Java I/O 文件加锁，压缩

文件加锁：

文件加锁机制允许我们同步访问某个作为共享资源的文件。

public class Test {

	public static void main(String[] args) throws IOException {

		FileOutputStream fos = new FileOutputStream("test.txt");

		/*

		 * 通过tryLock 或者 lock 获得整个文件的FileLock 

		 * tryLock(position, size, shared) 对文件进行部分加锁

		 */

		FileLock fileLock = fos.getChannel().tryLock();

		

		if (fileLock != null) {

			 System.out.println("Locked file...");

			 try {

				TimeUnit.MILLISECONDS.sleep(100);

			} catch (InterruptedException e) {

				// TODO Auto-generated catch block

				e.printStackTrace();

			}

			 fileLock.release();

			 System.out.println("Realased Lock ...");

		}



	}

}

　　

文件压缩：

GZIP进行简单的压缩解压：

public class Test {

	public static void main(String[] args) throws IOException {

		BufferedReader in = new BufferedReader(new FileReader("/home/estar/Test/a.java"));

		BufferedOutputStream bos = new BufferedOutputStream(new GZIPOutputStream(new FileOutputStream("test.gz",true)));

		

		System.out.println("GZIP 压缩写入文件 。。。");

		String s;

		while ((s = in.readLine()) != null) {

			s += "\n";

			bos.write(s.getBytes());

		}

		in.close(); bos.close();

		

		//InputStreamReader 起到了在字节流与字符流转换的桥梁。。。

		System.out.println("GZIP 解压读取文件。。。。");

		BufferedReader br = new BufferedReader(new InputStreamReader(new GZIPInputStream(new FileInputStream("test.gz"))));

		while ((s = br.readLine()) != null) {

			System.out.println(s);

		}

	}

}



输出：

GZIP 压缩写入文件 。。。

GZIP 解压读取文件。。。。

AAHJKHJKAAHJKHJKAAHJKHJKnixingAAHJKHJKAAHJKHJKAAHJKHJKnixingAAHJKHJKAAHJKHJK

AAHJKHJKnixing

AAHJKHJKAAHJKHJK

AAHJKHJKnixing

AAHJKHJKAAHJKHJK

AAHJKHJKnixing

AAHJKHJKAAHJKHJK

AAHJKHJKnixing

　　

ZIP进行多文件保存：

public class Test {

	//这里保存要压缩的文件路径

	public static String[] path = {"/home/estar/Test/a.java","/home/estar/Test/b.java","/home/estar/cbian/yyy/main.cpp"};

	public static void main(String[] args) throws IOException {

		FileOutputStream fos = new FileOutputStream("test.zip");

		CheckedOutputStream cos = new CheckedOutputStream(fos, new Adler32());

		ZipOutputStream zos = new ZipOutputStream(cos);

		BufferedOutputStream bos = new BufferedOutputStream(zos);

		

		for (String p : path) {

			//通过ZipEntry 将要压缩的文件的写入压缩文件test.zip

			zos.putNextEntry(new ZipEntry(p));

			

			//读出每个要压缩的文件的信息，

			BufferedReader br = new BufferedReader(new FileReader(p));

			String s;

			while ((s = br.readLine()) != null) {

				System.out.println("from " + p + "content : " + s);

				s += "\n";

				bos.write(s.getBytes());

			}

			br.close();

			bos.flush();

		}

		bos.close();

		

		System.out.println("Checksum : " + cos.getChecksum().getValue());

		

		

		//读压缩文件

		System.out.println("Reading file");

		FileInputStream fis = new FileInputStream("test.zip");

		CheckedInputStream cis = new CheckedInputStream(fis, new Adler32());

		ZipInputStream zis = new ZipInputStream(cis);

		BufferedReader br = new BufferedReader(new InputStreamReader(zis));

		

		ZipEntry ze;

		while ((ze = zis.getNextEntry()) != null) {

			System.out.println("reading ze : " + ze);

			String s;

			while ((s = br.readLine()) != null) {

				System.out.println(s);

			}

		}

		System.out.println("Checksum : " + cis.getChecksum().getValue());

		

		ZipFile zf = new ZipFile("test.zip");

		Enumeration e = zf.entries();

		while (e.hasMoreElements()){

			ZipEntry ze1 = (ZipEntry)e.nextElement();

			System.out.println("ze1 : " + ze1);

		}

		

	}

}

　　

 

 

 

 

 

 

 

 

 

Java编程思想P566