JsonProvider.java
/*
* Copyright (c) 2011, 2022 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package jakarta.json.spi;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Optional;
import java.util.ServiceLoader;
import java.util.logging.Level;
import java.util.logging.Logger;
import jakarta.json.JsonArray;
import jakarta.json.JsonArrayBuilder;
import jakarta.json.JsonBuilderFactory;
import jakarta.json.JsonException;
import jakarta.json.JsonMergePatch;
import jakarta.json.JsonNumber;
import jakarta.json.JsonObject;
import jakarta.json.JsonObjectBuilder;
import jakarta.json.JsonPatch;
import jakarta.json.JsonPatchBuilder;
import jakarta.json.JsonPointer;
import jakarta.json.JsonReader;
import jakarta.json.JsonReaderFactory;
import jakarta.json.JsonString;
import jakarta.json.JsonStructure;
import jakarta.json.JsonValue;
import jakarta.json.JsonWriter;
import jakarta.json.JsonWriterFactory;
import jakarta.json.stream.JsonGenerator;
import jakarta.json.stream.JsonGeneratorFactory;
import jakarta.json.stream.JsonParser;
import jakarta.json.stream.JsonParserFactory;
/**
* Service provider for JSON processing objects.
*
* <p>All the methods in this class are safe for use by multiple concurrent
* threads.
*
* @see ServiceLoader
*/
public abstract class JsonProvider {
/**
* The name of the property that contains the name of the class capable of creating new JsonProvider objects.
*/
public static final String JSONP_PROVIDER_FACTORY = "jakarta.json.provider";
/**
* A constant representing the name of the default
* {@code JsonProvider} implementation class.
*/
private static final String DEFAULT_PROVIDER
= "org.eclipse.parsson.JsonProviderImpl";
/** A logger */
private static final Logger LOG = Logger.getLogger(JsonProvider.class.getName());
/**
* Default constructor.
*/
protected JsonProvider() {
}
/**
* Creates a JSON provider object.
*
* Implementation discovery consists of following steps:
* <ol>
* <li>If the system property {@value #JSONP_PROVIDER_FACTORY} exists,
* then its value is assumed to be the provider factory class.
* This phase of the look up enables per-JVM override of the JsonProvider implementation.</li>
* <li>The provider is loaded using the {@link ServiceLoader#load(Class)} method.</li>
* <li>If all the steps above fail, then the rest of the look up is unspecified. That said,
* the recommended behavior is to simply look for some hard-coded platform default Jakarta
* JSON Processing implementation. This phase of the look up is so that a platform can have
* its own Jakarta JSON Processing implementation as the last resort.</li>
* </ol>
* Users are recommended to cache the result of this method.
*
* @see ServiceLoader
* @return a JSON provider
*/
public static JsonProvider provider() {
LOG.log(Level.FINE, "Checking system property {0}", JSONP_PROVIDER_FACTORY);
final String factoryClassName = System.getSecurityManager() != null
? AccessController.doPrivileged((PrivilegedAction<String>) () -> System.getProperty(JSONP_PROVIDER_FACTORY))
: System.getProperty(JSONP_PROVIDER_FACTORY);
if (factoryClassName != null) {
JsonProvider provider = newInstance(factoryClassName);
LOG.log(Level.FINE, "System property used; returning object [{0}]",
provider.getClass().getName());
return provider;
}
LOG.log(Level.FINE, "Checking ServiceLoader");
ServiceLoader<JsonProvider> loader = ServiceLoader.load(JsonProvider.class);
Iterator<JsonProvider> it = loader.iterator();
if (it.hasNext()) {
JsonProvider provider = it.next();
LOG.log(Level.FINE, "ServiceLoader loading Facility used; returning object [{0}]",
provider.getClass().getName());
return provider;
}
// handling OSGi (specific default)
if (isOsgi()) {
LOG.log(Level.FINE, "Checking OSGi");
JsonProvider provider = lookupUsingOSGiServiceLoader(JsonProvider.class);
if (provider != null) {
LOG.log(Level.FINE, "OSGi loading facility used; returning object [{0}].",
provider.getClass().getName());
return provider;
}
}
// else no provider found
LOG.fine("Trying to create the platform default provider");
return newInstance(DEFAULT_PROVIDER);
}
/**
* Creates a new instance from the specified class
* @param className name of the class to instantiate
* @return the JsonProvider instance
* @throws JsonException for issues during creation of an instance of the JsonProvider
*/
private static JsonProvider newInstance(String className) {
try {
checkPackageAccess(className);
@SuppressWarnings({"unchecked"})
Class<JsonProvider> clazz = (Class<JsonProvider>) Class.forName(className);
return clazz.getConstructor().newInstance();
} catch (ClassNotFoundException x) {
throw new JsonException(
"Provider " + className + " not found", x);
} catch (Exception x) {
throw new JsonException(
"Provider " + className + " could not be instantiated: " + x,
x);
}
}
/**
* Make sure that the current thread has an access to the package of the given name.
