Java使用NIO包實現(xiàn)Socket通信的實例代碼
前面幾篇文章介紹了使用java.io和java.net類庫實現(xiàn)的Socket通信,下面介紹一下使用java.nio類庫實現(xiàn)的Socket。
java.nio包是Java在1.4之后增加的,用來提高I/O操作的效率。在nio包中主要包括以下幾個類或接口:
- Buffer:緩沖區(qū),用來臨時存放輸入或輸出數(shù)據(jù)。
- Charset:用來把Unicode字符編碼和其它字符編碼互轉。
- Channel:數(shù)據(jù)傳輸通道,用來把Buffer中的數(shù)據(jù)寫入到數(shù)據(jù)源,或者把數(shù)據(jù)源中的數(shù)據(jù)讀入到Buffer。
- Selector:用來支持異步I/O操作,也叫非阻塞I/O操作。
nio包中主要通過下面兩個方面來提高I/O操作效率:
- 通過Buffer和Channel來提高I/O操作的速度。
- 通過Selector來支持非阻塞I/O操作。
下面來看一下程序中是怎么通過這些類庫實現(xiàn)Socket功能。
首先介紹一下幾個輔助類
輔助類SerializableUtil,這個類用來把java對象序列化成字節(jié)數(shù)組,或者把字節(jié)數(shù)組反序列化成java對象。
package com.googlecode.garbagecan.test.socket;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public class SerializableUtil {
public static byte[] toBytes(Object object) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream oos = null;
try {
oos = new ObjectOutputStream(baos);
oos.writeObject(object);
byte[] bytes = baos.toByteArray();
return bytes;
} catch(IOException ex) {
throw new RuntimeException(ex.getMessage(), ex);
} finally {
try {
oos.close();
} catch (Exception e) {}
}
}
public static Object toObject(byte[] bytes) {
ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
ObjectInputStream ois = null;
try {
ois = new ObjectInputStream(bais);
Object object = ois.readObject();
return object;
} catch(IOException ex) {
throw new RuntimeException(ex.getMessage(), ex);
} catch(ClassNotFoundException ex) {
throw new RuntimeException(ex.getMessage(), ex);
} finally {
try {
ois.close();
} catch (Exception e) {}
}
}
}
輔助類MyRequestObject和MyResponseObject,這兩個類是普通的java對象,實現(xiàn)了Serializable接口。MyRequestObject類是Client發(fā)出的請求,MyResponseObject是Server端作出的響應。
package com.googlecode.garbagecan.test.socket.nio;
import java.io.Serializable;
public class MyRequestObject implements Serializable {
private static final long serialVersionUID = 1L;
private String name;
private String value;
private byte[] bytes;
public MyRequestObject(String name, String value) {
this.name = name;
this.value = value;
this.bytes = new byte[1024];
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
@Override
public String toString() {
StringBuffer sb = new StringBuffer();
sb.append("Request [name: " + name + ", value: " + value + ", bytes: " + bytes.length+ "]");
return sb.toString();
}
}
package com.googlecode.garbagecan.test.socket.nio;
import java.io.Serializable;
public class MyResponseObject implements Serializable {
private static final long serialVersionUID = 1L;
private String name;
private String value;
private byte[] bytes;
public MyResponseObject(String name, String value) {
this.name = name;
this.value = value;
this.bytes = new byte[1024];
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
@Override
public String toString() {
StringBuffer sb = new StringBuffer();
sb.append("Response [name: " + name + ", value: " + value + ", bytes: " + bytes.length+ "]");
return sb.toString();
}
}
下面主要看一下Server端的代碼,其中有一些英文注釋對理解代碼很有幫助,注釋主要是來源jdk的文檔和例子,這里就沒有再翻譯
package com.googlecode.garbagecan.test.socket.nio;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.logging.Level;
import java.util.logging.Logger;
import com.googlecode.garbagecan.test.socket.SerializableUtil;
public class MyServer3 {
private final static Logger logger = Logger.getLogger(MyServer3.class.getName());
public static void main(String[] args) {
Selector selector = null;
ServerSocketChannel serverSocketChannel = null;
try {
// Selector for incoming time requests
selector = Selector.open();
// Create a new server socket and set to non blocking mode
serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.configureBlocking(false);
// Bind the server socket to the local host and port
serverSocketChannel.socket().setReuseAddress(true);
serverSocketChannel.socket().bind(new InetSocketAddress(10000));
// Register accepts on the server socket with the selector. This
// step tells the selector that the socket wants to be put on the
// ready list when accept operations occur, so allowing multiplexed
// non-blocking I/O to take place.
serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
// Here's where everything happens. The select method will
// return when any operations registered above have occurred, the
// thread has been interrupted, etc.
while (selector.select() > 0) {
// Someone is ready for I/O, get the ready keys
Iterator<SelectionKey> it = selector.selectedKeys().iterator();
// Walk through the ready keys collection and process date requests.
