com.marklogic.client.io.JAXBHandle Maven / Gradle / Ivy
/*
* Copyright 2012-2016 MarkLogic Corporation
*
* 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.marklogic.client.io;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.marklogic.client.MarkLogicIOException;
import com.marklogic.client.io.marker.BufferableHandle;
import com.marklogic.client.io.marker.ContentHandle;
import com.marklogic.client.io.marker.ContentHandleFactory;
import com.marklogic.client.io.marker.XMLReadHandle;
import com.marklogic.client.io.marker.XMLWriteHandle;
/**
* A JAXB Handle roundtrips a POJO (a Java data structure) to and from a database document.
*
* The POJO class must have JAXB annotations or must be generated by xjc from an XML Schema.
*
* The JAXB Handle must be initialized with a JAXB Context with which the root POJO classes
* have been registered.
*
* @param one of the classes (or the <?> wildcard for any of the classes) registered with the JAXB Context
*/
public class JAXBHandle
extends BaseHandle
implements OutputStreamSender, BufferableHandle, ContentHandle,
XMLReadHandle, XMLWriteHandle
{
static final private Logger logger = LoggerFactory.getLogger(JAXBHandle.class);
private JAXBContext context;
private Unmarshaller unmarshaller;
private Marshaller marshaller;
private C content;
/**
* Creates a factory to create a JAXBHandle instance for POJO instances
* of the specified classes.
* @param pojoClasses the POJO classes for which this factory provides a handle
* @return the factory
* @throws JAXBException if a JAXB error occurs while initializing the new factory
*/
static public ContentHandleFactory newFactory(Class... pojoClasses)
throws JAXBException {
if (pojoClasses == null || pojoClasses.length == 0)
return null;
return new JAXBHandleFactory(pojoClasses);
}
/**
* Creates a factory to create a JAXBHandle instance for POJO instances
* of the specified classes.
* @param context the JAXB context for marshaling the POJO classes
* @param pojoClasses the POJO classes for which this factory provides a handle
* @return the factory
* @throws JAXBException if a JAXB error occurs while initializing the new factory
*/
static public ContentHandleFactory newFactory(JAXBContext context, Class... pojoClasses)
throws JAXBException {
if (context == null || pojoClasses == null || pojoClasses.length == 0)
return null;
return new JAXBHandleFactory(context, pojoClasses);
}
/**
* Initializes the JAXB handle with the JAXB context for the classes
* of the marshalled or unmarshalled structure.
* @param context the JAXB context
*/
public JAXBHandle(JAXBContext context) {
super();
if (context == null) {
throw new IllegalArgumentException(
"null JAXB context for converting classes"
);
}
super.setFormat(Format.XML);
setResendable(true);
this.context = context;
}
/**
* Returns the root object of the JAXB structure for the content.
* @return the root JAXB object
*/
@Override
public C get() {
return content;
}
/**
* Returns the root object of the JAXB structure for the content
* cast to a more specific class.
* @param as the class of the object
* @param the type to return
* @return the root JAXB object
*/
public T get(Class as) {
if (content == null) {
return null;
}
if (as == null) {
throw new IllegalArgumentException("Cannot cast content to null class");
}
if (!as.isAssignableFrom(content.getClass())) {
throw new IllegalArgumentException(
"Cannot cast "+content.getClass().getName()+" to "+as.getName()
);
}
@SuppressWarnings("unchecked")
T content = (T) get();
return content;
}
/**
* Assigns the root object of the JAXB structure for the content.
* @param content the root JAXB object
*/
@Override
public void set(C content) {
this.content = content;
}
/**
* Assigns the root object of the JAXB structure for the content
* and returns the handle as a fluent convenience.
* @param content the root JAXB object
* @return this handle
*/
public JAXBHandle with(C content) {
set(content);
return this;
}
/**
* Restricts the format to XML.
*/
@Override
public void setFormat(Format format) {
if (format != Format.XML)
throw new IllegalArgumentException("JAXBHandle supports the XML format only");
}
/**
* Specifies the mime type of the content and returns the handle
* as a fluent convenience.
* @param mimetype the mime type of the content
* @return this handle
*/
public JAXBHandle withMimetype(String mimetype) {
setMimetype(mimetype);
return this;
}
/**
* fromBuffer() unmarshals a JAXB POJO from a byte array
* buffer. The buffer must store the marshaled XML for the
* JAXB POJO in UTF-8 encoding. JAXB cannot unmarshal arbitrary XML.
