修改项目.project文件，确保有maven2Builder和maven2Nature2个标签：

<?xml version="1.0" encoding="UTF-8"?>

<projectDescription>

<name>projectName</name>

<comment></comment>

<projects>

</projects>

<buildSpec>

<buildCommand>

<name>org.eclipse.jdt.core.javabuilder</name>

<arguments>

</arguments>

</buildCommand>

<buildCommand>

<name>org.eclipse.m2e.core.maven2Builder</name>

<arguments>

</arguments>

</buildCommand>

</buildSpec>

<natures>

<nature>org.eclipse.jdt.core.javanature</nature>

<nature>org.eclipse.m2e.core.maven2Nature</nature>

</natures>

</projectDescription>

 

.classpath 文件 :

<classpath>

  <classpathentry kind="src" path="src/test/java"

           output="target/test-classes" including="**/*.java"/>

  <classpathentry kind="src" path="src/main/java" including="**/*.java"/>

  <classpathentry kind="output" path="target/classes"/>

  <classpathentry kind="var" path="M2_REPO/junit/junit/3.8.1/junit-3.8.1.jar"

	   sourcepath="M2_REPO/junit/junit/3.8.1/junit-3.8.1-sources.jar"/>

  <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>

</classpath>