             System.err.println("压缩后字节长度:\t" + file.length());   
58.         } catch (Exception e) {   
59.             fail(e.getMessage());   
60.         }   
61.   
62.         byte[] output = null;   
63.   
64.         try {   
65.             FileInputStream fis = new FileInputStream(file);   
66.             output = ZLibUtils.decompress(fis);   
67.             fis.close();   
68.   
69.         } catch (Exception e) {   
70.             fail(e.getMessage());   
71.         }   
72.         System.err.println("解压缩后字节长度:\t" + output.length);   
73.         String outputStr = new String(output);   
74.         System.err.println("输出字符串:\t" + outputStr);   
75.   
76.         assertEquals(inputStr, outputStr);   
77.     }   
78. }  

/** * 2009-9-9 */package org.zlex.commons.io;import static org.junit.Assert.*;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import org.junit.Test;/** * ZLib压缩测试用例 *  * @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a> * @version 1.0 * @since 1.0 */public class ZLibUtilsTest {@Testpublic final void testBytes() {System.err.println("字节压缩／解压缩测试");String inputStr = "snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org";System.err.println("输入字符串:\t" + inputStr);byte[] input = inputStr.getBytes();System.err.println("输入字节长度:\t" + input.length);byte[] data = ZLibUtils.compress(input);System.err.println("压缩后字节长度:\t" + data.length);byte[] output = ZLibUtils.decompress(data);System.err.println("解压缩后字节长度:\t" + output.length);String outputStr = new String(output);System.err.println("输出字符串:\t" + outputStr);assertEquals(inputStr, outputStr);}@Testpublic final void testFile() {String filename = "zlib";File file = new File(filename);System.err.println("文件压缩／解压缩测试");String inputStr = "snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org";System.err.println("输入字符串:\t" + inputStr);byte[] input = inputStr.getBytes();System.err.println("输入字节长度:\t" + input.length);try {FileOutputStream fos = new FileOutputStream(file);ZLibUtils.compress(input, fos);fos.close();System.err.println("压缩后字节长度:\t" + file.length());} catch (Exception e) {fail(e.getMessage());}byte[] output = null;try {FileInputStream fis = new FileInputStream(file);output = ZLibUtils.decompress(fis);fis.close();} catch (Exception e) {fail(e.getMessage());}System.err.println("解压缩后字节长度:\t" + output.length);String outputStr = new String(output);System.err.println("输出字符串:\t" + outputStr);assertEquals(inputStr, outputStr);}}

输入结果

Consloe代码

1. 字节压缩／解压缩测试   
2. 输入字符串:  snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org   
3. 输入字节长度: 59  
4. 压缩后字节长度:    39  
5. 解压缩后字节长度:   59  
6. 输出字符串:  snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org   
7. 文件压缩／解压缩测试   
8. 输入字符串:  snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org   
9. 输入字节长度: 59  
10. 压缩后字节长度:    39  
11. 解压缩后字节长度:   59  
12. 输出字符串:  snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org  

字节压缩／解压缩测试输入字符串:snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org输入字节长度:59压缩后字节长度:39解压缩后字节长度:59输出字符串:snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org文件压缩／解压缩测试输入字符串:snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org输入字节长度:59压缩后字节长度:39解压缩后字节长度:59输出字符串:snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org

应该怎么计算呢？原数据长度59字节，压缩后39字节，大约是33％的压缩率！

ZLib压缩对大字节数据压缩，才能反映出压缩效果。
先占个位儿，回头细致整理！
有关ZLib可参见官方主页 http://www.zlib.net/
ZLib可以简单的理解为压缩/解压缩算法，它与ZIP、RAR等归档算法有所不同，与bzip2比较接近。

压缩工具代码如下：

/**
 * 2009-9-9
 */
package org.zlex.commons.io;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;

/**
 * ZLib压缩工具
 *
 * @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a>
 * @version 1.0
 * @since 1.0
 */
public abstract class ZLibUtils {

    /**
     * 压缩
     *
     * @param data
     *            待压缩数据
     * @return byte[] 压缩后的数据
     */
    public static byte[] compress(byte[] data) {
        byte[] output = new byte[0];

        Deflater compresser = new Deflater();

        compresser.reset();
        compresser.setInput(data);
        compresser.finish();
        ByteArrayOutputStream bos = new ByteArrayOutputStream(data.length);
        try {
            byte[] buf = new byte[1024];
            while (!compresser.finished()) {
                int i = compresser.deflate(buf);
                bos.write(buf, 0, i);
            }
            output = bos.toByteArray();
        } catch (Exception e) {
            output = data;
            e.printStackTrace();
        } finally {
            try {
                bos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        compresser.end();
        return output;
    }

