Get content in java (Post/Get)

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public class GET {

	public static void main(String[] args) throws Exception {  
		String urlstr = "http://s13.sinaimg.cn/middle/001IDODqty6FM269oy8fc&690";
		fetchImage(urlstr);
	}
	// HTTP GET request  
    private static void fetchImage(String imgUrl) throws Exception {     
		try {
			URL url = new URL(imgUrl);
			URLConnection conn = (URLConnection)url.openConnection(); 
			//add reuqest header
			//conn.setRequestMethod("GET");
			conn.setRequestProperty("User-Agent", "test");
			conn.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
			conn.setRequestProperty("Referer", "http://s13.sinaimg.cn");
			
			// Send post request
			conn.setDoOutput(true);
			//save to this filename
			String fileName = "bbb";
			File file = new File(fileName);
 
			if (!file.exists()) {
				file.createNewFile();
			}
			InputStream is = conn.getInputStream();
			FileOutputStream fileout = new FileOutputStream(file);
			// 根据实际运行效果 设置缓冲区大小
			byte[] buffer = new byte[10 * 1024];
			int ch = 0;
			while ((ch = is.read(buffer)) != -1) {
				fileout.write(buffer, 0, ch);
			}
			is.close();
			fileout.flush();
			fileout.close();
		} catch (MalformedURLException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} 
    }  
}

Java HttpURLConnection example

 
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
 
import javax.net.ssl.HttpsURLConnection;
 
public class HttpURLConnectionExample {
 
	private final String USER_AGENT = "Mozilla/5.0";
 
	public static void main(String[] args) throws Exception {
 
		HttpURLConnectionExample http = new HttpURLConnectionExample();
 
		System.out.println("Testing 1 - Send Http GET request");
		http.sendGet();
 
		System.out.println("\nTesting 2 - Send Http POST request");
		http.sendPost();
 
	}
 
	// HTTP GET request
	private void sendGet() throws Exception {
 
		String url = "http://www.google.com/search?q=mkyong";
 
		URL obj = new URL(url);
		HttpURLConnection con = (HttpURLConnection) obj.openConnection();
 
		// optional default is GET
		con.setRequestMethod("GET");
 
		//add request header
		con.setRequestProperty("User-Agent", USER_AGENT);
 
		int responseCode = con.getResponseCode();
		System.out.println("\nSending 'GET' request to URL : " + url);
		System.out.println("Response Code : " + responseCode);
 
		BufferedReader in = new BufferedReader(
		        new InputStreamReader(con.getInputStream()));
		String inputLine;
		StringBuffer response = new StringBuffer();
 
		while ((inputLine = in.readLine()) != null) {
			response.append(inputLine);
		}
		in.close();
 
		//print result
		System.out.println(response.toString());
 
	}
 
	// HTTP POST request
	private void sendPost() throws Exception {
 
		String url = "https://selfsolve.apple.com/wcResults.do";
		URL obj = new URL(url);
		HttpsURLConnection con = (HttpsURLConnection) obj.openConnection();
 
		//add reuqest header
		con.setRequestMethod("POST");
		con.setRequestProperty("User-Agent", USER_AGENT);
		con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
 
		String urlParameters = "sn=C02G8416DRJM&cn=&locale=&caller=&num=12345";
 
		// Send post request
		con.setDoOutput(true);
		DataOutputStream wr = new DataOutputStream(con.getOutputStream());
		wr.writeBytes(urlParameters);
		wr.flush();
		wr.close();
 
		int responseCode = con.getResponseCode();
		System.out.println("\nSending 'POST' request to URL : " + url);
		System.out.println("Post parameters : " + urlParameters);
		System.out.println("Response Code : " + responseCode);
 
		BufferedReader in = new BufferedReader(
		        new InputStreamReader(con.getInputStream()));
		String inputLine;
		StringBuffer response = new StringBuffer();
 
		while ((inputLine = in.readLine()) != null) {
			response.append(inputLine);
		}
		in.close();
 
		//print result
		System.out.println(response.toString());
 
	}
 
}

Apache HttpClient

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
 
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
 
public class HttpClientExample {
 
	private final String USER_AGENT = "Mozilla/5.0";
 
	public static void main(String[] args) throws Exception {
 
		HttpClientExample http = new HttpClientExample();
 
		System.out.println("Testing 1 - Send Http GET request");
		http.sendGet();
 
		System.out.println("\nTesting 2 - Send Http POST request");
		http.sendPost();
 
	}
 
	// HTTP GET request
	private void sendGet() throws Exception {
 
		String url = "http://www.google.com/search?q=developer";
 
		HttpClient client = new DefaultHttpClient();
		HttpGet request = new HttpGet(url);
 
		// add request header
		request.addHeader("User-Agent", USER_AGENT);
 
		HttpResponse response = client.execute(request);
 
		System.out.println("\nSending 'GET' request to URL : " + url);
		System.out.println("Response Code : " + 
                       response.getStatusLine().getStatusCode());
 
		BufferedReader rd = new BufferedReader(
                       new InputStreamReader(response.getEntity().getContent()));
 
		StringBuffer result = new StringBuffer();
		String line = "";
		while ((line = rd.readLine()) != null) {
			result.append(line);
		}
 
		System.out.println(result.toString());
 
	}
 
	// HTTP POST request
	private void sendPost() throws Exception {
 
		String url = "https://selfsolve.apple.com/wcResults.do";
 
		HttpClient client = new DefaultHttpClient();
		HttpPost post = new HttpPost(url);
 
		// add header
		post.setHeader("User-Agent", USER_AGENT);
 
		List<NameValuePair> urlParameters = new ArrayList<NameValuePair>();
		urlParameters.add(new BasicNameValuePair("sn", "C02G8416DRJM"));
		urlParameters.add(new BasicNameValuePair("cn", ""));
		urlParameters.add(new BasicNameValuePair("locale", ""));
		urlParameters.add(new BasicNameValuePair("caller", ""));
		urlParameters.add(new BasicNameValuePair("num", "12345"));
 
		post.setEntity(new UrlEncodedFormEntity(urlParameters));
 
		HttpResponse response = client.execute(post);
		System.out.println("\nSending 'POST' request to URL : " + url);
		System.out.println("Post parameters : " + post.getEntity());
		System.out.println("Response Code : " + 
                                    response.getStatusLine().getStatusCode());
 
		BufferedReader rd = new BufferedReader(
                        new InputStreamReader(response.getEntity().getContent()));
 
		StringBuffer result = new StringBuffer();
		String line = "";
		while ((line = rd.readLine()) != null) {
			result.append(line);
		}
 
		System.out.println(result.toString());
 
	}
 
}