自己动手写SSO（单点登录）

一、什么是单点登录SSO（Single Sign-On）

　　SSO是一种统一认证和授权机制，指访问同一服务器不同应用中的受保护资源的同一用户，只需要登录一次，即通过一个应用中的安全验证后，再访问其他应用中的受保护资源时，不再需要重新登录验证。

二、单点登录解决了什么问题

　　解决了用户只需要登录一次就可以访问所有相互信任的应用系统，而不用重复登录。

工程说明

SSO的实现一般会有一个SSO Server，也叫认证系统，同时也会有被认证的系统，如OA系统、采购系统等，他们就相当于SSO Server的client。

为了更形象体现SSO，我写的SSO是有三个工程：一个SSO Server端口为8081，一个OA系统端口为8082，一个采购系统端口为8083。如图：

 
  流程介绍

在整个SSO流程当，有两个流程非常重要，第一个是用户没有登录系统到登录系统的过程；第二是用户在一个系统当中已经登录（例如在OA系统中登录 了），但又想进入另一个系统（例如进入PRO系统）的过程，如果把这两个过程搞定了，那么SSO也就搞定了。我画了两幅图来说明这两个过程。

先看用户没有登录系统到登录系统的过程，如图：

 
 1：用户通过URL访问OA系统。

 2：在OA系统中的filter发现这个URL没有ticket（你暂且就把ticket看做是门票），此时就会跳转到SSO Server。

 3：SSO Server中的filter发现该客户端中的cookie中没有相应信息，也即是一个没有登录的用户，那么会跳转到登录页面。

 4：用户在登录页面填写相应信息，然后通过post方式提交到SSO Server中。

 5：SSO Server会校验用户信息（我为了快，我的校验方式就是要用户名为：admin，同时密码为：1111），同时在cookie中放username。

 6：将生成ticket和username放到JVMCache中，在实际项目应该放到Memcached中，它的用处等下分析。

7，8：就是在用户访问OA系统的URL基础上加上了一个ticket参数，这样跳转到OA系统。

（此时进入OA系统时，filter发现URL是带ticket的，则filter会根据带过来的ticket并通过HttpClient的形式去调用SSO Server中的TicektServlet，这样就会返回用户名，其实这个用户名就是从JVMCache拿到的，同时马上将这个ticket从JVMCache中移除，这样保证一个ticket只会用一次，然后把返回的用户名放到session中）

 9：session中有了用户名，说明用户登录成功了，则会去本应该返问的servlet。

10，11：将OA系统返回的视图给用户。

 

第二过程，用户已经登录成功了，但要访问另一个系统，如图：

 
  1：用户通过URL访问PRO系统。

  2：在PRO系统中的filter发现这个URL没有ticket，此时就会跳转到SSO Server。此时，由于用户登录了，所以cookie中有相应的信息（例如用户名），此时SSO Server中的filter会生成一个ticket。

 3：将生成的ticket和username放到JVMCache中。

 4：就是在用户访问PRO系统的URL基础上加上了一个ticket参数，这样跳转到PRO系统。

（此时进入PRO系统时，filter发现URL是带ticket的，则filter会根据带过来的ticket并通过HttpClient的形式去调用SSO Server中的TicektServlet，这样就会返回用户名，其实这个用户名就是从JVMCache拿到的，同时马上将这个ticket从JVMCache中移除，这样保证一个ticket只会用一次，然后把返回的用户名放到session中）

 5：session中有了用户名，说明用户登录成功了，则会去本应该返问的servlet。

5，7：将PRO系统返回的视图给用户。

 

关键代码

 

