解决Cannot change version of project facet Dynamic web module to 2.5

我们用Eclipse创建Maven结构的web项目的时候选择了Artifact Id为maven-artchetype-webapp，由于这个catalog比较老，用的servlet还是2.3的，而一般现在至少都是2.5，在Project Facets里面修改Dynamic web module为2.5的时候就会出现Cannot change version of project facet Dynamic web module to 2.5，如图：

1.把Servlet改成2.5，打开项目的web.xml，改之前：

<!DOCTYPE web-app PUBLIC  
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"  
 "http://java.sun.com/dtd/web-app_2_3.dtd" ><web-app><display-name>Archetype Created Web Application</display-name></web-app> 

改后：

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5"  
    xmlns="http://java.sun.com/xml/ns/javaee"  
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee  
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"><display-name>Archetype Created Web Application</display-name></web-app>  

2.修改项目的设置，在Navigator下打开项目.settings目录下的org.eclipse.jdt.core.prefs

eclipse.preferences.version=1  
org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled  
org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.5  
org.eclipse.jdt.core.compiler.compliance=1.5  
org.eclipse.jdt.core.compiler.problem.assertIdentifier=error  
org.eclipse.jdt.core.compiler.problem.enumIdentifier=error  
org.eclipse.jdt.core.compiler.problem.forbiddenReference=warning  
org.eclipse.jdt.core.compiler.source=1.5  

把1.5改成1.6

eclipse.preferences.version=1  
org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled  
org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.6  
org.eclipse.jdt.core.compiler.compliance=1.6  
org.eclipse.jdt.core.compiler.problem.assertIdentifier=error  
org.eclipse.jdt.core.compiler.problem.enumIdentifier=error  
org.eclipse.jdt.core.compiler.problem.forbiddenReference=warning  
org.eclipse.jdt.core.compiler.source=1.6 

打开org.eclipse.wst.common.component

<?xml version="1.0" encoding="UTF-8"?>  
<project-modules id="moduleCoreId" project-version="1.6.0">  
    <wb-module deploy-name="test">  
        <wb-resource deploy-path="/" source-path="/target/m2e-wtp/web-resources"/>  
        <wb-resource deploy-path="/" source-path="/src/main/webapp" tag="defaultRootSource"/>  
        <wb-resource deploy-path="/WEB-INF/classes" source-path="/src/main/java"/>  
        <wb-resource deploy-path="/WEB-INF/classes" source-path="/src/main/resources"/>  
        <property name="context-root" value="test"/>  
        <property name="java-output-path" value="/test/target/classes"/>  
    </wb-module>  
</project-modules>  

打开org.eclipse.wst.common.project.facet.core.xml

<?xml version="1.0" encoding="UTF-8"?>  
<faceted-project>  
  <fixed facet="wst.jsdt.web"/>  
  <installed facet="java" version="1.5"/>  
  <installed facet="jst.web" version="2.3"/>  
  <installed facet="wst.jsdt.web" version="1.0"/>  
</faceted-project> 

把<installed facet="java" version="1.5"/>改成<installed facet="java" version="1.6"/>，把  <installed facet="jst.web" version="2.3"/>改成  <installed facet="jst.web" version="2.5"/>

<?xml version="1.0" encoding="UTF-8"?>  
<faceted-project>  
  <fixed facet="wst.jsdt.web"/>  
  <installed facet="java" version="1.6"/>  
  <installed facet="jst.web" version="2.5"/>  
  <installed facet="wst.jsdt.web" version="1.0"/>  
</faceted-project> 

好了，大功搞成

出自：http://blog.csdn.net/steveguoshao/article/details/38414145