Java网络编程之TCP

时间：2022-12-18 07:47:06

1.客户端发送内容给服务端，服务端将内容打印到控制台上。
示例代码：
 
import java.io.IOException;import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;

import org.junit.Test;

//TCP编程例一：客户端给服务端发送信息。服务端输出此信息到控制台上
//网络编程实际上就是Socket的编程
public class TestTCP1 {
	// 客户端
	@Test
	public void client() {
		Socket socket = null;
		OutputStream os = null;
		try {
			// 1.创建一个Socket的对象，通过构造器指明服务端的IP地址，以及其接收程序的端口号
			socket = new Socket(InetAddress.getByName("127.0.0.1"), 9090);
			// 2.getOutputStream()：发送数据，方法返回OutputStream的对象
			os = socket.getOutputStream();
			// 3.具体的输出过程
			os.write("我是客户端我是客户端！接收到了吗？".getBytes());
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			// 4.关闭相应的流和Socket对象
			if(os != null) {
				try {
					os.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(socket != null) {
				try {
					socket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

	// 服务端
	@Test
	public void server() {
		ServerSocket ss = null;
		Socket socket = null;
		InputStream is = null;
		try {
			// 1.创建一个ServerSocket的对象，通过构造器指明自身的端口号
			ss = new ServerSocket(9090);
			// 2.调用其accept()方法，返回一个Socket的对象
			socket = ss.accept();
			// 3.调用Socket对象的getInputStream()获取一个从客户端发送过来的输入流
			is = socket.getInputStream();
			// 4.对获取的输入流进行的操作
			byte[] b = new byte[20];
			int len;
			while((len = is.read(b)) != -1) {
				String str = new String(b, 0, len);
				System.out.print(str);
			}
			System.out.println();
			System.out.println("收到来自"+socket.getInetAddress().getHostName()+"的连接。");
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			// 5.关闭相应的流以及Socket、ServerSocket的对象
			if(is != null) {
				try {
					is.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(socket != null) {
				try {
					socket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(ss != null) {
				try {
					ss.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}
}
2.客户端发送内容给服务端，服务端给予反馈。
示例代码： 
import java.io.IOException;import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;

import org.junit.Test;

//TCP编程例二：客户端给服务端发送信息，服务端将信息打印到控制台上，同时发送“已收到信息”给客户端
public class TestTCP2 {
	//客户端
	@Test
	public void client() {
		Socket socket = null;
		OutputStream os = null;
		InputStream is = null;
		try {
			socket = new Socket(InetAddress.getByName("127.0.0.1"), 9898);
			os = socket.getOutputStream();
			os.write("我是客户端，请接收！".getBytes());
			//shutdownOutput():执行此方法，显式的告诉服务端发送完毕！
			socket.shutdownOutput();

			is = socket.getInputStream();
			byte[] b = new byte[20];
			int len;
			while((len = is.read(b)) != -1) {
				String str = new String(b, 0, len);
				System.out.println(str);
			}
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if(is != null) {
				try {
					is.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(os != null) {
				try {
					os.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(socket != null) {
				try {
					socket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}

	}

	//服务端
	@Test
	public void server() {
		ServerSocket ss = null;
		Socket socket = null;
		InputStream is = null;
		OutputStream os = null;
		try {
			ss = new ServerSocket(9898);
			socket = ss.accept();
			is = socket.getInputStream();
			byte[] b = new byte[20];
			int len;
			while((len = is.read(b)) != -1) {
				String str = new String(b, 0, len);
				System.out.println(str);
			}

			os = socket.getOutputStream();
			os.write("已收到！".getBytes());
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if(os != null) {
				try {
					os.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(is != null) {
				try {
					is.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(socket != null) {
				try {
					socket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(ss != null) {
				try {
					ss.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}
}

3.从客户端发送文件给服务端，服务端保存到本地。并返回“发送成功”给客户端。并关闭相应的连接。
示例代码： 
import java.io.FileInputStream;import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;

import org.junit.Test;

//TCP编程例三：从客户端发送文件给服务端，服务端保存到本地。并返回“发送成功”给客户端。并关闭相应的连接。
public class TestTCP {
	@Test
	public void client() {
		Socket socket = null;
		FileInputStream fis = null;
		OutputStream os = null;
		InputStream is = null;
		try {
			//1.创建Socket的对象
			socket = new Socket("127.0.0.1", 9898);
			fis = new FileInputStream("1.jpg");
			//2.从本地获取一个文件发送给服务端
			os = socket.getOutputStream();
			byte[] b = new byte[2048];
			int len;
			while((len = fis.read(b)) != -1) {
				os.write(b, 0, len);
			}
			socket.shutdownOutput();
			//3.接收来自于服务端的信息
			is = socket.getInputStream();
			byte[] b1 = new byte[20];
			while((len = is.read(b1)) != -1) {
				String str = new String(b1, 0, len);
				System.out.print(str);
			}
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			//4.关闭相应的流和Socket对象
			if(is != null) {
				try {
					is.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(os != null) {
				try {
					os.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(fis != null) {
				try {
					fis.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(socket != null) {
				try {
					socket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

	@Test
	public void server() {
		ServerSocket ss = null;
		Socket socket = null;
		FileOutputStream fos = null;
		InputStream is = null;
		OutputStream os = null;
		try {
			//1.创建一个ServerSocket的对象
			ss = new ServerSocket(9898);
			//2.调用其accept()方法，返回一个Socket的对象
			socket = ss.accept();
			//3.将从客户端发送来的信息保存到本地
			fos = new FileOutputStream("2.jpg");
			is = socket.getInputStream();
			byte[] b = new byte[2048];
			int len;
			while((len = is.read(b)) != -1) {
				fos.write(b, 0, len);
			}
			System.out.println();
			System.out.println("从"+socket.getInetAddress().getHostName()+"的图片接收成功！");
			//4.发送"接收成功"的信息反馈给客户端
			os = socket.getOutputStream();
			os.write("发送成功！".getBytes());
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			//5.关闭相应的流和Socket及ServerSocket的对象
			if(os != null) {
				try {
					os.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(fos != null) {
				try {
					fos.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(is != null) {
				try {
					is.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(socket != null) {
				try {
					socket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if(ss != null) {
				try {
					ss.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}
}


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