我在Tomcat 8.0.15，MySql（带有Jconnector），Servlet / Jsp上有一个NetBeans
Web项目。我需要安全的登录！！！

有一个登录页面。成功登录后，如果是admin，则servlet重定向到管理页面；如果username是standardUser，则servlet重定向到主页。

目前没有任何效果。该页面没有被servlet重定向，在提交按钮上按error.html出现并显示 response.getStatus（）为0
！我测试了（无需登录）servlet对数据库的用户名/密码检查，并且它有效。

所以这是我的代码文件：login.jsp：

<form id="loginForm" method="POST" action="j_security_check">
                        <input name="j_username" id="j_username" type="email" value="test.admin@test.com"></input>
                        <input name="j_password" id="j_password" type="password" value="test"></input>
                        <input id="loginSubmit" type="submit" value="Login"></input></form>

web.xml：

  <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>ProjectP.Auth</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/j_servlet_check</url-pattern>
    </servlet-mapping>
<session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>Login.jsp</welcome-file>
        <welcome-file>index.html</welcome-file>
    </welcome-file-list>
    <login-config>
        <auth-method>FORM</auth-method>
        <realm-name>MyDatabase</realm-name>
        <form-login-config>
            <form-login-page>/Login.jsp</form-login-page>
            <form-error-page>/Error.html</form-error-page>
        </form-login-config>
    </login-config>
    <security-role>
        <description>Web Site Administrator</description>
        <role-name>admin</role-name>
    </security-role>
    <security-role>
        <description>Stansard user</description>
        <role-name>user</role-name>
    </security-role>
    <security-constraint>
        <web-resource-collection>
           <web-resource-name>ProjectP</web-resource-name>
           <url-pattern>/adminpages/*</url-pattern>
           <url-pattern>/userpages/*</url-pattern>
           <http-method>POST</http-method>
        </web-resource-collection>
        <auth-constraint>
           <role-name>admin</role-name>
        </auth-constraint>
    </security-constraint>
    <security-constraint>
        <web-resource-collection>
           <web-resource-name>ProjectP</web-resource-name>
           <url-pattern>/userpages/*</url-pattern>
           <http-method>POST</http-method>
        </web-resource-collection>
        <auth-constraint>
           <role-name>user</role-name>
        </auth-constraint>
    </security-constraint>
    <resource-ref>
        <description>DB Connection</description>
        <res-ref-name>MyDatabase</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
    </resource-ref>
</web-app>

Context.xml：

<Context antiJARLocking="true" path="/ProjectP" allowCasualMultipartParsing="true" >
    <Realm className="org.apache.catalina.realm.JDBCRealm" driverName="com.mysql.jdbc.Driver"
               name="MyDatabase" type="javax.sql.DataSource"
               connectionURL="jdbc:mysql://localhost:3306/mydatabase" 
                   connectionName="root" connectionPassword="sa" 
                   userTable="administrators" userNameCol="username" userCredCol="password"
                   userRoleTable="userroles" roleNameCol="role"
                   auth="Container" maxTotal="100" maxIdle="30" maxWaitMillis="10000"/>  
</Context>

LoginServlet.java：

@WebServlet("/j_servlet_check/*")
@MultipartConfig
public class LoginServlet extends HttpServlet {
protected void doPost(HttpS .......
response.setContentType("text/html;charset=UTF-8"); //text/plain
if (checkLoginUser(request.getParameter("j_username"), password)) { //it works for sure, tested...
request.getSession().setAttribute( "username", username );
request.getRequestDispatcher("../admin/Administration.jsp").forward(request, response);

是否需要context.xml-领域？

那么，如何创建安全登录？

j_security_check如何连接到我的MySql数据库！-可能是登录后显示的问题错误页面…？