开发中调试WEB项目算是程序员最基本的技能了！
厌烦了开发的时候将WEB项目打好war包，再部署到容器中运行，效率极低，而且修改了程序不能立即生效。
Eclipse中调试Web项目：
首选Jetty插件。当然也可以用Tomcat插件，不过比较喜欢Jetty的小巧。
使用Jetty有2种方法：
POM中配置Jetty插件；
run-jetty-run插件，更简单快速，若结合DCEVM将更厉害，增加方法都不用重启服务，Diao爆了！
先记录一种实验成功的方式（jetty-maven-plugin）
此方式支持方法体内代码的修改，会马上生效，不用重启服务。
如果想增加方法也立即生效，考虑使用DCEVM!
第一步：POM中配置Plugin
<plugins> <plugin> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-maven-plugin</artifactId> <configuration> <webApp> <defaultsDescriptor>src/main/resources/webdefault.xml</defaultsDescriptor> </webApp> </configuration> </plugin>
由于Jetty启动后会锁住静态资源文件，导致无法修改静态文件，如js文件修改后不能保存。。。
因此，需要关闭Jetty对静态资源的缓存。
在resources目录中增加webdefault.xml文件，重置缓存配置。（见最后）
第二步，在Eclipse菜单栏选择Run->External Tools->Extenal Tools Configuration
Program上右键，点击New
【Main】选项下，配置：
Location 选择系统中安装的Maven/bin/mvnDebug.bat
Working Directory 选择需要调试的项目
Arguments 输入jetty:run
【Environment】
输入Maven的配置参数
Name: MAVEN_OPTS
Value: -Xdebug-Xnoagent-Djava.compiler=NONE-Xrunjdwp:transport=dt_socket,address=4000,server=y,suspend=y
第三步，Run->Debug Configurations -> Remote Java Application
右键New
Project
Browse... 选择需要调试的项目
Connection Type
Standard(Socket Attach)
Connection Properties
Host：localhost
Port ： 8000 （此端口与第四步启动后监听的端口必须相同）
勾选Allow Terminate of reomte VM
第四步，运行第二步中配置好的Program
启动后，控制台会输出如下信息：
Preparing to Execute Maven in Debug Mode
Listening for transport dt_socket at address: 8000
第五步，运行第三步中配置好的调试命令，启动Jetty
验证：http://localhost:8080/index.html
正确停止Jetty
切换至Debug视图，在Debug窗口中Terminate掉Remote Java Application即可！
注意：如果直接在Console窗口时Terminate，再次运行时会发生端口被占用的情况。
================================================================================
解除Jetty启动后不能修改静态文件的限制：webdefault.xml
useFileMappedBuffer = false
<?xml version="1.0" encoding="UTF-8"?>
<web-app
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
metadata-complete="false"
version="3.1">
<!-- ===================================================================== -->
<!-- This file contains the default descriptor for web applications. -->
<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
<!-- The intent of this descriptor is to include jetty specific or common -->
<!-- configuration for all webapps. If a context has a webdefault.xml -->
<!-- descriptor, it is applied before the contexts own web.xml file -->
<!-- -->
<!-- A context may be assigned a default descriptor by: -->
<!-- + Calling WebApplicationContext.setDefaultsDescriptor -->
<!-- + Passed an arg to addWebApplications -->
<!-- -->
<!-- This file is used both as the resource within the jetty.jar (which is -->
<!-- used as the default if no explicit defaults descriptor is set) and it -->
<!-- is copied to the etc directory of the Jetty distro and explicitly -->
<!-- by the jetty.xml file. -->
<!-- -->
<!-- ===================================================================== -->
<description>
Default web.xml file.