    /**
     * 压缩
     *
     * @param data
     *            待压缩数据
     *
     * @param os
     *            输出流
     */
    public static void compress(byte[] data, OutputStream os) {
        DeflaterOutputStream dos = new DeflaterOutputStream(os);

        try {
            dos.write(data, 0, data.length);

            dos.finish();

            dos.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 解压缩
     *
     * @param data
     *            待压缩的数据
     * @return byte[] 解压缩后的数据
     */
    public static byte[] decompress(byte[] data) {
        byte[] output = new byte[0];

        Inflater decompresser = new Inflater();
        decompresser.reset();
        decompresser.setInput(data);

        ByteArrayOutputStream o = new ByteArrayOutputStream(data.length);
        try {
            byte[] buf = new byte[1024];
            while (!decompresser.finished()) {
                int i = decompresser.inflate(buf);
                o.write(buf, 0, i);
            }
            output = o.toByteArray();
        } catch (Exception e) {
            output = data;
            e.printStackTrace();
        } finally {
            try {
                o.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        decompresser.end();
        return output;
    }

    /**
     * 解压缩
     *
     * @param is
     *            输入流
     * @return byte[] 解压缩后的数据
     */
    public static byte[] decompress(InputStream is) {
        InflaterInputStream iis = new InflaterInputStream(is);
        ByteArrayOutputStream o = new ByteArrayOutputStream(1024);
        try {
            int i = 1024;
            byte[] buf = new byte[i];

            while ((i = iis.read(buf, 0, i)) > 0) {
                o.write(buf, 0, i);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
        return o.toByteArray();
    }
}

/**
 * 2009-9-9
 */
package org.zlex.commons.io;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;

/**
 * ZLib压缩工具
 * 
 * @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a>
 * @version 1.0
 * @since 1.0
 */
public abstract class ZLibUtils {

	/**
	 * 压缩
	 * 
	 * @param data
	 *            待压缩数据
	 * @return byte[] 压缩后的数据
	 */
	public static byte[] compress(byte[] data) {
		byte[] output = new byte[0];

		Deflater compresser = new Deflater();

		compresser.reset();
		compresser.setInput(data);
		compresser.finish();
		ByteArrayOutputStream bos = new ByteArrayOutputStream(data.length);
		try {
			byte[] buf = new byte[1024];
			while (!compresser.finished()) {
				int i = compresser.deflate(buf);
				bos.write(buf, 0, i);
			}
			output = bos.toByteArray();
		} catch (Exception e) {
			output = data;
			e.printStackTrace();
		} finally {
			try {
				bos.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		compresser.end();
		return output;
	}

	/**
	 * 压缩
	 * 
	 * @param data
	 *            待压缩数据
	 * 
	 * @param os
	 *            输出流
	 */
	public static void compress(byte[] data, OutputStream os) {
		DeflaterOutputStream dos = new DeflaterOutputStream(os);

		try {
			dos.write(data, 0, data.length);

			dos.finish();

			dos.flush();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	/**
	 * 解压缩
	 * 
	 * @param data
	 *            待压缩的数据
	 * @return byte[] 解压缩后的数据
	 */
	public static byte[] decompress(byte[] data) {
		byte[] output = new byte[0];

		Inflater decompresser = new Inflater();
		decompresser.reset();
		decompresser.setInput(data);

		ByteArrayOutputStream o = new ByteArrayOutputStream(data.length);
		try {
			byte[] buf = new byte[1024];
			while (!decompresser.finished()) {
				int i = decompresser.inflate(buf);
				o.write(buf, 0, i);
			}
			output = o.toByteArray();
		} catch (Exception e) {
			output = data;
			e.printStackTrace();
		} finally {
			try {
				o.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

		decompresser.end();
		return output;
	}

	/**
	 * 解压缩
	 * 
	 * @param is
	 *            输入流
	 * @return byte[] 解压缩后的数据
	 */
	public static byte[] decompress(InputStream is) {
		InflaterInputStream iis = new InflaterInputStream(is);
		ByteArrayOutputStream o = new ByteArrayOutputStream(1024);
		try {
			int i = 1024;
			byte[] buf = new byte[i];

			while ((i = iis.read(buf, 0, i)) > 0) {
				o.write(buf, 0, i);
			}

		} catch (IOException e) {
			e.printStackTrace();
		}
		return o.toByteArray();
	}
}

测试用例代码如下：

/**
 * 2009-9-9
 */
package org.zlex.commons.io;

import static org.junit.Assert.*;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

import org.junit.Test;

/**
 * ZLib压缩测试用例
 *
 * @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a>
 * @version 1.0
 * @since 1.0
 */
public class ZLibUtilsTest {