* @param className The class name to check.
*/
private static void checkPackageAccess(String className) {
SecurityManager s = System.getSecurityManager();
if (s != null) {
int i = className.lastIndexOf('.');
if (i != -1) {
s.checkPackageAccess(className.substring(0, i));
}
}
}
/**
* Creates a JSON parser from a character stream.
*
* @param reader i/o reader from which JSON is to be read
* @return a JSON parser
*/
public abstract JsonParser createParser(Reader reader);
/**
* Creates a JSON parser from the specified byte stream.
* The character encoding of the stream is determined
* as defined in <a href="http://tools.ietf.org/rfc/rfc7159.txt">RFC 7159
* </a>.
*
* @param in i/o stream from which JSON is to be read
* @throws JsonException if encoding cannot be determined
* or i/o error (IOException would be cause of JsonException)
* @return a JSON parser
*/
public abstract JsonParser createParser(InputStream in);
/**
* Creates a parser factory for creating {@link JsonParser} instances.
*
* @return a JSON parser factory
*
public abstract JsonParserFactory createParserFactory();
*/
/**
* Creates a parser factory for creating {@link JsonParser} instances.
* The factory is configured with the specified map of
* provider specific configuration properties. Provider implementations
* should ignore any unsupported configuration properties specified in
* the map.
*
* @param config a map of provider specific properties to configure the
* JSON parsers. The map may be empty or null
* @return a JSON parser factory
*/
public abstract JsonParserFactory createParserFactory(Map<String, ?> config);
/**
* Creates a JSON generator for writing JSON text to a character stream.
*
* @param writer a i/o writer to which JSON is written
* @return a JSON generator
*/
public abstract JsonGenerator createGenerator(Writer writer);
/**
* Creates a JSON generator for writing JSON text to a byte stream.
*
* @param out i/o stream to which JSON is written
* @return a JSON generator
*/
public abstract JsonGenerator createGenerator(OutputStream out);
/**
* Creates a generator factory for creating {@link JsonGenerator} instances.
*
* @return a JSON generator factory
*
public abstract JsonGeneratorFactory createGeneratorFactory();
*/
/**
* Creates a generator factory for creating {@link JsonGenerator} instances.
* The factory is configured with the specified map of provider specific
* configuration properties. Provider implementations should
* ignore any unsupported configuration properties specified in the map.
*
* @param config a map of provider specific properties to configure the
* JSON generators. The map may be empty or null
* @return a JSON generator factory
*/
public abstract JsonGeneratorFactory createGeneratorFactory(Map<String, ?> config);
/**
* Creates a JSON reader from a character stream.
*
* @param reader a reader from which JSON is to be read
* @return a JSON reader
*/
public abstract JsonReader createReader(Reader reader);
/**
* Creates a JSON reader from a byte stream. The character encoding of
* the stream is determined as described in
* <a href="http://tools.ietf.org/rfc/rfc7159.txt">RFC 7159</a>.
*
* @param in a byte stream from which JSON is to be read
* @return a JSON reader
*/
public abstract JsonReader createReader(InputStream in);
/**
* Creates a JSON writer to write a
* JSON {@link JsonObject object} or {@link JsonArray array}
* structure to the specified character stream.
*
* @param writer to which JSON object or array is written
* @return a JSON writer
*/
public abstract JsonWriter createWriter(Writer writer);
/**
* Creates a JSON writer to write a
* JSON {@link JsonObject object} or {@link JsonArray array}
* structure to the specified byte stream. Characters written to
* the stream are encoded into bytes using UTF-8 encoding.
*
* @param out to which JSON object or array is written
* @return a JSON writer
*/
public abstract JsonWriter createWriter(OutputStream out);
/**
* Creates a writer factory for creating {@link JsonWriter} objects.
* The factory is configured with the specified map of provider specific
* configuration properties. Provider implementations should ignore any
* unsupported configuration properties specified in the map.
*
* @param config a map of provider specific properties to configure the
* JSON writers. The map may be empty or null
* @return a JSON writer factory
*/
public abstract JsonWriterFactory createWriterFactory(Map<String,?> config);
/**
* Creates a reader factory for creating {@link JsonReader} objects.
* The factory is configured with the specified map of provider specific
* configuration properties. Provider implementations should ignore any
* unsupported configuration properties specified in the map.
