UDP/TCP/HTTP编程

1、UDP的receive和send

import java.net.*;
public class UdpSend
{
	public static void main(String [] args) throws Exception
	{
		DatagramSocket ds=new DatagramSocket();
		String str="hello world";
		DatagramPacket dp=new DatagramPacket(str.getBytes(),str.length(),
				InetAddress.getByName("127.0.0.1"),3000);
		
		System.out.println("UdpSend: 我要发送信息");
		ds.send(dp);
		System.out.println("UdpSend: 我发送信息结束");
		
		Thread.sleep(1000);
		byte [] buf=new byte[1024];
		DatagramPacket dp2=new DatagramPacket(buf,1024);
		System.out.println("UdpSend: 我在等待信息");
		ds.receive(dp2);
		System.out.println("UdpSend: 我接收到信息");
		String str2=new String(dp2.getData(),0,dp2.getLength()) +
				" from " + dp2.getAddress().getHostAddress()+":"+dp2.getPort(); 
		System.out.println(str2);
				
		ds.close();
	}
}

2、TCP的server和client

//server
import java.net.*;
import java.io.*;
public class TcpServer
{
	public static void main(String [] args) 
	{
		try
		{
			ServerSocket ss=new ServerSocket(8001); //驻守在8001端口
			Socket s=ss.accept();                   //阻塞，等到有客户端连接上来
			System.out.println("welcome to the java world");
			InputStream ips=s.getInputStream();     //有人连上来，打开输入流
			OutputStream ops=s.getOutputStream();   //打开输出流
			//同一个通道，服务端的输出流就是客户端的输入流；服务端的输入流就是客户端的输出流
			
			ops.write("Hello, Client!".getBytes());  //输出一句话给客户端
			
			
			BufferedReader br = new BufferedReader(new InputStreamReader(ips));
			//从客户端读取一句话			
			System.out.println("Client said: " + br.readLine());
			
			
			ips.close();          
			ops.close();
			s.close();
			ss.close();
		}
		catch(Exception e)
		{
			e.printStackTrace();
		}
	}
}

//client
public class TcpClient {
	public static void main(String[] args) {
		try {
			Socket s = new Socket(InetAddress.getByName("127.0.0.1"), 8001); //需要服务端先开启
			
			//同一个通道，服务端的输出流就是客户端的输入流；服务端的输入流就是客户端的输出流
			InputStream ips = s.getInputStream();    //开启通道的输入流
			BufferedReader brNet = new BufferedReader(new InputStreamReader(ips));
			
			OutputStream ops = s.getOutputStream();  //开启通道的输出流
			DataOutputStream dos = new DataOutputStream(ops);			

			BufferedReader brKey = new BufferedReader(new InputStreamReader(System.in));
			while (true) 
			{
				String strWord = brKey.readLine();
				if (strWord.equalsIgnoreCase("quit"))
				{
					break;
				}
				else
				{
					System.out.println("I want to send: " + strWord);
					dos.writeBytes(strWord + System.getProperty("line.separator"));
					
					System.out.println("Server said: " + brNet.readLine());
				}
				
			}
			
			dos.close();
			brNet.close();
			brKey.close();
			s.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

3、 HTTP简单get和post

import java.io.*;
import java.net.*;
import java.util.*;


public class URLConnectionGetTest
{
   public static void main(String[] args)
   {
      try
      {
         String urlName = "http://www.baidu.com";

         URL url = new URL(urlName);
         URLConnection connection = url.openConnection(); 
         connection.connect();

         // 打印http的头部信息

         Map<String, List<String>> headers = connection.getHeaderFields();
         for (Map.Entry<String, List<String>> entry : headers.entrySet())
         {
            String key = entry.getKey();
            for (String value : entry.getValue())
               System.out.println(key + ": " + value);
         }

         // 输出将要收到的内容属性信息

         System.out.println("----------");
         System.out.println("getContentType: " + connection.getContentType());
         System.out.println("getContentLength: " + connection.getContentLength());
         System.out.println("getContentEncoding: " + connection.getContentEncoding());
         System.out.println("getDate: " + connection.getDate());
         System.out.println("getExpiration: " + connection.getExpiration());
         System.out.println("getLastModifed: " + connection.getLastModified());
         System.out.println("----------");

         BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));

