java基础--网络编程

1、网络编程概述

A:用Java语言实现计算机间数据的信息传递和资源共享

B:网络编程模型

2、网络编程的三要素

A:IP地址

java提供InetAddress类

public static InetAddress getByName(String host):根据主机名或者IP地址的字符串表示得到IP地址对象

public String getHostName()   获取主机名

public String getHostAddress() 获取IP地址

B:端口

是应用程序的标识。范围：0-65535。其中0-1024不建议使用。

C:协议

UDP:数据打包,有限制,不连接,效率高,不可靠

TCP:建立数据通道,无限制,效率低,可靠

3、Socket机制

A:通信两端都应该有Socket对象

B:所有的通信都是通过Socket间的IO进行操作的

4、UDP编程

UDP协议发送和接收数据

发送：

创建UDP发送端的Socket对象

创建数据并把数据打包

发送数据

释放资源

public class SendDemo {public static void main(String[] args) throws IOException {// 创建发送端Socket对象// DatagramSocket()DatagramSocket ds = new DatagramSocket();// 创建数据，并把数据打包// DatagramPacket(byte[] buf, int length, InetAddress address, int port)// 创建数据byte[] bys = "hello,udp,我来了".getBytes();// 长度int length = bys.length;// IP地址对象InetAddress address = InetAddress.getByName("192.168.12.92");// 端口int port = 10086;DatagramPacket dp = new DatagramPacket(bys, length, address, port);// 调用Socket对象的发送方法发送数据包// public void send(DatagramPacket p)ds.send(dp);// 释放资源ds.close();}}

接收：

创建UDP接收端的Socket对象

创建数据包用于接收数据

接收数据

解析数据包

释放资源

public class ReceiveDemo {public static void main(String[] args) throws IOException {// 创建接收端Socket对象// DatagramSocket(int port)DatagramSocket ds = new DatagramSocket(10086);// 创建一个数据包(接收容器)// DatagramPacket(byte[] buf, int length)byte[] bys = new byte[1024];int length = bys.length;DatagramPacket dp = new DatagramPacket(bys, length);// 调用Socket对象的接收方法接收数据// public void receive(DatagramPacket p)ds.receive(dp); // 阻塞式// 解析数据包，并显示在控制台// 获取对方的ip// public InetAddress getAddress()InetAddress address = dp.getAddress();String ip = address.getHostAddress();// public byte[] getData():获取数据缓冲区// public int getLength():获取数据的实际长度byte[] bys2 = dp.getData();int len = dp.getLength();String s = new String(bys2, 0, len);System.out.println(ip + "传递的数据是:" + s);// 释放资源ds.close();}}

5、TCP编程

TCP协议发送和接收数据(掌握 自己补齐代码)

发送：

创建TCP客户端的Socket对象,这一步如果成功，就说明连接已经建立成功了

获取输出流，写数据

释放资源

public class ClientDemo {public static void main(String[] args) throws IOException {// 创建发送端的Socket对象// Socket(InetAddress address, int port)// Socket(String host, int port)// Socket s = new Socket(InetAddress.getByName("192.168.12.92"), 8888);Socket s = new Socket("192.168.12.92", 8888);// 获取输出流，写数据// public OutputStream getOutputStream()OutputStream os = s.getOutputStream();os.write("hello,tcp,我来了".getBytes());// 释放资源s.close();}}

接收：

创建TCP服务器端的Socket对象

监听客户端连接,返回一个对应的Socket对象

获取输入流，读取数据

释放资源

public class ServerDemo {public static void main(String[] args) throws IOException {// 创建接收端的Socket对象// ServerSocket(int port)ServerSocket ss = new ServerSocket(8888);// 监听客户端连接。返回一个对应的Socket对象// public Socket accept()Socket s = ss.accept(); // 侦听并接受到此套接字的连接。此方法在连接传入之前一直阻塞。// 获取输入流，读取数据显示在控制台InputStream is = s.getInputStream();byte[] bys = new byte[1024];int len = is.read(bys); // 阻塞式方法String str = new String(bys, 0, len);String ip = s.getInetAddress().getHostAddress();System.out.println(ip + "---" + str);// 释放资源s.close();// ss.close(); //这个不应该关闭}}

(6)案例：

A:UDP

a:一个简易聊天小程序并用多线程改进

public class SendThread implements Runnable {private DatagramSocket ds;public SendThread(DatagramSocket ds) {this.ds = ds;}@Overridepublic void run() {try {// 封装键盘录入数据BufferedReader br = new BufferedReader(new InputStreamReader(System.in));String line = null;while ((line = br.readLine()) != null) {if ("886".equals(line)) {break;}// 创建数据并打包byte[] bys = line.getBytes();// DatagramPacket dp = new DatagramPacket(bys, bys.length,// InetAddress.getByName("192.168.12.92"), 12345);DatagramPacket dp = new DatagramPacket(bys, bys.length,InetAddress.getByName("192.168.12.255"), 12306);// 发送数据ds.send(dp);}// 释放资源ds.close();} catch (IOException e) {e.printStackTrace();}}}

public class ReceiveThread implements Runnable {private DatagramSocket ds;public ReceiveThread(DatagramSocket ds) {this.ds = ds;}@Overridepublic void run() {try {while (true) {// 创建一个包裹byte[] bys = new byte[1024];DatagramPacket dp = new DatagramPacket(bys, bys.length);// 接收数据ds.receive(dp);// 解析数据String ip = dp.getAddress().getHostAddress();String s = new String(dp.getData(), 0, dp.getLength());System.out.println("from " + ip + " data is : " + s);}} catch (IOException e) {e.printStackTrace();}}}