*
* @param config a map of provider specific properties to configure the
* JSON readers. The map may be empty or null
* @return a JSON reader factory
*/
public abstract JsonReaderFactory createReaderFactory(Map<String,?> config);
/**
* Creates a JSON object builder.
*
* @return a JSON object builder
*/
public abstract JsonObjectBuilder createObjectBuilder();
/**
* Creates a JSON object builder, initialized with the specified object.
*
* @param object the initial JSON object in the builder
* @return a JSON object builder
*
* @since 1.1
*/
public JsonObjectBuilder createObjectBuilder(JsonObject object) {
throw new UnsupportedOperationException();
}
/**
* Creates a JSON object builder, initialized with the data from specified {@code map}.
* If the @{code map} contains {@link Optional}s then resulting JSON object builder
* contains the key from the {@code map} only if the {@link Optional} is not empty.
*
* @param map the initial object in the builder
* @return a JSON object builder
* @exception IllegalArgumentException if the value from the {@code map} cannot be converted
* to the corresponding {@link JsonValue}
*
* @since 1.1
*/
public JsonObjectBuilder createObjectBuilder(Map<String, ?> map) {
throw new UnsupportedOperationException();
}
/**
* Creates a JSON array builder.
*
* @return a JSON array builder
*/
public abstract JsonArrayBuilder createArrayBuilder();
/**
* Creates a JSON array builder, initialized with the specified array.
*
* @param array the initial JSON array in the builder
* @return a JSON array builder
*
* @since 1.1
*/
public JsonArrayBuilder createArrayBuilder(JsonArray array) {
throw new UnsupportedOperationException();
}
/**
* Creates JSON Pointer (<a href="http://tools.ietf.org/html/rfc6901">RFC 6901</a>)
* from given {@code jsonPointer} string.
* <ul>
* <li>An empty {@code jsonPointer} string defines a reference to the target itself.</li>
* <li>If the {@code jsonPointer} string is non-empty, it must be a sequence of '{@code /}' prefixed tokens.</li>
* </ul>
*
* @param jsonPointer the JSON Pointer string
* @throws NullPointerException if {@code jsonPointer} is {@code null}
* @throws JsonException if {@code jsonPointer} is not a valid JSON Pointer
* @return a JSON Pointer
*
* @since 1.1
*/
public JsonPointer createPointer(String jsonPointer) {
throw new UnsupportedOperationException();
}
/**
* Creates a JSON Patch builder (<a href="http://tools.ietf.org/html/rfc6902">RFC 6902</a>).
*
* @return a JSON Patch builder
*
* @since 1.1
*/
public JsonPatchBuilder createPatchBuilder() {
throw new UnsupportedOperationException();
}
/**
* Creates a JSON Patch builder
* (<a href="http://tools.ietf.org/html/rfc6902">RFC 6902</a>),
* initialized with the specified operations.
*
* @param array the initial patch operations
* @return a JSON Patch builder
*
* @since 1.1
*/
public JsonPatchBuilder createPatchBuilder(JsonArray array) {
throw new UnsupportedOperationException();
}
/**
* Creates a JSON Patch (<a href="http://tools.ietf.org/html/rfc6902">RFC 6902</a>)
* from the specified operations.
*
* @param array patch operations
* @return a JSON Patch
*
* @since 1.1
*/
public JsonPatch createPatch(JsonArray array) {
throw new UnsupportedOperationException();
}
/**
* Generates a JSON Patch (<a href="http://tools.ietf.org/html/rfc6902">RFC 6902</a>)
* from the source and target {@code JsonStructure}.
* The generated JSON Patch need not be unique.
*
* @param source the source
* @param target the target, must be the same type as the source
* @return a JSON Patch which when applied to the source, yields the target
*
* @since 1.1
*/
public JsonPatch createDiff(JsonStructure source, JsonStructure target) {
throw new UnsupportedOperationException();
}
/**
* Creates JSON Merge Patch (<a href="http://tools.ietf.org/html/rfc7396">RFC 7396</a>)
* from specified {@code JsonValue}.
*
* @param patch the patch
* @return a JSON Merge Patch
*
* @since 1.1
*/
public JsonMergePatch createMergePatch(JsonValue patch) {
throw new UnsupportedOperationException();
}
/**
* Generates a JSON Merge Patch (<a href="http://tools.ietf.org/html/rfc7396">RFC 7396</a>)
* from the source and target {@code JsonValue}s
* which when applied to the {@code source}, yields the {@code target}.
*
* @param source the source
* @param target the target
* @return a JSON Merge Patch
*
* @since 1.1
*/
public JsonMergePatch createMergeDiff(JsonValue source, JsonValue target) {
throw new UnsupportedOperationException();
}
/**
* Creates a JSON array builder, initialized with the content of specified {@code collection}.