while (it.hasNext()) {
SelectionKey readyKey = it.next();
it.remove();
// The key indexes into the selector so you
// can retrieve the socket that's ready for I/O
execute((ServerSocketChannel) readyKey.channel());
}
}
} catch (ClosedChannelException ex) {
logger.log(Level.SEVERE, null, ex);
} catch (IOException ex) {
logger.log(Level.SEVERE, null, ex);
} finally {
try {
selector.close();
} catch(Exception ex) {}
try {
serverSocketChannel.close();
} catch(Exception ex) {}
}
}
private static void execute(ServerSocketChannel serverSocketChannel) throws IOException {
SocketChannel socketChannel = null;
try {
socketChannel = serverSocketChannel.accept();
MyRequestObject myRequestObject = receiveData(socketChannel);
logger.log(Level.INFO, myRequestObject.toString());
MyResponseObject myResponseObject = new MyResponseObject(
"response for " + myRequestObject.getName(),
"response for " + myRequestObject.getValue());
sendData(socketChannel, myResponseObject);
logger.log(Level.INFO, myResponseObject.toString());
} finally {
try {
socketChannel.close();
} catch(Exception ex) {}
}
}
private static MyRequestObject receiveData(SocketChannel socketChannel) throws IOException {
MyRequestObject myRequestObject = null;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ByteBuffer buffer = ByteBuffer.allocate(1024);
try {
byte[] bytes;
int size = 0;
while ((size = socketChannel.read(buffer)) >= 0) {
buffer.flip();
bytes = new byte[size];
buffer.get(bytes);
baos.write(bytes);
buffer.clear();
}
bytes = baos.toByteArray();
Object obj = SerializableUtil.toObject(bytes);
myRequestObject = (MyRequestObject)obj;
} finally {
try {
baos.close();
} catch(Exception ex) {}
}
return myRequestObject;
}
private static void sendData(SocketChannel socketChannel, MyResponseObject myResponseObject) throws IOException {
byte[] bytes = SerializableUtil.toBytes(myResponseObject);
ByteBuffer buffer = ByteBuffer.wrap(bytes);
socketChannel.write(buffer);
}
}
下面是Client的代碼,代碼比較簡單就是啟動了100個線程來訪問Server
package com.googlecode.garbagecan.test.socket.nio;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.logging.Level;
import java.util.logging.Logger;
import com.googlecode.garbagecan.test.socket.SerializableUtil;
public class MyClient3 {
private final static Logger logger = Logger.getLogger(MyClient3.class.getName());
public static void main(String[] args) throws Exception {
for (int i = 0; i < 100; i++) {
final int idx = i;
new Thread(new MyRunnable(idx)).start();
}
}
private static final class MyRunnable implements Runnable {
private final int idx;
private MyRunnable(int idx) {
this.idx = idx;
}
public void run() {
SocketChannel socketChannel = null;
try {
socketChannel = SocketChannel.open();
SocketAddress socketAddress = new InetSocketAddress("localhost", 10000);
socketChannel.connect(socketAddress);
MyRequestObject myRequestObject = new MyRequestObject("request_" + idx, "request_" + idx);
logger.log(Level.INFO, myRequestObject.toString());
sendData(socketChannel, myRequestObject);
MyResponseObject myResponseObject = receiveData(socketChannel);
logger.log(Level.INFO, myResponseObject.toString());
} catch (Exception ex) {
logger.log(Level.SEVERE, null, ex);
} finally {
try {
socketChannel.close();
} catch(Exception ex) {}
}
}
private void sendData(SocketChannel socketChannel, MyRequestObject myRequestObject) throws IOException {
byte[] bytes = SerializableUtil.toBytes(myRequestObject);
ByteBuffer buffer = ByteBuffer.wrap(bytes);
socketChannel.write(buffer);
socketChannel.socket().shutdownOutput();
}
private MyResponseObject receiveData(SocketChannel socketChannel) throws IOException {
MyResponseObject myResponseObject = null;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try {
ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
byte[] bytes;
int count = 0;
while ((count = socketChannel.read(buffer)) >= 0) {
buffer.flip();
bytes = new byte[count];
buffer.get(bytes);
baos.write(bytes);
buffer.clear();
}
bytes = baos.toByteArray();
Object obj = SerializableUtil.toObject(bytes);
myResponseObject = (MyResponseObject) obj;
socketChannel.socket().shutdownInput();
} finally {
try {
baos.close();
} catch(Exception ex) {}
}
return myResponseObject;
}
}
}
最后測試上面的代碼,首先運行Server類,然后運行Client類,就可以分別在Server端和Client端控制臺看到發(fā)送或接收到的MyRequestObject或MyResponseObject對象了。
以上就是本文的全部內(nèi)容,希望對大家的學習有所幫助,也希望大家多多支持腳本之家。
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