Java tutorial
/* * Copyright 2010 Proofpoint, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package io.airlift.jaxrs; import com.fasterxml.jackson.core.JsonGenerator; import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.JavaType; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.dataformat.smile.SmileFactory; import com.google.common.collect.ImmutableList; import com.google.common.collect.ImmutableSet; import com.google.inject.Inject; import io.airlift.log.Logger; import javax.validation.ConstraintViolation; import javax.validation.Validation; import javax.validation.Validator; import javax.ws.rs.Consumes; import javax.ws.rs.Produces; import javax.ws.rs.WebApplicationException; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.MultivaluedMap; import javax.ws.rs.core.Response; import javax.ws.rs.ext.MessageBodyReader; import javax.ws.rs.ext.MessageBodyWriter; import javax.ws.rs.ext.Provider; import java.io.EOFException; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.lang.annotation.Annotation; import java.lang.reflect.Type; import java.util.Collection; import java.util.List; import java.util.Set; // This code is based on JacksonJsonProvider @Provider @Consumes("application/x-jackson-smile") @Produces("application/x-jackson-smile; qs=0.1") public class SmileMapper implements MessageBodyReader<Object>, MessageBodyWriter<Object> { public static final Validator VALIDATOR = Validation.buildDefaultValidatorFactory().getValidator(); /** * Looks like we need to worry about accidental * data binding for types we shouldn't be handling. This is * probably not a very good way to do it, but let's start by * blacklisting things we are not to handle. */ private static final ImmutableSet<Class<?>> IO_CLASSES = ImmutableSet.<Class<?>>builder().add(InputStream.class) .add(java.io.Reader.class).add(OutputStream.class).add(java.io.Writer.class).add(byte[].class) .add(char[].class).add(javax.ws.rs.core.StreamingOutput.class).add(Response.class).build(); public static final Logger log = Logger.get(SmileMapper.class); private final ObjectMapper objectMapper; @Inject public SmileMapper(ObjectMapper objectMapper) { this.objectMapper = objectMapper; } @Override public boolean isReadable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) { return canReadOrWrite(type); } @Override public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) { return canReadOrWrite(type); } private static boolean canReadOrWrite(Class<?> type) { if (IO_CLASSES.contains(type)) { return false; } for (Class<?> ioClass : IO_CLASSES) { if (ioClass.isAssignableFrom(type)) { return false; } } return true; } @Override public Object readFrom(Class<Object> type, Type genericType, Annotation[] annotations, MediaType mediaType, MultivaluedMap<String, String> httpHeaders, InputStream inputStream) throws IOException { Object object; try { JsonParser jsonParser = new SmileFactory().createParser(inputStream); // Important: we are NOT to close the underlying stream after // mapping, so we need to instruct parser: jsonParser.disable(JsonParser.Feature.AUTO_CLOSE_SOURCE); object = objectMapper.readValue(jsonParser, objectMapper.getTypeFactory().constructType(genericType)); } catch (Exception e) { // we want to return a 400 for bad JSON but not for a real IO exception if (e instanceof IOException && !(e instanceof JsonProcessingException) && !(e instanceof EOFException)) { throw (IOException) e; } // log the exception at debug so it can be viewed during development // Note: we are not logging at a higher level because this could cause a denial of service log.debug(e, "Invalid json for Java type %s", type); // invalid json request throw new WebApplicationException(Response.status(Response.Status.BAD_REQUEST) .entity("Invalid json for Java type " + type).build()); } // validate object using the bean validation framework Set<ConstraintViolation<Object>> violations = VALIDATOR.validate(object); if (!violations.isEmpty()) { throw new WebApplicationException( Response.status(Response.Status.BAD_REQUEST).entity(messagesFor(violations)).build()); } return object; } @Override public long getSize(Object value, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) { // In general figuring output size requires actual writing; usually not // worth it to write everything twice. return -1; } @Override public void writeTo(Object value, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream outputStream) throws IOException { JsonGenerator jsonGenerator = new SmileFactory().createGenerator(outputStream); // Important: we are NOT to close the underlying stream after // mapping, so we need to instruct generator: jsonGenerator.disable(JsonGenerator.Feature.AUTO_CLOSE_TARGET); // 04-Mar-2010, tatu: How about type we were given? (if any) JavaType rootType = null; if (genericType != null && value != null) { // 10-Jan-2011, tatu: as per [JACKSON-456], it's not safe to just force root // type since it prevents polymorphic type serialization. Since we really // just need this for generics, let's only use generic type if it's truly // generic. if (genericType.getClass() != Class.class) { // generic types are other implementations of 'java.lang.reflect.Type' // This is still not exactly right; should root type be further // specialized with 'value.getClass()'? Let's see how well this works before // trying to come up with more complete solution. rootType = objectMapper.getTypeFactory().constructType(genericType); // 26-Feb-2011, tatu: To help with [JACKSON-518], we better recognize cases where // type degenerates back into "Object.class" (as is the case with plain TypeVariable, // for example), and not use that. // if (rootType.getRawClass() == Object.class) { rootType = null; } } } if (rootType != null) { objectMapper.writerWithType(rootType).writeValue(jsonGenerator, value); } else { objectMapper.writeValue(jsonGenerator, value); } } private static List<String> messagesFor(Collection<? extends ConstraintViolation<?>> violations) { ImmutableList.Builder<String> messages = new ImmutableList.Builder<>(); for (ConstraintViolation<?> violation : violations) { messages.add(violation.getPropertyPath() + " " + violation.getMessage()); } return messages.build(); } }