* If the @{code collection} contains {@link Optional}s then resulting JSON array builder
* contains the value from the {@code collection} only if the {@link Optional} is not empty.
*
* @param collection the initial data for the builder
* @return a JSON array builder
* @exception IllegalArgumentException if the value from the {@code collection} cannot be converted
* to the corresponding {@link JsonValue}
*
* @since 1.1
*/
public JsonArrayBuilder createArrayBuilder(Collection<?> collection) {
throw new UnsupportedOperationException();
}
/**
* Creates a builder factory for creating {@link JsonArrayBuilder}
* and {@link JsonObjectBuilder} objects.
* The factory is configured with the specified map of provider specific
* configuration properties. Provider implementations should ignore any
* unsupported configuration properties specified in the map.
*
* @param config a map of provider specific properties to configure the
* JSON builders. The map may be empty or null
* @return a JSON builder factory
*/
public abstract JsonBuilderFactory createBuilderFactory(Map<String,?> config);
/**
* Creates a JsonString.
*
* @param value a JSON string
* @return the JsonString for the string
*
* @since 1.1
*/
public JsonString createValue(String value) {
throw new UnsupportedOperationException();
}
/**
* Creates a JsonNumber.
*
* @param value a JSON number
* @return the JsonNumber for the number
*
* @since 1.1
*/
public JsonNumber createValue(int value) {
throw new UnsupportedOperationException();
}
/**
* Creates a JsonNumber.
*
* @param value a JSON number
* @return the JsonNumber for the number
*
* @since 1.1
*/
public JsonNumber createValue(long value) {
throw new UnsupportedOperationException();
}
/**
* Creates a JsonNumber.
*
* @param value a JSON number
* @return the JsonNumber for the number
*
* @since 1.1
*/
public JsonNumber createValue(double value) {
throw new UnsupportedOperationException();
}
/**
* Creates a JsonNumber.
*
* @param value a JSON number
* @return the JsonNumber for the number
*
* @since 1.1
*/
public JsonNumber createValue(BigDecimal value) {
throw new UnsupportedOperationException();
}
/**
* Creates a JsonNumber.
*
* @param value a JSON number
* @return the JsonNumber for the number
*
* @since 1.1
*/
public JsonNumber createValue(BigInteger value) {
throw new UnsupportedOperationException();
}
/**
* Creates a JsonNumber.
*
* When it is not implemented it checks the type and delegates
* to an existing method that already handles that type. It throws
* UnsupportedOperationException in case the type is not known.
*
* @param number a JSON number
* @return the JsonNumber for the number
*
* @since 2.1
*/
public JsonNumber createValue(Number number) {
if (number instanceof Integer) {
return createValue(number.intValue());
} else if (number instanceof Long) {
return createValue(number.longValue());
} else if (number instanceof Double) {
return createValue(number.doubleValue());
} else if (number instanceof BigInteger) {
return createValue((BigInteger) number);
} else if (number instanceof BigDecimal) {
return createValue((BigDecimal) number);
} else {
throw new UnsupportedOperationException(number + " type is not known");
}
}
/** OSGI aware service loader by HK2 */
private static final String OSGI_SERVICE_LOADER_CLASS_NAME = "org.glassfish.hk2.osgiresourcelocator.ServiceLoader";
/**
* Check availability of HK2 service loader.
*
* @return true if HK2 service locator is available
*/
private static boolean isOsgi() {
try {
Class.forName(OSGI_SERVICE_LOADER_CLASS_NAME);
return true;
} catch (ClassNotFoundException ignored) {
}
return false;
}
/**
* Lookup the service class by the HK2 service locator.
*
* @param serviceClass service class
* @param <T> type of the service
* @return a provider
*/
private static <T> T lookupUsingOSGiServiceLoader(Class<? extends T> serviceClass) {
try {
// Use reflection to avoid having any dependendcy on HK2 ServiceLoader class
Class<?>[] args = new Class<?>[]{serviceClass};
Class<?> target = Class.forName(OSGI_SERVICE_LOADER_CLASS_NAME);
Method m = target.getMethod("lookupProviderInstances", Class.class);
@SuppressWarnings({"unchecked"})
Iterator<? extends T> iter = ((Iterable<? extends T>) m.invoke(null, (Object[]) args)).iterator();
return iter.hasNext() ? iter.next() : null;
} catch (Exception ex) {
LOG.log(Level.FINE, "Unable to find from OSGi: [" + serviceClass.getName() + "]", ex);
return null;
}
}
}