Wednesday, April 12, 2023

pring boot java read json file with json schema into java object

 To read a JSON file with a JSON schema into a Java object in Spring Boot, you can use the Jackson library. Here's a step-by-step guide:

  1. Add the Jackson dependency to your project. You can do this by adding the following dependency to your pom.xml file if you are using Maven:
<dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>{version}</version> </dependency>

Replace {version} with the version of the Jackson library you want to use. You can find the latest version on the Maven Central Repository.

  1. Define your JSON schema. You can use a tool like JSON Schema Generator to generate a JSON schema from your JSON file.

  2. Create a Java class that represents the structure of your JSON file. You can use annotations from the Jackson library to map the fields in your Java class to the properties in your JSON file.

For example, if your JSON file looks like this:

{ "name": "John", "age": 30 }

You can create a Java class like this:

public class Person { @JsonProperty("name") private String name; @JsonProperty("age") private int age; // getters and setters }

The @JsonProperty annotation is used to map the name field in the JSON file to the name field in the Java class, and the age field in the JSON file to the age field in the Java class.

  1. Read the JSON file into a Java object using the ObjectMapper class from the Jackson library. You can use the readValue() method to read the JSON file into a Java object.

For example, if your JSON file is called person.json, and is located in the resources folder of your Spring Boot project, you can read it into a Person object like this:

ObjectMapper mapper = new ObjectMapper(); File file = new ClassPathResource("person.json").getFile(); Person person = mapper.readValue(file, Person.class);

The ClassPathResource class is used to get a reference to the person.json file in the resources folder.

That's it! You can now use the person object to access the data in the JSON file.

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