    @Test
    public final void testBytes() {
        System.err.println("字节压缩／解压缩测试");
        String inputStr = "snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org";
        System.err.println("输入字符串:\t" + inputStr);
        byte[] input = inputStr.getBytes();
        System.err.println("输入字节长度:\t" + input.length);

        byte[] data = ZLibUtils.compress(input);
        System.err.println("压缩后字节长度:\t" + data.length);

        byte[] output = ZLibUtils.decompress(data);
        System.err.println("解压缩后字节长度:\t" + output.length);
        String outputStr = new String(output);
        System.err.println("输出字符串:\t" + outputStr);

        assertEquals(inputStr, outputStr);
    }

    @Test
    public final void testFile() {
        String filename = "zlib";
        File file = new File(filename);
        System.err.println("文件压缩／解压缩测试");
        String inputStr = "snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org";
        System.err.println("输入字符串:\t" + inputStr);
        byte[] input = inputStr.getBytes();
        System.err.println("输入字节长度:\t" + input.length);

        try {

            FileOutputStream fos = new FileOutputStream(file);
            ZLibUtils.compress(input, fos);
            fos.close();
            System.err.println("压缩后字节长度:\t" + file.length());
        } catch (Exception e) {
            fail(e.getMessage());
        }

        byte[] output = null;

        try {
            FileInputStream fis = new FileInputStream(file);
            output = ZLibUtils.decompress(fis);
            fis.close();

        } catch (Exception e) {
            fail(e.getMessage());
        }
        System.err.println("解压缩后字节长度:\t" + output.length);
        String outputStr = new String(output);
        System.err.println("输出字符串:\t" + outputStr);

        assertEquals(inputStr, outputStr);
    }
}

/**
 * 2009-9-9
 */
package org.zlex.commons.io;

import static org.junit.Assert.*;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

import org.junit.Test;

/**
 * ZLib压缩测试用例
 * 
 * @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a>
 * @version 1.0
 * @since 1.0
 */
public class ZLibUtilsTest {

	@Test
	public final void testBytes() {
		System.err.println("字节压缩／解压缩测试");
		String inputStr = "snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org";
		System.err.println("输入字符串:\t" + inputStr);
		byte[] input = inputStr.getBytes();
		System.err.println("输入字节长度:\t" + input.length);

		byte[] data = ZLibUtils.compress(input);
		System.err.println("压缩后字节长度:\t" + data.length);

		byte[] output = ZLibUtils.decompress(data);
		System.err.println("解压缩后字节长度:\t" + output.length);
		String outputStr = new String(output);
		System.err.println("输出字符串:\t" + outputStr);

		assertEquals(inputStr, outputStr);
	}

	@Test
	public final void testFile() {
		String filename = "zlib";
		File file = new File(filename);
		System.err.println("文件压缩／解压缩测试");
		String inputStr = "snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org";
		System.err.println("输入字符串:\t" + inputStr);
		byte[] input = inputStr.getBytes();
		System.err.println("输入字节长度:\t" + input.length);

		try {

			FileOutputStream fos = new FileOutputStream(file);
			ZLibUtils.compress(input, fos);
			fos.close();
			System.err.println("压缩后字节长度:\t" + file.length());
		} catch (Exception e) {
			fail(e.getMessage());
		}

		byte[] output = null;

		try {
			FileInputStream fis = new FileInputStream(file);
			output = ZLibUtils.decompress(fis);
			fis.close();

		} catch (Exception e) {
			fail(e.getMessage());
		}
		System.err.println("解压缩后字节长度:\t" + output.length);
		String outputStr = new String(output);
		System.err.println("输出字符串:\t" + outputStr);

		assertEquals(inputStr, outputStr);
	}
}

输入结果

字节压缩／解压缩测试
输入字符串:  snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org
输入字节长度: 59
压缩后字节长度:    39
解压缩后字节长度:   59
输出字符串:  snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org
文件压缩／解压缩测试
输入字符串:  snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org
输入字节长度: 59
压缩后字节长度:    39
解压缩后字节长度:   59
输出字符串:  snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org

字节压缩／解压缩测试
输入字符串:	snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org
输入字节长度:	59
压缩后字节长度:	39
解压缩后字节长度:	59
输出字符串:	snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org
文件压缩／解压缩测试
输入字符串:	snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org
输入字节长度:	59
压缩后字节长度:	39
解压缩后字节长度:	59
输出字符串:	snowolf@zlex.org;dongliang@zlex.org;zlex.dongliang@zlex.org

应该怎么计算呢？原数据长度59字节，压缩后39字节，大约是33％的压缩率！

ZLib压缩对大字节数据压缩，才能反映出压缩效果。
先占个位儿，回头细致整理！