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gwt-jackson is a GWT JSON serializer/deserializer mechanism based on Jackson annotations
/*
* Copyright 2013 Nicolas Morel
*
* 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 com.github.nmorel.gwtjackson.rebind;
import javax.lang.model.element.Modifier;
import java.io.PrintWriter;
import com.fasterxml.jackson.annotation.JsonRootName;
import com.github.nmorel.gwtjackson.client.AbstractObjectMapper;
import com.github.nmorel.gwtjackson.client.AbstractObjectReader;
import com.github.nmorel.gwtjackson.client.AbstractObjectWriter;
import com.github.nmorel.gwtjackson.client.JsonDeserializer;
import com.github.nmorel.gwtjackson.client.JsonSerializer;
import com.github.nmorel.gwtjackson.client.ObjectMapper;
import com.github.nmorel.gwtjackson.rebind.exception.UnsupportedTypeException;
import com.github.nmorel.gwtjackson.rebind.type.JDeserializerType;
import com.github.nmorel.gwtjackson.rebind.type.JSerializerType;
import com.google.gwt.core.ext.GeneratorContext;
import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.core.ext.TreeLogger.Type;
import com.google.gwt.core.ext.UnableToCompleteException;
import com.google.gwt.core.ext.typeinfo.JClassType;
import com.google.gwt.core.ext.typeinfo.JParameterizedType;
import com.google.gwt.thirdparty.guava.common.base.Optional;
import com.google.gwt.thirdparty.guava.common.base.Strings;
import com.squareup.javapoet.ClassName;
import com.squareup.javapoet.MethodSpec;
import com.squareup.javapoet.ParameterizedTypeName;
import com.squareup.javapoet.TypeSpec;
import static com.github.nmorel.gwtjackson.rebind.CreatorUtils.findFirstEncounteredAnnotationsOnAllHierarchy;
import static com.github.nmorel.gwtjackson.rebind.writer.JTypeName.DEFAULT_WILDCARD;
import static com.github.nmorel.gwtjackson.rebind.writer.JTypeName.parameterizedName;
import static com.github.nmorel.gwtjackson.rebind.writer.JTypeName.typeName;
/**
* ObjectMapperCreator class.
*
* @author Nicolas Morel
* @version $Id: $
*/
public class ObjectMapperCreator extends AbstractCreator {
private static final String OBJECT_MAPPER_CLASS = "com.github.nmorel.gwtjackson.client.ObjectMapper";
private static final String OBJECT_READER_CLASS = "com.github.nmorel.gwtjackson.client.ObjectReader";
private static final String OBJECT_WRITER_CLASS = "com.github.nmorel.gwtjackson.client.ObjectWriter";
/**
* Constructor for ObjectMapperCreator.
*
* @param logger a {@link com.google.gwt.core.ext.TreeLogger} object.
* @param context a {@link com.google.gwt.core.ext.GeneratorContext} object.
* @param configuration a {@link com.github.nmorel.gwtjackson.rebind.RebindConfiguration} object.
* @param typeOracle a {@link com.github.nmorel.gwtjackson.rebind.JacksonTypeOracle} object.
* @throws com.google.gwt.core.ext.UnableToCompleteException if any.
*/
public ObjectMapperCreator( TreeLogger logger, GeneratorContext context, RebindConfiguration configuration, JacksonTypeOracle
typeOracle ) throws UnableToCompleteException {
super( logger, context, configuration, typeOracle );
}
/** {@inheritDoc} */
@Override
protected Optional getMapperInfo() {
return Optional.absent();
}
/**
* Creates the implementation of the interface denoted by interfaceClass and extending {@link ObjectMapper}
*
* @param interfaceClass the interface to generate an implementation
* @return the fully qualified name of the created class
* @throws com.google.gwt.core.ext.UnableToCompleteException if any.
*/
public String create( JClassType interfaceClass ) throws UnableToCompleteException {
// We concatenate the name of all the enclosing class.
StringBuilder builder = new StringBuilder( interfaceClass.getSimpleSourceName() + "Impl" );
JClassType enclosingType = interfaceClass.getEnclosingType();
while ( null != enclosingType ) {
builder.insert( 0, enclosingType.getSimpleSourceName() + "_" );
enclosingType = enclosingType.getEnclosingType();
}
String mapperClassSimpleName = builder.toString();
String packageName = interfaceClass.getPackage().getName();
String qualifiedMapperClassName = packageName + "." + mapperClassSimpleName;
PrintWriter printWriter = getPrintWriter( packageName, mapperClassSimpleName );
// The class already exists, no need to continue.
if ( printWriter == null ) {
return qualifiedMapperClassName;
}
try {
// Extract the type of the object to map.
JClassType mappedTypeClass = extractMappedType( interfaceClass );
boolean reader = typeOracle.isObjectReader( interfaceClass );
boolean writer = typeOracle.isObjectWriter( interfaceClass );
Class abstractClass;
if ( reader ) {
if ( writer ) {
abstractClass = AbstractObjectMapper.class;
} else {
abstractClass = AbstractObjectReader.class;
}
} else {
abstractClass = AbstractObjectWriter.class;
}
TypeSpec.Builder mapperBuilder = TypeSpec.classBuilder( mapperClassSimpleName )
.addModifiers( Modifier.PUBLIC, Modifier.FINAL )
.addSuperinterface( typeName( interfaceClass ) )
.superclass( parameterizedName( abstractClass, mappedTypeClass ) )
.addMethod( buildConstructor( mappedTypeClass ) );
if ( reader ) {
mapperBuilder.addMethod( buildNewDeserializerMethod( mappedTypeClass ) );
}
if ( writer ) {
mapperBuilder.addMethod( buildNewSerializerMethod( mappedTypeClass ) );
}
write( packageName, mapperBuilder.build(), printWriter );
} finally {
printWriter.close();
}
return qualifiedMapperClassName;
}
/**
* Extract the type to map from the interface.
