Table of Contents
Problem Description
Abnormal
Solution
1. Check the method names in the code
2. Use appropriate HTTP request method constants
3. Use third-party HTTP libraries
4. Check the request URL
5. Debugging and logging
in conclusion
Problem description
When writing web applications in Java, you sometimes encounter exceptions similar to ??java.lang.IllegalArgumentException: Invalid character found in method name. HTTP method names??. This exception indicates that an illegal character was found in the method name. This article will describe the cause of this exception and how to resolve it.
Exception reason
In HTTP communication, the request method name usually consists of uppercase letters, such as GET, POST, PUT, etc. However, sometimes we may mistakenly use other characters as method names in our code, such as spaces, special symbols, or non-ASCII characters. These illegal characters will cause Java to throw a ??java.lang.IllegalArgumentException?? exception.
Solution
To solve the java.lang.IllegalArgumentException: Invalid character found in method name. HTTP method names exception, we need to check the HTTP request method names in the code to ensure that they only contain legal characters. Here are some common workarounds:
1. Check the method name in the code
Check all HTTP request method names in your code to make sure they only contain legal characters. Remove or replace illegal characters, such as spaces or special symbols.
2. Use appropriate HTTP request method constants
In Java, there are some predefined HTTP request method constants, such as ??HttpURLConnection.HTTP_GET??, ??HttpURLConnection.HTTP_POST??, etc. Using these constants instead of manually typing method names can avoid exceptions caused by misspellings or illegal characters.
3. Use third-party HTTP library
If you are using a third-party HTTP library, such as Apache HttpClient or OkHttp, these libraries usually provide friendlier exception information and more flexible method naming rules. Check out the library’s documentation to learn how to properly set up and use HTTP request methods.
4. Check request URL
Sometimes, the java.lang.IllegalArgumentException: Invalid character found in method name exception may be because the request URL contains illegal characters. Check the request URL to make sure it only contains legal characters.
5. Debugging and logging
If none of the above methods solve the problem, you can use debugging tools and logs to further troubleshoot the cause of the exception. Examine the exception stack trace to see which method name raised the exception and further investigate the cause.
The following is a sample code that demonstrates an HTTP request method name that uses illegal characters and how to solve it:
javaCopy codeimport java.net.HttpURLConnection;
import java.net.URL;
public class HttpRequestExample {
public static void main(String[] args) {
String invalidMethodName = "GET@";
try {
//Create URL object
URL url = new URL("https://www.example.com");
//Open HTTP connection
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
//Set request method
connection.setRequestMethod(invalidMethodName); // Method name using illegal characters
//Send the request and get the response code
int responseCode = connection.getResponseCode();
System.out.println("Response Code: " + responseCode);
// close connection
connection.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the above sample code, we use an illegal character ??@?? as the HTTP request method name, namely ??GET@??. When we run this code, it will throw java.lang.IllegalArgumentException: Invalid character found in method name exception. To solve this exception, we need to replace illegal characters with legal characters, such as using ??GET?? as the request method name. The modified code is as follows:
javaCopy codeimport java.net.HttpURLConnection;
import java.net.URL;
public class HttpRequestExample {
public static void main(String[] args) {
String validMethodName = "GET";
try {
//Create URL object
URL url = new URL("https://www.example.com");
//Open HTTP connection
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
//Set request method
connection.setRequestMethod(validMethodName); // Use legal method names
//Send the request and get the response code
int responseCode = connection.getResponseCode();
System.out.println("Response Code: " + responseCode);
// close connection
connection.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the modified code, we replace the illegal character ??@? with the legal character ??GET?. In this way, the code can execute normally, send a GET request and get the response code. By modifying the method name in the code, we can solve the java.lang.IllegalArgumentException: Invalid character found in method name exception and ensure the normal operation of the network application.
A practical application scenario is to send data to the server through HTTP requests. The following is a sample code that demonstrates how to send JSON data to the server using the HTTP POST method:
javaCopy codeimport java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class HttpPostExample {
public static void main(String[] args) {
try {
//Create URL object
URL url = new URL("https://www.example.com/api/data");
//Open HTTP connection
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
//Set the request method to POST
connection.setRequestMethod("POST");
//Set request header information
connection.setRequestProperty("Content-Type", "application/json");
connection.setRequestProperty("Accept", "application/json");
//Set request body data
String jsonData = "{"name":"John","age":30}";
connection.setDoOutput(true);
OutputStream outputStream = connection.getOutputStream();
outputStream.write(jsonData.getBytes());
outputStream.flush();
outputStream.close();
//Send the request and get the response code
int responseCode = connection.getResponseCode();
System.out.println("Response Code: " + responseCode);
// close connection
connection.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the above sample code, we used the HTTP POST method to send JSON data to the server. We first create a URL object and then open an HTTP connection. Then, we set the request method to POST and set the request header information, including Content-Type and Accept. Next, we set the request body data, which is a JSON string. We use OutputStream to write JSON data into the request body, and then call the flush and close methods to ensure that the data is sent to the server. Finally, we send the request, get the response code, and close the connection. This sample code can be used in actual applications, such as sending user registration information to the server, submitting form data, etc. According to actual needs, the URL, request header information and request body data can be modified as needed.
Conclusion
??java.lang.IllegalArgumentException: Invalid character found in method name. HTTP method names??Exception indicates that illegal characters were found in the HTTP request method name. By checking the method names in the code, using appropriate HTTP request method constants, using third-party HTTP libraries, checking the request URL, and using debugging and logging tools, we can resolve this exception and ensure the normal operation of the web application. I hope this article can help you understand and solve the java.lang.IllegalArgumentException: Invalid character found in method name. HTTP method names exception. If you have any questions or queries, please feel free to leave them in the comments section.
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