Java网络编程

//根据主机名来获取对应的InetAddress实例
InetAddress ip = InetAddress.getByName("www.oneedu.cn");
//判断是否可达
System.out.println("oneedu是否可达：" + ip.isReachable(2000));
//获取该InetAddress实例的IP字符串
System.out.println(ip.getHostAddress());
//根据原始IP地址(字节数组形式)来获取对应的InetAddress实例
InetAddress local = InetAddress.getByAddress(new byte[]
{127,0,0,1});
System.out.println("本机是否可达：" + local.isReachable(5000));
//获取该InetAddress实例对应的全限定域名
System.out.println(local.getCanonicalHostName());

//将application/x-www-form-urlencoded字符串
//转换成普通字符串
String keyWord = URLDecoder.decode(
"%E6%9D%8E%E5%88%9A+j2ee", "UTF-8");
System.out.println(keyWord);
//将普通字符串转换成
//application/x-www-form-urlencoded字符串
String urlStr = URLEncoder.encode(
"ROR敏捷开发最佳指南" , "GBK");
System.out.println(urlStr);

//1. 向指定URL发送GET方法的请求
String urlName = url + "?" + param;
URL realUrl = new URL(urlName);
//打开和URL之间的连接
URLConnection conn = realUrl.openConnection();
//设置通用的请求属性
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
conn.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
//建立实际的连接
conn.connect();

//2. 向指定URL发送POST方法的请求
URL realUrl = new URL(url);
//打开和URL之间的连接
URLConnection conn = realUrl.openConnection();
//设置通用的请求属性
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
conn.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
//发送POST请求必须设置如下两行
conn.setDoOutput(true);
conn.setDoInput(true);
//获取URLConnection对象对应的输出流
out = new PrintWriter(conn.getOutputStream());
//发送请求参数
out.print(param);

//创建一个ServerSocket，用于监听客户端Socket的连接请求
ServerSocket ss = new ServerSocket(30000);
//采用循环不断接受来自客户端的请求
while (true)
{
//每当接受到客户端Socket的请求，服务器端也对应产生一个Socket
Socket s = ss.accept();
//将Socket对应的输出流包装成PrintStream
PrintStream ps = new PrintStream(s.getOutputStream());
//进行普通IO操作
ps.println("您好，您收到了服务器的新年祝福！");
//关闭输出流，关闭Socket
ps.close();
s.close();
}

Socket socket = new Socket("127.0.0.1" , 30000);
//将Socket对应的输入流包装成BufferedReader
BufferedReader br = new BufferedReader(
new InputStreamReader(socket.getInputStream()));
//进行普通IO操作
String line = br.readLine();
System.out.println("来自服务器的数据：" + line);
//关闭输入流、socket
br.close();
socket.close();

public class MyServer
{
//定义保存所有Socket的ArrayList
public static ArrayList<Socket> socketList = new ArrayList<Socket>();
public static void main(String[] args)
throws IOException
{
ServerSocket ss = new ServerSocket(30000);
while(true)
{
//此行代码会阻塞，将一直等待别人的连接
Socket s = ss.accept();
socketList.add(s);
//每当客户端连接后启动一条ServerThread线程为该客户端服务
new Thread(new ServerThread(s)).start();
}
}
}

public class MyClient
{
public static void main(String[] args)
throws IOException
{
Socket s = s = new Socket("127.0.0.1" , 30000);
//客户端启动ClientThread线程不断读取来自服务器的数据
new Thread(new ClientThread(s)).start();
//获取该Socket对应的输出流
PrintStream ps = new PrintStream(s.getOutputStream());
String line = null;
//不断读取键盘输入
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
while ((line = br.readLine()) != null)
{
//将用户的键盘输入内容写入Socket对应的输出流
ps.println(line);
}
}
}

public interface YeekuProtocol
{
//定义协议字符串的长度
int PROTOCOL_LEN = 2;
//下面是一些协议字符串，服务器和客户端交换的信息
//都应该在前、后添加这种特殊字符串。
String MSG_ROUND = "§γ";
String USER_ROUND = "∏∑";
String LOGIN_SUCCESS = "1";
String NAME_REP = "-1";
String PRIVATE_ROUND = "★【";
String SPLIT_SIGN = "※";
}