This file is applied to a Web application before it's own WEB_INF/web.xml file
</description>
<!-- ==================================================================== -->
<!-- Removes static references to beans from javax.el.BeanELResolver to -->
<!-- ensure webapp classloader can be released on undeploy -->
<!-- ==================================================================== -->
<listener>
<listener-class>org.eclipse.jetty.servlet.listener.ELContextCleaner</listener-class>
</listener>
<!-- ==================================================================== -->
<!-- Removes static cache of Methods from java.beans.Introspector to -->
<!-- ensure webapp classloader can be released on undeploy -->
<!-- ==================================================================== -->
<listener>
<listener-class>org.eclipse.jetty.servlet.listener.IntrospectorCleaner</listener-class>
</listener>
<!-- ==================================================================== -->
<!-- Context params to control Session Cookies -->
<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
<!--
UNCOMMENT TO ACTIVATE
<context-param>
<param-name>org.eclipse.jetty.servlet.SessionDomain</param-name>
<param-value>127.0.0.1</param-value>
</context-param>
<context-param>
<param-name>org.eclipse.jetty.servlet.SessionPath</param-name>
<param-value>/</param-value>
</context-param>
<context-param>
<param-name>org.eclipse.jetty.servlet.MaxAge</param-name>
<param-value>-1</param-value>
</context-param>
-->
<!-- ==================================================================== -->
<!-- The default servlet. -->
<!-- This servlet, normally mapped to /, provides the handling for static -->
<!-- content, OPTIONS and TRACE methods for the context. -->
<!-- The following initParameters are supported: -->
<!--
* acceptRanges If true, range requests and responses are
* supported
*
* dirAllowed If true, directory listings are returned if no
* welcome file is found. Else 403 Forbidden.
*
* welcomeServlets If true, attempt to dispatch to welcome files
* that are servlets, but only after no matching static
* resources could be found. If false, then a welcome
* file must exist on disk. If "exact", then exact
* servlet matches are supported without an existing file.
* Default is true.
*
* This must be false if you want directory listings,
* but have index.jsp in your welcome file list.
*
* redirectWelcome If true, welcome files are redirected rather than
* forwarded to.
*
* gzip If set to true, then static content will be served as
* gzip content encoded if a matching resource is
* found ending with ".gz"
*
* resourceBase Set to replace the context resource base
*
* resourceCache If set, this is a context attribute name, which the servlet
* will use to look for a shared ResourceCache instance.
*
* relativeResourceBase
* Set with a pathname relative to the base of the
* servlet context root. Useful for only serving static content out
* of only specific subdirectories.
*
* pathInfoOnly If true, only the path info will be applied to the resourceBase
*
* stylesheet Set with the location of an optional stylesheet that will be used
* to decorate the directory listing html.
*
* aliases If True, aliases of resources are allowed (eg. symbolic
* links and caps variations). May bypass security constraints.
*
* etags If True, weak etags will be generated and handled.
*
* maxCacheSize The maximum total size of the cache or 0 for no cache.
* maxCachedFileSize The maximum size of a file to cache
* maxCachedFiles The maximum number of files to cache
*
* useFileMappedBuffer
* If set to true, it will use mapped file buffer to serve static content
* when using NIO connector. Setting this value to false means that
* a direct buffer will be used instead of a mapped file buffer.
* By default, this is set to true.
*
* cacheControl If set, all static content will have this value set as the cache-control
* header.
