Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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 org.apache.nifi.processors.email; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.ArrayList; import java.util.Collections; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Properties; import java.util.Set; import java.util.Date; import javax.activation.DataSource; import javax.mail.Address; import javax.mail.MessagingException; import javax.mail.Session; import javax.mail.internet.MimeMessage; import org.apache.commons.io.IOUtils; import org.apache.commons.lang3.StringUtils; import org.apache.commons.mail.util.MimeMessageParser; import org.apache.nifi.annotation.behavior.EventDriven; import org.apache.nifi.annotation.behavior.InputRequirement; import org.apache.nifi.annotation.behavior.InputRequirement.Requirement; import org.apache.nifi.annotation.behavior.SideEffectFree; import org.apache.nifi.annotation.behavior.SupportsBatching; import org.apache.nifi.annotation.behavior.WritesAttribute; import org.apache.nifi.annotation.behavior.WritesAttributes; import org.apache.nifi.annotation.documentation.CapabilityDescription; import org.apache.nifi.annotation.documentation.Tags; import org.apache.nifi.components.PropertyDescriptor; import org.apache.nifi.flowfile.FlowFile; import org.apache.nifi.flowfile.attributes.CoreAttributes; import org.apache.nifi.logging.ComponentLog; import org.apache.nifi.processor.AbstractProcessor; import org.apache.nifi.processor.ProcessContext; import org.apache.nifi.processor.ProcessSession; import org.apache.nifi.processor.ProcessorInitializationContext; import org.apache.nifi.processor.Relationship; import org.apache.nifi.processor.exception.FlowFileHandlingException; import org.apache.nifi.processor.io.InputStreamCallback; import org.apache.nifi.processor.io.OutputStreamCallback; import org.apache.nifi.stream.io.BufferedInputStream; @SupportsBatching @EventDriven @SideEffectFree @Tags({ "split", "email" }) @InputRequirement(Requirement.INPUT_REQUIRED) @CapabilityDescription("Extract attachments from a mime formatted email file, splitting them into individual flowfiles.") @WritesAttributes({ @WritesAttribute(attribute = "filename ", description = "The filename of the attachment"), @WritesAttribute(attribute = "email.attachment.parent.filename ", description = "The filename of the parent FlowFile"), @WritesAttribute(attribute = "email.attachment.parent.uuid", description = "The UUID of the original FlowFile."), @WritesAttribute(attribute = "mime.type", description = "The mime type of the attachment.") }) public class ExtractEmailAttachments extends AbstractProcessor { public static final String ATTACHMENT_ORIGINAL_FILENAME = "email.attachment.parent.filename"; public static final String ATTACHMENT_ORIGINAL_UUID = "email.attachment.parent.uuid"; public static final Relationship REL_ATTACHMENTS = new Relationship.Builder().name("attachments") .description("Each individual attachment will be routed to the attachments relationship").build(); public static final Relationship REL_ORIGINAL = new Relationship.Builder().name("original") .description("The original file").build(); public static final Relationship REL_FAILURE = new Relationship.Builder().name("failure") .description("Flowfiles that could not be parsed").build(); private Set<Relationship> relationships; private List<PropertyDescriptor> descriptors; @Override protected void init(final ProcessorInitializationContext context) { final Set<Relationship> relationships = new HashSet<>(); relationships.add(REL_ATTACHMENTS); relationships.add(REL_ORIGINAL); relationships.add(REL_FAILURE); this.relationships = Collections.unmodifiableSet(relationships); final List<PropertyDescriptor> descriptors = new ArrayList<>(); this.descriptors = Collections.unmodifiableList(descriptors); } @Override public void onTrigger(final ProcessContext context, final ProcessSession session) { final ComponentLog logger = getLogger(); final FlowFile originalFlowFile = session.get(); if (originalFlowFile == null) { return; } final List<FlowFile> attachmentsList = new ArrayList<>(); final List<FlowFile> invalidFlowFilesList = new ArrayList<>(); final List<FlowFile> originalFlowFilesList = new ArrayList<>(); session.read(originalFlowFile, new InputStreamCallback() { @Override public void process(final InputStream rawIn) throws IOException { try (final InputStream in = new BufferedInputStream(rawIn)) { Properties props = new Properties(); Session mailSession = Session.getDefaultInstance(props, null); MimeMessage originalMessage = new MimeMessage(mailSession, in); MimeMessageParser parser = new MimeMessageParser(originalMessage).parse(); // RFC-2822 determines that a message must have a "From:" header // if a message lacks the field, it is flagged as invalid Address[] from = originalMessage.getFrom(); Date sentDate = originalMessage.getSentDate(); if (from == null || sentDate == null) { // Throws MessageException due to lack of minimum required headers throw new MessagingException("Message failed RFC2822 validation"); } originalFlowFilesList.add(originalFlowFile); if (parser.hasAttachments()) { final String originalFlowFileName = originalFlowFile .getAttribute(CoreAttributes.FILENAME.key()); try { for (final DataSource data : parser.getAttachmentList()) { FlowFile split = session.create(originalFlowFile); final Map<String, String> attributes = new HashMap<>(); if (StringUtils.isNotBlank(data.getName())) { attributes.put(CoreAttributes.FILENAME.key(), data.getName()); } if (StringUtils.isNotBlank(data.getContentType())) { attributes.put(CoreAttributes.MIME_TYPE.key(), data.getContentType()); } String parentUuid = originalFlowFile.getAttribute(CoreAttributes.UUID.key()); attributes.put(ATTACHMENT_ORIGINAL_UUID, parentUuid); attributes.put(ATTACHMENT_ORIGINAL_FILENAME, originalFlowFileName); split = session.append(split, new OutputStreamCallback() { @Override public void process(OutputStream out) throws IOException { IOUtils.copy(data.getInputStream(), out); } }); split = session.putAllAttributes(split, attributes); attachmentsList.add(split); } } catch (FlowFileHandlingException e) { // Something went wrong // Removing splits that may have been created session.remove(attachmentsList); // Removing the original flow from its list originalFlowFilesList.remove(originalFlowFile); logger.error( "Flowfile {} triggered error {} while processing message removing generated FlowFiles from sessions", new Object[] { originalFlowFile, e }); invalidFlowFilesList.add(originalFlowFile); } } } catch (Exception e) { // Another error hit... // Removing the original flow from its list originalFlowFilesList.remove(originalFlowFile); logger.error("Could not parse the flowfile {} as an email, treating as failure", new Object[] { originalFlowFile, e }); // Message is invalid or triggered an error during parsing invalidFlowFilesList.add(originalFlowFile); } } }); session.transfer(attachmentsList, REL_ATTACHMENTS); // As per above code, originalFlowfile may be routed to invalid or // original depending on RFC2822 compliance. session.transfer(invalidFlowFilesList, REL_FAILURE); session.transfer(originalFlowFilesList, REL_ORIGINAL); if (attachmentsList.size() > 10) { logger.info("Split {} into {} files", new Object[] { originalFlowFile, attachmentsList.size() }); } else if (attachmentsList.size() > 1) { logger.info("Split {} into {} files: {}", new Object[] { originalFlowFile, attachmentsList.size(), attachmentsList }); } } @Override public Set<Relationship> getRelationships() { return this.relationships; } @Override public final List<PropertyDescriptor> getSupportedPropertyDescriptors() { return descriptors; } }