maven tomcat:run 无法启动

解决方法：
pom.xml中添加一下内容，运行：mvn tomcat7:run,原理未知。

<plugin>
        <groupId>org.apache.tomcat.maven</groupId>
        <artifactId>tomcat7-maven-plugin</artifactId>
        <version>2.1</version>
        <configuration>
          <!--<url>http://localhost:8080/manager/text</url>
          <server>my-tomcat</server>
          <path>/myapp</path>-->
          <port>8081</port>
          <uriEncoding>UTF-8</uriEncoding><!-- 参数乱码 -->
        </configuration>
      </plugin>

常用的依赖，以免忘记

<!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>

    <!-- https://mvnrepository.com/artifact/javax.servlet.jsp/javax.servlet.jsp-api -->
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.3.0</version>
      <scope>provided</scope>
    </dependency>