定做Jetty配置

定制Jetty配置
尽管etc/jetty.xml设置了合理的缺省值，但为了满足你的实际需要，你仍然可以定制Jetty.Jetty的配置文件结构如下：

<?xml version="1.0"?><!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "http://jetty.mortbay.org/configure.dtd"> <Configure id="Server" name="code"><?xml version="1.0" encoding="ISO-8859-1"?><!--This is the document type descriptor for theorg.mortbay.XmlConfiguration class.  It allows a java object to beconfigured by with a sequence of Set, Put and Call elements.  These tags aremapped to methods on the object to be configured as follows:  <Set  name="Test">value</Set>              ==  obj.setTest("value");  <Put  name="Test">value</Put>              ==  obj.put("Test","value");  <Call name="test"><Arg>value</Arg></Call>  ==  obj.test("value");Values themselves may be configured objects that are created with the<New> tag or returned from a <Call> tag.Values are matched to arguments on a best effort approach, but typesmy be specified if a match is not achieved.$Id: configure_1_3.dtd,v 1.2 2005/10/26 20:48:48 gregwilkins Exp $--><!ENTITY % CONFIG "Set|Get|Put|Call|New|Ref|Array|Map|Property"><!ENTITY % VALUE "#PCDATA|Get|Call|New|Ref|Array|Map|SystemProperty|Property"><!ENTITY % TYPEATTR "type CDATA #IMPLIED " > <!-- String|Character|Short|Byte|Integer|Long|Boolean|Float|Double|char|short|byte|int|long|boolean|float|double|URL|InetAddress|InetAddrPort| #classname --><!ENTITY % IMPLIEDCLASSATTR "class NMTOKEN #IMPLIED" ><!ENTITY % CLASSATTR "class NMTOKEN #REQUIRED" ><!ENTITY % NAMEATTR "name NMTOKEN #REQUIRED" ><!ENTITY % DEFAULTATTR "default CDATA #IMPLIED" ><!ENTITY % IDATTR "id NMTOKEN #IMPLIED" ><!ENTITY % REQUIREDIDATTR "id NMTOKEN #REQUIRED" ><!--Configure Element.This is the root element that specifies the class of object thatcan be configured:    <Configure name="test">   <Arg>value1</Arg>   <Set name="Test">Value2</Set> </Call>This is equivalent to: Object o2 = o1.test("value1"); o2.setTest("value2");A Call with a class attribute is treated as a static call.--><!ELEMENT Call (Arg*,(%CONFIG;)*)><!ATTLIST Call %NAMEATTR; %IMPLIEDCLASSATTR; %IDATTR;><!--Arg Element.This element defines a positional argument for the Call element.The optional type attribute can force the type of the value.An Arg element can contain value text and/or value elements such as Call,New, SystemProperty, etc. If no value type is specified, then whitespace is trimmed out of the value. If it contains multiple valueelements they are added as strings before being converted to anyspecified type.--><!ELEMENT Arg ( %VALUE; )* ><!ATTLIST Arg %TYPEATTR; ><!--New Element.This element allows the creation of a new object as part of avalue for elements such as Set, Put, Arg, etc. The class attribute determinesthe type of the new object and the contained Arg elementsare used to select the constructor for the new object.A New element can contain a sequence of Arg elements followed bya sequence of elements such as Set, Put, Call, etc. elementswhich act on the new object: <New id="o" default="value" />This is equivalent to: System.getProperty("Test","value");--><!ELEMENT SystemProperty EMPTY><!ATTLIST SystemProperty %NAMEATTR; %DEFAULTATTR; %IDATTR;><!--Property Element.This element allows arbitrary properties to be retrieved by name.The name attribute specifies the property name and the optionaldefault argument provides a default value.A Property element can contain a sequence of elements such as Set, Put, Call, etc.which act on the retrieved object: <Property name="Server">   <Call id="jdbcIdMgr" name="getAttribute">     <Arg>jdbcIdMgr</Arg>   </Call> </Property>--><!ELEMENT Property ((%CONFIG;)*)><!ATTLIST Property %NAMEATTR; %DEFAULTATTR; %IDATTR;>

Jetty配置文件分解

Doctype(必需)

在jetty.xml中声明的所有标签和元素必须符合configure.dtd的规范。

<!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "http://jetty.mortbay.org/configure.dtd"

Server(必需)

org.mortbay.jetty.Server是Jetty HTTP服务器的主类。当运行服务器时，这是第一个被调用的实例。它用于整合连接器(Connectors,HTTP请求接收者)和请求处理器(request Handlers).server本身是一个处理器(handler)和线程池(TreadPool).连接器使用线程池的方法来运行任务，这些任务最后将调用处理方法。

<Configure id="Server" name="code"><Set name="connectors"> <Array type="org.mortbay.jetty.Connector">  <Item>   <New /></Set>        <Set name="port"><SystemProperty name="jetty.port" default="8080"/></Set>...      </New>    </Item> </Array></Set>