/* * 通过多线程改进的聊天程序，这样我就可以实现在一个窗口发送和接收数据了 */public class ChatRoom {public static void main(String[] args) throws IOException {DatagramSocket dsSend = new DatagramSocket();DatagramSocket dsReceive = new DatagramSocket(12306);SendThread st = new SendThread(dsSend);ReceiveThread rt = new ReceiveThread(dsReceive);Thread t1 = new Thread(st);Thread t2 = new Thread(rt);t1.start();t2.start();}}

B:TCP

a客户端读取文本文件服务器写到文本文件

/* * 按照我们正常的思路加入反馈信息，结果却没反应。为什么呢? * 读取文本文件是可以以null作为结束信息的，但是呢，通道内是不能这样结束信息的。 * 所以，服务器根本就不知道你结束了。而你还想服务器给你反馈。所以，就相互等待了。 *  * 如何解决呢? * A:在多写一条数据，告诉服务器，读取到这条数据说明我就结束，你也结束吧。 * 这样做可以解决问题，但是不好。 * B:Socket对象提供了一种解决方案 * public void shutdownOutput() */public class UploadClient {public static void main(String[] args) throws IOException {// 创建客户端Socket对象Socket s = new Socket("192.168.12.92", 11111);// 封装文本文件BufferedReader br = new BufferedReader(new FileReader("InetAddressDemo.java"));// 封装通道内流BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));String line = null;while ((line = br.readLine()) != null) { // 阻塞bw.write(line);bw.newLine();bw.flush();}//自定义一个结束标记//bw.write("over");//bw.newLine();//bw.flush();//Socket提供了一个终止，它会通知服务器你别等了，我没有数据过来了s.shutdownOutput();// 接收反馈BufferedReader brClient = new BufferedReader(new InputStreamReader(s.getInputStream()));String client = brClient.readLine(); // 阻塞System.out.println(client);// 释放资源br.close();s.close();}}

public class UploadServer {public static void main(String[] args) throws IOException {// 创建服务器端的Socket对象ServerSocket ss = new ServerSocket(11111);// 监听客户端连接Socket s = ss.accept();// 阻塞// 封装通道内的流BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()));// 封装文本文件BufferedWriter bw = new BufferedWriter(new FileWriter("Copy.java"));String line = null;while ((line = br.readLine()) != null) { // 阻塞// if("over".equals(line)){// break;// }bw.write(line);bw.newLine();bw.flush();}// 给出反馈BufferedWriter bwServer = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));bwServer.write("文件上传成功");bwServer.newLine();bwServer.flush();// 释放资源bw.close();s.close();}}

b:多线程上传图片

public class UploadClient {public static void main(String[] args) throws IOException {// 创建客户端Socket对象Socket s = new Socket("192.168.12.92", 11111);// 封装文本文件// BufferedReader br = new BufferedReader(new FileReader(// "InetAddressDemo.java"));BufferedReader br = new BufferedReader(new FileReader("ReceiveDemo.java"));// 封装通道内流BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));String line = null;while ((line = br.readLine()) != null) { // 阻塞bw.write(line);bw.newLine();bw.flush();}// Socket提供了一个终止，它会通知服务器你别等了，我没有数据过来了s.shutdownOutput();// 接收反馈BufferedReader brClient = new BufferedReader(new InputStreamReader(s.getInputStream()));String client = brClient.readLine(); // 阻塞System.out.println(client);// 释放资源br.close();s.close();}}

public class UploadServer {public static void main(String[] args) throws IOException {// 创建服务器Socket对象ServerSocket ss = new ServerSocket(11111);while (true) {Socket s = ss.accept();new Thread(new UserThread(s)).start();}}}

public class UserThread implements Runnable {private Socket s;public UserThread(Socket s) {this.s = s;}@Overridepublic void run() {try {// 封装通道内的流BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()));// 封装文本文件// BufferedWriter bw = new BufferedWriter(new// FileWriter("Copy.java"));// 为了防止名称冲突String newName = System.currentTimeMillis() + ".java";BufferedWriter bw = new BufferedWriter(new FileWriter(newName));String line = null;while ((line = br.readLine()) != null) { // 阻塞bw.write(line);bw.newLine();bw.flush();}// 给出反馈BufferedWriter bwServer = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));bwServer.write("文件上传成功");bwServer.newLine();bwServer.flush();// 释放资源bw.close();s.close();} catch (IOException e) {e.printStackTrace();}}}