java解压gz文件【转】

转载地址：http://blog.csdn.net/caolaosanahnu/article/details/9299865
import java.util.zip.GZIPInputStream;
import java.io.FileOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

public class UncompressFileGZIP {

    /**
     * Uncompress the incoming file.   解压缩的文件。
     * @param inFileName              未压缩文件的名称
     */
    private static void doUncompressFile(String inFileName) {

        try {

            if (!getExtension(inFileName).equalsIgnoreCase("gz")) {
                System.err.println("文件名必须有扩展名 \".gz\"");
                System.exit(1);
            }

            System.out.println("打开压缩文件.");
            GZIPInputStream in = null;
            try {
                in = new GZIPInputStream(new FileInputStream(inFileName));
            } catch(FileNotFoundException e) {
                System.err.println("文件未找到. " + inFileName);
                System.exit(1);
            }

            System.out.println("打开输出文件.");
            String outFileName = getFileName(inFileName);
            FileOutputStream out = null;
            try {
                out = new FileOutputStream(outFileName);
            } catch (FileNotFoundException e) {
                System.err.println("不能写入文件. " + outFileName);
                System.exit(1);
            }

            System.out.println("将字节从压缩文件传输到输出文件.");
            byte[] buf = new byte[1024];
            int len;
            while((len = in.read(buf)) > 0) {
                out.write(buf, 0, len);
            }

            System.out.println("关闭文件和流");
            in.close();
            out.close();

        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }

    }

    /**
     * Used to extract and return the extension of a given file.   用于提取和返回给定文件的扩展名
     * @param f Incoming file to get the extension of   输入文件以获得扩展
     * @return <code>String</code> representing the extension of the incoming   表示传入的扩展
     *         file.   
     */
    public static String getExtension(String f) {
        String ext = "";
        int i = f.lastIndexOf('.');

        if (i > 0 &&  i < f.length() - 1) {
            ext = f.substring(i+1);
        }
        return ext;
    }

    /**
     * Used to extract the filename without its extension.   用于在没有扩展名的情况下提取文件名。
     * @param f Incoming file to get the filename   输入文件以获取文件名
     * @return <code>String</code> representing the filename without its   在没有它的情况下表示文件名
     *         extension.   
     */
    public static String getFileName(String f) {
        String fname = "";
        int i = f.lastIndexOf('.');

        if (i > 0 &&  i < f.length() - 1) {
            fname = f.substring(0,i);
        }
        return fname;
    }

    /**
     * Sole entry point to the class and application.   唯一进入类和应用程序的入口点。
     * @param args Array of String arguments. 字符串参数的args数组
     */
    public static void main(String[] args) {
        doUncompressFile("C:\\Users\\Administrator\\Desktop\\2017091117.gz");
    }

}