Eclipse Maven 编译错误 Dynamic Web Module 3.0 requires Java 1.6 or newer 解决方案

Eclipse Maven 开发一个 jee 项目时，编译时遇到以下错误：
Description Resource Path Location Type
Dynamic Web Module 3.0 requires Java 1.6 or newer. bdp line 1 Maven Java EE Configuration Problem

Description Resource Path Location Type
One or more constraints have not been satisfied. bdp line 1 Maven Java EE Configuration Problem

但是 Eclipse 明明已经将编译级别设置为 1.8

解决办法：
使用 maven-compiler-plugin 将 maven 编译级别改为 jdk1.6 以上：

<build>  
    <plugins>  
        <!-- define the project compile level -->  
        <plugin>  
            <groupId>org.apache.maven.plugins</groupId>  
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>  
                <source>1.8</source>  
                <target>1.8</target>  
            </configuration>  
        </plugin>  
    </plugins>  
</build>