HttpClients download and getting started, httpclients getting started

HttpClients download and getting started, httpclients getting started

I don't need to say much about the importance of the Http protocol. Compared with the URLConnection provided by the traditional JDK, HttpClient adds ease of use and flexibility (the specific difference will be discussed later ), it not only makes it easy for the client to send Http requests, but also facilitates the developer to test the interface (based on the Http protocol), which improves the development efficiency and code robustness. Therefore, it is very important to master HttpClient. After you master HttpClient, I believe that you will have a better understanding of the Http protocol.

 

You can get the latest official version: http://hc.apache.org/index.html. You can also obtain the official getting started example from here.
The following example outputs all the header content and the content returned by the page.

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import java.io.ByteArrayOutputStream;import java.io.InputStream;import java.util.ArrayList;import java.util.List;import org.apache.http.Header;import org.apache.http.HttpEntity;import org.apache.http.NameValuePair;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.CloseableHttpResponse;import org.apache.http.client.methods.HttpGet;import org.apache.http.client.methods.HttpPost;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.message.BasicNameValuePair;public class QuickStart { public static void main(String[] args) {  try {   CloseableHttpClient httpclient = HttpClients.createDefault();   HttpGet httpGet = new HttpGet("http://javacui.com");   CloseableHttpResponse response1 = httpclient.execute(httpGet);   try {       System.out.println(response1.getStatusLine()); // Read status information               Header[] hd = response1.getAllHeaders(); // All header information       for(Header h : hd){        System.out.println(h.getName() + "：" + h.getValue());       }               HttpEntity entity1 = response1.getEntity();       System.out.println(EntityUtils.toString(entity1));   } finally {       response1.close();   }   HttpPost httpPost = new HttpPost("http://javacui.com");   List <NameValuePair> paras = new ArrayList <NameValuePair>(); // Set form parameters   paras.add(new BasicNameValuePair("username", "name"));   paras.add(new BasicNameValuePair("password", "pass"));   httpPost.setEntity(new UrlEncodedFormEntity(paras));   CloseableHttpResponse response2 = httpclient.execute(httpPost);   try {    System.out.println(response1.getStatusLine()); // Read status information               Header[] hd = response1.getAllHeaders(); // All header information       for(Header h : hd){        System.out.println(h.getName() + "：" + h.getValue());       }               HttpEntity entity1 = response1.getEntity();       System.out.println(EntityUtils.toString(entity1));   } finally {       response2.close();   }  } catch (Exception e) {   e.printStackTrace();  } }   /**  * Stream reading  */ public static byte[] readStream(InputStream inStream) throws Exception {  ByteArrayOutputStream outSteam = new ByteArrayOutputStream();  byte[] buffer = new byte[1024];  int len = -1;  while ((len = inStream.read(buffer)) != -1) {   outSteam.write(buffer, 0, len);  }  outSteam.close();  inStream.close();  return outSteam.toByteArray(); }} // End

The GET and POST requests both output the obtained server content, and the post request sets the form parameters of the request.

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