java文件

1、利用BufferedReader字符流。

public static StringBuffer getFileContent(File target) {
		StringBuffer content = new StringBuffer();
		BufferedReader read = null;
		try {
			InputStream is = new FileInputStream(target);
			read = new BufferedReader(new InputStreamReader(is));
			String line = null;
			while ((line = read.readLine()) != null) {
				content.append(line);
			}
			// 关闭流
			read.close();
			is.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return content;
	}

 方式二:使用BufferedInputSteam读取

/**
 * 描述:读取一个文件
 */
public static void readFile(String filePath) throws Exception {
	BufferedInputStream bis = null;
	byte[] buffer = new byte[1024];
	// 文本内容
	StringBuffer content = new StringBuffer();
	File file = new File(filePath);
	if (!file.exists()) {
		file.createNewFile();
	}
	bis = new BufferedInputStream(new FileInputStream(file));
	int temp = 0;
	while ((temp = bis.read(buffer)) != -1) {
		// 将读取的数据保存为字符串
		content.append(new String(buffer, 0, temp));
	}
	// 关闭流
	bis.close();
}

3、方式三:利用NIO

/**
 * 描述:读取一个文件
 */
public static void readFile(String filePath) throws Exception {
	FileInputStream fis = null;
	FileChannel channel = null;
	StringBuffer content = new StringBuffer();
	File file = new File(filePath);
	if (!file.exists()) {
		file.createNewFile();
	}
	fis = new FileInputStream(file);
	channel = fis.getChannel();
	ByteBuffer buffer = ByteBuffer.allocate(1024);
	int temp = 0;
	while ((temp = channel.read(buffer)) != -1) {
		content.append(new String(buffer.array()));
		//让缓冲区可以将新的数据写入到另一个通道，一定要写否则会跑出内存溢出的异常
		buffer.flip();
	}
	channel.close();
	fis.close();
}

其它方式略。

2、文件的压缩与解压缩

压缩流:ZipOutputStream,ZipInputStream

ZipEntry:压缩包文件

public ZipEntry(String name):创建对象并指定ZipEntry的名称

public boolean isDirectory()

ZipOutputStream(OutputStream out):创建新的Zip输出流

public void putNextEntry(ZipEntry e):设置ZipEntry对象

public void setComment(String s):设置Zip文件注释

创建压缩文件的的步骤:

1）实例化输入输出流

2）创建ZipEntity对象

3）设置ZipEntity对象(把zipEntity对象加入到压缩包中)

4）设置注释

5）读文件/压缩文件

6）关闭流

/**
 * 创建一个压缩文件,只考虑一级目录,多级使用递归进行操作
 * 
 * @param filePath
 *            ：文件路径
 * @param zipFilePath
 *            : 压缩文件名称路径
 */
public static void createZipFile(String filePath, String zipFilePath) throws Exception {
	ZipOutputStream zos = null;
	BufferedInputStream bis = null;
	File file = new File(filePath);
	File zipFile = new File(zipFilePath);
	if (!zipFile.exists()) {
		zipFile.createNewFile();
	}
	// 创建压缩流
	zos = new ZipOutputStream(new FileOutputStream(zipFile));
	File[] subFiles = file.listFiles();
	for (File subFile : subFiles) {
		// 创建ZipEntry对象
		ZipEntry ze = new ZipEntry(subFile.getName());
		// 设置ZipEntry对象
		zos.putNextEntry(ze);
		bis = new BufferedInputStream(new FileInputStream(subFile));
		int temp=0;
		while ((temp = bis.read()) != -1) {
			// 边读边写
			zos.write(temp);
		}
		// 关闭流
		bis.close();
	}
	zos.close();
}

解压缩:同样只考虑一级目录，多级使用递归

/**
 * 解压缩
 * 
 * @param openFilePath
 *            :解开压缩文件的存放路径
 * @param zipFilePath
 *            :压缩文件名称路径
 */
public static void openZipFile(String openFilePath, String zipFilePath) throws Exception {
	OutputStream os = null;
	ZipInputStream zis = null;
	ZipFile zipFile = new ZipFile(zipFilePath);
	File file = new File(openFilePath);
	if (!file.exists()) {
		file.mkdirs();
	}
	// 实例化
	zis = new ZipInputStream(new FileInputStream(zipFilePath));
	ZipEntry ze = zis.getNextEntry();
	int fileCount=0;
	while (ze != null) {
		System.out.println("正在解压" + ze.getName() + "文件...");
		File subFile = new File(openFilePath + File.separator + ze.getName());
		if(!subFile.exists()){
			subFile.createNewFile();
		}
		InputStream is=zipFile.getInputStream(ze);
		os=new FileOutputStream(subFile);
		int temp=0;
		while((temp=is.read())!=-1){
			os.write(temp);
		}
		ze=zis.getNextEntry();
		is.close();
		fileCount++;
	}
	System.out.println("解压完成!");
	os.close();
	zis.close();
}