StructuredLogEncoder Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/logging/logback/StructuredLogEncoder.java lines 48–156

public class StructuredLogEncoder extends EncoderBase<ILoggingEvent> {

	private final ThrowableProxyConverter throwableProxyConverter = new ThrowableProxyConverter();

	private @Nullable String format;

	private @Nullable StructuredLogFormatter<ILoggingEvent> formatter;

	private @Nullable Charset charset = StandardCharsets.UTF_8;

	public void setFormat(String format) {
		this.format = format;
	}

	public void setCharset(@Nullable Charset charset) {
		this.charset = charset;
	}

	@Override
	public void start() {
		Assert.state(this.format != null, "Format has not been set");
		this.formatter = createFormatter(this.format);
		super.start();
		this.throwableProxyConverter.start();
	}

	private StructuredLogFormatter<ILoggingEvent> createFormatter(String format) {
		Environment environment = (Environment) getContext().getObject(Environment.class.getName());
		Assert.state(environment != null, "Unable to find Spring Environment in logger context");
		return new StructuredLogFormatterFactory<>(ILoggingEvent.class, environment, this::addAvailableParameters,
				this::addCommonFormatters)
			.get(format);
	}

	private void addAvailableParameters(AvailableParameters availableParameters) {
		availableParameters.add(ThrowableProxyConverter.class, this.throwableProxyConverter);
	}

	private void addCommonFormatters(CommonFormatters<ILoggingEvent> commonFormatters) {
		commonFormatters.add(CommonStructuredLogFormat.ELASTIC_COMMON_SCHEMA, this::createEcsFormatter);
		commonFormatters.add(CommonStructuredLogFormat.GRAYLOG_EXTENDED_LOG_FORMAT, this::createGraylogFormatter);
		commonFormatters.add(CommonStructuredLogFormat.LOGSTASH, this::createLogstashFormatter);
	}

	private StructuredLogFormatter<ILoggingEvent> createEcsFormatter(Instantiator<?> instantiator) {
		Environment environment = instantiator.getArg(Environment.class);
		StackTracePrinter stackTracePrinter = instantiator.getArg(StackTracePrinter.class);
		ContextPairs contextPairs = instantiator.getArg(ContextPairs.class);
		ThrowableProxyConverter throwableProxyConverter = instantiator.getArg(ThrowableProxyConverter.class);
		StructuredLoggingJsonMembersCustomizer.Builder<?> jsonMembersCustomizerBuilder = instantiator
			.getArg(StructuredLoggingJsonMembersCustomizer.Builder.class);
		Assert.state(environment != null, "'environment' must not be null");
		Assert.state(contextPairs != null, "'contextPairs' must not be null");
		Assert.state(throwableProxyConverter != null, "'throwableProxyConverter' must not be null");
		Assert.state(jsonMembersCustomizerBuilder != null, "'jsonMembersCustomizerBuilder' must not be null");
		return new ElasticCommonSchemaStructuredLogFormatter(environment, stackTracePrinter, contextPairs,
				throwableProxyConverter, jsonMembersCustomizerBuilder);
	}

	private StructuredLogFormatter<ILoggingEvent> createGraylogFormatter(Instantiator<?> instantiator) {
		Environment environment = instantiator.getArg(Environment.class);
		StackTracePrinter stackTracePrinter = instantiator.getArg(StackTracePrinter.class);
		ContextPairs contextPairs = instantiator.getArg(ContextPairs.class);
		ThrowableProxyConverter throwableProxyConverter = instantiator.getArg(ThrowableProxyConverter.class);
		StructuredLoggingJsonMembersCustomizer<?> jsonMembersCustomizer = instantiator
			.getArg(StructuredLoggingJsonMembersCustomizer.class);
		Assert.state(environment != null, "'environment' must not be null");
		Assert.state(contextPairs != null, "'contextPairs' must not be null");
		Assert.state(throwableProxyConverter != null, "'throwableProxyConverter' must not be null");
		return new GraylogExtendedLogFormatStructuredLogFormatter(environment, stackTracePrinter, contextPairs,
				throwableProxyConverter, jsonMembersCustomizer);
	}

	private StructuredLogFormatter<ILoggingEvent> createLogstashFormatter(Instantiator<?> instantiator) {
		StackTracePrinter stackTracePrinter = instantiator.getArg(StackTracePrinter.class);
		ContextPairs contextPairs = instantiator.getArg(ContextPairs.class);
		ThrowableProxyConverter throwableProxyConverter = instantiator.getArg(ThrowableProxyConverter.class);
		StructuredLoggingJsonMembersCustomizer<?> jsonMembersCustomizer = instantiator
			.getArg(StructuredLoggingJsonMembersCustomizer.class);
		Assert.state(contextPairs != null, "'contextPairs' must not be null");
		Assert.state(throwableProxyConverter != null, "'throwableProxyConverter' must not be null");
		return new LogstashStructuredLogFormatter(stackTracePrinter, contextPairs, throwableProxyConverter,
				jsonMembersCustomizer);
	}

	@Override
	public void stop() {
		this.throwableProxyConverter.stop();
		super.stop();
	}

	@Override
	public byte @Nullable [] headerBytes() {
		return null;
	}

	@Override
	public byte[] encode(ILoggingEvent event) {
		Assert.state(this.formatter != null,
				"formatter must not be null. Make sure to call start() before this method");
		return this.formatter.formatAsBytes(event, (this.charset != null) ? this.charset : StandardCharsets.UTF_8);
	}

	@Override
	public byte @Nullable [] footerBytes() {
		return null;
	}

}