先看SSO Server工程中的代码：

pom.xml

（注意：端口为8081）

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.cloud.sso.server</groupId><artifactId>sso-server</artifactId><packaging>war</packaging><version>0.0.1-SNAPSHOT</version><name>sso-server Maven Webapp</name><url>http://maven.apache.org</url><dependencies><dependency><groupId>javax.servlet</groupId><artifactId>servlet-api</artifactId><version>2.5</version><scope>provided</scope></dependency></dependencies><build><finalName>sso-server</finalName><plugins><plugin><groupId>org.mortbay.jetty</groupId><artifactId>jetty-maven-plugin</artifactId><version>8.1.9.v20130131</version><configuration><!-- 配置jetty的容器 端口等 --><connectors><connector implementation="org.eclipse.jetty.server.nio.SelectChannelConnector"><port>8081</port><maxIdleTime>30000</maxIdleTime></connector></connectors><!-- 添加一个特殊的端口和控制键(mvn jetty:stop 停止jetty服务) --><stopKey>stop</stopKey><stopPort>9977</stopPort><!-- 发现内容改变，进行热部署，默认是0，不热部署 --><scanIntervalSeconds>1</scanIntervalSeconds><!-- 配置web容器 --><webAppSourceDirectory>src/main/webapp</webAppSourceDirectory><webAppConfig><!-- 项目的根目录,默认是"/" --><contextPath>/sso-server</contextPath><!-- <descriptor></descriptor> --> <!-- The path to the web.xml file for your webapp --><!-- <defaultsDescriptor>src/main/resources/webdefault.xml</defaultsDescriptor> webdefault.xml的路径，若没有配置就是用jetty默认，这个文件在web.xml加载之前加载 --></webAppConfig><!-- 自动部署默认是 automatic --><reload>automatic</reload><systemProperties><systemProperty><name>org.mortbay.util.URI.charset</name><value>UTF-8</value></systemProperty></systemProperties></configuration></plugin></plugins></build></project>

SSO Server中的filter

package com.cloud.sso.server.filter;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.cloud.sso.server.JVMCache;public class SSOServerFilter implements Filter {    @Override    public void destroy() {    }    @Override    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {        HttpServletRequest request = (HttpServletRequest) servletRequest;        HttpServletResponse response = (HttpServletResponse) servletResponse;        String service = request.getParameter("service");        //String ticket = request.getParameter("ticket");        Cookie[] cookies = request.getCookies();        String username = "";                //判断用户是否已经登陆认证中心        if (null != cookies) {            for (Cookie cookie : cookies) {                 if ("sso".equals(cookie.getName())) {                    username = cookie.getValue();                                  break;                }            }        }//        if (null == service && null != ticket) {//            filterChain.doFilter(servletRequest, servletResponse);//            return;//        }                //实现一处登录处处登录        if (null != username && !"".equals(username)) {            long time = System.currentTimeMillis();            //生成认证凭据--ticket            String ticket = username + time;            JVMCache.TICKET_AND_NAME.put(ticket, username);            StringBuilder url = new StringBuilder();            url.append(service);                        if (0 <= service.indexOf("?")) {                url.append("&");            } else {                url.append("?");            }            //返回给用户一个认证的凭据--ticket            url.append("ticket=").append(ticket);            response.sendRedirect(url.toString());                    } else {            filterChain.doFilter(servletRequest, servletResponse);        }    }    @Override    public void init(FilterConfig arg0) throws ServletException {    }}

两个servlet:

package com.cloud.sso.server.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.cloud.sso.server.JVMCache;public class LoginServlet extends HttpServlet {    private static final long serialVersionUID = -3170191388656385924L;    @Override    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doPost(request, response);    }    @Override    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        String username = request.getParameter("username");        String password = request.getParameter("password");        String service = request.getParameter("service");        //判断用户名和密码是否正确        if ("admin".equals(username) && "1111".equals(password)) {            Cookie cookie = new Cookie("sso", username);            cookie.setPath("/");            response.addCookie(cookie);            long times = System.currentTimeMillis();            //生成认证凭据--ticket            String ticket = username + times;            JVMCache.TICKET_AND_NAME.put(ticket, username);            if (null != service) {                StringBuilder url = new StringBuilder();                url.append(service);                if (0 <= service.indexOf("?")) {                    url.append("&");                } else {                    url.append("?");                }                //返回给用户一个认证的凭据--ticket                url.append("ticket=").append(ticket);                response.sendRedirect(url.toString());                            } else {                response.sendRedirect("/sso-server/index.jsp");            }                    } else {            response.sendRedirect("/sso-server/index.jsp?service=" + service);        }    }}

package com.cloud.sso.server.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.cloud.sso.server.JVMCache;/** * HttpClient调用这个Servlet获取username * @author Hys * */public class TicketServlet extends HttpServlet {    private static final long serialVersionUID = 5964206637772848290L;    @Override    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        super.doGet(request, response);    }    @Override    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        String ticket = request.getParameter("ticket");        String username = JVMCache.TICKET_AND_NAME.get(ticket);        //保证一个ticket只会用一次        JVMCache.TICKET_AND_NAME.remove(ticket);        PrintWriter writer = response.getWriter();        writer.write(username);    }}

