composer.json文件怎么使用

"psr-4": {
            "tools\\": "tools/"
        }

composer dump-autoload -o

dump-autoload

If you need to update the autoloader(类加载器) because of new classes in a classmap package for example, you can use "dump-autoload" to do that without having to go through an install or update.
Additionally, it can dump an optimized(优化) autoloader that converts(转化) PSR-0/4 packages into classmap ones for performance(性能) reasons. In large applications with many classes, the autoloader can take up a substantial portion of every request's time. Using classmaps for everything is less convenient in development, but using this option you can still use PSR-0/4 for convenience and classmaps for performance.
Options:
--no-scripts: Skips the execution of all scripts defined in composer.json file.
--optimize (-o): Convert PSR-0/4 autoloading to classmap to get a faster autoloader. This is recommended especially for production, but can take a bit of time to run so it is currently not done by default.
--classmap-authoritative (-a): Autoload classes from the classmap only. Implicitly enables --optimize.
--apcu: Use APCu to cache found/not-found classes.
--no-dev: Disables autoload-dev rules.