JAVA網絡編程基於TCP和IP協議簇

InetAddress:代表ip地址,一個InetAddress的對象就代表一個IP地址

TCP編程例一：客戶端給服務端發送信息。服務端輸出此信息到控制檯上

客戶端:

package bank;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;

public class Client {
public static void main (String[] args){
    Socket socket =null;
    OutputStream out =null;

    try {
        //1.創建一個Socket的對象,通過構造器指明服務端的ip地址,以及接受程序的端口號
        socket = new Socket(InetAddress.getByName("127.0.0.1"),9090);
        //2.使用getOutputStream()發送數據,方法返回OutputStream的對象
        out = socket.getOutputStream();
        //3.具體的輸出過程
        out.write("我是客戶端,請多關照".getBytes());
    } catch (IOException e) {
        e.printStackTrace();
    } finally {

        if (out !=null){
            try {
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (socket != null){
            try {
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }




}
}

服務端

package bank;

import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
public static void main(String[] args) {
    ServerSocket ss = null;
    Socket s = null;
    InputStream is = null;

    try {
        //1.創建一個ServerSocket的對象,通過構造器指明自身的端口
        ss = new ServerSocket(9090);
        //2.調用其accept()方法,返回一個Socket對象
        s = ss.accept();
        //3.調用Socket對象的getInputStream()獲取一個從客戶端發送過來的輸入流
        is = s.getInputStream();
        //4.對獲取的輸入流進行操作
        byte[] b = new byte[20];
        int len;
        while ((len = is.read(b)) != -1) {
            String str = new String(b, 0, len);
            System.out.println(str);
        }
        System.out.println("收到來自於" + s.getInetAddress().getHostAddress() + "的連接");
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (is != null) {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (s != null) {
            try {
                s.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (ss != null) {
            try {
                ss.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

}
}

TCP編程例二：客戶端給服務端發送信息，服務端將信息打印到控制檯上，同時發送“已收到信息”給客戶端

服務端

	package bank;
	
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.OutputStream;
	import java.net.ServerSocket;
	import java.net.Socket;
	
	public class Server {
	    public static void main(String[] args) {
    ServerSocket ss = null;
    Socket s = null;
    InputStream is = null;
    OutputStream os = null;
    try {
        //1.創建一個ServerSocket的對象,通過構造器指明自身的端口
        ss = new ServerSocket(9090);
        //2.調用其accept()方法,返回一個Socket對象
        s = ss.accept();
        //3.調用Socket對象的getInputStream()獲取一個從客戶端發送過來的輸入流
        is = s.getInputStream();
        //4.對獲取的輸入流進行操作
        byte[] b = new byte[20];
        int len;
        while ((len = is.read(b)) != -1) {
            String str = new String(b, 0, len);
            System.out.println(str);
        }
        System.out.println("收到來自於" + s.getInetAddress().getHostAddress() + "的連接");
        os = s.getOutputStream();
        os.write("我收到client".getBytes());
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (os != null) {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (is != null) {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (s != null) {
            try {
                s.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (ss != null) {
            try {
                ss.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

}
}

客戶端

package bank;


import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;

public class Client {
public static void main (String[] args){

    Socket socket = null;
    OutputStream os = null;
    InputStream is = null;
    try {
        //1.創建一個Socket對象,通過構造器指明服務端的ip地址以及接受程序的端口號
        socket = new Socket(InetAddress.getByName("127.0.0.1"),9090);
        //2.getOutputStream:發送數據,方法返回OutputStream的對象
        os = socket.getOutputStream();
        //3.具體的輸出過程
        os.write("我是客戶端".getBytes());
        //shutdownOutput():執行此方法,顯式告訴服務器發送完畢,防止服務器持續等待
        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 (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();
            }
        }
    }


}
}

代碼對比

客戶端,使用輸出流,輸入到服務端

		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.print(str);
		}	

服務端:

os = s.getOutputStream();
os.write("我已收到你的情意".getBytes());

對於使用inputstream與outputstream的疑惑

1.對於socket而言

client向server發信息,使用outputStream,得到server的信息,使用inputStream

2.對於serverSocket
server向client發信息用outputStream(輸出）,從客戶端得到信息就用inputstream（輸入)

基本原理:應用程序數據流向來說,服務端從客戶端,本地文件系統等其他地方得到inputStream都是讀入內存供應用程序使用
應用程序往科幻,我呢間,數據庫等寫出數據的話使用outputStream,也就是從內存中寫出,

假設讀取本地文件a寫入到b,就是講inputStream把a的內容讀到內存,然後outputStream寫入b

TCP編程例三：客戶端發送文件給服務端,服務端保存在本地,並返回"發送成功"給客戶端,並關閉相應的連接

客戶端
	package bank;
	
	import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
//處理異常,一般使用try-catch 只是爲了書寫方便
public class Client {
    public static void main (String[] args) throws IOException {
        //1.創建Socket對象
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9898);
        //2.從本地獲取一個文件發送給服務端
        OutputStream os = socket.getOutputStream();
        FileInputStream fis = new FileInputStream(new File("C:/Users/Administrator/Desktop/1.jpg"));
        byte[] b = new  byte[1024];
        int len;
        while ((len = fis.read(b))!=-1){
            os.write(b,0,len);
        }
        socket.shutdownOutput();
        //3.接受來自服務端的信息
        InputStream is = socket.getInputStream();
        byte[] b1 = new byte[1024];
        int len1;
        while ((len1=is.read(b1))!=-1){
            String str = new String(b1,0,len1);
            System.out.println(str);
        }

        //4.關閉相應的流和Socket對象
        is.close();
        os.close();
        fis.close();
        socket.close();
    }
}

服務端

package bank;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
    public static void main(String[] args) throws IOException {
        //1.創建一個ServerSocket的對象
    ServerSocket ss = new ServerSocket(9898);
    //2.調用其accept()方法,返回一個Socket的對象
    Socket s = ss.accept();
    //3.將從客戶端發送來的信息保存在本地
    InputStream is = s.getInputStream();
    FileOutputStream fos = new FileOutputStream(new File("C:/Users/Administrator/Desktop/1.jpg"));
    byte[] b = new byte[1024];
    int len;
    while ((len = is.read(b))!=-1){
        fos.write(b,0,len);
    }
    System.out.println("收到來自於"+s.getInetAddress().getHostAddress()+"的文件");
    //4.發送"接受成功"的信息反饋給客戶端
    OutputStream os = s.getOutputStream();
    os.write("你發送的圖片接受成功".getBytes());
    //5.關閉相應的流和Socket以及ServerSocket的對象
    os.close();
    fos.close();
    is.close();
    s.close();
    ss.close();
    }
}