maven 项目出现 java.lang.ClassNotFoundException

需要修改的有两个地方
1.项目根目录下的.project文件,用记事本打开,加入以下代码(把原来的<buildSpec>节点和<natures>替换了):

　　<buildSpec>
        <buildCommand>
            <name>org.eclipse.wst.jsdt.core.javascriptValidator</name>
            <arguments>
            </arguments>
        </buildCommand>
        <buildCommand>
            <name>org.eclipse.jdt.core.javabuilder</name>
            <arguments>
            </arguments>
        </buildCommand>
        <buildCommand>
            <name>org.eclipse.wst.common.project.facet.core.builder</name>
            <arguments>
            </arguments>
        </buildCommand>
        <buildCommand>
            <name>org.eclipse.wst.validation.validationbuilder</name>
            <arguments>
            </arguments>
        </buildCommand>
        <buildCommand>
            <name>org.eclipse.m2e.core.maven2Builder</name>
            <arguments>
            </arguments>
        </buildCommand>
        <buildCommand>
            <name>org.maven.ide.eclipse.maven2Builder</name>
            <arguments>
            </arguments>
        </buildCommand>
    </buildSpec>
    <natures>
        <nature>org.maven.ide.eclipse.maven2Nature</nature>
        <nature>org.eclipse.m2e.core.maven2Nature</nature>
        <nature>org.eclipse.jem.workbench.JavaEMFNature</nature>
        <nature>org.eclipse.wst.common.modulecore.ModuleCoreNature</nature>
        <nature>org.eclipse.wst.common.project.facet.core.nature</nature>
        <nature>org.eclipse.jdt.core.javanature</nature>
        <nature>org.eclipse.wst.jsdt.core.jsNature</nature>
    </natures>

2.项目根目录下的.classpath,找到

<classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER"/>

替换为:

<classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER">
    <attributes>
        <attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/>
    </attributes>
</classpathentry>

新增加一个classpathentry节点:

<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
    <attributes>
        <attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/>
    </attributes>
</classpathentry>

在.classpath文件中:

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

改为:

<classpathentry kind="output" path="WebContent/WEB-INF/classes"/>

refresh一下工程，重启tomact就可以了