错误如下：
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Apache Tomcat Setup
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Failed to install Tomcat7 service.
Check your settings and permissions.
Ignore and continue anyway (not recommended)?
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中止(A) 重试(R) 忽略(I)
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解决办法：开始-->运行-->cmd-->sc delete tomcat7(管理员身份运行CMD)
提示 DeleteService成功
再重新安装就可以了