JAVA程序员培训定制课程.ppt

第十五章,网络编程,2,本章内容,使用包中的类在程序中实现网络通信 URL类及其用法 Socket通信,3,URL,URL(Uniform Resource Locator)-统一资源定位器，表示Internet上某一资源的地址。 URL组成: 协议名和资源名 protocol:resourceName URL举例: / /home/welcome.html /developers/,4,.URL类,常用构造方法 public URL(String spec); URL u1 = new URL(“/home/”); public URL(URL context, String spec); URL u2 = new URL(u1, “welcome.html”); public URL(String protocol, String host, String file); URL u3 = new URL(“http”, “”, “developers/index.html” ); public URL (String protocol, String host, int port, String file); URL u4 = new URL(“http”, “”, 80, “developers/index.html” );,5,URL类应用举例(1),import java.io.*; import .*; public class URLReader public static void main(String args) try URL tirc = new URL(“/“); BufferedReader in = new BufferedReader(new InputStreamReader(tirc.openStream(); String s; while(s = in.readLine()!=null) System.out.println(s); in.close(); catch(MalformedURLException e) System.out.println(e); catch(IOException e) System.out.println(e); ,6,URL类应用举例(2),程序URLReader.java输出结果: 清华大学网站首页 ,7,Socket,两个Java应用程序可通过一个双向的网络通信连接实现数据交换，这个双向链路的一端称为一个socket。 socket通常用来实现client-server连接。 包中定义的两个类Socket和ServerSocket，分别用来实现双向连接的client和server端 建立连接时所需的寻址信息 远程计算机的机器名或IP地址 试图连接的端口号(Port number),8,Socket通信模型,Server,ServerSocket s (port #),s.accept()/等待连接,Socket(),OutputStream,InputStream,socket.close(),Client,Socket (host, port #) （Attempt to connect）,OutputStream,InputStream,socket.close(),9,网络编程的四个基本步骤,创建socket; 打开连接到socket的输入/输出流； 按照一定的协议对socket进行读/写操作； 关闭socket;,10,创建socket,Socket/ServerSocket类的构造方法 Socket(InetAddress address, int port); Socket(InetAddress address, int port, boolean stream); Socket(String host, int port); Socket(String host, int port, boolean stream); ServerSocket(int port); ServerSocket(int port, int count);,11,客户端Socket的建立 try Socket socket=new Socket(”“,2000); catch(IOException e) System.out.println(“Error:“+e); ,12,服务器端Socket的建立 ServerSocket server=null; try server=new ServerSocket(2000); catch(IOException e) System.out.println(“can not listen to :“+e); Socket socket=null; try socket=server.accept(); catch(IOException e) System.out.println(“Error:“+e); ,13,打开输入/出流 PrintStream os=new PrintStream(new BufferedOutputStream(socket.getOutputStream(); DataInputStream is=new DataInputStream(socket.getInputStream(); 关闭Socket os.close(); is.close(); socket.close();,14,简单的client/server程序,import .*; import java.io.*; public class TestServer public static void main(String args) ServerSocket s = null; try s = new ServerSocket(8888); catch (IOException e) while (true) try Socket s1 = s.accept(); OutputStream os = s1.getOutputStream(); DataOutputStream dos = new DataOutputStream(os); dos.writeUTF(“Hello,bye-bye!“); dos.close(); s1.close(); catch (IOException e) ,15,简单的client/server程序,import .*; import java.io.*; public class TestClient public static void main(String args) try Socket s1 = new Socket(““, 8888); InputStream is = s1.getInputStream(); DataInputStream dis = new DataInputStream(is); System.out.println(dis.readUTF(); dis.c