JSONPaths can be "definite" (i.e. single-valued):
$.idor "indefinite" (i.e. multivalued):
$..id
They're cross-platform, but I've been using a Jayway library:
<dependency>
<groupId>com.jayway.jsonpath</groupId>
<artifactId>json-path</artifactId>
<version>2.0.0</version>
</dependency>
This is based around a class JsonPath with straightforward static methods. This adds a compilation overhead, so if you're using the same expression repeatedly you should look into the "compile" method, which gives a nonstatic version.
JSON schema is much less intuitive, and seems to have surprisingly little support in Java: http://json-schema.org/implementations.html
There's a useful online tool to generate a schema for a given JSON example:
http://jsonschema.net/#/
This seems to be the best publicized JSON schema library:
https://github.com/fge/json-schema-validator/
To build a schema object, you first need to convert it into Jackson's JSON types:
// Marshall schema
ObjectMapper mapper = new ObjectMapper();
JsonNode actualObj = mapper.readTree(config.getJsonSchema());
// Build schema object
final JsonSchemaFactory factory = JsonSchemaFactory.byDefault();
jsonSchema = factory.getJsonSchema(actualObj);
Once the schema object is built, validating documents against it requires a similar set of steps:
ObjectMapper mapper = new ObjectMapper();
JsonNode jn = mapper.readTree(entity.toString());
ProcessingReport report = jsonSchema.validate(jn);
if (!report.isSuccess()) {
throw new IllegalArgumentException(
"Entity did not conform to configured schema.");
}
Helpfully, json-schema-validator comes with a set of example classes, which show it in action.
