使用nio传输文件需要注意的是会出现粘包和服务器端缓冲区满的情况。第一种情况,客户端发送30次数据,而服务器端只接收到18次的情况,这种情况出现 主要是服务器端是以流的方式接收数据,它并不知道每次客户端传输数据的大小而造成的。第二种情况是服务器端缓冲区满,导致客户端数据传输失败,这种情况 下,需要判断传输int send = client.write(sendBuffer)的send值,如果send值为0,则服务器端的数据缓冲区可能满了。
客户端实现代码:
- import java.io.FileInputStream;
- import java.net.InetSocketAddress;
- import java.nio.ByteBuffer;
- import java.nio.channels.FileChannel;
- import java.nio.channels.SelectionKey;
- import java.nio.channels.Selector;
- import java.nio.channels.SocketChannel;
- import java.util.Set;
- public class FileClient {
- private int port = 8000;
- /* 发送数据缓冲区 */
- private static ByteBuffer sendBuffer = ByteBuffer.allocate(1024);
- /* 接受数据缓冲区 */
- private static ByteBuffer revBuffer = ByteBuffer.allocate(1024);
- private InetSocketAddress SERVER;
- private static Selector selector;
- private static SocketChannel client;
- public FileClient(){
- try{
- SERVER = new InetSocketAddress("localhost", port);
- init();
- }
- catch(Exception e){
- e.printStackTrace();
- }
- }
- private void init(){
- try {
- SocketChannel socketChannel = SocketChannel.open();
- socketChannel.configureBlocking(false);
- selector = Selector.open();
- socketChannel.register(selector, SelectionKey.OP_CONNECT);
- socketChannel.connect(SERVER);
- while (true) {
- selector.select();
- Set<SelectionKey> keySet = selector.selectedKeys();
- for (final SelectionKey key : keySet) {
- if(key.isConnectable()){
- client = (SocketChannel)key.channel();
- client.finishConnect();
- client.register(selector, SelectionKey.OP_WRITE);
- }
- else if(key.isWritable()){
- sendFile(client);
- }
- }
- keySet.clear();
- }
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
- private void sendFile(SocketChannel client) {
- FileInputStream fis = null;
- FileChannel channel = null;
- try {
- // fis = new FileInputStream("E:\\1.txt");
- // fis = new FileInputStream("E:\\1.rar");
- fis = new FileInputStream("G:\\3.rar");
- channel = fis.getChannel();
- int i = 1;
- int count = 0;
- while((count = channel.read(sendBuffer)) != -1) {
- sendBuffer.flip();
- int send = client.write(sendBuffer);
- System.out.println("i===========" + (i++) + " count:" + count + " send:" + send);
- // 服务器端可能因为缓存区满,而导致数据传输失败,需要重新发送
- while(send == 0){
- Thread.sleep(10);
- send = client.write(sendBuffer);
- System.out.println("i重新传输====" + i + " count:" + count + " send:" + send);
- }
- sendBuffer.clear();
- }
- } catch (Exception e) {
- e.printStackTrace();
- } finally {
- try {
- channel.close();
- fis.close();
- client.close();
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
- }
- public static void main(String[] args){
- new FileClient();
- }
- }
- import java.io.FileOutputStream;
- import java.net.InetSocketAddress;
- import java.net.ServerSocket;
- import java.nio.ByteBuffer;
- import java.nio.channels.FileChannel;
- import java.nio.channels.SelectionKey;
- import java.nio.channels.Selector;
- import java.nio.channels.ServerSocketChannel;
- import java.nio.channels.SocketChannel;
- import java.util.Set;
- public class FileServer {
- private int port = 8000;
- /* 发送数据缓冲区 */
- private static ByteBuffer revBuffer = ByteBuffer.allocate(1024);
- private static Selector selector;
- private static FileOutputStream fout;
- private static FileChannel ch;
- public FileServer(){
- try{
- init();
- }
- catch(Exception e){
- e.printStackTrace();
- }
- }
- private void init() throws Exception{
- ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
- serverSocketChannel.configureBlocking(false);
- ServerSocket serverSocket = serverSocketChannel.socket();
- serverSocket.bind(new InetSocketAddress(port));
- selector = Selector.open();
- serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
- System.out.println("server start on port:" + port);
- while (true) {
- try {
- selector.select();// 返回值为本次触发的事件数
- Set<SelectionKey> selectionKeys = selector.selectedKeys();
- for (SelectionKey key : selectionKeys) {
- ServerSocketChannel server = null;
- SocketChannel client = null;
- int count = 0;
- if (key.isAcceptable()) {
- server = (ServerSocketChannel) key.channel();
- System.out.println("有客户端连接进入=============)");
- client = server.accept();
- client.configureBlocking(false);
- client.register(selector, SelectionKey.OP_READ);
- fout = new FileOutputStream("G:\\" + client.hashCode() + ".rar");
- ch = fout.getChannel();
- } else if (key.isReadable()) {
- client = (SocketChannel) key.channel();
- revBuffer.clear();
- count = client.read(revBuffer);
- int k = 0;
- // 循环读取缓存区的数据,
- while(count > 0){
- System.out.println("k=" + (k++) + " 读取到数据量:" + count);
- revBuffer.flip();
- ch.write(revBuffer);
- fout.flush();
- revBuffer.clear();
- count = client.read(revBuffer);
- }
- if(count == -1){
- client.close();
- ch.close();
- fout.close();
- }
- }
- else if (key.isWritable()) {
- System.out.println("selectionKey.isWritable()");
- }
- }
- System.out.println("=======selectionKeys.clear()");
- selectionKeys.clear();
- } catch (Exception e) {
- e.printStackTrace();
- break;
- }
- }
- }
- public static void main(String[] args){
- new FileServer();
- }
- }
来源: http://www.phpxs.com/code/1001697/