网络编程

1:网络编程(理解)

(1)计算机网络

是指将地理位置不同的具有独立功能的多台计算机及其外部设备，通过通信线路连接起来，在网络操作系统，网络管理软件及网络通信协议的管理和协调下，实现资源共享和信息传递的计算机系统。

(2)网络编程

就是用来实现网络互连的不同计算机上运行的程序间可以进行数据交换。

用Java语言实现计算机间数据的信息传递和资源共享

(2)网络编程模型及参考模型图

OSI（Open System Interconnection开放系统互连）参考模型

物、数、网、传、会、表、应

TCP/IP参考模型

 

 

 

 

(3)网络编程的三要素

A:IP地址

a:点分十进制

b:IP地址的组成

c:IP地址的分类

d:dos命令

e:InetAddress

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

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

(5)TCP协议发送和接收数据

发送：

创建TCP客户端的Socket对象

获取输出流，写数据

释放资源

接收：

创建TCP服务器端的Socket对象

监听客户端连接

获取输入流，读取数据

释放资源

(6)案例：

A:UDP

a:最基本的UDP协议发送和接收数据

SendDemo:

/* * UDP协议发送数据： * A:创建发送端Socket对象 * B:创建数据，并把数据打包 * C:调用Socket对象的发送方法发送数据包 * D: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();}}

 

 

ReceiveDemo:

/* * UDP协议接收数据： * A:创建接收端Socket对象 * B:创建一个数据包(接收容器) * C:调用Socket对象的接收方法接收数据 * D:解析数据包，并显示在控制台 * E: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();}}

 

b:把发送数据改进为键盘录入

SendDemo:

/* * 数据来自于键盘录入 * 键盘录入数据要自己控制录入结束。 */public class SendDemo {public static void main(String[] args) throws IOException {// 创建发送端的Socket对象DatagramSocket ds = new DatagramSocket(); // 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"), 12345); // 发送数据ds.send(dp);} // 释放资源ds.close();}}

 

 

ReceiveDemo:

/* * 多次启动接收端： * java.net.BindException: Address already in use: Cannot bind * 端口被占用。 */public class ReceiveDemo {public static void main(String[] args) throws IOException {// 创建接收端的Socket对象DatagramSocket ds = new DatagramSocket(12345); 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);} // 释放资源// 接收端应该一直开着等待接收数据，是不需要关闭// ds.close();}}

c:一个简易聊天小程序并用多线程改进

ChatRoom:

/* * 通过多线程改进刚才的聊天程序，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();}}

 

SendThread:

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();}} }

ReceiveThread:

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();}} }  

B:TCP

a:最基本的TCP协议发送和接收数据

ServerDemo:

/* * TCP协议接收数据： * A:创建接收端的Socket对象 * B:监听客户端连接。返回一个对应的Socket对象 * C:获取输入流，读取数据显示在控制台 * D: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}} 

ClientDemo:

/* * TCP协议发送数据： * A:创建发送端的Socket对象 * 这一步如果成功，就说明连接已经建立成功了。 * B:获取输出流，写数据 * C:释放资源 * * 连接被拒绝。TCP协议一定要先看服务器。 * java.net.ConnectException: Connection refused: connect */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();}} 

b:服务器给出反馈

UploadClient :

/* * 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();}} 

 

UploadServer :

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();}}

 

c:客户端键盘录入服务器控制台输出

ServerDemo:

public class ServerDemo {public static void main(String[] args) throws IOException {// 创建服务器Socket对象ServerSocket ss = new ServerSocket(22222); // 监听客户端连接Socket s = ss.accept(); // 包装通道内容的流BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()));String line = null;while ((line = br.readLine()) != null) {System.out.println(line);} // br.close();s.close();// ss.close();} 

ClientDemo:

