1.ecplise使用maven创建一web工程 webProject1
2. 步骤1完成后，webProject1/src/main/webapp/WEB-INF/web.xml中内容如下
<!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>
修改为
<?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"
id="WebApp_ID" version="3.0">
<display-name>Archetype Created Web Application</display-name>
</web-app>
3.在webProject1/.settings/org.eclipse.jdt.core.prefs
修改前
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
修改后 （只要大于等于1.6即可）
eclipse.preferences.version=1
org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
org.eclipse.jdt.core.compiler.compliance=1.8
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=1.8
4.在webProject1/.settings/org.eclipse.wst.common.project.facet.core.xml
修改前
<?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>
修改后
<?xml version="1.0" encoding="UTF-8"?>
<faceted-project>
<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>