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INT-4118: Detect EOF on stdin

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JIRA: https://jira.spring.io/browse/INT-4118

Add an option to the `CharacterStreamReadingMessageSource` to detect EOF
on the stream and close the context.

Publish event instead of closing context.

Polishing - PR Comments

Polishing

Docs about stopping the poller.

* Fix typos in the docs
This commit is contained in:
Gary Russell
2016-09-22 11:54:00 -04:00
committed by Artem Bilan
parent a7171c4db9
commit f9ddefec2c
9 changed files with 306 additions and 21 deletions
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103
spring-integration-stream/src/main/java/org/springframework/integration/stream/CharacterStreamReadingMessageSource.java
View File

@@ -1,5 +1,5 @@
/*
* Copyright 2002-2010 the original author or authors.
* Copyright 2002-2016 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -22,10 +22,12 @@ import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessagingException;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.integration.context.IntegrationObjectSupport;
import org.springframework.integration.core.MessageSource;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessagingException;
import org.springframework.messaging.support.GenericMessage;
import org.springframework.util.Assert;
@@ -33,19 +35,61 @@ import org.springframework.util.Assert;
* A pollable source for {@link Reader Readers}.
*
* @author Mark Fisher
* @author Gary Russell
*/
public class CharacterStreamReadingMessageSource extends IntegrationObjectSupport implements MessageSource<String> {
public class CharacterStreamReadingMessageSource extends IntegrationObjectSupport implements MessageSource<String>,
ApplicationEventPublisherAware {
private final BufferedReader reader;
private final Object monitor;
private final boolean blockToDetectEOF;
private ApplicationEventPublisher applicationEventPublisher;
/**
* Construct an instance with the provider reader.
* {@link #receive()} will return {@code null} when the reader is not ready.
* @param reader the reader.
*/
public CharacterStreamReadingMessageSource(Reader reader) {
this(reader, -1);
this(reader, -1, false);
}
/**
* Construct an instance with the provider reader and buffer size.
* {@link #receive()} will return {@code null} when the reader is not ready.
* @param reader the reader.
* @param bufferSize the buffer size.
*/
public CharacterStreamReadingMessageSource(Reader reader, int bufferSize) {
this(reader, bufferSize, false);
}
/**
* Construct an instance with the provided reader and buffer size.
* When {@code blockToDetectEOF} is {@code false},
* {@link #receive()} will return {@code null} when the reader is not ready.
* When it is {@code true}, the thread will block until data is available; when the
* underlying stream is closed, a {@link StreamClosedEvent} is published to inform
* the application via an {@link org.springframework.context.ApplicationListener}.
* This can be useful, for example, when piping stdin
* <pre class="code">
* cat foo.txt | java -jar my.jar
* </pre>
* or
* <pre class="code">
* java -jar my.jar &lt; foo.txt
* </pre>
* @param reader the reader.
* @param bufferSize the buffer size; if negative use the default in
* {@link BufferedReader}.
* @param blockToDetectEOF true to block the thread until data is available and
* publish a {@link StreamClosedEvent} at EOF.
* @since 5.0
*/
public CharacterStreamReadingMessageSource(Reader reader, int bufferSize, boolean blockToDetectEOF) {
Assert.notNull(reader, "reader must not be null");
this.monitor = reader;
if (reader instanceof BufferedReader) {
@@ -57,20 +101,30 @@ public class CharacterStreamReadingMessageSource extends IntegrationObjectSuppor
else {
this.reader = new BufferedReader(reader);
}
this.blockToDetectEOF = blockToDetectEOF;
}
@Override
public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
this.applicationEventPublisher = applicationEventPublisher;
}
@Override
public String getComponentType() {
return "stream:stdin-channel-adapter(character)";
}
@Override
public Message<String> receive() {
try {
synchronized (this.monitor) {
if (!this.reader.ready()) {
if (!this.blockToDetectEOF && !this.reader.ready()) {
return null;
}
String line = this.reader.readLine();
if (line == null && this.applicationEventPublisher != null) {
this.applicationEventPublisher.publishEvent(new StreamClosedEvent(this));
}
return (line != null) ? new GenericMessage<String>(line) : null;
}
}
@@ -80,10 +134,19 @@ public class CharacterStreamReadingMessageSource extends IntegrationObjectSuppor
}
/**
* Create a source that reads from {@link System#in}. EOF will not be detected.
* @return the stream.
*/
public static final CharacterStreamReadingMessageSource stdin() {
return new CharacterStreamReadingMessageSource(new InputStreamReader(System.in));
}
/**
* Create a source that reads from {@link System#in}. EOF will not be detected.
* @param charsetName the charset to use when converting bytes to String.
* @return the stream.
*/
public static final CharacterStreamReadingMessageSource stdin(String charsetName) {
try {
return new CharacterStreamReadingMessageSource(new InputStreamReader(System.in, charsetName));
@@ -93,4 +156,32 @@ public class CharacterStreamReadingMessageSource extends IntegrationObjectSuppor
}
}
/**
* Create a source that reads from {@link System#in}. EOF will be detected and the application
* context closed.
* @return the stream.
* @see CharacterStreamReadingMessageSource#CharacterStreamReadingMessageSource(Reader, int, boolean)
* @since 5.0
*/
public static final CharacterStreamReadingMessageSource stdinPipe() {
return new CharacterStreamReadingMessageSource(new InputStreamReader(System.in), -1, true);
}
/**
* Create a source that reads from {@link System#in}. EOF will be detected and the application
* context closed.
* @param charsetName the charset to use when converting bytes to String.
* @return the stream.
* @see CharacterStreamReadingMessageSource#CharacterStreamReadingMessageSource(Reader, int, boolean)
* @since 5.0
*/
public static final CharacterStreamReadingMessageSource stdinPipe(String charsetName) {
try {
return new CharacterStreamReadingMessageSource(new InputStreamReader(System.in, charsetName), -1, true);
}
catch (UnsupportedEncodingException e) {
throw new IllegalArgumentException("unsupported encoding: " + charsetName, e);
}
}
}

