1.在默认生命周期的compile阶段执行 maven-dependency-plugin:copy-dependencies命令即可：
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>install</id>
<phase>install</phase>
<goals>
<goal>sources</goal>
</goals>
</execution>
<execution>
<id>compile</id>
<phase>compile</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>src/main/webapp/WEB-INF/lib</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
2.当依赖jar包发生变更时，应该执行clean生命周期，删除所有旧的jar包；这样才能保证WEB-INF/lib和Maven的依赖管理的Jar包一致。
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-clean-plugin</artifactId>
<executions>
<execution>
<id>clean</id>
<phase>pre-clean</phase>
<goals>
<goal>clean</goal>
</goals>
<configuration>
<directory>src/main/webapp/WEB-INF/lib</directory>
</configuration>
</execution>
</executions>
</plugin>

如何让maven 将工程依赖的jar 复制到WEB-INF/lib 目录下