*/
@Override
public void fromBuffer(byte[] buffer) {
if (buffer == null || buffer.length == 0)
content = null;
else
receiveContent(new ByteArrayInputStream(buffer));
}
@Override
public byte[] toBuffer() {
try {
if (content == null)
return null;
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
write(buffer);
return buffer.toByteArray();
} catch (IOException e) {
throw new MarkLogicIOException(e);
}
}
/**
* Returns the JAXB structure as an XML string.
*/
@Override
public String toString() {
try {
return new String(toBuffer(),"UTF-8");
} catch (UnsupportedEncodingException e) {
throw new MarkLogicIOException(e);
}
}
/**
* Returns the unmarshaller that converts a tree data structure
* from XML to Java objects, reusing any existing unmarshaller.
* @return the unmarshaller for the JAXB context
* @throws JAXBException if unmarshaller initialization fails
*/
public Unmarshaller getUnmarshaller()
throws JAXBException {
return getUnmarshaller(true);
}
/**
* Returns the unmarshaller that converts a tree data structure
* from XML to Java objects.
* @param reuse whether to reuse an existing unmarshaller
* @return the unmarshaller for the JAXB context
* @throws JAXBException if unmarshaller initialization fails
*/
public Unmarshaller getUnmarshaller(boolean reuse)
throws JAXBException {
if (!reuse || unmarshaller == null) {
unmarshaller = context.createUnmarshaller();
}
return unmarshaller;
}
/**
* Returns the marshaller that converts a tree data structure
* from Java objects to XML, reusing any existing marshaller.
* @return the marshaller for the JAXB context
* @throws JAXBException if marshaller initialization fails
*/
public Marshaller getMarshaller()
throws JAXBException {
return getMarshaller(true);
}
/**
* Returns the marshaller that converts a tree data structure
* from Java objects to XML.
* @param reuse whether to reuse an existing marshaller
* @return the marshaller for the JAXB context
* @throws JAXBException if marshaller initialization fails
*/
public Marshaller getMarshaller(boolean reuse)
throws JAXBException {
if (!reuse || this.marshaller == null) {
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");
this.marshaller = marshaller;
}
return this.marshaller;
}
@Override
protected Class receiveAs() {
return InputStream.class;
}
@Override
protected void receiveContent(InputStream content) {
try {
@SuppressWarnings("unchecked")
C unmarshalled = (C) getUnmarshaller().unmarshal(
new InputStreamReader(content, "UTF-8")
);
this.content = unmarshalled;
} catch (JAXBException e) {
logger.error("Failed to unmarshall object read from database document",e);
throw new MarkLogicIOException(e);
} catch (UnsupportedEncodingException e) {
logger.error("Failed to unmarshall object read from database document",e);
throw new MarkLogicIOException(e);
} finally {
try {
content.close();
} catch (IOException e) {
// ignore.
}
}
}
@Override
protected OutputStreamSender sendContent() {
if (content == null) {
throw new IllegalStateException("No object to write");
}
return this;
}
@Override
public void write(OutputStream out) throws IOException {
try {
getMarshaller().marshal(content, out);
} catch (JAXBException e) {
logger.error("Failed to marshall object for writing to database document",e);
throw new MarkLogicIOException(e);
}
}
static private class JAXBHandleFactory implements ContentHandleFactory {
private Class[] pojoClasses;
private JAXBContext factoryContext;
private Set> classSet;
private JAXBHandleFactory(Class... pojoClasses)
throws JAXBException {
this(JAXBContext.newInstance(pojoClasses), pojoClasses);
}
private JAXBHandleFactory(JAXBContext factoryContext, Class... pojoClasses)
throws JAXBException {
super();
this.pojoClasses = pojoClasses;
this.factoryContext = factoryContext;
this.classSet = new HashSet>(Arrays.asList(pojoClasses));
}
@Override
public Class[] getHandledClasses() {
return pojoClasses;
}
@Override
public boolean isHandled(Class type) {
return classSet.contains(type);
}
@Override
public ContentHandle newHandle(Class type) {
ContentHandle handle = isHandled(type) ?
(ContentHandle) new JAXBHandle(factoryContext) : null;
return handle;
}
}
}