Introduction to the technical principles of the Commons HTTP Client framework in the Java class library
Commons HTTP Client is an open source Java class library that provides a powerful HTTP client framework.It can be used to send HTTP requests in Java applications and receive and process server responses.In this article, we will introduce the technical principles of the Commons HTTP Client framework and provide some Java code examples.
The technical principles of the Commons HTTP Client framework can be divided into the following aspects:
1. Connection management: Commons HTTP Client uses the connection manager to manage HTTP connection.The connection manager is responsible for creating, maintenance and release of the HTTP connection.It uses the connection pool technology to reuse the established connection to reduce the overhead of the creation connection.This can greatly improve the performance and efficiency of the application.
Below is a sample code that uses Commons HTTP Client to create and send HTTP requests:
CloseableHttpClient httpClient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet("http://www.example.com");
try {
CloseableHttpResponse response = httpClient.execute(httpGet);
try {
// Treat the server's response
int statusCode = response.getStatusLine().getStatusCode();
HttpEntity entity = response.getEntity();
String content = EntityUtils.toString(entity, "UTF-8");
System.out.println("Status Code: " + statusCode);
System.out.println("Response Content: " + content);
} finally {
response.close();
}
} finally {
httpClient.close();
}
2. Request configuration: Commons HTTP Client allows various parameters of HTTP requests by request configuration objects.For example, you can set timeout time, agency, redirect strategy, etc.The request configuration object is immutable, so it can be shared between multiple requests.
The following is an example code that uses the request configuration object to set the timeout and agent:
RequestConfig requestConfig = RequestConfig.custom()
.setConnectionRequestTimeout (5000) // Set the timeout of the connection request is 5 seconds
.setsockettimeout (5000) // Set the timeout of the jacking word for 5 seconds
.setproxy (new httphost ("proxy.example.com", 8080) // Set proxy
.build();
CloseableHttpClient httpClient = HttpClients.custom()
.setDefaultRequestConfig(requestConfig)
.build();
HttpGet httpGet = new HttpGet("http://www.example.com");
// Send HTTP request ...
3. Request execution: Commons HTTP Client uses the HTTPClient object to execute the HTTP request.You can use HTTPGET, HTTPPOST, HTTPPUT and other request objects to build different types of HTTP requests.When performing HTTP requests, you can provide additional parameters and status information by executing context objects.
The following is an example code that uses the request request with the request body with the HTTPPOST object:
CloseableHttpClient httpClient = HttpClients.createDefault();
HttpPost httpPost = new HttpPost("http://www.example.com");
httpPost.setEntity(new StringEntity("request body"));
try {
CloseableHttpResponse response = httpClient.execute(httpPost);
// Processing the server's response ...
} finally {
httpClient.close();
}
4. Response processing: Commons HTTP Client uses a response processor to handle the server's response.The response processor can obtain information from the status code, response head, response body and other information from the response, and processed accordingly.For example, the response can be converted into string, parsing into JSON objects, etc.
The following is an example code that uses a response processor to convert the response body into a string:
CloseableHttpClient httpClient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet("http://www.example.com");
ResponseHandler<String> responseHandler = new ResponseHandler<String>() {
@Override
public String handleResponse(HttpResponse response) throws IOException {
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode >= 200 && statusCode < 300) {
HttpEntity entity = response.getEntity();
return entity != null ? EntityUtils.toString(entity, "UTF-8") : null;
} else {
throw new ClientProtocolException("Unexpected response status: " + statusCode);
}
}
};
try {
String responseBody = httpClient.execute(httpGet, responseHandler);
System.out.println("Response Body: " + responseBody);
} finally {
httpClient.close();
}
In summary, the Commons HTTP Client framework provides a powerful HTTP client framework through technical principles such as connecting management, request configuration, request execution, and response processing to facilitate developers to communicate HTTP communication in Java applications.You can configure and use the Commons HTTP Client framework according to specific needs to achieve customized HTTP requests and response processing.