         // 输出收到的内容
         String line = "";
         while((line=br.readLine()) != null)
         {
        	 System.out.println(line);
         }
         br.close();
      }
      catch (IOException e)
      {
         e.printStackTrace();
      }
   }
}
   

import java.io.*;
import java.net.*;
import java.nio.file.*;
import java.util.*;

public class URLConnectionPostTest
{
   public static void main(String[] args) throws IOException
   {
      String urlString = "https://tools.usps.com/go/ZipLookupAction.action";
      Object userAgent = "HTTPie/0.9.2";
      Object redirects = "1";
      CookieHandler.setDefault(new CookieManager(null, CookiePolicy.ACCEPT_ALL));
      
      Map<String, String> params = new HashMap<String, String>();
      params.put("tAddress", "1 Market Street");  
      params.put("tCity", "San Francisco");
      params.put("sState", "CA");
      String result = doPost(new URL(urlString), params, 
         userAgent == null ? null : userAgent.toString(), 
         redirects == null ? -1 : Integer.parseInt(redirects.toString()));
      System.out.println(result);
   }   

   public static String doPost(URL url, Map<String, String> nameValuePairs, String userAgent, int redirects)
         throws IOException
   {        
      HttpURLConnection connection = (HttpURLConnection) url.openConnection();
      if (userAgent != null)
         connection.setRequestProperty("User-Agent", userAgent);
      
      if (redirects >= 0)
         connection.setInstanceFollowRedirects(false);
      
      connection.setDoOutput(true);
      
      //输出请求的参数
      try (PrintWriter out = new PrintWriter(connection.getOutputStream()))
      {
         boolean first = true;
         for (Map.Entry<String, String> pair : nameValuePairs.entrySet())
         {
        	//参数必须这样拼接 a=1&b=2&c=3
            if (first) 
            {
            	first = false;
            }
            else
            {
            	out.print('&');
            }
            String name = pair.getKey();
            String value = pair.getValue();
            out.print(name);
            out.print('=');
            out.print(URLEncoder.encode(value, "UTF-8"));
         }
      }      
      String encoding = connection.getContentEncoding();
      if (encoding == null) 
      {
    	  encoding = "UTF-8";
      }
            
      if (redirects > 0)
      {
         int responseCode = connection.getResponseCode();
         System.out.println("responseCode: " + responseCode);
         if (responseCode == HttpURLConnection.HTTP_MOVED_PERM 
               || responseCode == HttpURLConnection.HTTP_MOVED_TEMP
               || responseCode == HttpURLConnection.HTTP_SEE_OTHER) 
         {
            String location = connection.getHeaderField("Location");
            if (location != null)
            {
               URL base = connection.getURL();
               connection.disconnect();
               return doPost(new URL(base, location), nameValuePairs, userAgent, redirects - 1);
            }
            
         }
      }
      else if (redirects == 0)
      {
         throw new IOException("Too many redirects");
      }
      
      //接下来获取html 内容
      StringBuilder response = new StringBuilder();
      try (Scanner in = new Scanner(connection.getInputStream(), encoding))
      {
         while (in.hasNextLine())
         {
            response.append(in.nextLine());
            response.append("\n");
         }         
      }
      catch (IOException e)
      {
         InputStream err = connection.getErrorStream();
         if (err == null) throw e;
         try (Scanner in = new Scanner(err))
         {
            response.append(in.nextLine());
            response.append("\n");
         }
      }

      return response.toString();
   }
}

4、HTTP，jdk9及以后的版本有java.net.http包

或者使用Apache HttpComponents的HttpClien工具包

JDK自带：get

import java.io.IOException;
import java.net.URI;
import java.net.URLEncoder;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.charset.Charset;

public class JDKHttpClientGetTest {

	public static void main(String[] args) throws IOException, InterruptedException {
		doGet();
	}
	
	public static void doGet() {
		try{
			HttpClient client = HttpClient.newHttpClient();
			HttpRequest request = HttpRequest.newBuilder(URI.create("http://www.baidu.com")).build();
			HttpResponse response = client.send(request, HttpResponse.BodyHandlers.ofString());
			System.out.println(response.body());
		}
		catch(Exception e) {
			e.printStackTrace();
		}
	}
}

jdk自带：post

import java.io.IOException;
import java.net.URI;
import java.net.URLEncoder;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class JDKHttpClientPostTest {

	public static void main(String[] args) throws IOException, InterruptedException {
		doPost();
	}
	
