NIO - FileChannel

转自：http://blog.csdn.net/java2000_wl/article/details/7614611

 

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.Channel;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;

public class FileChannelMain {

    private static final Charset charset = Charset.forName("GBK");

    private static final int BUFFER_CAPACITY  = 1024;

    public static void main(String[] args) throws IOException, InterruptedException {
        final String srcfilePath = "D:/tomcat-6.0.26/logs/catalina.2012-04-30.log";
        readFile(srcfilePath);

        final String writeFilePath = "D:/test.txt";
        final String[] lines = new String[]{"line1xxssss", "中文测试", "!@#$%^&*()"};
        writeFile(writeFilePath, lines, Boolean.TRUE);
        readFile(writeFilePath);

        final String targetFilePath = "D:/test-copy.txt";
        copyFile1(srcfilePath, targetFilePath);
        copyFile2(srcfilePath, targetFilePath);
    }

    /**
     *
     * <br>------------------------------<br>
     * @param srcfilePath
     * @param targetPath
     * @throws IOException
     */
    private static void copyFile2(String srcfilePath, String targetPath) throws IOException {
        File file = new File(targetPath);
        if (!file.getParentFile().exists()) {
            file.mkdirs();
        }
        FileInputStream fileInputStream = new FileInputStream(srcfilePath);
        FileOutputStream fileOutputStream = new FileOutputStream(file);
        FileChannel inChannel = fileInputStream.getChannel();
        FileChannel outChannel = fileOutputStream.getChannel();
        //两者等价
//      inChannel.transferTo(0, inChannel.size(), outChannel);
        outChannel.transferFrom(inChannel, 0, inChannel.size());

        close(fileOutputStream);
        close(fileInputStream);
        close(inChannel);
        close(outChannel);
    }

    /**
     *
     * <br>------------------------------<br>
     * @param srcfilePath
     * @param targetPath
     * @throws IOException
     */
    private static void copyFile1(String srcfilePath, String targetPath) throws IOException {
        File file = new File(targetPath);
        if (!file.getParentFile().exists()) {
            file.mkdirs();
        }
        FileInputStream fileInputStream = new FileInputStream(srcfilePath);
        FileOutputStream fileOutputStream = new FileOutputStream(file);
        FileChannel inChannel = fileInputStream.getChannel();
        FileChannel outChannel = fileOutputStream.getChannel();
        ByteBuffer inBuffer = ByteBuffer.allocate(BUFFER_CAPACITY);
        while (inChannel.read(inBuffer) != -1) {
            inBuffer.flip();
            outChannel.write(inBuffer);
            inBuffer.clear();
        }
        close(fileOutputStream);
        close(fileInputStream);
        close(inChannel);
        close(outChannel);
    }

    /**
     * <br>------------------------------<br>
     * @param writeFilePath
     * @param lines
     * @param append
     * @throws IOException
     */
    private static void writeFile(String writeFilePath, String[] lines, boolean append) throws IOException {
        File file = new File(writeFilePath);
        if (!file.getParentFile().exists()) {
            file.mkdirs();
        }
        FileOutputStream fileOutputStream = new FileOutputStream(file, append);
        FileChannel fileChannel = fileOutputStream.getChannel();
        ByteBuffer buffer = ByteBuffer.allocate(BUFFER_CAPACITY);
        for (String line : lines) {
            buffer.put(line.getBytes());
            buffer.put("\r\n".getBytes());
            buffer.flip();
            fileChannel.write(buffer);
            buffer.clear();
        }
        close(fileOutputStream);
        close(fileChannel);
    }

    /**
     * <br>------------------------------<br>
     * @param path
     * @throws IOException
     */
    private static void readFile(String path) throws IOException {
        if (isFileNotExists(path)) {
            throw new FileNotFoundException();
        }
        FileInputStream fileInputStream = new FileInputStream(path);
        FileChannel fileChanne = fileInputStream.getChannel();
        ByteBuffer buffer = ByteBuffer.allocate(BUFFER_CAPACITY);
        while (fileChanne.read(buffer) != -1) {
            buffer.flip();
            System.out.println(charset.decode(buffer));
            buffer.clear();
        }
        close(fileInputStream);
        close(fileChanne);
    }

    private static boolean isFileNotExists(String path) {
        File file = new File(path);
        return !file.exists();
    }

    /**
     *
     * <br>------------------------------<br>
     * @param outputStream
     */
    private static void close(OutputStream outputStream) {
        if (outputStream == null) return;
        try {
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     *
     * <br>------------------------------<br>
     * @param channel
     */
    private static void close(Channel channel) {
        if (channel == null ) return;
        try {
            channel.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     *
     * <br>------------------------------<br>
     * @param inputStream
     */
    private static void close(InputStream inputStream) {
        if (inputStream == null) return;
        try {
            inputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}