JAVA NIO的BufferByte与Channel DEMO实例

package nio;import java.io.FileInputStream;import java.io.FileOutputStream;import java.nio.ByteBuffer;import java.nio.CharBuffer;import java.nio.channels.FileChannel;import java.nio.charset.Charset;import java.nio.charset.CharsetDecoder;/**<strong><span style="font-size:24px;color:#ff0000;"> * 实现功能，从一个文件读取数据输出到另一个文件</span></strong> * @author Administrator * */public class Test2 {public static void main(String[] args) {try {FileInputStream fin = new FileInputStream("F://e.txt");FileChannel fc = fin.getChannel();ByteBuffer byteBuffer = ByteBuffer.allocate(1024);FileOutputStream fos = new FileOutputStream("F://t.txt");FileChannel foc = fos.getChannel();while (true) {byteBuffer.clear();int len = fc.read(byteBuffer);if (len == -1) {break;}byteBuffer.flip();foc.write(byteBuffer);byteBuffer.flip();System.out.println(decode(byteBuffer));}foc.close();fc.close();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}public static String decode(ByteBuffer sendBuffer) {// ByteBuffer read// StringCharset cs = Charset.forName("utf-8");byte[] bs = new byte[sendBuffer.limit()];sendBuffer.get(bs);return new String(bs, cs);// return new String(sendBuffer.array(),cs);}}

package nio;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;<strong><span style="font-size:24px;color:#ff0000;">//输入格式化数据</span></strong>public class Test7 {<span style="white-space:pre"></span>public static void main(String[] args) throws Exception {<span style="white-space:pre"></span>ByteBuffer bookBuf = ByteBuffer.wrap("java".getBytes("utf-8"));<span style="white-space:pre"></span>ByteBuffer autBuf = ByteBuffer.wrap("tianyi".getBytes("utf-8"));<span style="white-space:pre"></span>int booklen = bookBuf.limit();<span style="white-space:pre"></span>int authlen = autBuf.limit();<span style="white-space:pre"></span>System.out.println(booklen + " " + authlen);<span style="white-space:pre"></span>ByteBuffer[] bufs = new ByteBuffer[] { bookBuf, autBuf };<span style="white-space:pre"></span>File file = new File("F://t1.txt");<span style="white-space:pre"></span>if (!file.exists()) {<span style="white-space:pre"></span>file.createNewFile();<span style="white-space:pre"></span>}<span style="white-space:pre"></span>// FileOutputStream fos = new FileOutputStream(file);<span style="white-space:pre"></span>// FileChannel fc = fos.getChannel();<span style="white-space:pre"></span>// fc.write(bufs);<span style="white-space:pre"></span>// fos.close();<span style="white-space:pre"></span>ByteBuffer b1 = ByteBuffer.allocate(23);<span style="white-space:pre"></span>ByteBuffer b2 = ByteBuffer.allocate(9);<span style="white-space:pre"></span>bufs = new ByteBuffer[] { b1, b2 };<span style="white-space:pre"></span>FileInputStream fis = new FileInputStream(file);<span style="white-space:pre"></span>FileChannel fc = fis.getChannel();<span style="white-space:pre"></span>fc.read(bufs);<span style="white-space:pre"></span>String bookname = new String(bufs[0].array(), "utf-8");<span style="white-space:pre"></span>String autname = new String(bufs[1].array(), "utf-8");<span style="white-space:pre"></span>System.out.println(bookname + autname);<span style="white-space:pre"></span>}}