	public static void doPost() {
		try {
			HttpClient client = HttpClient.newBuilder().build();
			HttpRequest request = HttpRequest.newBuilder()
					.uri(URI.create("https://tools.usps.com/go/ZipLookupAction.action"))
					//.header("Content-Type","application/x-www-form-urlencoded")
					.header("User-Agent", "HTTPie/0.9.2")
					.header("Content-Type","application/x-www-form-urlencoded;charset=utf-8")
					//.method("POST", HttpRequest.BodyPublishers.ofString("tAddress=1 Market Street&tCity=San Francisco&sState=CA"))
					//.version(Version.HTTP_1_1)
					.POST(HttpRequest.BodyPublishers.ofString("tAddress=" 
					    + URLEncoder.encode("1 Market Street", "UTF-8") 
					    + "&tCity=" + URLEncoder.encode("San Francisco", "UTF-8") + "&sState=CA"))
					//.POST(HttpRequest.BodyPublishers.ofString("tAddress=" + URLEncoder.encode("1 Market Street", "UTF-8") + "&tCity=" + URLEncoder.encode("San Francisco", "UTF-8") + "&sState=CA"))
					.build();
			HttpResponse response = client.send(request, HttpResponse.BodyHandlers.ofString());
			System.out.println(response.statusCode());
			System.out.println(response.headers());
			System.out.println(response.body().toString());

		}
		catch(Exception e) {
			e.printStackTrace();
		}
	}	
}

 Apache HttpComponents的HttpClien工具包：

import java.io.IOException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class HttpComponentsGetTest {

    public final static void main(String[] args) throws Exception {
    	
    	CloseableHttpClient httpClient = HttpClients.createDefault();
        RequestConfig requestConfig = RequestConfig.custom()
                .setConnectTimeout(5000)   //设置连接超时时间
                .setConnectionRequestTimeout(5000) // 设置请求超时时间
                .setSocketTimeout(5000)
                .setRedirectsEnabled(true)//默认允许自动重定向
                .build();
        
        HttpGet httpGet = new HttpGet("http://www.baidu.com");
        httpGet.setConfig(requestConfig);
        String srtResult = "";
        try {
            HttpResponse httpResponse = httpClient.execute(httpGet);
            if(httpResponse.getStatusLine().getStatusCode() == 200){
                srtResult = EntityUtils.toString(httpResponse.getEntity(), "UTF-8");//获得返回的结果                
                System.out.println(srtResult);
            }else
            {
                //异常处理
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                httpClient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

import java.io.IOException;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpResponse;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.LaxRedirectStrategy;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

public class HttpComponentsPostTest {

    public final static void main(String[] args) throws Exception {
    	
    	//获取可关闭的 httpCilent
        //CloseableHttpClient httpClient = HttpClients.createDefault();
    	CloseableHttpClient httpClient = HttpClientBuilder.create().setRedirectStrategy(new LaxRedirectStrategy()).build();
    	//配置超时时间
        RequestConfig requestConfig = RequestConfig.custom().
                setConnectTimeout(10000).setConnectionRequestTimeout(10000)
                .setSocketTimeout(10000).setRedirectsEnabled(false).build();
         
        HttpPost httpPost = new HttpPost("https://tools.usps.com/go/ZipLookupAction.action");
        //设置超时时间
        httpPost.setConfig(requestConfig);
        
        //装配post请求参数
        List<BasicNameValuePair> list = new ArrayList<BasicNameValuePair>(); 
        list.add(new BasicNameValuePair("tAddress", URLEncoder.encode("1 Market Street", "UTF-8")));  //请求参数
        list.add(new BasicNameValuePair("tCity", URLEncoder.encode("San Francisco", "UTF-8"))); //请求参数
        list.add(new BasicNameValuePair("sState", "CA")); //请求参数
        try {
            UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list,"UTF-8"); 
            //设置post求情参数
            httpPost.setEntity(entity);
            httpPost.setHeader("User-Agent", "HTTPie/0.9.2");
            //httpPost.setHeader("Content-Type","application/form-data");
            HttpResponse httpResponse = httpClient.execute(httpPost);
            String strResult = "";
            if(httpResponse != null){ 
                System.out.println(httpResponse.getStatusLine().getStatusCode());
                if (httpResponse.getStatusLine().getStatusCode() == 200) {
                    strResult = EntityUtils.toString(httpResponse.getEntity());
                }
                else {
                    strResult = "Error Response: " + httpResponse.getStatusLine().toString();
                } 
            }else{
                 
            }
            System.out.println(strResult);
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                if(httpClient != null){
                    httpClient.close(); //释放资源
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}