一、实现网络通信需要解决的两个问题
二、网络通信的两个要素:
三、通信要素一:IP和端口号
1.IP的理解
此类的一个对象就代表着一个具体的IP地址
getByName(String host) 、 getLocalHost()
getHostName() / getHostAddress()
代码案例:
public class InetAddressTest {
public static void main(String[] args) {
try {
//File file = new File("hello.txt");
InetAddress inet1 = InetAddress.getByName("192.168.10.14");
System.out.println(inet1);
InetAddress inet2 = InetAddress.getByName("www.atguigu.com");
System.out.println(inet2);
InetAddress inet3 = InetAddress.getByName("127.0.0.1");
System.out.println(inet3);
//获取本地ip
InetAddress inet4 = InetAddress.getLocalHost();
System.out.println(inet4);
//getHostName()
System.out.println(inet2.getHostName());
//getHostAddress()
System.out.println(inet2.getHostAddress());
} catch (UnknownHostException e) {
e.printStackTrace();
}
}
1.IP的理解
2.端口号:正在计算机上运行的进程。
端口号与IP地址的组合得出一个网络套接字:Socket
代码示例1:客户端发送信息给服务端,服务端将数据显示在控制台上
//客户端
@Test
public void client() {
Socket socket = null;
OutputStream os = null;
try {
//1.创建Socket对象,指明服务器端的ip和端口号
InetAddress inet = InetAddress.getByName("192.168.14.100");
socket = new Socket(inet,8899);
//2.获取一个输出流,用于输出数据
os = socket.getOutputStream();
//3.写出数据的操作
os.write("你好,我是客户端mm".getBytes());
} catch (IOException e) {
e.printStackTrace();
} finally {
//4.资源的关闭
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;
ByteArrayOutputStream baos = null;
try {
//1.创建服务器端的ServerSocket,指明自己的端口号
ss = new ServerSocket(8899);
//2.调用accept()表示接收来自于客户端的socket
socket = ss.accept();
//3.获取输入流
is = socket.getInputStream();
//不建议这样写,可能会乱码
// byte[] buffer = new byte[1024];
// int len;
// while((len = is.read(buffer)) != -1){
// String str = new String(buffer,0,len);
// System.out.print(str);
// }
//4.读取输入流中的数据
baos = new ByteArrayOutputStream();
byte[] buffer = new byte[5];
int len;
while((len = is.read(buffer)) != -1){
baos.write(buffer,0,len);
}
System.out.println(baos.toString());
System.out.println("收到了来自于:" + socket.getInetAddress().getHostAddress() + "的数据");
} catch (IOException e) {
e.printStackTrace();
} finally {
if(baos != null){
//5.关闭资源
try {
baos.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();
}
}
}
}
代码示例2:客户端发送文件给服务端,服务端将文件保存在本地。
/*
这里涉及到的异常,应该使用try-catch-finally处理
*/
@Test
public void client() throws IOException {
//1.
Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9090);
//2.
OutputStream os = socket.getOutputStream();
//3.
FileInputStream fis = new FileInputStream(new File("beauty.jpg"));
//4.
byte[] buffer = new byte[1024];
int len;
while((len = fis.read(buffer)) != -1){
os.write(buffer,0,len);
}
//5.
fis.close();
os.close();
socket.close();
}
/*
这里涉及到的异常,应该使用try-catch-finally处理
*/
@Test
public void server() throws IOException {
//1.
ServerSocket ss = new ServerSocket(9090);
//2.
Socket socket = ss.accept();
//3.
InputStream is = socket.getInputStream();
//4.
FileOutputStream fos = new FileOutputStream(new File("beauty1.jpg"));
//5.
byte[] buffer = new byte[1024];
int len;
while((len = is.read(buffer)) != -1){
fos.write(buffer,0,len);
}
//6.
fos.close();
is.close();
socket.close();
ss.close();
}
代码示例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。
/*
这里涉及到的异常,应该使用try-catch-finally处理
*/
@Test
public void client() throws IOException {
//1.
Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9090);
//2.
OutputStream os = socket.getOutputStream();
//3.
FileInputStream fis = new FileInputStream(new File("beauty.jpg"));
//4.
byte[] buffer = new byte[1024];
int len;
while((len = fis.read(buffer)) != -1){
os.write(buffer,0,len);
}
//关闭数据的输出
socket.shutdownOutput();
//5.接收来自于服务器端的数据,并显示到控制台上
InputStream is = socket.getInputStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] bufferr = new byte[20];
int len1;
while((len1 = is.read(buffer)) != -1){
baos.write(buffer,0,len1);
}
System.out.println(baos.toString());
//6.
fis.close();
os.close();
socket.close();
baos.close();
}
/*
这里涉及到的异常,应该使用try-catch-finally处理
*/
@Test
public void server() throws IOException {
//1.
ServerSocket ss = new ServerSocket(9090);
//2.
Socket socket = ss.accept();
//3.
InputStream is = socket.getInputStream();
//4.
FileOutputStream fos = new FileOutputStream(new File("beauty2.jpg"));
//5.
byte[] buffer = new byte[1024];
int len;
while((len = is.read(buffer)) != -1){
fos.write(buffer,0,len);
}
System.out.println("图片传输完成");
//6.服务器端给予客户端反馈
OutputStream os = socket.getOutputStream();
os.write("你好,美女,照片我已收到,非常漂亮!".getBytes());
//7.
fos.close();
is.close();
socket.close();
ss.close();
os.close();
}
代码示例:
//发送端
@Test
public void sender() throws IOException {
DatagramSocket socket = new DatagramSocket();
String str = "我是UDP方式发送的导弹";
byte[] data = str.getBytes();
InetAddress inet = InetAddress.getLocalHost();
DatagramPacket packet = new DatagramPacket(data,0,data.length,inet,9090);
socket.send(packet);
socket.close();
}
//接收端
@Test
public void receiver() throws IOException {
DatagramSocket socket = new DatagramSocket(9090);
byte[] buffer = new byte[100];
DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);
socket.receive(packet);
System.out.println(new String(packet.getData(),0,packet.getLength()));
socket.close();
}
1.URL(Uniform Resource Locator)的理解:
统一资源定位符,对应着互联网的某一资源地址
2.URL的5个基本结构:
代码:
public static void main(String[] args) {
HttpURLConnection urlConnection = null;
InputStream is = null;
FileOutputStream fos = null;
try {
URL url = new URL("http://localhost:8080/examples/beauty.jpg");
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.connect();
is = urlConnection.getInputStream();
fos = new FileOutputStream("day10\\beauty3.jpg");
byte[] buffer = new byte[1024];
int len;
while((len = is.read(buffer)) != -1){
fos.write(buffer,0,len);
}
System.out.println("下载完成");
} catch (IOException e) {
e.printStackTrace();
} finally {
//关闭资源
if(is != null){
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(fos != null){
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(urlConnection != null){
urlConnection.disconnect();
}
}
}