35
spring-integration-stream/src/main/java/org/springframework/integration/stream/StreamClosedEvent.java Normal file
View File

@@ -0,0 +1,35 @@
/*
* Copyright 2016 the original author or authors.
*
* 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 org.springframework.integration.stream;
import org.springframework.integration.event.IntegrationEvent;
/**
* Application event published when EOF is detected on a stream.
*
* @author Gary Russell
* @since 5.0
*
*/
@SuppressWarnings("serial")
public class StreamClosedEvent extends IntegrationEvent {
public StreamClosedEvent(Object source) {
super(source);
}
}

14
spring-integration-stream/src/main/java/org/springframework/integration/stream/config/ConsoleInboundChannelAdapterParser.java
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@@ -1,5 +1,5 @@
/*
* Copyright 2002-2010 the original author or authors.
* Copyright 2002-2016 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -22,20 +22,28 @@ import org.springframework.beans.BeanMetadataElement;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.integration.config.xml.AbstractPollingInboundChannelAdapterParser;
import org.springframework.integration.stream.CharacterStreamReadingMessageSource;
import org.springframework.util.StringUtils;
/**
* Parser for the &lt;stdin-channel-adapter&gt; element.
*
* @author Mark Fisher
* @author Gary Russell
*/
public class ConsoleInboundChannelAdapterParser extends AbstractPollingInboundChannelAdapterParser {
@Override
protected BeanMetadataElement parseSource(Element element, ParserContext parserContext) {
BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(
"org.springframework.integration.stream.CharacterStreamReadingMessageSource");
builder.setFactoryMethod("stdin");
CharacterStreamReadingMessageSource.class);
String pipe = element.getAttribute("detect-eof");
if (StringUtils.hasText(pipe)) {
builder.setFactoryMethod("stdinPipe");
}
else {
builder.setFactoryMethod("stdin");
}
String charsetName = element.getAttribute("charset");
if (StringUtils.hasText(charsetName)) {
builder.addConstructorArgValue(charsetName);

21
spring-integration-stream/src/main/resources/org/springframework/integration/stream/config/spring-integration-stream-5.0.xsd
View File

@@ -32,7 +32,26 @@
<xsd:element ref="integration:poller" minOccurs="0" maxOccurs="1"/>
</xsd:sequence>
<xsd:attributeGroup ref="integration:channelAdapterAttributes"/>
<xsd:attribute name="charset" type="xsd:string"/>
<xsd:attribute name="charset" type="xsd:string">
<xsd:annotation>
<xsd:documentation>
The charset to use when converting the byte stream from stdin to
String.
</xsd:documentation>
</xsd:annotation>
</xsd:attribute>
<xsd:attribute name="detect-eof">
<xsd:annotation>
<xsd:documentation>
When 'true' an application event is published when EOF is detected
on stdin. To facilitate this, the poller thread will block until data is
present or EOF is detected.
</xsd:documentation>
</xsd:annotation>
<xsd:simpleType>
<xsd:union memberTypes="xsd:boolean xsd:string"/>
</xsd:simpleType>
</xsd:attribute>
</xsd:complexType>
</xsd:element>