maven-compiler-plugin problems

[big data]

I use maven-compiler-plugin to load /lib/*.jar files, like this in pom.xml:

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.0</version>
            <configuration>
                <source>1.7</source>
                <target>1.7</target>
                <encoding>UTF-8</encoding>
                <compilerArguments>
                    <extdirs>${project.basedir}/lib/</extdirs>
                </compilerArguments>
            </configuration>
        </plugin>
    </plugins>
</build>

I've put jar files into ${project.basedir}/lib folder, but in source code, it 
still can not find the jar's classes...