Error:JDK1.8 Cannot change version of project facet Dynamic Web Module to 3.1.

问题：

Error:JDK1.8 Cannot change version of project facet Dynamic Web Module to 3.1.

此工程为名为mybatis：maven webapp project:'mybatis':解决检查以下文件中配置的，参数：

解决设置1：设置\src\main\webapp\WEB-INF\web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app 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"
         version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee">

解决设置2：eclipse的workspace下，\workspace\mybatis\.settings\org.eclipse.jdt.core.prefs

eclipse.preferences.version=1
org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
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

解决设置3：eclipse的workspace下，\workspace\mybatis\.settings\org.eclipse.wst.common.component

<project-modules id="moduleCoreId" project-version="1.5.0">
    <wb-module deploy-name="mybatis">
        <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"/>
        <wb-resource deploy-path="/WEB-INF/classes" source-path="/src/test/java"/>
        <property name="context-root" value="mybatis"/>
        <property name="java-output-path" value="/mybatis/target/classes"/>
    </wb-module>
</project-modules>

解决设置4：eclipse的workspace下，\workspace\mybatis\.settings\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="1.8"/>
  <installed facet="jst.web" version="3.1"/>
  <installed facet="wst.jsdt.web" version="1.0"/>
</faceted-project>

解决操作5：eclipse菜单，Project下clean...， 项目右键后 refresh

解决操作6：项目右键，properties：java build path:jdk SE -> jdk workspace default JRE设置本机的设有环境变量的JDK

解决操作7：项目右键，properties：选择Project Facets java -> 1.8 和选择Dynamic Web Module ->3.1

解决设置8[可选]：设置 pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>demo.mybatis</groupId>
  <artifactId>mybatis</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>mybatis Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.1.0</version>
    <scope>provided</scope>
	</dependency>
  </dependencies>
  <build>
    <finalName>mybatis</finalName>
    <plugins>
    <plugin>
	    <groupId>org.apache.maven.plugins</groupId>
	    <artifactId>maven-compiler-plugin</artifactId>
	    <version>3.1</version>
	    <configuration>
	        <source>1.8</source>
	        <target>1.8</target>
	    </configuration>
	</plugin>
    </plugins>
  </build>
</project>