BIO
BIO
在 JDK1.4 推出 Java NIO 之前，基于 Java 的所有 Socket 通信都采用了同步阻塞模式(BIO)，这种一请求一应答的通信模型简化了上层的应用开发，但是在性能和可靠性方面却存在着巨大的瓶颈。因此，在很长的一段时间里，大型的应用服务器都采用 C 或者 C++，因为它们可以直接使用操作系统提供的异步 IO 能力。
一般来说 BIO 提供的都是面向流的 IO 系统，系统一次一个字节地处理数据，一个输入流产生一个字节的数据，一个输出流消费一个字节的数据，面向流的 IO 速度非常慢，而 NIO 是一个面向块的 IO 系统，系统以块的方式处理处理，每一个操作在一步中产生或者消费一个数据库，按块处理要比按字节处理数据快的多。
public class Server {
public static void main(String[] args) {
int port = genPort(args);
ServerSocket server = null;
ExecutorService service = Executors.newFixedThreadPool(50);
try{
server = new ServerSocket(port);
System.out.println("server started!");
while(true){
Socket socket = server.accept();
service.execute(new Handler(socket));
}
}catch(Exception e){
e.printStackTrace();
}finally{
if(server != null){
try {
server.close();
} catch (IOException e) {
e.printStackTrace();
}
}
server = null;
}
}
static class Handler implements Runnable{
Socket socket = null;
public Handler(Socket socket){
this.socket = socket;
}
@Override
public void run() {
BufferedReader reader = null;
PrintWriter writer = null;
try{
reader = new BufferedReader(
new InputStreamReader(socket.getInputStream(), "UTF-8"));
writer = new PrintWriter(
new OutputStreamWriter(socket.getOutputStream(), "UTF-8"));
String readMessage = null;
while(true){
System.out.println("server reading... ");
if((readMessage = reader.readLine()) == null){
break;
}
System.out.println(readMessage);
writer.println("server recive : " + readMessage);
writer.flush();
}
}catch(Exception e){
e.printStackTrace();
}finally{
if(socket != null){
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
socket = null;
if(reader != null){
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
reader = null;
if(writer != null){
writer.close();
}
writer = null;
}
}
}
private static int genPort(String[] args){
if(args.length > 0){
try{
return Integer.parseInt(args[0]);
}catch(NumberFormatException e){
return 9999;
}
}else{
return 9999;
}
}
}
客户端的实现如下：
public class Client {
public static void main(String[] args) {
String host = null;
int port = 0;
if(args.length > 2){
host = args[0];
port = Integer.parseInt(args[1]);
}else{
host = "127.0.0.1";
port = 9999;
}
Socket socket = null;
BufferedReader reader = null;
PrintWriter writer = null;
Scanner s = new Scanner(System.in);
try{
socket = new Socket(host, port);
String message = null;
reader = new BufferedReader(
new InputStreamReader(socket.getInputStream(), "UTF-8"));
writer = new PrintWriter(
socket.getOutputStream(), true);
while(true){
message = s.nextLine();
if(message.equals("exit")){
break;
}
writer.println(message);
writer.flush();
System.out.println(reader.readLine());
}
}catch(Exception e){
e.printStackTrace();
}finally{
if(socket != null){
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
socket = null;
if(reader != null){
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
reader = null;
if(writer != null){
writer.close();
}
writer = null;
}
}
}