What is HttpClient :
HttpClient is a client side HTTP transport library whose purpose is to transmit and receive HTTP messages. The HTTP (Hyper Text Transfer Protocol ) is the most significant protocol used on the internet today. HttpClient can be used by anyone building HTTP-aware client applications such as Web Browsers , Web services clients or any system that uses HTTP protocol for distributed communication.
HttpClient is not a browser :
Though it seems that HttpClient is simulating the functionality of a web browser , but that's not true . HttpClient is not a browser. HttpClient will not attempt to cache content, execute javascript embedded in HTML pages, try to guess content type, or reformat request / redirect location URIs.
Get Ready :
Download HttpClient dependencies and put them in the classpath of your application
or if you are a maven user , add dependency in pom :
<dependency>
<groupId>commons-httpclient</groupId>
<artifactId>commons-httpclient</artifactId>
<version>3.0</version>
</dependency>
Steps to create HttpClient :
1. Create an instance of HttpClient.
2. Create an instance of HttpMethod.
3. Tell HttpClient to execute method.
4. Read the respose.
5. Release connection.
6. Deal with the respone.
Example : This code demonstrates how HttpClient makes a GET request to Google Server and bring back the results.
HttpClient is a client side HTTP transport library whose purpose is to transmit and receive HTTP messages. The HTTP (Hyper Text Transfer Protocol ) is the most significant protocol used on the internet today. HttpClient can be used by anyone building HTTP-aware client applications such as Web Browsers , Web services clients or any system that uses HTTP protocol for distributed communication.
HttpClient is not a browser :
Though it seems that HttpClient is simulating the functionality of a web browser , but that's not true . HttpClient is not a browser. HttpClient will not attempt to cache content, execute javascript embedded in HTML pages, try to guess content type, or reformat request / redirect location URIs.
Get Ready :
Download HttpClient dependencies and put them in the classpath of your application
or if you are a maven user , add dependency in pom :
<dependency>
<groupId>commons-httpclient</groupId>
<artifactId>commons-httpclient</artifactId>
<version>3.0</version>
</dependency>
Steps to create HttpClient :
1. Create an instance of HttpClient.
2. Create an instance of HttpMethod.
3. Tell HttpClient to execute method.
4. Read the respose.
5. Release connection.
6. Deal with the respone.
Example : This code demonstrates how HttpClient makes a GET request to Google Server and bring back the results.
public class GoogleSearch {
private static String searchUrl = "https://www.google.com/search?hl=en&q=httpclient&btnG=Google+Search";
public static void main(String[] args) {
// Create an instance of HttpClient.
HttpClient client = new HttpClient();
// Create a method instance.
GetMethod method = new GetMethod(searchUrl);
// Provide custom retry handler.
method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,new DefaultHttpMethodRetryHandler(3, false));
try {
// Execute the method.
int statusCode = client.executeMethod(method);
if (statusCode != HttpStatus.SC_OK) {
System.err.println("Method failed: " + method.getStatusLine());
}
// Read the response body.
String responseBody = method.getResponseBodyAsString();
// Deal with the response.
System.out.println(responseBody);
} catch (HttpException e) {
System.err.println("Fatal protocol violation: " + e.getMessage());
} catch (IOException e) {
System.err.println("Fatal transport error: " + e.getMessage());
} finally {
// Release the connection.
method.releaseConnection();
}
}
}
