简单又好用的Tomcat 页面权限控制

不废话,就2个配置文件，直接上代码。
web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://java.sun.com/xml/ns/javaee"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
	id="WebApp_ID" version="3.0">
	<!-- 
	<resource-ref>
		<res-ref-name>jdbc/mt</res-ref-name>
		<res-type>javax.sql.DataSource</res-type>
		<res-auth>Container</res-auth>
		<res-sharing-scope>Shareable</res-sharing-scope>
	</resource-ref>
	<security-role>
		<role-name>R_CASE_IT</role-name>
	</security-role>
	 -->
	
	<security-constraint>
		<display-name>web</display-name>
		<web-resource-collection>
			<url-pattern>/index.jsp</url-pattern>
		</web-resource-collection>
		<auth-constraint>
			<role-name>R_CASE_IT</role-name>
		</auth-constraint>
	</security-constraint>
	<login-config>
		<auth-method>FORM</auth-method>
		<form-login-config>
			<form-login-page>/login.jsp</form-login-page>
			<form-error-page>/error.jsp</form-error-page>
		</form-login-config>
	</login-config>
	<error-page>
		<error-code>403</error-code>
		<location>/403.jsp</location>
	</error-page>
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
</web-app>

tomcat中的context.xml

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/web">
	<Resource auth="Container" 
		driverClassName="oracle.jdbc.OracleDriver"
		maxActive="10" 
		maxIdle="4" 
		maxWait="5000" 
		name="jdbc/mt" 
		password=""
		type="javax.sql.DataSource"
		url=""
		username="" />
	<!-- 
	 -->
	<Realm className="org.apache.catalina.realm.DataSourceRealm"
		localDataSource="true"
		dataSourceName="jdbc/mt"
		roleNameCol="role_id" 
		userCredCol="password" 
		userNameCol="user_id"
		userRoleTable="rsms_user_in_roles" 
		userTable="rsms_users" />
</Context> 

登录页面login.jsp

       <form action="j_security_check" method="post">
           Username<input type="text" name="j_username" /><br />
           Password<input type="password" name="j_password" /><br />
          <input type="submit" />
       </form>

在配置中遇到的问题：
在登录的时候报这个：name jdbc is not bound in this context
解决办法，在realm配置中加上 localDataSource="true"，否则会在tomcat中定义的realm中找dataSource,即（针对tomcat-user.xml定义的UserDataSource），原因看下面的源代码。
在org.apache.catalina.realm.DataSourceRealm中打开数据库连接的源代码：

            Context context = null;
            if (localDataSource) {
                context = ContextBindings.getClassLoader();
                context = (Context) context.lookup("comp/env");
            } else {
                context =
                    ((StandardServer)getServer()).getGlobalNamingContext();
            }
            DataSource dataSource = (DataSource)context.lookup(dataSourceName);

如果要自定义用户验证方式，将realm中的DataSourceRealm换成自定义的类（继承RealmBase或实现Realm接口，实现其验证方法）即可