JAVA 文件操作

平常经常使用JAVA对文件进行读写等操作，这里汇总一下常用的文件操作。

1、创建文件

	public static boolean createFile(String filePath){
		boolean result = false;
		File file = new File(filePath);
		if(!file.exists()){
			try {
				result = file.createNewFile();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		
		return result;
	}

2、创建文件夹

	public static boolean createDirectory(String directory){
		boolean result = false;
		File file = new File(directory);
		if(!file.exists()){
			result = file.mkdirs();
		}
		
		return result;
	}

3、删除文件

	public static boolean deleteFile(String filePath){
		boolean result = false;
		File file = new File(filePath);
		if(file.exists() && file.isFile()){
			result = file.delete();
		}
		
		return result;
	}

4、删除文件夹

递归删除文件夹下面的子文件和文件夹

	public static void deleteDirectory(String filePath){
		File file = new File(filePath);
		if(!file.exists()){
			return;
		}
		
		if(file.isFile()){
			file.delete();
		}else if(file.isDirectory()){
			File[] files = file.listFiles();
			for (File myfile : files) {
				deleteDirectory(filePath + "/" + myfile.getName());
			}
			
			file.delete();
		}
	}

5、读文件

（1）以字节为单位读取文件，常用于读二进制文件，如图片、声音、影像等文件

	public static String readFileByBytes(String filePath){
		File file = new File(filePath);
		if(!file.exists() || !file.isFile()){
			return null;
		}
		
		StringBuffer content = new StringBuffer();
		
		try {
			byte[] temp = new byte[1024];
			FileInputStream fileInputStream = new FileInputStream(file);
			while(fileInputStream.read(temp) != -1){
				content.append(new String(temp));
				temp = new byte[1024];
			}
			
			fileInputStream.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		return content.toString();
	}

 （2）以字符为单位读取文件，常用于读文本，数字等类型的文件，支持读取中文

	public static String readFileByChars(String filePath){
		File file = new File(filePath);
		if(!file.exists() || !file.isFile()){
			return null;
		}
		
		StringBuffer content = new StringBuffer();
		try {
			char[] temp = new char[1024];
			FileInputStream fileInputStream = new FileInputStream(file);
			InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream, "GBK");
			while(inputStreamReader.read(temp) != -1){
				content.append(new String(temp));
				temp = new char[1024];
			}
			
			fileInputStream.close();
			inputStreamReader.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		return content.toString();
	}

（3）以行为单位读取文件，常用于读面向行的格式化文件

	public static List<String> readFileByLines(String filePath){
		File file = new File(filePath);
		if(!file.exists() || !file.isFile()){
			return null;
		}
		
		List<String> content = new ArrayList<String>();
		try {
			FileInputStream fileInputStream = new FileInputStream(file);
			InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream, "GBK");
			BufferedReader reader = new BufferedReader(inputStreamReader);
			String lineContent = "";
			while ((lineContent = reader.readLine()) != null) {
				content.add(lineContent);
				System.out.println(lineContent);
			}
			
			fileInputStream.close();
			inputStreamReader.close();
			reader.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		return content;
	}

6、写文件

字符串写入文件的几个类中，FileWriter效率最高，BufferedOutputStream次之，FileOutputStream最差。

（1）通过FileOutputStream写入文件

	public static void writeFileByFileOutputStream(String filePath, String content) throws IOException{
		File file = new File(filePath);
		synchronized (file) {
			FileOutputStream fos = new FileOutputStream(filePath);
			fos.write(content.getBytes("GBK"));
			fos.close();
		}
	}

（2）通过BufferedOutputStream写入文件

	public static void writeFileByBufferedOutputStream(String filePath, String content) throws IOException{
		File file = new File(filePath);
		synchronized (file) {
			BufferedOutputStream fos = new BufferedOutputStream(new FileOutputStream(filePath));
			fos.write(content.getBytes("GBK"));
			fos.flush();
			fos.close();
		}
	}

（3）通过FileWriter将字符串写入文件

public static void writeFileByFileWriter(String filePath, String content) throws IOException{
		File file = new File(filePath);
		synchronized (file) {
			FileWriter fw = new FileWriter(filePath);
			fw.write(content);
			fw.close();
		}
	}