How to solve the problem of HTTP request connection refused in Java development

How to solve the problem of HTTP request connection being refused in Java development

In Java development, we often encounter the problem of HTTP request connection being refused. This problem may occur because the server side restricts access rights, or the network firewall blocks access to HTTP requests. Fixing this problem requires some adjustments to your code and environment. This article will introduce several common solutions.

1. Check the network connection and server status

First, make sure your network connection is normal. You can try to access other websites or services to see if you can connect normally. At the same time, you also need to check whether the server is running normally and whether the service is available. Sometimes, the problem of HTTP request connection refused may be caused by the server being down or out of service.

2. Check the requested URL and port

Check whether the URL and port of your HTTP request are correct. The connection may be refused because the requested URL is incorrect or the port is occupied by other programs. Make sure your URL and port are consistent with the server configuration.

3. Check firewall and proxy settings

If there is a firewall or proxy server in your network environment, it is possible that they are blocking access to HTTP requests. If this is the case, you need to check your firewall or proxy server settings and make sure your HTTP requests are allowed through.

4. Increase the connection timeout

Sometimes, connection rejection is caused by network delays or slow response to requests. This problem can be solved by increasing the connection timeout. In Java, you can use the setConnectTimeout method of URLConnection to set the connection timeout.

URL url = new URL("http://www.example.com");
URLConnection connection = url.openConnection();
connection.setConnectTimeout(5000); // 设置连接超时时间为5秒

5. Use a proxy server

If a proxy server is used in your network environment, you may consider using a proxy server to solve the problem of connection refusal. In Java, you can specify the address and port of the proxy server by setting the System property.

System.setProperty("http.proxyHost", "proxy.example.com");
System.setProperty("http.proxyPort", "8080");

6. Use HTTPS protocol

If your HTTP request connection refused problem is because the server requires the use of HTTPS protocol for communication, you may consider modifying your code to use HTTPS protocol sends the request. In Java, you can use HttpsURLConnection to send HTTPS requests.

URL url = new URL("https://www.example.com");
HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();

7. Contact the service provider

If none of the above methods can solve the problem, it is recommended to contact the service provider. They may be able to provide a more detailed solution or adjust the server configuration to resolve the connection refused issue.

Summary:

In Java development, HTTP request connection refused is a common problem. Fixing this problem requires checking the network connection and server status, checking the requested URL and port, checking the firewall and proxy settings, increasing the connection timeout, using a proxy server or HTTPS protocol, and contacting the service provider. Through each solution, I believe you can solve the problem of HTTP request connection being refused and smoothly develop Java.

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