JVMCache.java

package com.cloud.sso.server;import java.util.HashMap;import java.util.Map;public class JVMCache {//存放username，再通过HttpClient获取（在实际项目应该放到Memcached中）    public static Map<String, String> TICKET_AND_NAME = new HashMap<String, String>();}

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" xmlns:jsp="http://java.sun.com/xml/ns/javaee/jsp" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">    <welcome-file-list>        <welcome-file>index.jsp</welcome-file>    </welcome-file-list>    <filter>        <filter-name>ssoServerFilter</filter-name>        <filter-class>com.cloud.sso.server.filter.SSOServerFilter</filter-class>    </filter>    <filter-mapping>        <filter-name>ssoServerFilter</filter-name>        <url-pattern>/*</url-pattern>    </filter-mapping>    <servlet>        <servlet-name>login</servlet-name>        <servlet-class>com.cloud.sso.server.servlet.LoginServlet</servlet-class>    </servlet>    <servlet-mapping>        <servlet-name>login</servlet-name>        <url-pattern>/user/login</url-pattern>    </servlet-mapping>    <servlet>        <servlet-name>ticket</servlet-name>        <servlet-class>com.cloud.sso.server.servlet.TicketServlet</servlet-class>    </servlet>    <servlet-mapping>        <servlet-name>ticket</servlet-name>        <url-pattern>/ticket</url-pattern>    </servlet-mapping></web-app>

下面是OA系统中的代码：

pom.xml

（注意：端口为8082）

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.cloud.sso.oa</groupId><artifactId>sso-oa</artifactId><packaging>war</packaging><version>0.0.1-SNAPSHOT</version><name>sso-oa Maven Webapp</name><url>http://maven.apache.org</url><dependencies><dependency><groupId>javax.servlet</groupId><artifactId>servlet-api</artifactId><version>2.5</version><scope>provided</scope></dependency><dependency><groupId>commons-httpclient</groupId><artifactId>commons-httpclient</artifactId><version>3.1</version></dependency></dependencies><build><finalName>sso-oa</finalName><plugins><plugin><groupId>org.mortbay.jetty</groupId><artifactId>jetty-maven-plugin</artifactId><version>8.1.9.v20130131</version><configuration><!-- 配置jetty的容器 端口等 --><connectors><connector implementation="org.eclipse.jetty.server.nio.SelectChannelConnector"><port>8082</port><maxIdleTime>30000</maxIdleTime></connector></connectors><!-- 添加一个特殊的端口和控制键(mvn jetty:stop 停止jetty服务) --><stopKey>stop</stopKey><stopPort>9966</stopPort><!-- 发现内容改变，进行热部署，默认是0，不热部署 --><scanIntervalSeconds>1</scanIntervalSeconds><!-- 配置web容器 --><webAppSourceDirectory>src/main/webapp</webAppSourceDirectory><webAppConfig><!-- 设置项目的虚拟根目录,默认是"/" --><contextPath>/sso-oa</contextPath><!-- <descriptor></descriptor> --> <!-- The path to the web.xml file for your webapp --><!-- <defaultsDescriptor>src/main/resources/webdefault.xml</defaultsDescriptor> webdefault.xml的路径，若没有配置就是用jetty默认，这个文件在web.xml加载之前加载 --></webAppConfig><!-- 自动部署默认是 automatic --><reload>automatic</reload><systemProperties><systemProperty><name>org.mortbay.util.URI.charset</name><value>UTF-8</value></systemProperty></systemProperties></configuration></plugin></plugins></build></project>

