Скачать или смотреть How to Configure Jackson PrettyPrinter for JSON Formatting Like Gson

Learn how to configure Jackson's PrettyPrinter to format JSON without spaces before colons and ensure each element in arrays starts from a new line, just like Gson.
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Introduction

When working with JSON in Java, both Jackson and Gson libraries are popular choices for parsing and generating JSON data. However, differing formatting styles can occasionally become a nuisance, especially if you're trying to maintain consistency with your JSON outputs. If you prefer the structure provided by Gson but are using Jackson, you might be wondering how to configure Jackson's PrettyPrinter to adhere to Gson's formatting style.

In this guide, we will explore how to configure Jackson's PrettyPrinter to format JSON without spaces before colons and ensure that each element of an array starts on a new line. Let's dive into it!

Understanding the Challenge

By default, the Jackson PrettyPrinter produces a JSON format with spaces before colons, which can look like this:

[[See Video to Reveal this Text or Code Snippet]]

However, you might prefer a cleaner format that doesn't include spaces before the colons, and also starts array elements on new lines like this:

[[See Video to Reveal this Text or Code Snippet]]

Solution: Custom PrettyPrinter

To achieve the Gson-like formatting with Jackson, we will create a custom PrettyPrinter by extending DefaultPrettyPrinter. This will allow us to control the indentation structure and remove any unwanted spaces. Follow along with the code implementation below.

Code Implementation

Here is the Java code that implements the custom PrettyPrinter:

[[See Video to Reveal this Text or Code Snippet]]

Key Features of This Implementation

Custom Indentation for Arrays and Objects:

The MyPrettyPrinter class adjusts the array and object indenters to use system line feeds (SYSTEM_LINEFEED_INSTANCE), ensuring each element starts on a new line.

Removing Spaces Before Colons:

The override of withSeparators allows you to tailor the separators used in writing the JSON without leaving spaces before colons.

Handling End of Structures:

By overriding writeEndArray and writeEndObject, we can control how Jackson handles the closing of arrays and objects to ensure the desired formatting is consistently applied, even for empty structures.

Conclusion

By implementing a custom PrettyPrinter in Jackson, you can achieve a JSON output format that closely mirrors that of Gson. This not only ensures consistency in your application's JSON responses but also enhances readability for developers who will be working with your JSON data.

Whether you are developing a new application or maintaining an existing one, leveraging the configuration options provided by Jackson can greatly improve your output formatting. Start using this custom PrettyPrinter, and enjoy cleaner JSON formatting today!