package nio;//传统IO与NIO性能测试对比import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.DataInputStream;import java.io.DataOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;public class Test8 {<span style="white-space:pre"></span>static int numOfInts = 8000000;<span style="white-space:pre"></span>public static void main(String[] args) throws Exception {<span style="white-space:pre"></span>System.out.println("传统IO");<span style="white-space:pre"></span>ioTest1();<span style="white-space:pre"></span>System.out.println("NIO");<span style="white-space:pre"></span>ioTest2();<span style="white-space:pre"></span>}<span style="white-space:pre"></span>public static void ioTest2() throws Exception {<span style="white-space:pre"></span>// NIO<span style="white-space:pre"></span>long start = System.currentTimeMillis();<span style="white-space:pre"></span>FileOutputStream fout = new FileOutputStream(new File("F://ctio.txt"));<span style="white-space:pre"></span>FileChannel fc = fout.getChannel();<span style="white-space:pre"></span>ByteBuffer byteBuffer = ByteBuffer.allocate(numOfInts * 4);<span style="white-space:pre"></span>for (int i = 0; i < numOfInts; i++) {<span style="white-space:pre"></span>byteBuffer.put(int2byte(i));<span style="white-space:pre"></span>}<span style="white-space:pre"></span>long mid = System.currentTimeMillis();<span style="white-space:pre"></span>System.out.println((mid - start) );<span style="white-space:pre"></span><span style="white-space:pre"></span>byteBuffer.flip();<span style="white-space:pre"></span>fc.write(byteBuffer);<span style="white-space:pre"></span>  mid = System.currentTimeMillis();<span style="white-space:pre"></span>System.out.println((mid - start) );<span style="white-space:pre"></span>FileInputStream fin = new FileInputStream(new File("F://ctio.txt"));<span style="white-space:pre"></span>FileChannel fic = fin.getChannel();<span style="white-space:pre"></span>byteBuffer = ByteBuffer.allocate(numOfInts * 4);<span style="white-space:pre"></span>fic.read(byteBuffer);<span style="white-space:pre"></span>fic.close();<span style="white-space:pre"></span>byteBuffer.flip();<span style="white-space:pre"></span>while ((byteBuffer.hasRemaining())) {<span style="white-space:pre"></span>byteBuffer.get();<span style="white-space:pre"></span>}<span style="white-space:pre"></span>long end = System.currentTimeMillis();<span style="white-space:pre"></span>System.out.println((end - mid) );<span style="white-space:pre"></span>}<span style="white-space:pre"></span>/** 32位int转byte[] */<span style="white-space:pre"></span>public static byte[] int2byte(int res) {<span style="white-space:pre"></span>byte[] targets = new byte[4];<span style="white-space:pre"></span>targets[0] = (byte) (res & 0xff);// 最低位<span style="white-space:pre"></span>targets[1] = (byte) ((res >> 8) & 0xff);// 次低位<span style="white-space:pre"></span>targets[2] = (byte) ((res >> 16) & 0xff);// 次高位<span style="white-space:pre"></span>targets[3] = (byte) (res >>> 24);// 最高位,无符号右移。<span style="white-space:pre"></span>return targets;<span style="white-space:pre"></span>}<span style="white-space:pre"></span>/**<span style="white-space:pre"></span> * 将长度为2的byte数组转换为16位int<span style="white-space:pre"></span> * <span style="white-space:pre"></span> * @param res<span style="white-space:pre"></span> *            byte[]<span style="white-space:pre"></span> * @return int<span style="white-space:pre"></span> * */<span style="white-space:pre"></span>public static int byte2int(byte b1, byte b2, byte b3, byte b4) {<span style="white-space:pre"></span>// res = InversionByte(res);<span style="white-space:pre"></span>// 一个byte数据左移24位变成0x??000000，再右移8位变成0x00??0000<span style="white-space:pre"></span>int targets = (b1 & 0xff) << 24 | ((b2 & 0xff) << 16)<span style="white-space:pre"></span>| ((b3 & 0xff) << 8) | (b4 & 0xff); // | 表示安位或<span style="white-space:pre"></span>return targets;<span style="white-space:pre"></span>}<span style="white-space:pre"></span>public static void ioTest1() throws Exception {<span style="white-space:pre"></span>// 传统IO<span style="white-space:pre"></span>long start = System.currentTimeMillis();<span style="white-space:pre"></span>DataOutputStream dos = new DataOutputStream(new BufferedOutputStream(<span style="white-space:pre"></span>new FileOutputStream(new File("F://ctio.txt"))));<span style="white-space:pre"></span>for (int i = 0; i < numOfInts; i++) {<span style="white-space:pre"></span>dos.writeInt(i);<span style="white-space:pre"></span>}<span style="white-space:pre"></span>if (dos != null) {<span style="white-space:pre"></span>dos.close();<span style="white-space:pre"></span>}<span style="white-space:pre"></span>long mid = System.currentTimeMillis();<span style="white-space:pre"></span>System.out.println((mid - start) );<span style="white-space:pre"></span>DataInputStream dis = new DataInputStream(new BufferedInputStream(<span style="white-space:pre"></span>new FileInputStream(new File("F://ctio.txt"))));<span style="white-space:pre"></span>for (int i = 0; i < numOfInts; i++) {<span style="white-space:pre"></span>dis.readInt();<span style="white-space:pre"></span>}<span style="white-space:pre"></span>if (dis != null) {<span style="white-space:pre"></span>dis.close();<span style="white-space:pre"></span>}<span style="white-space:pre"></span>long end = System.currentTimeMillis();<span style="white-space:pre"></span>System.out.println((end - mid) );<span style="white-space:pre"></span>}}