/* * 客户端键盘录入，服务器输出到控制台 */public class ClientDemo {public static void main(String[] args) throws IOException {// 创建客户端Socket对象Socket s = new Socket("192.168.12.92", 22222); // 键盘录入数据BufferedReader br = new BufferedReader(new InputStreamReader(System.in));// 把通道内的流给包装一下BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream())); String line = null;while ((line = br.readLine()) != null) {// 键盘录入数据要自定义结束标记if ("886".equals(line)) {break;}bw.write(line);bw.newLine();bw.flush();} // 释放资源// bw.close();// br.close();s.close();}} 

d:客户端键盘录入服务器写到文本文件

ServerDemo :

public class ServerDemo {public static void main(String[] args) throws IOException {// 创建服务器Socket对象ServerSocket ss = new ServerSocket(23456); // 监听客户端连接Socket s = ss.accept(); // 封装通道内的数据BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()));// 封装文本文件BufferedWriter bw = new BufferedWriter(new FileWriter("a.txt")); String line = null;while ((line = br.readLine()) != null) {bw.write(line);bw.newLine();bw.flush();} bw.close();// br.close();s.close();// ss.close();}}

 

ClientDemo:

/* * 客户端键盘录入，服务器输出文本文件 */public class ClientDemo {public static void main(String[] args) throws IOException {// 创建客户端Socket对象Socket s = new Socket("192.168.12.92", 23456); // 封装键盘录入BufferedReader br = new BufferedReader(new InputStreamReader(System.in));// 封装通道内的数据BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream())); String line = null;while ((line = br.readLine()) != null) {if ("over".equals(line)) {break;} bw.write(line);bw.newLine();bw.flush();} // bw.close();// br.close();s.close();}}

 

e:客户端读取文本文件服务器控制台输出

ClientDemo:

/* * 客户端文本文件，服务器输出到控制台 */public class ClientDemo {public static void main(String[] args) throws IOException {// 创建Socket对象Socket s = new Socket("192.168.12.92", 34567); // 封装文本文件BufferedReader br = new BufferedReader(new FileReader("InetAddressDemo.java"));// 封装通道内的流BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream())); String line = null;while ((line = br.readLine()) != null) {bw.write(line);bw.newLine();bw.flush();} br.close();s.close();}} 

ServerDemo:

public class ServerDemo {public static void main(String[] args) throws IOException {// 创建服务器Socket对象ServerSocket ss = new ServerSocket(34567); // 监听客户端连接Socket s = ss.accept(); // 封装通道内的流BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream())); String line = null;while ((line = br.readLine()) != null) {System.out.println(line);} s.close();}}

 

f:客户端读取文本文件服务器写到文本文件

UploadServer :

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(); // 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) {bw.write(line);bw.newLine();bw.flush();} bw.close();s.close();}} 

 

UploadClient :

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) {bw.write(line);bw.newLine();bw.flush();} // 释放资源br.close();s.close();}} 

 

g:上传图片

UploadClient :

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", 19191); // 封装图片文件BufferedInputStream bis = new BufferedInputStream(new FileInputStream("林青霞.jpg"));// 封装通道内的流BufferedOutputStream bos = new BufferedOutputStream(s.getOutputStream()); byte[] bys = new byte[1024];int len = 0;while ((len = bis.read(bys)) != -1) {bos.write(bys, 0, len);bos.flush();}s.shutdownOutput(); // 读取反馈InputStream is = s.getInputStream();byte[] bys2 = new byte[1024];int len2 = is.read(bys2);String client = new String(bys2, 0, len2);System.out.println(client); // 释放资源bis.close();s.close();}}

 

UploadServer :

public class UploadServer {public static void main(String[] args) throws IOException {// 创建服务器Socket对象ServerSocket ss = new ServerSocket(19191); // 监听客户端连接Socket s = ss.accept(); // 封装通道内流BufferedInputStream bis = new BufferedInputStream(s.getInputStream());// 封装图片文件BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("mn.jpg")); byte[] bys = new byte[1024];int len = 0;while ((len = bis.read(bys)) != -1) {bos.write(bys, 0, len);bos.flush();} // 给一个反馈OutputStream os = s.getOutputStream();os.write("图片上传成功".getBytes()); bos.close();s.close();}} 

h:多线程改进上传文件

UserThread :

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();}} }

 

UploadClient :

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();}}

 

 

UploadServer :

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();}}}