Java tutorial
/** * 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 net.logstash.logback.composite; import java.io.IOException; import java.io.OutputStream; import java.io.Writer; import java.lang.ref.SoftReference; import net.logstash.logback.decorate.JsonFactoryDecorator; import net.logstash.logback.decorate.JsonGeneratorDecorator; import net.logstash.logback.decorate.NullJsonFactoryDecorator; import net.logstash.logback.decorate.NullJsonGeneratorDecorator; import ch.qos.logback.access.spi.IAccessEvent; import ch.qos.logback.classic.spi.ILoggingEvent; import ch.qos.logback.core.spi.ContextAware; import ch.qos.logback.core.spi.ContextAwareBase; import ch.qos.logback.core.spi.DeferredProcessingAware; import ch.qos.logback.core.spi.LifeCycle; import com.fasterxml.jackson.core.JsonEncoding; import com.fasterxml.jackson.core.JsonFactory; import com.fasterxml.jackson.core.JsonGenerator; import com.fasterxml.jackson.core.io.SegmentedStringWriter; import com.fasterxml.jackson.core.util.BufferRecycler; import com.fasterxml.jackson.core.util.ByteArrayBuilder; import com.fasterxml.jackson.databind.MappingJsonFactory; /** * Formats logstash Events as JSON using {@link JsonProvider}s. * <p> * * The {@link CompositeJsonFormatter} starts the JSON object ('{'), * then delegates writing the contents of the object to the {@link JsonProvider}s, * and then ends the JSON object ('}'). * * @param <Event> type of event ({@link ILoggingEvent} or {@link IAccessEvent}). */ public abstract class CompositeJsonFormatter<Event extends DeferredProcessingAware> extends ContextAwareBase implements LifeCycle { /** * This <code>ThreadLocal</code> contains a {@link java.lang.ref.SoftReference} * to a {@link BufferRecycler} used to provide a low-cost * buffer recycling between writer instances. */ private final ThreadLocal<SoftReference<BufferRecycler>> recycler = new ThreadLocal<SoftReference<BufferRecycler>>() { protected SoftReference<BufferRecycler> initialValue() { final BufferRecycler bufferRecycler = new BufferRecycler(); return new SoftReference<BufferRecycler>(bufferRecycler); } }; /** * Used to create the necessary {@link JsonGenerator}s for generating JSON. */ private MappingJsonFactory jsonFactory = (MappingJsonFactory) new MappingJsonFactory() .enable(JsonGenerator.Feature.ESCAPE_NON_ASCII) /* * When generators are flushed, don't flush the underlying outputStream. * * This allows some streaming optimizations when using an encoder. * * The encoder generally determines when the stream should be flushed * by an 'immediateFlush' property. * * The 'immediateFlush' property of the encoder can be set to false * when the appender performs the flushes at appropriate times * (such as the end of a batch in the AbstractLogstashTcpSocketAppender). */ .disable(JsonGenerator.Feature.FLUSH_PASSED_TO_STREAM); /** * Decorates the {@link #jsonFactory}. * Allows customization of the {@link #jsonFactory}. */ private JsonFactoryDecorator jsonFactoryDecorator = new NullJsonFactoryDecorator(); /** * Decorates the generators generated by the {@link #jsonFactory}. * Allows customization of the generators. */ private JsonGeneratorDecorator jsonGeneratorDecorator = new NullJsonGeneratorDecorator(); /** * The providers that are used to populate the output JSON object. */ private JsonProviders<Event> jsonProviders = new JsonProviders<Event>(); private JsonEncoding encoding = JsonEncoding.UTF8; private volatile boolean started; public CompositeJsonFormatter(ContextAware declaredOrigin) { super(declaredOrigin); } @Override public void start() { if (jsonProviders.getProviders().isEmpty()) { addError("No providers configured"); } jsonFactory = this.jsonFactoryDecorator.decorate(this.jsonFactory); jsonProviders.setJsonFactory(jsonFactory); jsonProviders.setContext(context); jsonProviders.start(); started = true; } @Override public void stop() { jsonProviders.stop(); started = false; } @Override public boolean isStarted() { return started; } public byte[] writeEventAsBytes(Event event) throws IOException { ByteArrayBuilder outputStream = new ByteArrayBuilder(getBufferRecycler()); try { writeEventToOutputStream(event, outputStream); outputStream.flush(); return outputStream.toByteArray(); } finally { outputStream.release(); } } public void writeEventToOutputStream(Event event, OutputStream outputStream) throws IOException { JsonGenerator generator = createGenerator(outputStream); writeEventToGenerator(generator, event); /* * Do not flush the outputStream. * * Allow something higher in the stack (e.g. the encoder/appender) * to determine appropriate times to flush. */ } public String writeEventAsString(Event event) throws IOException { SegmentedStringWriter writer = new SegmentedStringWriter(getBufferRecycler()); JsonGenerator generator = createGenerator(writer); writeEventToGenerator(generator, event); writer.flush(); return writer.getAndClear(); } protected void writeEventToGenerator(JsonGenerator generator, Event event) throws IOException { if (!isStarted()) { throw new IllegalStateException("Encoding attempted before starting."); } generator.writeStartObject(); jsonProviders.writeTo(generator, event); generator.writeEndObject(); generator.flush(); } protected void prepareForDeferredProcessing(Event event) { event.prepareForDeferredProcessing(); jsonProviders.prepareForDeferredProcessing(event); } private JsonGenerator createGenerator(OutputStream outputStream) throws IOException { return this.jsonGeneratorDecorator.decorate(jsonFactory.createGenerator(outputStream, encoding)); } private JsonGenerator createGenerator(Writer writer) throws IOException { return this.jsonGeneratorDecorator.decorate(jsonFactory.createGenerator(writer)); } private BufferRecycler getBufferRecycler() { SoftReference<BufferRecycler> bufferRecyclerReference = recycler.get(); BufferRecycler bufferRecycler = bufferRecyclerReference.get(); if (bufferRecycler == null) { recycler.remove(); return getBufferRecycler(); } return bufferRecycler; } public JsonFactory getJsonFactory() { return jsonFactory; } public JsonFactoryDecorator getJsonFactoryDecorator() { return jsonFactoryDecorator; } public void setJsonFactoryDecorator(JsonFactoryDecorator jsonFactoryDecorator) { this.jsonFactoryDecorator = jsonFactoryDecorator; } public JsonGeneratorDecorator getJsonGeneratorDecorator() { return jsonGeneratorDecorator; } public void setJsonGeneratorDecorator(JsonGeneratorDecorator jsonGeneratorDecorator) { this.jsonGeneratorDecorator = jsonGeneratorDecorator; } public JsonProviders<Event> getProviders() { return jsonProviders; } public String getEncoding() { return encoding.getJavaName(); } public void setEncoding(String encodingName) { for (JsonEncoding encoding : JsonEncoding.values()) { if (encoding.getJavaName().equals(encodingName) || encoding.name().equals(encodingName)) { this.encoding = encoding; return; } } throw new IllegalArgumentException("Unknown encoding " + encodingName); } public void setProviders(JsonProviders<Event> jsonProviders) { this.jsonProviders = jsonProviders; } }