Sentry是如何捕获异常的？

Sentry is cross-platform application monitoring, with a focus on error reporting.

在Sentry提供的Java SDK中，提供了项目异常收集功能。对于已捕获的异常，可以通过logger框架集成对应的appender实现自动上传； 对于未捕获的异常，比如runtimeException或者人工吃掉的异常，可以通过 Thread.setDefaultUncaughtExceptionHandler() 设置默认的全局异常处理器来收集。

Sentry异常收集.png

io.sentry.SentryUncaughtExceptionHandler

package io.sentry;

public class SentryUncaughtExceptionHandler implements Thread.UncaughtExceptionHandler {
    /**
     * Configures an uncaught exception handler which sends events to
     * Sentry, then calls the preexisting uncaught exception handler.
     *
     * @return {@link SentryUncaughtExceptionHandler} that was setup.
     */
    public static SentryUncaughtExceptionHandler setup() {
        logger.debug("Configuring uncaught exception handler.");

        Thread.UncaughtExceptionHandler currentHandler = Thread.getDefaultUncaughtExceptionHandler();
        if (currentHandler != null) {
            logger.debug("default UncaughtExceptionHandler class='" + currentHandler.getClass().getName() + "'");
        }

        SentryUncaughtExceptionHandler handler = new SentryUncaughtExceptionHandler(currentHandler);
        Thread.setDefaultUncaughtExceptionHandler(handler);
        return handler;
    }


·····省略

/**
     * Sends any uncaught exception to Sentry, then passes the exception on to the pre-existing
     * uncaught exception handler.
     *
     * @param thread thread that threw the error
     * @param thrown the uncaught throwable
     */
    @Override
    public void uncaughtException(Thread thread, Throwable thrown) {
        if (enabled) {
            logger.trace("Uncaught exception received.");

            EventBuilder eventBuilder = new EventBuilder()
                .withMessage(thrown.getMessage())
                .withLevel(Event.Level.FATAL)
                .withSentryInterface(new ExceptionInterface(thrown));

            try {
                Sentry.capture(eventBuilder);
            } catch (RuntimeException e) {
                logger.error("Error sending uncaught exception to Sentry.", e);
            }
        }

        // taken from ThreadGroup#uncaughtException
        if (defaultExceptionHandler != null) {
            // call the original handler
            defaultExceptionHandler.uncaughtException(thread, thrown);
        } else if (!(thrown instanceof ThreadDeath)) {
            // CHECKSTYLE.OFF: RegexpSinglelineJava
            System.err.print("Exception in thread \"" + thread.getName() + "\" ");
            thrown.printStackTrace(System.err);
            // CHECKSTYLE.ON: RegexpSinglelineJava
        }
    }
}