我们在通过页面访问Java web 的url 时可以通过访问http://localhost:8080/里面的manager app进入
通过点击选择想要进入的页面。
方法：
1.tomcat 安装路径下面的conf/tomcat-users.xml
添加绿色的一行内容。保存即可
<tomcat-users>
<!--
NOTE: By default, no user is included in the "manager-gui" role required
to operate the "/manager/html" web application. If you wish to use this app,
you must define such a user - the username and password are arbitrary. It is
strongly recommended that you do NOT use one of the users in the commented out
section below since they are intended for use with the examples web
application.
-->
<!--
NOTE: The sample user and role entries below are intended for use with the
examples web application. They are wrapped in a comment and thus are ignored
when reading this file. If you wish to configure these users for use with the
examples web application, do not forget to remove the <!.. ..> that surrounds
them. You will also need to set the passwords to something appropriate.
-->
<!--
<role rolename="tomcat"/>
<role rolename="role1"/>
<user username="tomcat" password="<must-be-changed>" roles="tomcat"/>
<user username="both" password="<must-be-changed>" roles="tomcat,role1"/>
<user username="role1" password="<must-be-changed>" roles="role1"/>
-->
<user username="admin" password="admin" roles="manager-gui"/> <!-- 添加这行代码即可-->
</tomcat-users>
2.访问http://localhost:8080/
点击manager app 输入 用户名 admin 密码 admin
原文：http://www.cnblogs.com/huodaihao/p/6791750.html