Tomcat server.xml 文件中的连接器定义

Question

我想了解 Tomcat 在 server.xml 文件中的连接器定义。以下配置有什么区别：

    <Connector port="8080"
               protocol="HTTP/1.1"
               socket.directBuffer="true"
               redirectPort="8083"
               keyAlias="tomcat"
               enableLookups="true"
               connectionTimeout="60000"
               URIEncoding="UTF-8"
               server="NA"
               minSpareThreads="2"
               maxThreads="10"
               acceptCount="10"/>

    <Connector address="127.0.0.1"
               port="8080"
               protocol="HTTP/1.1"
               socket.directBuffer="true"
               redirectPort="8083"
               keyAlias="tomcat"
               enableLookups="false"
               connectionTimeout="60000"
               URIEncoding="UTF-8"
               server="NA"
               minSpareThreads="2"
               maxThreads="10"
               acceptCount="10"/>

    <Connector address="::1"
               port="8080"
               protocol="HTTP/1.1"
               redirectPort="8083"
               enableLookups="false"
               connectionTimeout="60000"
               URIEncoding="UTF-8"
               server="NA"
               minSpareThreads="2"
               maxThreads="5"
               acceptCount="10"/>

根据Tomcat 8 connectors documentation，地址属性应该只在服务器有多个IP地址时使用。通常此配置会在 Tomcat 启动期间导致下一个 2 异常（因为所有 3 个连接器都尝试侦听相同的 IP 和端口）：

26/10/2015 10:07:56 SEVERE org.apache.coyote.AbstractProtocol init Failed to initialize end point associated with ProtocolHandler ["http-nio-127.0.0.1-8080"]
java.net.BindException: Address already in use
    at sun.nio.ch.Net.bind0(Native Method)
    at sun.nio.ch.Net.bind(Net.java:437)
    at sun.nio.ch.Net.bind(Net.java:429)
    at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223)
    at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)
    at org.apache.tomcat.util.net.NioEndpoint.bind(NioEndpoint.java:340)
    at org.apache.tomcat.util.net.AbstractEndpoint.init(AbstractEndpoint.java:743)
    at org.apache.coyote.AbstractProtocol.init(AbstractProtocol.java:457)
    at org.apache.coyote.http11.AbstractHttp11JsseProtocol.init(AbstractHttp11JsseProtocol.java:120)
    at org.apache.catalina.connector.Connector.initInternal(Connector.java:960)
    at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:102)
    at org.apache.catalina.core.StandardService.initInternal(StandardService.java:567)
    at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:102)
    at org.apache.catalina.core.StandardServer.initInternal(StandardServer.java:851)
    at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:102)
    at org.apache.catalina.startup.Catalina.load(Catalina.java:576)
    at org.apache.catalina.startup.Catalina.load(Catalina.java:599)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.apache.catalina.startup.Bootstrap.load(Bootstrap.java:310)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:484)

26/10/2015 10:07:56 SEVERE org.apache.coyote.AbstractProtocol init Failed to initialize end point associated with ProtocolHandler ["http-nio-0:0:0:0:0:0:0:1-8080"]
java.net.BindException: Address already in use
    at sun.nio.ch.Net.bind0(Native Method)
    at sun.nio.ch.Net.bind(Net.java:437)
    at sun.nio.ch.Net.bind(Net.java:429)
    at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223)
    at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)
    at org.apache.tomcat.util.net.NioEndpoint.bind(NioEndpoint.java:340)
    at org.apache.tomcat.util.net.AbstractEndpoint.init(AbstractEndpoint.java:743)
    at org.apache.coyote.AbstractProtocol.init(AbstractProtocol.java:457)
    at org.apache.coyote.http11.AbstractHttp11JsseProtocol.init(AbstractHttp11JsseProtocol.java:120)
    at org.apache.catalina.connector.Connector.initInternal(Connector.java:960)
    at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:102)
    at org.apache.catalina.core.StandardService.initInternal(StandardService.java:567)
    at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:102)
    at org.apache.catalina.core.StandardServer.initInternal(StandardServer.java:851)
    at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:102)
    at org.apache.catalina.startup.Catalina.load(Catalina.java:576)
    at org.apache.catalina.startup.Catalina.load(Catalina.java:599)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.apache.catalina.startup.Bootstrap.load(Bootstrap.java:310)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:484)

有什么理由像上面那样定义 3 个连接器？

Answer 1

您不能多次绑定到同一个 TCP 端口，除非每个绑定也绑定到一个特定的 IP 地址。您的第一个 Connector 未通过此测试。另外两个指定 address=，这使它们有效。

According to Tomcat 8 connectors documentation the address property should be used only when the server has more than one IP address

它实际上并没有这么说，但它并不相关，因为每个主机至少有两个地址：127.0.0.1 和它的真实 IP 地址。在你的情况 3 中，因为你也有 ::1，IPv6 环回地址。

Tomcat server.xml 文件中的连接器定义

Tomcat Connectors definition in server.xml file

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