OA系统中的filter：

SSOClientFilter.java

package com.cloud.sso.oa.filter;import java.io.IOException;import java.net.URLEncoder;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.apache.commons.httpclient.HttpClient;import org.apache.commons.httpclient.methods.PostMethod;public class SSOClientFilter implements Filter {    @Override    public void destroy() {    }    @Override    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {    HttpServletRequest request = (HttpServletRequest) servletRequest;        HttpServletResponse response = (HttpServletResponse) servletResponse;        HttpSession session = request.getSession();        String username = (String) session.getAttribute("username");        String ticket = request.getParameter("ticket");        String url = URLEncoder.encode(request.getRequestURL().toString(), "UTF-8");        System.out.println("用户名1："+username);        //判断用户是否已经登录oa系统        if (null == username) {         //1.判断用户是否有认证凭据--ticket（认证中心生成）            if (null != ticket && !"".equals(ticket)) {                PostMethod postMethod = new PostMethod("http://localhost:8081/sso-server/ticket");                //给url添加新的参数                postMethod.addParameter("ticket", ticket);                HttpClient httpClient = new HttpClient();                try {                //通过httpClient调用SSO Server中的TicektServlet                    httpClient.executeMethod(postMethod);                    //将HTTP方法的响应正文（如果有）返回为String                    username = postMethod.getResponseBodyAsString();                    //释放此HTTP方法正在使用的连接                    postMethod.releaseConnection();                } catch (Exception e) {                    e.printStackTrace();                }                                //2.判断认证凭据是否有效                if (null != username && !"".equals(username)) {                //session设置用户名，说明用户登录成功了                    session.setAttribute("username", username);                    filterChain.doFilter(request, response);                } else {                    response.sendRedirect("http://localhost:8081/sso-server/index.jsp?service=" + url);                }                            } else {//第一次访问oa系统，需要到sso-server系统验证                response.sendRedirect("http://localhost:8081/sso-server/index.jsp?service=" + url);            }                    } else {            filterChain.doFilter(request, response);        }    }    @Override    public void init(FilterConfig arg0) throws ServletException {    }}

OAServlet.java

package com.cloud.sso.oa.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class OAServlet extends HttpServlet {    private static final long serialVersionUID = 3615122544373006252L;    @Override    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        request.getRequestDispatcher("/WEB-INF/jsp/welcome.jsp").forward(request, response);    }    @Override    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request, response);    }    }

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" xmlns:jsp="http://java.sun.com/xml/ns/javaee/jsp" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">    <welcome-file-list>        <welcome-file>index.jsp</welcome-file>    </welcome-file-list>   <filter>        <filter-name>ssoClientFilter</filter-name>        <filter-class>com.cloud.sso.oa.filter.SSOClientFilter</filter-class>    </filter>    <filter-mapping>        <filter-name>ssoClientFilter</filter-name>        <url-pattern>/*</url-pattern>    </filter-mapping><servlet>        <servlet-name>list</servlet-name>        <servlet-class>com.cloud.sso.oa.servlet.OAServlet</servlet-class>    </servlet>    <servlet-mapping>        <servlet-name>list</servlet-name>        <url-pattern>/list</url-pattern>    </servlet-mapping>    </web-app>

下面是PRO系统的代码：

pom.xml

（注意：端口为8083）

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">  <modelVersion>4.0.0</modelVersion>  <groupId>com.cloud.sso.pro</groupId>  <artifactId>sso-pro</artifactId>  <packaging>war</packaging>  <version>0.0.1-SNAPSHOT</version>  <name>sso-pro Maven Webapp</name>  <url>http://maven.apache.org</url>    <dependencies>    <dependency>          <groupId>javax.servlet</groupId>          <artifactId>servlet-api</artifactId>          <version>2.5</version>          <scope>provided</scope>      </dependency>      <dependency>          <groupId>commons-httpclient</groupId>          <artifactId>commons-httpclient</artifactId>          <version>3.1</version>       </dependency>  </dependencies>    <build>    <finalName>sso-pro</finalName>    <plugins><plugin><groupId>org.mortbay.jetty</groupId><artifactId>jetty-maven-plugin</artifactId><version>8.1.9.v20130131</version><configuration><!-- 配置jetty的容器 端口等 --><connectors><connector implementation="org.eclipse.jetty.server.nio.SelectChannelConnector"><port>8083</port><maxIdleTime>30000</maxIdleTime></connector></connectors><!-- 添加一个特殊的端口和控制键(mvn jetty:stop 停止jetty服务) --><stopKey>stop</stopKey>  <stopPort>6000</stopPort>  <!-- 发现内容改变，进行热部署，默认是0，不热部署 --><scanIntervalSeconds>1</scanIntervalSeconds><!-- 配置web容器 --><webAppSourceDirectory>src/main/webapp</webAppSourceDirectory><webAppConfig><!-- 设置项目的虚拟根目录,默认是"/" --><contextPath>/sso-pro</contextPath><!-- <descriptor></descriptor> --> <!-- The path to the web.xml file for your webapp --><!-- <defaultsDescriptor>src/main/resources/webdefault.xml</defaultsDescriptor>  webdefault.xml的路径，若没有配置就是用jetty默认，这个文件在web.xml加载之前加载 --></webAppConfig><!-- 自动部署默认是 automatic --><reload>automatic</reload><systemProperties><systemProperty><name>org.mortbay.util.URI.charset</name><value>UTF-8</value></systemProperty></systemProperties></configuration></plugin></plugins>  </build></project>

