The design ideas and principles of the basic framework of the HTTP client in the Java class library
The design ideas and principles of the basic framework of the HTTP client in the Java class library
The HTTP protocol is an application layer protocol for data transmission between clients and servers.To achieve communication with the HTTP server, the Java class library provides a basic HTTP client framework.
Design ideas:
The design ideas of the HTTP client in the Java class library mainly include the following aspects:
1. Create a URL object: First of all, you need to create a URL object that indicates the target server through the URL class.The URL class provides some methods to analyze and build a URL string, and to extract each part of the URL.
2. Establish a connection: Use the OpenConnection () method of the URL object to open the connection to the server.This method returns a UrlConnection object, which is the base class that represents the connection with the server.
3. Set the request attribute: the URLConnection object allows us to set the request attribute, such as the request method (get, post, etc.), the request head field (user-agent, etc.), timeout time, etc.
4. Send requested: After the connection is established, you can call the GetInputStream () or GetoutStream () method of UrlConnection to send the request and obtain the server's response.If you send data to the server, you can use the getoutputStream () method to obtain an output stream and write the request content through this output stream.If you get the server's response, you can use the getinputStream () method to obtain an input stream and read the response content through this input flow.
5. Processing response: After reading the response of the server, processing needs to be processed according to the content and status code of the response.You can obtain the response status code through the GetresPonsecode () method of the UrlConnection, obtain the head field through the GetheaderFields () method, and obtain the input flow of the response content through the GetInputStream () method.
6. Close connection: After using the URLConnection object, you should turn off the connection in time to release resources.You can call the disconnect () method of UrlConnection to close the connection with the server.
Founded framework instance:
Below is an example code of a basic HTTP client, which shows how to use the HTTP client framework in the Java class library to send GET requests and obtain the server's response.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class HttpClientExample {
public static void main(String[] args) {
try {
// Create a URL object
URL url = new URL("http://example.com");
// establish connection
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
// Set the request attribute
connection.setRequestMethod("GET");
connection.setConnectTimeout(5000);
connection.setReadTimeout(5000);
// send request
int responseCode = connection.getResponseCode();
// Treatment response
if (responseCode == HttpURLConnection.HTTP_OK) {
InputStream inputStream = connection.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
StringBuilder response = new StringBuilder();
while ((line = reader.readLine()) != null) {
response.append(line);
}
reader.close();
System.out.println("Server response:" + response.toString());
} else {
System.out.println("Server returned response code: " + responseCode);
}
// Turn off the connection
connection.disconnect();
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above example, we first created a URL object, and then established a connection to the server through the OpenConnection () method.Next, we set the request method to get, the timeout is 5 seconds.Then, call the getResponsecode () method to get the response status code of the server. If the status code is 200, it means that the request is successful, we can read the response content of the server and process it.Finally, we close the connection to the server through the disconnect () method to release resources.
Summarize:
The HTTP client framework in the Java class library provides a convenient API to communicate with the HTTP server.Design ideas include creating a URL object, establishing connection, setting request attributes, sending requests, processing response and closing connections.By learning the basic framework of the HTTP client, we can better understand and use the HTTP client function using the Java library.
