java中Gzip压缩与解压技术

短命女 2022-09-23 11:52 266阅读 0赞

# java中Gzip压缩与解压技术 #

### java中自带有Gzip压缩与解压的类，GZIPOutputStream类是用于压缩的类，里面传递的参数是字节流对象。GZIPIntputStream类是用于解压的类，传递的参数也是字节流。Gzip压缩需要把文件压缩成xxx.gz文件（不过我试了以.g或.z及其他格式，也是可以解压出来的，不过打开可能乱码）。 ###

### GZIPOutputStream在写完数据后，需要调用finish()方法。 ###

以下是代码实现：

### GZipUtils ###

package com.zhang;
    
    
    /** * Created by Administrator on 2016/7/18. */
    public class GzipUtils { 
    
        private static final int BUFFER = 1024;
    
        public static void compress(File orginalFile, File compressFile) throws IOException {
            if (orginalFile != null && orginalFile.isFile() && compressFile != null && compressFile.isFile()) {
                FileInputStream is = new FileInputStream(orginalFile);
                FileOutputStream os = new FileOutputStream(compressFile);
                compress(is, os);
                is.close();
                os.close();
            }
        }
    
        public static void compress(String orginalFile, String compressFile) throws IOException {
            if (orginalFile != null && compressFile != null) {
                FileInputStream is = new FileInputStream(orginalFile);
                FileOutputStream os = new FileOutputStream(compressFile);
                compress(is, os);
                is.close();
                os.close();
            }
        }
    
        public static byte[] compress(byte[] bytes) throws IOException {
            if (bytes != null) {
                ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
                ByteArrayOutputStream baos = new ByteArrayOutputStream();
                compress(bais, baos);
                bytes = baos.toByteArray();
                bais.close();
                baos.close();
            }
            return bytes;
        }
    
        public static void compress(InputStream is, OutputStream os) throws IOException {
            GZIPOutputStream gos = new GZIPOutputStream(os);
            int len = 0;
            byte[] buffer = new byte[BUFFER];
            while ((len = is.read(buffer)) != -1) {
                gos.write(buffer, 0, len);
            }
            gos.finish();
            gos.flush();
            gos.close();
        }
    
        public static void deCompress(File compressFile, File orginalFile) throws IOException {
            if (orginalFile != null && orginalFile.isFile() && compressFile != null && compressFile.isFile()) {
                FileInputStream is = new FileInputStream(compressFile);
                FileOutputStream os = new FileOutputStream(orginalFile);
                deCompress(is, os);
                is.close();
                os.close();
            }
        }
    
        public static void deCompress(String compressFile, String orginalFile) throws IOException {
            if (orginalFile != null && compressFile != null) {
                FileInputStream is = new FileInputStream(compressFile);
                FileOutputStream os = new FileOutputStream(orginalFile);
                deCompress(is, os);
                is.close();
                os.close();
            }
        }
    
        public static byte[] deCompress(byte[] bytes) throws IOException {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
            deCompress(bais, baos);
            bytes = baos.toByteArray();
            bais.close();
            baos.close();
            return bytes;
        }
    
    
        public static void deCompress(InputStream is, OutputStream os) throws IOException {
            GZIPInputStream gis = new GZIPInputStream(is);
            int len = 0;
            byte[] buffer = new byte[BUFFER];
            while ((len = gis.read(buffer)) != -1) {
                os.write(buffer, 0, len);
            }
            os.flush();
            gis.close();
        }
    
    
    }

### 程序入口 ###

public class Test {
        public static void main(String[] args) throws IOException {
            stringTest();
            fileTest();
            byteTest();
        }
    
        public static void fileTest() throws IOException {
            String orginal = "C:\\MyPrivate\\1.txt";
            String compress = "C:\\MyPrivate\\1.gz";
            String decompress = "C:\\MyPrivate\\1(1).txt";
    
            File orginalFile = new File(orginal);
            File compressFile = new File(compress);
            File decompressFile = new File(decompress);
            if (!compressFile.exists()) {
                compressFile.createNewFile();
            }
            if (!decompressFile.exists()) {
                decompressFile.createNewFile();
            }
            GzipUtils.compress(orginalFile, compressFile);
            GzipUtils.deCompress(compressFile, decompressFile);
        }
    
        public static void stringTest() throws IOException {
            String orginal = "C:\\MyPrivate\\2.png";
            String compress = "C:\\MyPrivate\\2.gz";
            String decompress = "C:\\MyPrivate\\2(2).png";
    
            GzipUtils.compress(orginal, compress);
    
            GzipUtils.deCompress(compress, decompress);
        }
    
        public static void byteTest() throws IOException {
            String test = "zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.orgzlex@zlex.org,snowolf@zlex.org," +
                    "zlex.snowolf@zlex.orgzlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org";
    
            System.out.println("compress before:" + test.getBytes().length);
            byte[] bytes = GzipUtils.compress(test.getBytes());
            System.out.println("compress after:" + bytes.length);
            bytes = GzipUtils.deCompress(bytes);
            System.out.println("decompress after:" + bytes.length);
        }
    }

#### 控制台打印结果(文件测试也是可以的,就不显示了)： ####

compress before:156
    compress after:48
    decompress after:156