while(true)
{
String userName = JOptionPane.showInputDialog(tip + "输入用户名");
//将用户输入的用户名的前后增加协议字符串后发送
ps.println(YeekuProtocol.USER_ROUND + userName
+ YeekuProtocol.USER_ROUND);
//读取服务器的响应
String result = brServer.readLine();
//如果用户重复，开始下次循环
if (result.equals(YeekuProtocol.NAME_REP))
{
tip = "用户名重复！请重新";
continue;
}
//如果服务器返回登陆成功，结束循环
if (result.equals(YeekuProtocol.LOGIN_SUCCESS))
{
break;
}
}

if (line.startsWith(YeekuProtocol.PRIVATE_ROUND)
&& line.endsWith(YeekuProtocol.PRIVATE_ROUND))
{
//得到真实消息
String userAndMsg = getRealMsg(line);
//以SPLIT_SIGN来分割字符串，前面部分是私聊用户，后面部分是聊天信息
String user = userAndMsg.split(YeekuProtocol.SPLIT_SIGN)[0];
String msg = userAndMsg.split(YeekuProtocol.SPLIT_SIGN)[1];
//获取私聊用户对应的输出流，并发送私聊信息
Server.clients.get(user).println(
Server.clients.getKeyByValue(ps) + "悄悄地对你说：" + msg);
}

//接收端的DatagaramSocket内部包含一个空的数组，接收传递过来的数据报中的数组信息。可以通过DatagaramSocket对象的getData()方法返回的数组来获取其中的包含的数组。
Private DatagaramSocket udpSocket=new DatagaramSocket(buf,buf.length);
//发送端的DatagaramSocket内部包含一个将要传递的数组，同时需要包含目标IP和端口。如果初始化时传递的数组参数是空，可以通过调用DatagaramSocket对象的setData()方法设置内容。
Private DatagaramSocket udpSocket=new DatagaramSocket(buf,buf.length,IP,PORT);
udpSocket。setData(outBuf);

//创建用于发送、接收数据的MulticastSocket对象
//因为该MulticastSocket对象需要接收，所以有指定端口
socket = new MulticastSocket(BROADCAST_PORT);
broadcastAddress = InetAddress.getByName(BROADCAST_IP);
//将该socket加入指定的多点广播地址
socket.joinGroup(broadcastAddress);
//设置本MulticastSocket发送的数据报被回送到自身
socket.setLoopbackMode(false);
//初始化发送用的DatagramSocket，它包含一个长度为0的字节数组
outPacket = new DatagramPacket(new byte[0] , 0 ,
broadcastAddress , BROADCAST_PORT);

public class ProxyTest
{
Proxy proxy;
URL url;
URLConnection conn;
//从网络通过代理读数据
Scanner scan;
PrintStream ps ;
//下面是代理服务器的地址和端口，
//换成实际有效的代理服务器的地址和端口
String proxyAddress = "202.128.23.32";
int proxyPort;
//下面是你试图打开的网站地址
String urlStr = "http://www.oneedu.cn";

public void init()
{
try
{
url = new URL(urlStr);
//创建一个代理服务器对象
proxy = new Proxy(Proxy.Type.HTTP,
new InetSocketAddress(proxyAddress , proxyPort));
//使用指定的代理服务器打开连接
conn = url.openConnection(proxy);
//设置超时时长。
conn.setConnectTimeout(5000);
scan = new Scanner(conn.getInputStream());
//初始化输出流
ps = new PrintStream("Index.htm");
while (scan.hasNextLine())
{
String line = scan.nextLine();
//在控制台输出网页资源内容
System.out.println(line);
//将网页资源内容输出到指定输出流
ps.println(line);
}
}
catch(MalformedURLException ex)
{
System.out.println(urlStr + "不是有效的网站地址！");
}
catch(IOException ex)
{
ex.printStackTrace();
}
//关闭资源
finally
{
if (ps != null)
{
ps.close();
}
}
}

}