springboot容器配置源码解读

springboot内嵌了三个容器，tomcat(默认)，jetty，undertow；如何替换容器可以见这篇文章 springboot将tomcat容器换为jetty容器该文只从源码上面讨论容器的配置
相关包为spring-boot-qutoconfigure:2.4.3

第一个入口类为：
org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration

该类会加载配置类：ServerProperties

若是使用默认tomcat容器，则会创建TomcatWebServerFactoryCustomizer这个bean

ServerProperties类里面有三个非常重要的内部类Jetty,Tomcat,Undertow三个类；该类部分代码如下：

@ConfigurationProperties(prefix = "server", ignoreUnknownFields = true)
public class ServerProperties {

    /**
     * Server HTTP port.
     */
    private Integer port;

    /**
     * Network address to which the server should bind.
     */
    private InetAddress address;

    @NestedConfigurationProperty
    private final ErrorProperties error = new ErrorProperties();

    /**
     * Strategy for handling X-Forwarded-* headers.
     */
    private ForwardHeadersStrategy forwardHeadersStrategy;

    /**
     * Value to use for the Server response header (if empty, no header is sent).
     */
    private String serverHeader;

    /**
     * Maximum size of the HTTP message header.
     */
    private DataSize maxHttpHeaderSize = DataSize.ofKilobytes(8);

    /**
     * Type of shutdown that the server will support.
     */
    private Shutdown shutdown = Shutdown.IMMEDIATE;

    @NestedConfigurationProperty
    private Ssl ssl;

    @NestedConfigurationProperty
    private final Compression compression = new Compression();

    @NestedConfigurationProperty
    private final Http2 http2 = new Http2();

    private final Servlet servlet = new Servlet();

    private final Tomcat tomcat = new Tomcat();

    private final Jetty jetty = new Jetty();

    private final Netty netty = new Netty();

    private final Undertow undertow = new Undertow();
}

配置以server.开头，然后接上属性名，如下所示：
server.port 配置启动端口

默认容器Tomcat内部类代码如下：

    public static class Tomcat {

        /**
         * Access log configuration.
         */
        private final Accesslog accesslog = new Accesslog();

        /**
         * Thread related configuration.
         */
        private final Threads threads = new Threads();

        /**
         * Tomcat base directory. If not specified, a temporary directory is used.
         */
        private File basedir;

        /**
         * Delay between the invocation of backgroundProcess methods. If a duration suffix
         * is not specified, seconds will be used.
         */
        @DurationUnit(ChronoUnit.SECONDS)
        private Duration backgroundProcessorDelay = Duration.ofSeconds(10);

        /**
         * Maximum size of the form content in any HTTP post request.
         */
        private DataSize maxHttpFormPostSize = DataSize.ofMegabytes(2);

        /**
         * Maximum amount of request body to swallow.
         */
        private DataSize maxSwallowSize = DataSize.ofMegabytes(2);

        /**
         * Whether requests to the context root should be redirected by appending a / to
         * the path. When using SSL terminated at a proxy, this property should be set to
         * false.
         */
        private Boolean redirectContextRoot = true;

        /**
         * Whether HTTP 1.1 and later location headers generated by a call to sendRedirect
         * will use relative or absolute redirects.
         */
        private boolean useRelativeRedirects;

        /**
         * Character encoding to use to decode the URI.
         */
        private Charset uriEncoding = StandardCharsets.UTF_8;

        /**
         * Maximum number of connections that the server accepts and processes at any
         * given time. Once the limit has been reached, the operating system may still
         * accept connections based on the "acceptCount" property.
         */
        private int maxConnections = 8192;

        /**
         * Maximum queue length for incoming connection requests when all possible request
         * processing threads are in use.
         */
        private int acceptCount = 100;

        /**
         * Maximum number of idle processors that will be retained in the cache and reused
         * with a subsequent request. When set to -1 the cache will be unlimited with a
         * theoretical maximum size equal to the maximum number of connections.
         */
        private int processorCache = 200;

        /**
         * Comma-separated list of additional patterns that match jars to ignore for TLD
         * scanning. The special '?' and '*' characters can be used in the pattern to
         * match one and only one character and zero or more characters respectively.
         */
        private List<String> additionalTldSkipPatterns = new ArrayList<>();

        /**
         * Comma-separated list of additional unencoded characters that should be allowed
         * in URI paths. Only "< > [ \ ] ^ ` { | }" are allowed.
         */
        private List<Character> relaxedPathChars = new ArrayList<>();

        /**
         * Comma-separated list of additional unencoded characters that should be allowed
         * in URI query strings. Only "< > [ \ ] ^ ` { | }" are allowed.
         */
        private List<Character> relaxedQueryChars = new ArrayList<>();

        /**
         * Amount of time the connector will wait, after accepting a connection, for the
         * request URI line to be presented.
         */
        private Duration connectionTimeout;

        /**
         * Static resource configuration.
         */
        private final Resource resource = new Resource();

        /**
         * Modeler MBean Registry configuration.
         */
        private final Mbeanregistry mbeanregistry = new Mbeanregistry();

        /**
         * Remote Ip Valve configuration.
         */
        private final Remoteip remoteip = new Remoteip();

}

默认参数基本都够用了，其中处理请求线程的配置Threads代码如下：

/**
* Tomcat thread properties.
*/
public static class Threads {

    /**
    * Maximum amount of worker threads.
    */
    private int max = 200;

    /**
    * Minimum amount of worker threads.
    */
    private int minSpare = 10;
}

若是网站并发较高，可以调max大小，
server.tomcat.threads.max = 300

总结：
1，配置都在ServerProperties这个类中
2，配置以server.开头，加类的属性名即可