001/* 002 * (C) Copyright 2013 Nuxeo SA (http://nuxeo.com/) and others. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 * 016 * Contributors: 017 * dmetzler 018 */ 019package org.nuxeo.ecm.automation.jaxrs.io; 020 021import java.io.IOException; 022import java.io.OutputStream; 023import java.lang.annotation.Annotation; 024import java.lang.reflect.ParameterizedType; 025import java.lang.reflect.Type; 026 027import javax.ws.rs.WebApplicationException; 028import javax.ws.rs.core.Context; 029import javax.ws.rs.core.MediaType; 030import javax.ws.rs.core.MultivaluedMap; 031import javax.ws.rs.ext.MessageBodyWriter; 032 033import com.fasterxml.jackson.core.JsonEncoding; 034import com.fasterxml.jackson.core.JsonFactory; 035import com.fasterxml.jackson.core.JsonGenerator; 036 037/** 038 * Base class to write json entities 039 * 040 * @since 5.7.3 041 */ 042public abstract class EntityWriter<T> implements MessageBodyWriter<T> { 043 044 @Context 045 protected JsonFactory factory; 046 047 @SuppressWarnings({ "rawtypes", "unchecked" }) 048 @Override 049 public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) { 050 if (genericType instanceof ParameterizedType) { 051 // See EntityListWriter to write Writer of parametrized class 052 return false; 053 } else { 054 ParameterizedType ptype = (ParameterizedType) this.getClass().getGenericSuperclass(); 055 Type[] ts = ptype.getActualTypeArguments(); 056 Class c = (Class) ts[0]; 057 return c.isAssignableFrom(type); 058 } 059 } 060 061 @Override 062 public long getSize(T t, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) { 063 return -1; 064 } 065 066 @Override 067 public void writeTo(T entity, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType, 068 MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) 069 throws IOException, WebApplicationException { 070 071 writeEntity(factory.createJsonGenerator(entityStream, JsonEncoding.UTF8), entity); 072 } 073 074 public void writeEntity(JsonGenerator jg, T item) throws IOException { 075 jg.writeStartObject(); 076 jg.writeStringField("entity-type", getEntityType()); 077 078 writeEntityBody(jg, item); 079 jg.writeEndObject(); 080 jg.flush(); 081 082 } 083 084 /** 085 * Write the body of the entity. The object has already been opened and it entity-type rendered. 086 */ 087 abstract protected void writeEntityBody(JsonGenerator jg, T item) throws IOException; 088 089 /** 090 * get the Entity type of the current entity type. It MUST follow camelCase notation 091 * 092 * @return the string representing the entity-type. 093 */ 094 abstract protected String getEntityType(); 095 096}