Java新IO

 

FileChannel

FileLock ...文件锁操作 

lock(),tryLock(),

关于锁定的方式：

共享锁:允许多个线程进行文件的读取操作；

独占锁：只允许一个线程进行文件的读写操作。

字符集:有个Charset类来负责处理编码的问题，

包含了创建编码器(CharsetEncoder)和创建解码器(CharsetDecoder)的操作

Selector,构建一个非阻塞的网络服务。

之前在Socket程序的时候，服务器必须始终等着客户端的连接,造成浪费资源，所以引入了非阻塞的IO操作。

 把内容写到文件中去

 

package Demo.javatest;import java.io.File;import java.io.FileOutputStream;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;public class NewIoChanel_01 {/** * 把内容写到文件中去 * @param args * @throws Exception */public static void main(String[] args) throws Exception{String info[] = {"wangs","hehe","wangshao","北京"};File file = new File("d:"+File.separator+"myfile.txt");FileOutputStream output= null;output = new FileOutputStream(file);FileChannel fout = null;fout = output.getChannel();ByteBuffer buf = ByteBuffer.allocate(1024);for(int i=0;i<info.length;i++){buf.put(info[i].getBytes()); //字符串变为字节数组放入缓冲区}buf.flip();fout.write(buf);//输出缓冲区的内容fout.close();output.close();}} 

读取文件

package Demo.javatest;import java.io.File;import java.io.FileInputStream;import java.nio.MappedByteBuffer;import java.nio.channels.FileChannel;public class NewIoChanel_02 {/** * 读取文件 * @param args * @throws Exception */public static void main(String[] args) throws Exception{File file = new File("d:"+File.separator+"myfile.txt");FileInputStream input = null;FileChannel fin = null;input = new FileInputStream(file);fin = input.getChannel();MappedByteBuffer mbb = null;mbb = fin.map(FileChannel.MapMode.READ_ONLY, 0, file.length());byte data [] = new byte[(int) file.length()];int foot =0;while(mbb.hasRemaining()){data[foot++] = mbb.get();}System.out.println(new String(data));fin.close();input.close();}} 

读取文件，写到文件中去

package Demo.javatest;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;public class NewIoChanel_03 {/** * 读取文件，写到文件中去 * @param args * @throws Exception */public static void main(String[] args) throws Exception{File file = new File("d:"+File.separator+"myfile.txt");File file2 = new File("d:"+File.separator+"myfile2.txt");FileInputStream input= null;FileOutputStream output= null;input = new FileInputStream(file);output = new FileOutputStream(file2);FileChannel fout = null;FileChannel fin = null;fin = input.getChannel();fout = output.getChannel();ByteBuffer buf = ByteBuffer.allocate(1024);int temp = 0;while((temp = fin.read(buf))!= -1){ //以1024为单位，边读边写buf.flip();fout.write(buf);buf.clear(); //不清空内容进不来,所有变量位置恢复到原点}fin.close();fout.close();input.close();output.close();}} 

 

 

 

 

 

/**

* 对一个文件进行锁定 

* @param args FileOutputStream具有可写操作,FileInputStream找不到写操作，无法锁定

*/

 

package Demo.javatest;import java.io.File;import java.io.FileOutputStream;import java.nio.channels.FileChannel;import java.nio.channels.FileLock;public class FileLockDemo {/** * 对一个文件进行锁定 * @param args FileOutputStream具有可写操作,FileInputStream找不到写操作，无法锁定 */public static void main(String[] args) throws Exception {File file = new File("d:"+File.separator+"myfile.txt");FileOutputStream output= null;output = new FileOutputStream(file,true); //这里需要加trueFileChannel fout =null;fout = output.getChannel();FileLock lock = fout.tryLock();if(lock!= null){System.out.println(file.getName()+"文件被锁定30秒");Thread.sleep(30000);lock.release(); //释放锁定System.out.println(file.getName()+"文件被解锁");}fout.close();output.close();}} 

进行编码,解码操作。

package Demo.javatest;import java.nio.ByteBuffer;import java.nio.CharBuffer;import java.nio.charset.CharacterCodingException;import java.nio.charset.Charset;import java.nio.charset.CharsetDecoder;import java.nio.charset.CharsetEncoder;public class CharSetEnDeDemo {/**进行编码,解码操作。 * @param args * @throws Exception */public static void main(String[] args) throws Exception {Charset latin1 = Charset.forName("ISO8859-1");CharsetEncoder encoder = latin1.newEncoder(); //得到编码器CharsetDecoder decoder = latin1.newDecoder();//得到解码器CharBuffer cb = CharBuffer.wrap("hello,charset"); //准备编译内容ByteBuffer bb = encoder.encode(cb); //进行编码System.out.println(decoder.decode(bb));}} 

得到所有Charset编码

package Demo.javatest;import java.nio.charset.Charset;import java.util.Iterator;import java.util.Map;import java.util.SortedMap;public class GetAllCharSetDemo {/**得到所有Charset编码 * @param args */public static void main(String[] args) {SortedMap<String, Charset> all =null;all= Charset.availableCharsets();Iterator<Map.Entry<String, Charset>> iter= null;iter = all.entrySet().iterator();while(iter.hasNext()){Map.Entry<String, Charset> me= iter.next();System.out.println(me.getKey()+"---->"+me.getValue());}}} 

一个非阻塞的服务器端

package Demo.javatest;import java.io.IOException;import java.net.InetSocketAddress;import java.net.ServerSocket;import java.nio.ByteBuffer;import java.nio.channels.SelectionKey;import java.nio.channels.Selector;import java.nio.channels.ServerSocketChannel;import java.nio.channels.SocketChannel;import java.util.Date;import java.util.Iterator;import java.util.Set;public class SelectorDemo {/**一个非阻塞的服务器端 * @param args * @throws Exception */public static void main(String[] args) throws Exception {int ports[]= {8888,8880,8881,8882};Selector selector = Selector.open();for(int i=0;i< ports.length;i++){ServerSocketChannel initSer = null;initSer = ServerSocketChannel.open(); //打开服务器套接字通道initSer.configureBlocking(false); //设置为非阻塞ServerSocket initSock = initSer.socket(); //检索相关的套接字InetSocketAddress address = null;address = new InetSocketAddress(ports[i]); //实例化绑定监听地址initSock.bind(address);initSer.register(selector, SelectionKey.OP_ACCEPT); //相当于accept(),注册选择器System.out.println("服务器运行在"+ports[i]+"端口.");}int addKey = 0;while((addKey=selector.select())>0){Set<SelectionKey> selectKeys = selector.selectedKeys();Iterator<SelectionKey> iter = selectKeys.iterator();while(iter.hasNext()){SelectionKey key = iter.next();if(key.isAcceptable()){ServerSocketChannel server = (ServerSocketChannel) key.channel();SocketChannel client = server.accept();client.configureBlocking(false); //配置为非阻塞ByteBuffer outbuf = ByteBuffer.allocateDirect(1024);outbuf.put(("当前的时候:"+new Date()).getBytes());outbuf.flip();client.write(outbuf);client.close();}}selectKeys.clear();}}}