*
-->
<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
<servlet>
<servlet-name>default</servlet-name>
<servlet-class>org.eclipse.jetty.servlet.DefaultServlet</servlet-class>
<init-param>
<param-name>aliases</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>acceptRanges</param-name>
<param-value>true</param-value>
</init-param>
<init-param>
<param-name>dirAllowed</param-name>
<param-value>true</param-value>
</init-param>
<init-param>
<param-name>welcomeServlets</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>redirectWelcome</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>maxCacheSize</param-name>
<param-value>256000000</param-value>
</init-param>
<init-param>
<param-name>maxCachedFileSize</param-name>
<param-value>200000000</param-value>
</init-param>
<init-param>
<param-name>maxCachedFiles</param-name>
<param-value>2048</param-value>
</init-param>
<init-param>
<param-name>gzip</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>etags</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>useFileMappedBuffer</param-name>
<param-value>false</param-value>
</init-param>
<!--
<init-param>
<param-name>resourceCache</param-name>
<param-value>resourceCache</param-value>
</init-param>
-->
<!--
<init-param>
<param-name>cacheControl</param-name>
<param-value>max-age=3600,public</param-value>
</init-param>
-->
<load-on-startup>0</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<!-- ==================================================================== -->
<!-- JSP Servlet -->
<!-- This is the jasper JSP servlet from the jakarta project -->
<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
<!-- The JSP page compiler and execution servlet, which is the mechanism -->
<!-- used by Glassfish to support JSP pages. Traditionally, this servlet -->
<!-- is mapped to URL patterh "*.jsp". This servlet supports the -->
<!-- following initialization parameters (default values are in square -->
<!-- brackets): -->
<!-- -->
<!-- checkInterval If development is false and reloading is true, -->
<!-- background compiles are enabled. checkInterval -->
<!-- is the time in seconds between checks to see -->
<!-- if a JSP page needs to be recompiled. [300] -->
<!-- -->
<!-- compiler Which compiler Ant should use to compile JSP -->
<!-- pages. See the Ant documenation for more -->
<!-- information. [javac] -->
<!-- -->
<!-- classdebuginfo Should the class file be compiled with -->
<!-- debugging information? [true] -->
<!-- -->
<!-- classpath What class path should I use while compiling -->
<!-- generated servlets? [Created dynamically -->
<!-- based on the current web application] -->
<!-- Set to ? to make the container explicitly set -->
<!-- this parameter. -->
<!-- -->
<!-- development Is Jasper used in development mode (will check -->
<!-- for JSP modification on every access)? [true] -->
<!-- -->
<!-- enablePooling Determines whether tag handler pooling is -->
<!-- enabled [true] -->
<!-- -->
<!-- fork Tell Ant to fork compiles of JSP pages so that -->
<!-- a separate JVM is used for JSP page compiles -->
<!-- from the one Tomcat is running in. [true] -->
<!-- -->
<!-- ieClassId The class-id value to be sent to Internet -->
<!-- Explorer when using <jsp:plugin> tags. -->
<!-- [clsid:8AD9C840-044E-11D1-B3E9-00805F499D93] -->
<!-- -->
<!-- javaEncoding Java file encoding to use for generating java -->
<!-- source files. [UTF-8] -->
<!-- -->
<!-- keepgenerated Should we keep the generated Java source code -->
<!-- for each page instead of deleting it? [true] -->
<!-- -->
<!-- logVerbosityLevel The level of detailed messages to be produced -->
<!-- by this servlet. Increasing levels cause the -->
<!-- generation of more messages. Valid values are -->
<!-- FATAL, ERROR, WARNING, INFORMATION, and DEBUG. -->
<!-- [WARNING] -->
<!-- -->
<!-- mappedfile Should we generate static content with one -->
<!-- print statement per input line, to ease -->
<!-- debugging? [false] -->
<!-- -->
<!-- -->
<!-- reloading Should Jasper check for modified JSPs? [true] -->
<!-- -->
<!-- suppressSmap Should the generation of SMAP info for JSR45 -->
<!-- debugging be suppressed? [false] -->
<!-- -->
<!-- dumpSmap Should the SMAP info for JSR45 debugging be -->
<!-- dumped to a file? [false] -->
<!-- False if suppressSmap is true -->
<!-- -->
<!-- scratchdir What scratch directory should we use when -->
<!-- compiling JSP pages? [default work directory -->
<!-- for the current web application] -->
<!-- -->
<!-- tagpoolMaxSize The maximum tag handler pool size [5] -->
<!-- -->
<!-- xpoweredBy Determines whether X-Powered-By response -->
<!-- header is added by generated servlet [false] -->
<!-- -->
<!-- If you wish to use Jikes to compile JSP pages: -->
<!-- Set the init parameter "compiler" to "jikes". Define -->
<!-- the property "-Dbuild.compiler.emacs=true" when starting Jetty -->
<!-- to cause Jikes to emit error messages in a format compatible with -->
<!-- Jasper. -->
<!-- If you get an error reporting that jikes can't use UTF-8 encoding, -->
<!-- try setting the init parameter "javaEncoding" to "ISO-8859-1". -->
<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
<servlet id="jsp">
<servlet-name>jsp</servlet-name>
<servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
<init-param>
<param-name>logVerbosityLevel</param-name>
