Java IO Demo

package com.hotfey.demo;

import static com.hotfey.util.IOUtil.closeIO;

import java.io.*;
import java.util.logging.Logger;


public class InputDemo {
	private static Logger logger = Logger.getLogger("JavaIODemo");

	private static Reader reader;
	private static InputStream inputStream;

	private static BufferedReader bufferedReader;

	public static void main(String[] args) {
		String pathname = "D:/test.txt";
		File file = new File(pathname);
		inputStream(file);
		inputStream2Reader(file);
		inputStream2BufferedReader(file);
	}

	private static void inputStream(File file) {
		try {

			inputStream = new FileInputStream(file);
			byte[] b = new byte[1024];
			int len = 0;
			while ((len = inputStream.read(b)) != -1) {
				logger.info(new String(b, 0, len));
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			closeIO(inputStream);
		}
	}

	private static void inputStream2Reader(File file) {
		try {

			inputStream = new FileInputStream(file);
			reader = new InputStreamReader(inputStream, "UTF-8");
			char[] cbuf = new char[1024];
			int len = 0;
			while ((len = reader.read(cbuf)) != -1) {
				logger.info(new String(cbuf, 0, len));
			}
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			closeIO(inputStream);
			closeIO(reader);
		}
	}

	private static void inputStream2BufferedReader(File file) {

		try {
			inputStream = new FileInputStream(file);
			reader = new InputStreamReader(inputStream, "UTF-8");
			bufferedReader = new BufferedReader(reader);
			String string = "";
			while ((string = bufferedReader.readLine()) != null) {
				logger.info(string);
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			closeIO(bufferedReader);
			closeIO(reader);
			closeIO(inputStream);
		}
	}

}

package com.hotfey.demo;

import static com.hotfey.util.IOUtil.closeIO;
import static com.hotfey.util.IOUtil.createNewFileByFile;

import java.io.*;


public class OutputDemo {
	private static Reader reader;
	private static Writer writer;
	private static InputStream inputStream;
	private static OutputStream outputStream;

	private static BufferedReader bufferedReader;
	private static BufferedWriter bufferedWriter;

	public static void main(String[] args) {
		String pathname = "D:/test.txt";
		File inputFile = new File(pathname);
		File outputfile = createNewFileByFile(inputFile);
		inputStream2OutputStream(inputFile, outputfile);
		inputStream2Writer(inputFile, outputfile);
		inputStream2BufferedWriter(inputFile, outputfile);
	}

	private static void inputStream2OutputStream(File inputFile, File outputfile) {
		try {
			inputStream = new FileInputStream(inputFile);
			outputStream = new FileOutputStream(outputfile);
			byte[] b = new byte[1024];
			int len = 0;
			while ((len = inputStream.read(b)) != -1) {
				outputStream.write(b, 0, len);
				outputStream.flush();
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			closeIO(outputStream);
			closeIO(inputStream);
		}
	}

	private static void inputStream2Writer(File inputFile, File outputfile) {
		try {
			inputStream = new FileInputStream(inputFile);
			reader = new InputStreamReader(inputStream, "UTF-8");

			outputStream = new FileOutputStream(outputfile);
			writer = new OutputStreamWriter(outputStream, "UTF-8");

			char[] cbuf = new char[1024];
			int len = 0;
			while ((len = reader.read(cbuf)) != -1) {
				writer.write(cbuf, 0, len);
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			closeIO(writer);
			closeIO(outputStream);
			closeIO(reader);
			closeIO(inputStream);
		}
	}

	private static void inputStream2BufferedWriter(File inputFile,
			File outputfile) {
		try {
			inputStream = new FileInputStream(inputFile);
			reader = new InputStreamReader(inputStream, "UTF-8");
			bufferedReader = new BufferedReader(reader);

			outputStream = new FileOutputStream(outputfile);
			writer = new OutputStreamWriter(outputStream, "UTF-8");
			bufferedWriter = new BufferedWriter(writer);

			String string = "";
			while ((string = bufferedReader.readLine()) != null) {
				bufferedWriter.write(string + "\r\n");
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			closeIO(bufferedWriter);
			closeIO(writer);
			closeIO(outputStream);
			closeIO(bufferedReader);
			closeIO(reader);
			closeIO(inputStream);
		}
	}

}

package com.hotfey.util;

import java.io.*;


public class IOUtil {
	public static File createNewFileByFile(File file) {
		String fileName = file.getName();
		String newPath = file.getName().substring(0, fileName.indexOf("."));
		newPath = file.getPath().replace(fileName, newPath);
		newPath += File.separator + fileName;
		File newFile = new File(newPath);
		File newDirectory = new File(newPath.replace(fileName, ""));
		if (!newDirectory.exists()) {
			newDirectory.mkdirs();
		}
		if (!newFile.exists()) {
			try {
				newFile.createNewFile();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return newFile;
	}

	public static void closeIO(Reader reader) {
		try {
			reader.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void closeIO(Writer writer) {
		try {
			writer.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void closeIO(InputStream inputStream) {
		try {
			inputStream.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void closeIO(OutputStream outputStream) {
		try {
			outputStream.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

引用

public abstract int read() throws IOException

Reads the next byte of data from the input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

A subclass must provide an implementation of this method.

Returns:
    the next byte of data, or -1 if the end of the stream is reached.
Throws:
    IOException - if an I/O error occurs.

引用

public int read(byte[] b) throws IOException

Reads some number of bytes from the input stream and stores them into the buffer array b. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown.

If the length of b is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at the end of the file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[0], the next one into b[1], and so on. The number of bytes read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] unaffected.

The read(b) method for class InputStream has the same effect as:

read(b, 0, b.length)

Parameters:
    b - the buffer into which the data is read.
Returns:
    the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
Throws:
    IOException - If the first byte cannot be read for any reason other than the end of the file, if the input stream has been closed, or if some other I/O error occurs.
    NullPointerException - if b is null.
See Also:
    read(byte[], int, int)

引用

public int read(byte[] b, int off, int len) throws IOException

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. The default implementation of this method blocks until the requested amount of input data len has been read, end of file is detected, or an exception is thrown. Subclasses are encouraged to provide a more efficient implementation of this method.

Parameters:
    b - the buffer into which the data is read.
    off - the start offset in array b at which the data is written.
    len - the maximum number of bytes to read.
Returns:
    the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
Throws:
    IOException - If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs.
    NullPointerException - If b is null.
    IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off
See Also:
    read()

引用

public String readLine() throws IOException

Reads a line of text. A line is considered to be terminated by any one of a line feed ('\n'), a carriage return ('\r'), or a carriage return followed immediately by a linefeed.

Returns:
    A String containing the contents of the line, not including any line-termination characters, or null if the end of the stream has been reached
Throws:
    IOException - If an I/O error occurs
See Also:
    Files.readAllLines(java.nio.file.Path, java.nio.charset.Charset)