Spring Boot內嵌的Web容器

Spring Boot內嵌Web容器主要有三種：

• tomcat（默認）
• jetty
• undertow

1. tomcat容器

在spring boot中，有關內嵌tomcat的默認屬性配置以下，前綴爲 server.tomcat （參考官方文檔）：

server.tomcat.accept-count=100 # Maximum queue length for incoming connection requests when all possible request processing threads are in use.
server.tomcat.accesslog.buffered=true # Whether to buffer output such that it is flushed only periodically.
server.tomcat.accesslog.directory=logs # Directory in which log files are created. Can be absolute or relative to the Tomcat base dir.
server.tomcat.accesslog.enabled=false # Enable access log.
server.tomcat.accesslog.file-date-format=.yyyy-MM-dd # Date format to place in the log file name.
server.tomcat.accesslog.pattern=common # Format pattern for access logs.
server.tomcat.accesslog.prefix=access_log # Log file name prefix.
server.tomcat.accesslog.rename-on-rotate=false # Whether to defer inclusion of the date stamp in the file name until rotate time.
server.tomcat.accesslog.request-attributes-enabled=false # Set request attributes for the IP address, Hostname, protocol, and port used for the request.
server.tomcat.accesslog.rotate=true # Whether to enable access log rotation.
server.tomcat.accesslog.suffix=.log # Log file name suffix.
server.tomcat.additional-tld-skip-patterns= # Comma-separated list of additional patterns that match jars to ignore for TLD scanning.
server.tomcat.background-processor-delay=10s # Delay between the invocation of backgroundProcess methods. If a duration suffix is not specified, seconds will be used.
server.tomcat.basedir= # Tomcat base directory. If not specified, a temporary directory is used.
server.tomcat.internal-proxies=10\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}|\\
        192\\.168\\.\\d{1,3}\\.\\d{1,3}|\\
        169\\.254\\.\\d{1,3}\\.\\d{1,3}|\\
        127\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}|\\
        172\\.1[6-9]{1}\\.\\d{1,3}\\.\\d{1,3}|\\
        172\\.2[0-9]{1}\\.\\d{1,3}\\.\\d{1,3}|\\
        172\\.3[0-1]{1}\\.\\d{1,3}\\.\\d{1,3}\\
        0:0:0:0:0:0:0:1\\
        ::1 # Regular expression that matches proxies that are to be trusted.
server.tomcat.max-connections=10000 # Maximum number of connections that the server accepts and processes at any given time.
server.tomcat.max-http-post-size=2MB # Maximum size of the HTTP post content.
server.tomcat.max-swallow-size=2MB # Maximum amount of request body to swallow.
server.tomcat.max-threads=200 # Maximum amount of worker threads.
server.tomcat.min-spare-threads=10 # Minimum amount of worker threads.
server.tomcat.port-header=X-Forwarded-Port # Name of the HTTP header used to override the original port value.
server.tomcat.protocol-header= # Header that holds the incoming protocol, usually named "X-Forwarded-Proto".
server.tomcat.protocol-header-https-value=https # Value of the protocol header indicating whether the incoming request uses SSL.
server.tomcat.redirect-context-root=true # Whether requests to the context root should be redirected by appending a / to the path.
server.tomcat.remote-ip-header= # Name of the HTTP header from which the remote IP is extracted. For instance, `X-FORWARDED-FOR`.
server.tomcat.resource.allow-caching=true # Whether static resource caching is permitted for this web application.
server.tomcat.resource.cache-ttl= # Time-to-live of the static resource cache.
server.tomcat.uri-encoding=UTF-8 # Character encoding to use to decode the URI.

另外還能夠經過源碼來查看tomcat的相關配置屬性，位於org.springframework.boot.autoconfigure包下org.springframework.boot.autoconfigure.web.ServerProperties 中，部分源碼以下：

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

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

        /**
         * Regular expression that matches proxies that are to be trusted.
         */
        private String internalProxies = "10\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}|" // 10/8
                + "192\\.168\\.\\d{1,3}\\.\\d{1,3}|" // 192.168/16
                + "169\\.254\\.\\d{1,3}\\.\\d{1,3}|" // 169.254/16
                + "127\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}|" // 127/8
                + "172\\.1[6-9]{1}\\.\\d{1,3}\\.\\d{1,3}|" // 172.16/12
                + "172\\.2[0-9]{1}\\.\\d{1,3}\\.\\d{1,3}|"
                + "172\\.3[0-1]{1}\\.\\d{1,3}\\.\\d{1,3}|" //
                + "0:0:0:0:0:0:0:1|::1";
        
