Fixing %20 Encoding Issues in Spring Boot: How to Properly Decode URL Parameters

Learn how to resolve the issue of receiving `%20` instead of spaces for URL parameters in your Spring Boot application. Discover simple solutions and best practices for sending and handling requests.
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Fixing %20 Encoding Issues in Spring Boot: How to Properly Decode URL Parameters

In the world of web services, encoding and decoding URL parameters is a critical aspect of ensuring that data is transmitted accurately. If you've ever encountered the frustrating issue of receiving %20 in your parameters instead of a space, you're not alone. This problem often plagues developers working with Spring Boot applications when they start sending requests between services. In this guide, we'll explore a specific situation where this occurs and provide a solution to ensure your parameters are received correctly in your controller.

Background of the Problem

Consider a scenario where you have a Spring Boot server that includes a REST controller set up to receive certain parameters:

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Here, you have an endpoint /readProperty that is supposed to take in query parameters like channel and service_name. You also have another Spring Boot application that sends a request to this endpoint using RestTemplate:

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When logging the URL created, you see an output like this:

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The Issue: Different Parameter Values

When calling the endpoint using curl, you receive the expected value of service_name as Some Value. However, when using RestTemplate to make the same request, the parameter comes through as Some%20Value. This inconsistency happens due to double encoding. Let's break this down further.

Understanding the Cause of the Problem

The root cause of the issue lies in double encoding. Here’s how it happens:

First Encoding: When you construct the URL using UriComponentsBuilder, it encodes the query parameters. Spaces are converted to %20 as part of the URL encoding process.

Solution: Correcting the URL Encoding

The aim is to ensure that your parameters are sent without being doubly encoded. You can do this by modifying your method that prepares the URL for the RestTemplate call. Instead of using toUriString(), use toString():

Updated Code

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Result

Once you've made this change, the parameter service_name will be received correctly as Some Value in your Spring Boot controller, eliminating the %20 encoding issue.

Conclusion

Handling URL parameters in web services, especially with frameworks like Spring Boot, requires careful attention to encoding and decoding. By understanding the cause of the %20 encoding issue and applying the straightforward fix of using toString() instead of toUriString(), you ensure your parameters are transmitted accurately. This not only simplifies debugging but also enhances the reliability of your API communications.

Happy coding, and may all your queries come through as intended!