How do I validate incoming JSON data inside a REST service?
import com.github.fge.jsonschema.core.report.ProcessingReport;
import com.github.fge.jsonschema.main.JsonSchema;
import com.github.fge.jsonschema.main.JsonSchemaFactory;
import com.github.fge.jackson.JsonLoader;
import com.fasterxml.jackson.databind.JsonNode;
public class ValidationJSON {
public static void main(String[] arr){
String jsonData = "{\"name\": \"prem\"}";
String jsonSchema = ""; //Schema we can generate online using http://jsonschema.net/
final JsonNode data = JsonLoader.fromString(jsonData);
final JsonNode schema = JsonLoader.fromString(jsonSchema);
final JsonSchemaFactory factory = JsonSchemaFactory.byDefault();
JsonValidator validator = factory.getValidator();
ProcessingReport report = validator.validate(schema, data);
System.out.println(report.isSuccess());
}
}
I searched for the best practice to enforce validation for incoming json data into a RESTful service. My suggestion is to use a MessageBodyReader
which performs the validation inside the readFrom
method. Below there is an message-body-reader example which is non-generic for the sake of simplicity.
I also was interesed in finding the best framework for doing json data validation. Because I use the jackson framework (version 1.8.5) for marshaling and unmarshaling between json and java, it would have been nice if this framework would provide a json data validation functionality. Unfortunately I couldn't find any possibility to do this with jackson. Finally I got it working with the json-schema-validator available at https://github.com. The version I use is 2.1.7
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import javax.servlet.ServletContext;
import javax.ws.rs.Consumes;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyReader;
import javax.ws.rs.ext.Provider;
import org.codehaus.jackson.map.ObjectMapper;
import at.fhj.ase.dao.data.Address;
import at.fhj.ase.xmlvalidation.msbreader.MessageBodyReaderValidationException;
import com.fasterxml.jackson.databind.JsonNode;
import com.github.fge.jackson.JsonLoader;
import com.github.fge.jsonschema.exceptions.ProcessingException;
import com.github.fge.jsonschema.main.JsonSchemaFactory;
import com.github.fge.jsonschema.main.JsonValidator;
import com.github.fge.jsonschema.report.ProcessingReport;
@Provider
@Consumes(MediaType.APPLICATION_JSON)
public class AddressJsonValidationReader implements MessageBodyReader<Address> {
private final String jsonSchemaFileAsString;
public AddressJsonValidationReader(@Context ServletContext servletContext) {
this.jsonSchemaFileAsString = servletContext
.getRealPath("/json/Address.json");
}
@Override
public boolean isReadable(Class<?> type, Type genericType,
Annotation[] annotations, MediaType mediaType) {
if (type == Address.class) {
return true;
}
return false;
}
@Override
public Address readFrom(Class<Address> type, Type genericType,
Annotation[] annotations, MediaType mediaType,
MultivaluedMap<String, String> httpHeaders, InputStream entityStream)
throws IOException, WebApplicationException {
final String jsonData = getStringFromInputStream(entityStream);
System.out.println(jsonData);
InputStream isSchema = new FileInputStream(jsonSchemaFileAsString);
String jsonSchema = getStringFromInputStream(isSchema);
/*
* Perform JSON data validation against schema
*/
validateJsonData(jsonSchema, jsonData);
/*
* Convert stream to data entity
*/
ObjectMapper m = new ObjectMapper();
Address addr = m.readValue(stringToStream(jsonData), Address.class);
return addr;
}
/**
* Validate the given JSON data against the given JSON schema
*
* @param jsonSchema
* as String
* @param jsonData
* as String
* @throws MessageBodyReaderValidationException
* in case of an error during validation process
*/
private void validateJsonData(final String jsonSchema, final String jsonData)
throws MessageBodyReaderValidationException {
try {
final JsonNode d = JsonLoader.fromString(jsonData);
final JsonNode s = JsonLoader.fromString(jsonSchema);
final JsonSchemaFactory factory = JsonSchemaFactory.byDefault();
JsonValidator v = factory.getValidator();
ProcessingReport report = v.validate(s, d);
System.out.println(report);
if (!report.toString().contains("success")) {
throw new MessageBodyReaderValidationException(
report.toString());
}
} catch (IOException e) {
throw new MessageBodyReaderValidationException(
"Failed to validate json data", e);
} catch (ProcessingException e) {
throw new MessageBodyReaderValidationException(
"Failed to validate json data", e);
}
}
/**
* Taken from <a href=
* "http://www.mkyong.com/java/how-to-convert-inputstream-to-string-in-java/"
* >www.mkyong.com</a>
*
* @param is
* {@link InputStream}
* @return Stream content as String
*/
private String getStringFromInputStream(InputStream is) {
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String line;
try {
br = new BufferedReader(new InputStreamReader(is));
while ((line = br.readLine()) != null) {
sb.append(line);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return sb.toString();
}
private InputStream stringToStream(final String str) throws UnsupportedEncodingException {
return new ByteArrayInputStream(str.getBytes("UTF-8"));
}
}