Handlers(必需)

处理器用于处理接收到的请求。org.mortbay.jetty.webapp.WebAppContext专门用于服务web应用程序。如果不想完全成熟的应用程序，而只是想处理静态内容和一些servlets,那么你可以使用ContextHandler和配置只需要的服务。server的handlers列表可通过下面的调用来定义：

<Set name="handlers">  <Array type="org.mortbay.jetty.Handler">   ...</Set>

ThreadPool(可选)

线程池可以确保线程在运行方法退出后被线程池重用，从而避免线程创建时带来的开销。配置如下：

<Set name="ThreadPool"> <New name="code"><Set name="UserRealms"><Array type="org.mortbay.jetty.security.UserRealm">  <Item>    <New name="code"><?xml version="1.0"?><!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "http://jetty.mortbay.org/configure.dtd"> <Configure id="Server" default="."/>/webapps</Set>      </New>     </Arg>   </Call></Configure>

启动：

java -jar start.jar etc/myjetty.xml

View your webapplications at http://localhost:8080/webappfolder/. If you have no webapp defined for the root context ("/"), visiting http://localhost:8080/ will give you a normal 404 page.

静态部署2

<?xml version="1.0"?><!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "http://jetty.mortbay.org/configure.dtd"> <Configure id="Server" /></Set>         <Set name="port"><SystemProperty name="jetty.port" default="8080"/></Set>   </New>   </Arg>   </Call>   <Set name="handler">     <New id="Handlers" default="."/>/webapps</Set>    <Set name="parentLoaderPriority">false</Set>     <Set name="extract">true</Set>     <Set name="allowDuplicates">false</Set>         <Set name="defaultsDescriptor"><SystemProperty name="jetty.home" default="."/>/etc/webdefault.xml</Set>     </New>    </Arg>   </Call></Configure>

As before, start up Jetty with this command:

java -jar start.jar etc/myjetty.xml 

View your webapplications at http://localhost:8080/webappfolder/.

Other than the extra configuration settings, the biggest change is the addition of the org.mortbay.jetty.handler.DefaultHandler, which deals with unhandled requests in the server. If you have no webapps defined in the root context ("/"), visiting http://localhost:8080/ will 404, but will present a list of contexts that have been deployed on the server. DefaultHandler also serves up a Jetty favicon.

For more details about configuring static deployment, see WebAppDeployer.

Hot Deployment of Customized Contexts

In addition to deploying webapps at start-up, you can also do hot deployment: configure a context deployer which scans a specific directory for XML configuration files, and deploys/redeploys/undeploys a webapp if its configuration file has been modified, added, or removed. These configuration files also allow you to configure certain Jetty-specific per-context settings; configuration file and its format is specific to Jetty. To keep things short, I am not going to reproduce the entire configuration. Add this block to either of the previous examples:

<Call name="addLifeCycle">    <Arg>       <New default="."/>/contexts</Set>  <Set name="scanInterval">5</Set>        </New>     </Arg>  </Call>

That sets up a ContextDeployer, which will scan the $JETTY_HOME/contexts folder every 5 seconds for changes to the XML descriptors, and hot deploy as necessary. For more details, see ContextDeployer.

File Server, One Handler

Simple HTTP file server with one handler, similar to the embedded FileServer example and embedded OneHandler example. This example serves up purely static files from your current directory:

<?xml version="1.0"?><!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "http://jetty.mortbay.org/configure.dtd"> <Configure id="Server" default="8080"/></Set>     </New>   </Arg>    </Call>  <Set name="handler">       <New id="ResourceHandler" name="code"><?xml version="1.0"?><!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "http://jetty.mortbay.org/configure.dtd"> <Configure id="Server" default="8080"/></Set>  </New>     </Arg>  </Call>   <Set name="handler">  <New id="Handlers" default="./logs"/>/request.log</Set>        <Set name="append">false</Set></New>     </Set>   </Ref></Configure>

Similar to the one handler example, but defines multiple handlers. A handler can be configured either as soon as it is declared, or further down using the Ref tag. There is no difference in effect between the two. That example serves up static files in the logs directory under your current directory, and logs all requests since the server was last started to request.log.

To see this in action, go to http://localhost:8080/request.log and refresh a few times (you may need to hard refresh, to make sure you are not seeing a cached copy of the data).

For simplicity's sake, the logfile's name does not contain a date; see jetty.xml for an extended configuration which does.

Either a HandlerCollection or a HandlerList can be used when setting multiple handlers. org.mortbay.jetty.handler.HandlerCollection calls all handlers in turn. org.mortbay.jetty.handler.HandlerList calls each contained handler until either an exception is thrown, the response is committed,or a positive response status is sent. In this case, HandlerCollection was chosen so that the RequestLogHandler could log the requests.


参考资料：

http://docs.codehaus.org/display/JETTY/Newbie+Guide+to+Jetty

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