        .......(省略)
        
        /**
         * Maximum amount of worker threads.
         */
        private int maxThreads = 200;

        /**
         * Minimum amount of worker threads.
         */
        private int minSpareThreads = 10;
        
        .......(省略)
        
        /**
         * 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 = 10000;

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

在默認狀況下，常常會關注的幾個屬性值：

• server.tomcat.max-threads=200：最大工做線程數是200
• server.tomcat.min-spare-threads=10：最小工做線程數是10
• server.tomcat.max-connections = 10000：最大鏈接數爲10000

若是須要覆蓋默認的配置，能夠在application.properties或者application.yml中指定相關屬性值

server:
    tomcat:
        uri-encoding: UTF-8
        max-threads: 20
        min-spare-threads: 5
        max-connections: 1000

2. jetty容器

有關jetty的默認屬性配置以下：

server.jetty.acceptors=-1 # Number of acceptor threads to use. When the value is -1, the default, the number of acceptors is derived from the operating environment.
server.jetty.accesslog.append=false # Append to log.
server.jetty.accesslog.date-format=dd/MMM/yyyy:HH:mm:ss Z # Timestamp format of the request log.
server.jetty.accesslog.enabled=false # Enable access log.
server.jetty.accesslog.extended-format=false # Enable extended NCSA format.
server.jetty.accesslog.file-date-format= # Date format to place in log file name.
server.jetty.accesslog.filename= # Log filename. If not specified, logs redirect to "System.err".
server.jetty.accesslog.locale= # Locale of the request log.
server.jetty.accesslog.log-cookies=false # Enable logging of the request cookies.
server.jetty.accesslog.log-latency=false # Enable logging of request processing time.
server.jetty.accesslog.log-server=false # Enable logging of the request hostname.
server.jetty.accesslog.retention-period=31 # Number of days before rotated log files are deleted.
server.jetty.accesslog.time-zone=GMT # Timezone of the request log.
server.jetty.max-http-post-size=200000B # Maximum size of the HTTP post or put content.
server.jetty.selectors=-1 # Number of selector threads to use. When the value is -1, the default, the number of selectors is derived from the operating environment.

默認狀況下，spring-boot-starter-web 使用的容器爲 tomcat，若是想要替換成jetty，只須要在pom文件中移除tomcat依賴，而後引入jetty依賴便可

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <!-- 移除默認的tomcat -->
        <exclusions>
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-tomcat</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <!-- 添加jetty依賴 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jetty</artifactId>
    </dependency>

3. undertow容器

有關內嵌的undertow的默認屬性配置以下：

server.undertow.accesslog.dir= # Undertow access log directory.
server.undertow.accesslog.enabled=false # Whether to enable the access log.
server.undertow.accesslog.pattern=common # Format pattern for access logs.
server.undertow.accesslog.prefix=access_log. # Log file name prefix.
server.undertow.accesslog.rotate=true # Whether to enable access log rotation.
server.undertow.accesslog.suffix=log # Log file name suffix.
server.undertow.buffer-size= # Size of each buffer.
server.undertow.direct-buffers= # Whether to allocate buffers outside the Java heap. The default is derived from the maximum amount of memory that is available to the JVM.
server.undertow.eager-filter-init=true # Whether servlet filters should be initialized on startup.
server.undertow.io-threads= # Number of I/O threads to create for the worker. The default is derived from the number of available processors.
server.undertow.max-http-post-size=-1B # Maximum size of the HTTP post content. When the value is -1, the default, the size is unlimited.
server.undertow.worker-threads= # Number of worker threads. The default is 8 times the number of I/O threads.

主要關注的兩個屬性：

• server.undertow.io-threads：默認狀況下IO線程數等於CPU處理器個數
• server.undertow.worker-threads：默認狀況下Worker線程數等於IO線城數的8倍

同上，若是想要使用undertow容器，只須要在pom文件中移除tomcat依賴，而後引入undertow依賴便可

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <!-- 移除默認的tomcat -->
        <exclusions>
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-tomcat</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <!-- 添加undertow依賴 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-undertow</artifactId>
    </dependency>

參考資料：

• https://docs.spring.io/spring...
• https://github.com/spring-pro...