原贴:https://www.cnblogs.com/gmq-sh/p/4737130.html
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 3.0
其实在右边可以看到改到3.0需要的条件以及有冲突的facets,解决这个问题的步骤如下:
1.把Servlet改成3.0,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 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<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
打开org.eclipse.wst.common.component
<?xml version="1.0" encoding="UTF-8"?><project-modules id="moduleCoreId" project-version="1.5.0">
<wb-module deploy-name="springboot">
<wb-resource deploy-path="/" source-path="/target/m2e-wtp/web-resources"/>
<wb-resource deploy-path="/" source-path="/src/main/webapp" tag="defaultRootSource"/>
<property name="context-root" value="springboot"/>
<property name="java-output-path" value="/springboot/build/classes"/>
</wb-module>
</project-modules>
把project-version="1.5.0"改成project-version="1.8.0"
<?xml version="1.0" encoding="UTF-8"?><project-modules id="moduleCoreId" project-version="1.8.0">
<wb-module deploy-name="springboot">
<wb-resource deploy-path="/" source-path="/target/m2e-wtp/web-resources"/>
<wb-resource deploy-path="/" source-path="/src/main/webapp" tag="defaultRootSource"/>
<property name="context-root" value="springboot"/>
<property name="java-output-path" value="/springboot/build/classes"/>
</wb-module>
</project-modules>
打开org.eclipse.wst.common.project.facet.core.xml
<?xml version="1.0" encoding="UTF-8"?>
<faceted-project>
<runtime name="Apache Tomcat v8.0"/>
<fixed facet="wst.jsdt.web"/>
<installed facet="java" version="1.8"/>
<installed facet="jst.web" version="3.0"/>
<installed facet="wst.jsdt.web" version="1.0"/>
</faceted-project>
把 <installed facet="jst.web" version="2.3"/>改成 <installed facet="jst.web" version="3.0"/>
<?xml version="1.0" encoding="UTF-8"?>
<faceted-project>
<runtime name="Apache Tomcat v8.0"/>
<fixed facet="wst.jsdt.web"/>
<installed facet="java" version="1.8"/>
<installed facet="jst.web" version="3.0"/>
<installed facet="wst.jsdt.web" version="1.0"/>
</faceted-project>
都改好之后在打开看看,已经把Dynamic web module改成了3.0