PRO系统中的filter

SSOClientFilter.java

package com.cloud.sso.pro.filter;import java.io.IOException;import java.net.URLEncoder;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.apache.commons.httpclient.HttpClient;import org.apache.commons.httpclient.methods.PostMethod;public class SSOClientFilter implements Filter {    @Override    public void destroy() {    }    @Override    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {        HttpServletRequest request = (HttpServletRequest) servletRequest;        HttpServletResponse response = (HttpServletResponse) servletResponse;        HttpSession session = request.getSession();        String username = (String) session.getAttribute("username");        String ticket = request.getParameter("ticket");        String url = URLEncoder.encode(request.getRequestURL().toString(), "UTF-8");        if (null == username) {            if (null != ticket && !"".equals(ticket)) {                PostMethod postMethod = new PostMethod("http://localhost:8081/sso-server/ticket");                postMethod.addParameter("ticket", ticket);                HttpClient httpClient = new HttpClient();                try {                    httpClient.executeMethod(postMethod);                    username = postMethod.getResponseBodyAsString();                    postMethod.releaseConnection();                } catch (Exception e) {                    e.printStackTrace();                }                if (null != username && !"".equals(username)) {                    session.setAttribute("username", username);                    filterChain.doFilter(request, response);                } else {                    response.sendRedirect("http://localhost:8081/sso-server/index.jsp?service=" + url);                }            } else {                response.sendRedirect("http://localhost:8081/sso-server/index.jsp?service=" + url);            }        } else {            filterChain.doFilter(request, response);        }    }    @Override    public void init(FilterConfig arg0) throws ServletException {    }}

ProServlet.java

package com.cloud.sso.pro.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ProServlet extends HttpServlet {    private static final long serialVersionUID = -1334093914490423930L;    @Override    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        request.getRequestDispatcher("/WEB-INF/jsp/welcome.jsp").forward(request, response);    }        @Override    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        super.doPost(request, response);    }}

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" xmlns:jsp="http://java.sun.com/xml/ns/javaee/jsp" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">    <welcome-file-list>        <welcome-file>index.jsp</welcome-file>    </welcome-file-list>    <filter>        <filter-name>ssoClientFilter</filter-name>        <filter-class>com.cloud.sso.pro.filter.SSOClientFilter</filter-class>    </filter>    <filter-mapping>        <filter-name>ssoClientFilter</filter-name>        <url-pattern>/*</url-pattern>    </filter-mapping>    <servlet>        <servlet-name>list</servlet-name>        <servlet-class>com.cloud.sso.pro.servlet.ProServlet</servlet-class>    </servlet>    <servlet-mapping>        <servlet-name>list</servlet-name>        <url-pattern>/list</url-pattern>    </servlet-mapping></web-app>

运行结果：

1：分别启动这三个工程。

2：访问OA系统，URL：http://localhost:8082/oa/list

3：这样到登录页面，如图：

  
 
 

4：用户名为：admin，密码为：1111，点击登录则会显示，如图：

 
 

 

5：然后去进入PRO系统，URL：http://localhost:8083/pro/list，则就不需要登录了，直接进入，如图：

奉上源码：http://pan.baidu.com/s/1qYHbhRe