<!-- compiler插件, 设定JDK版本 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.0</version>
                <configuration>
                    <source>${jdk.version}</source>
                    <target>${jdk.version}</target>
                    <showWarnings>true</showWarnings>
                    <encoding>${project.build.sourceEncoding}</encoding>
		<compilerArguments>
	                   <extdirs>src/main/webapp/WEB-INF/lib</extdirs>
	          </compilerArguments>
                </configuration>
            </plugin>