*
* @param interfaceClass the interface
*
* @return the extracted type to map
* @throws UnableToCompleteException if we don't find the type
*/
private JClassType extractMappedType( JClassType interfaceClass ) throws UnableToCompleteException {
JClassType intf = interfaceClass.isInterface();
if ( intf == null ) {
logger.log( TreeLogger.Type.ERROR, "Expected " + interfaceClass + " to be an interface." );
throw new UnableToCompleteException();
}
JClassType[] intfs = intf.getImplementedInterfaces();
for ( JClassType t : intfs ) {
if ( t.getQualifiedSourceName().equals( OBJECT_MAPPER_CLASS ) ) {
return extractParameterizedType( OBJECT_MAPPER_CLASS, t.isParameterized() );
} else if ( t.getQualifiedSourceName().equals( OBJECT_READER_CLASS ) ) {
return extractParameterizedType( OBJECT_READER_CLASS, t.isParameterized() );
} else if ( t.getQualifiedSourceName().equals( OBJECT_WRITER_CLASS ) ) {
return extractParameterizedType( OBJECT_WRITER_CLASS, t.isParameterized() );
}
}
logger.log( TreeLogger.Type.ERROR, "Expected " + interfaceClass + " to extend one of the following interface : " +
OBJECT_MAPPER_CLASS + ", " + OBJECT_READER_CLASS + " or " + OBJECT_WRITER_CLASS );
throw new UnableToCompleteException();
}
/**
* Extract the parameter's type.
*
* @param clazz the name of the interface
* @param parameterizedType the parameterized type
*
* @return the extracted type
* @throws UnableToCompleteException if the type contains zero or more than one parameter
*/
private JClassType extractParameterizedType( String clazz, JParameterizedType parameterizedType ) throws UnableToCompleteException {
if ( parameterizedType == null ) {
logger.log( TreeLogger.Type.ERROR, "Expected the " + clazz + " declaration to specify a parameterized type." );
throw new UnableToCompleteException();
}
JClassType[] typeParameters = parameterizedType.getTypeArgs();
if ( typeParameters == null || typeParameters.length != 1 ) {
logger.log( TreeLogger.Type.ERROR, "Expected the " + clazz + " declaration to specify 1 parameterized type." );
throw new UnableToCompleteException();
}
return typeParameters[0];
}
/**
* Build the constructor.
*
* @param mappedTypeClass the type to map
*
* @return the constructor method
*/
private MethodSpec buildConstructor( JClassType mappedTypeClass ) {
Optional jsonRootName
= findFirstEncounteredAnnotationsOnAllHierarchy( configuration, mappedTypeClass, JsonRootName.class );
String rootName;
if ( !jsonRootName.isPresent() || Strings.isNullOrEmpty( jsonRootName.get().value() ) ) {
rootName = mappedTypeClass.getSimpleSourceName();
} else {
rootName = jsonRootName.get().value();
}
return MethodSpec.constructorBuilder()
.addModifiers( Modifier.PUBLIC )
.addStatement( "super($S)", rootName )
.build();
}
/**
* Build the new deserializer method.
*
* @param mappedTypeClass the type to map
*
* @return the method
*/
private MethodSpec buildNewDeserializerMethod( JClassType mappedTypeClass ) throws UnableToCompleteException {
JDeserializerType type;
try {
type = getJsonDeserializerFromType( mappedTypeClass );
} catch ( UnsupportedTypeException e ) {
logger.log( Type.ERROR, "Cannot generate mapper due to previous errors : " + e.getMessage() );
throw new UnableToCompleteException();
}
return MethodSpec.methodBuilder( "newDeserializer" )
.addModifiers( Modifier.PROTECTED )
.addAnnotation( Override.class )
.returns( parameterizedName( JsonDeserializer.class, mappedTypeClass ) )
.addStatement( "return $L", type.getInstance() )
.build();
}
/**
* Build the new serializer method.
*
* @param mappedTypeClass the type to map
*
* @return the method
*/
private MethodSpec buildNewSerializerMethod( JClassType mappedTypeClass ) throws UnableToCompleteException {
JSerializerType type;
try {
type = getJsonSerializerFromType( mappedTypeClass );
} catch ( UnsupportedTypeException e ) {
logger.log( Type.ERROR, "Cannot generate mapper due to previous errors : " + e.getMessage() );
throw new UnableToCompleteException();
}
return MethodSpec.methodBuilder( "newSerializer" )
.addModifiers( Modifier.PROTECTED )
.addAnnotation( Override.class )
.returns( ParameterizedTypeName.get( ClassName.get( JsonSerializer.class ), DEFAULT_WILDCARD ) )
.addStatement( "return $L", type.getInstance() )
.build();
}
}
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