网络编程
一、IP和端口号
一、网络编程中有两个主要的问题:
1.如何准确地定位网络上一台或多台主机;定位主机上的特定的应用
2.找到主机后如何可靠高效地进行数据传输
二、网络编程中的两个要素:
1.对应问题一:IP和端口号
2.对应问题二:提供网络通信协议:TCP/IP参考模型(应用层、传输层、网络层、物理+数据链路层)
三、通信要素一:IP和端口号
1. IP:唯一的标识 Internet 上的计算机(通信实体)
2. 在Java中使用InetAddress类代表IP
3. IP分类:IPv4 和 IPv6 ; 万维网 和 局域网
4. 域名:
5. 本地回路地址:127.0.0.1 对应着:localhost
6. 如何实例化InetAddress:两个方法:getByName(String host) 、 getLocalHost()
两个常用方法:getHostName() / getHostAddress()
7. 端口号:正在计算机上运行的进程。
要求:不同的进程有不同的端口号
范围:被规定为一个 16 位的整数 0~65535。
8. 端口号与IP地址的组合得出一个网络套接字:Socket
二、网络通信协议
传输层的TCP协议和UDP协议的主要区别
TCP:可靠的数据传输(三次握手);进行大数据量的传输;效率低
UDP:不可靠;以数据报形式发送,数据报限定为64k;效率高
三、TCP网络编程
例子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
@Test
@Test
public void client(){
Socket socket = null;
OutputStream os = null;
try {
InetAddress inet = InetAddress.getByName("192.168.1.107");
socket = new Socket(inet,8899);
os = socket.getOutputStream();
os.write("你好,我是客户端mm".getBytes());
} catch (IOException e) {
e.printStackTrace();
} finally {
if(os != null){
try {
os.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;
InputStream is = null;
ByteArrayOutputStream baos = null;
try {
ss = new ServerSocket(8899);
socket = ss.accept();
is = socket.getInputStream();
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){
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();
}
}
}
}
例题2: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。
@Test
@Test
public void client(){
Socket socket = null;
OutputStream os = null;
FileInputStream fis = null;
try {
socket = new Socket(InetAddress.getByName("192.168.1.107"),9090);
os = socket.getOutputStream();
fis = new FileInputStream(new File(""));
byte[] buffer = new byte[1024];
int len;
while((len = fis.read(buffer)) != -1){
os.write(buffer,0,len);
}
socket.shutdownOutput();
InputStream is = socket.getInputStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer1 = new byte[20];
int len1;
while((len1 = is.read(buffer1)) != -1){
baos.write(buffer1,0,len1);
}
System.out.println(baos.toString());
} catch (IOException e) {
e.printStackTrace();
} finally {
}
if(fis != null){
try {
fis.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();
}
}
if(baos != null){
try {
baos.close();
} catch (IOException e){
e.printStactTrace();
}
}
}
@Test
public void server(){
ServerSocket ss = null;
Socket socket = null;
InputStream is = null;
FileOutputStream fos = null;
try {
ss = new ServerSocket(9090);
socket = ss.accept();
is = socket.getInputStream();
fos = new FileOutputStream(new File(""));
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");
OutputStream os = socket.getOutputStream();
os.write("你好,美女,照片我已收到,非常漂亮!".getBytes());
} catch (IOException e) {
e.printStackTrace();
} finally {
}
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();
}
}
}
四、UDP网络编程
@Test
@Test
public void sender(){
DatagramSocket socket = null;
try {
socket = new DatagramSocket();
String str = "我是UDP方式发送的导弹";
byte[] data = str.getBytes();
InetAddress inet = InetAddress.getByName("192.168.1.107");
DatagramPacket packet = new DatagramPacket(data,0,data.length,inet,9090);
socket.send(packet);
} catch (IOException e) {
e.printStackTrace();
} finally {
socket.close();
}
}
@Test
public void receiver(){
DatagramSocket socket = null;
try {
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()));
} catch (IOException e) {
e.printStackTrace();
} finally {
socket.close();
}
}
五、URL编程
:统一资源定位符,对应着互联网的某一资源地址
2.格式:
http://localhost:8080/examples/?username=Tom
协议 主机名 端口号 资源地址 参数列表
@Test
@Test
public void URLTest(){
try {
URL url = new URL("http://localhost:8080/examples/?username=Tom");
System.out.println(url.getProtocol());
System.out.println(url.getHost());
System.out.println(url.getPort());
System.out.println(url.getPath());
System.out.println(url.getFile());
System.out.println(url.getQuery());
} catch (MalformedURLException e) {
e.printStackTrace();
}
}
@Test
public void URLTest1(){
HttpURLConnection urlConnection = null;
InputStream is = null;
FileOutputStream fos = null;
try {
URL url = new URL("http://localhost:8080/examples/");
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.connect();
is = urlConnection.getInputStream();
fos = new FileOutputStream("day10\\");
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 {
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();
}
}
}