<param-value>DEBUG</param-value>
</init-param>
<init-param>
<param-name>fork</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>xpoweredBy</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>compilerTargetVM</param-name>
<param-value>1.7</param-value>
</init-param>
<init-param>
<param-name>compilerSourceVM</param-name>
<param-value>1.7</param-value>
</init-param>
<!--
<init-param>
<param-name>classpath</param-name>
<param-value>?</param-value>
</init-param>
-->
<load-on-startup>0</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>jsp</servlet-name>
<url-pattern>*.jsp</url-pattern>
<url-pattern>*.jspf</url-pattern>
<url-pattern>*.jspx</url-pattern>
<url-pattern>*.xsp</url-pattern>
<url-pattern>*.JSP</url-pattern>
<url-pattern>*.JSPF</url-pattern>
<url-pattern>*.JSPX</url-pattern>
<url-pattern>*.XSP</url-pattern>
</servlet-mapping>
<!-- ==================================================================== -->
<session-config>
<session-timeout>30</session-timeout>
</session-config>
<!-- ==================================================================== -->
<!-- Default MIME mappings -->
<!-- The default MIME mappings are provided by the mime.properties -->
<!-- resource in the org.eclipse.jetty.server.jar file. Additional or modified -->
<!-- mappings may be specified here -->
<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
<!-- UNCOMMENT TO ACTIVATE
<mime-mapping>
<extension>mysuffix</extension>
<mime-type>mymime/type</mime-type>
</mime-mapping>
-->
<!-- ==================================================================== -->
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<!-- ==================================================================== -->
<locale-encoding-mapping-list>
<locale-encoding-mapping>
<locale>ar</locale>
<encoding>ISO-8859-6</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>be</locale>
<encoding>ISO-8859-5</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>bg</locale>
<encoding>ISO-8859-5</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>ca</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>cs</locale>
<encoding>ISO-8859-2</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>da</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>de</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>el</locale>
<encoding>ISO-8859-7</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>en</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>es</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>et</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>fi</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>fr</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>hr</locale>
<encoding>ISO-8859-2</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>hu</locale>
<encoding>ISO-8859-2</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>is</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>it</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>iw</locale>
<encoding>ISO-8859-8</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>ja</locale>
<encoding>Shift_JIS</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>ko</locale>
<encoding>EUC-KR</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>lt</locale>
<encoding>ISO-8859-2</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>lv</locale>
<encoding>ISO-8859-2</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>mk</locale>
<encoding>ISO-8859-5</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>nl</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>no</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>pl</locale>
<encoding>ISO-8859-2</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>pt</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>ro</locale>
<encoding>ISO-8859-2</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>ru</locale>
<encoding>ISO-8859-5</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>sh</locale>
<encoding>ISO-8859-5</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>sk</locale>
<encoding>ISO-8859-2</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>sl</locale>
<encoding>ISO-8859-2</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>sq</locale>
<encoding>ISO-8859-2</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>sr</locale>
<encoding>ISO-8859-5</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>sv</locale>
<encoding>ISO-8859-1</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>tr</locale>
<encoding>ISO-8859-9</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>uk</locale>
<encoding>ISO-8859-5</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>zh</locale>
<encoding>GB2312</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>zh_TW</locale>
<encoding>Big5</encoding>
</locale-encoding-mapping>
</locale-encoding-mapping-list>
<security-constraint>
<web-resource-collection>
<web-resource-name>Disable TRACE</web-resource-name>
<url-pattern>/</url-pattern>
<http-method>TRACE</http-method>
</web-resource-collection>
<auth-constraint/>
</security-constraint>
<security-constraint>
<web-resource-collection>
<web-resource-name>Enable everything but TRACE</web-resource-name>
<url-pattern>/</url-pattern>
<http-method-omission>TRACE</http-method-omission>
</web-resource-collection>
</security-constraint>
</web-app>