maven-jar-plugin

[????????]

I add this plugin to my project ,but it doesn't work ,the generated jar package 
doesn't  contain dependcy jars
who can help me?


<plugin>
                                <groupId>org.apache.maven.plugins</groupId>
                                <artifactId>maven-jar-plugin</artifactId>
                                <version>2.4</version>
                                <configuration>
                                        <archive>
                                                <manifest>
                                                        
<mainClass>cn.com.epicc.StartMain</mainClass>
                                                        
<addClasspath>true</addClasspath>
                                                        
<classpathPrefix>lib/</classpathPrefix>
                                                        
<addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                                                </manifest>
                                        </archive>
                                        <classesDirectory>
                                        </classesDirectory>
                                </configuration>
                        </plugin>