自己動手寫SSO（單點登錄）

SSO在我們的應用中非常常見，例如我們在OA系統登錄了，我們就可以直接進入採購系統，不需要再登錄了，這樣使我們非常方便。現在網上也有很多實現方法，於是乎我也想寫一個看看。我主要用到的是cookie的機制。在此，分享給大家， 同時提供源代碼下載。

進入主題：

工程說明

SSO的實現一般是會有一個SSO Server，也會叫認證中心，同時也會有被認證的系統，如OA系統、採購系統等，他們就相當於SSO Server的client。

爲了更形象體現SSO，我寫的SSO是有三個工程：一個SSO Server端口爲8081，一個OA系統端口爲8082，一個採購系統端口爲8083。如圖：

流程介紹

在整個SSO流程當，有兩個流程非常重要，第一個是用戶沒有登錄系統到登錄系統的過程；第二是用戶在一個系統當中已經登錄（例如在OA系統中登錄了），但又想進入另一個系統（例如進入PRO系統）的過程，如果把這兩個過程搞定了，那麼SSO也就搞定了。我畫了兩幅圖來說明這兩個過程。

先看用戶沒有登錄系統到登錄系統的過程，如圖：

1：用戶通過URL訪問OA系統。

2：在OA系統中的filter發現這個URL沒有ticket（你暫且就把ticket看做是門票），此時就會跳轉到SSO Server。

3：SSO Server中的filter發現該客戶端中的cookie中沒有相應信息，也即是一個沒有登錄的用戶，那麼會跳轉到登錄頁面。

4：用戶在登錄頁面填寫相應信息，然後通過post方式提交到SSO Server中。

5：SSO Server會校驗用戶信息（我爲了快，我的校驗方式就是要用戶名爲：cloud，同時密碼爲：cloud），同時在cookie中放username。

6：將生成ticket和username放到JVMCache中，在實際項目應該放到Memcached中，它的用處等下分析。

7，8：就是在用戶訪問OA系統的URL基礎上加上了一個ticket參數，這樣跳轉到OA系統。

（此時進入OA系統時，filter發現URL是帶ticket的，則filter會根據帶過來的ticket並通過HttpClient的形式去調用SSO Server中的TicektServlet，這樣就會返回用戶名，其實這個用戶名就是從JVMCache拿到的，同時馬上將這個ticket從JVMCache中移除，這樣保證一個ticket只會用一次，然後把返回的用戶名放到session中）

9：session中有了用戶名，說明用戶登錄成功了，則會去本應該返問的servlet。

10，11：將OA系統返回的視圖給用戶。

第二過程，用戶已經登錄成功了，但要訪問另一個系統，如圖：

1：用戶通過URL訪問PRO系統。

2：在PRO系統中的filter發現這個URL沒有ticket，此時就會跳轉到SSO Server。此時，由於用戶登錄了，所以cookie中有相應的信息（例如用戶名），此時SSO Server中的filter會生成一個ticket。

3：將生成的ticket和username放到JVMCache中。

4：就是在用戶訪問PRO系統的URL基礎上加上了一個ticket參數，這樣跳轉到PRO系統。

（此時進入PRO系統時，filter發現URL是帶ticket的，則filter會根據帶過來的ticket並通過HttpClient的形式去調用SSO Server中的TicektServlet，這樣就會返回用戶名，其實這個用戶名就是從JVMCache拿到的，同時馬上將這個ticket從JVMCache中移除，這樣保證一個ticket只會用一次，然後把返回的用戶名放到session中）

5：session中有了用戶名，說明用戶登錄成功了，則會去本應該返問的servlet。

5，7：將PRO系統返回的視圖給用戶。

關鍵代碼

先看SSO Server工程中的代碼：

pom.xml

（注意：端口爲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>
              <stopKey>stop</stopKey>
              <stopPort>6000</stopPort>
              <webAppConfig>
                  <contextPath>/sso</contextPath>
              </webAppConfig>
              <scanIntervalSeconds>4</scanIntervalSeconds>
              <connectors>
                  <connector implementation="org.eclipse.jetty.server.nio.SelectChannelConnector">
                      <port>8081</port>
                      <maxIdleTime>60000</maxIdleTime>
                  </connector>
              </connectors>
          </configuration>
      </plugin>
    </plugins>
  </build>
</project>

SSO Server中的filter

SSOServerFilter.java

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 = "";
        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;
        }

        if (null != username && !"".equals(username)) {
            long time = System.currentTimeMillis();
            String timeString = username + time;
            JVMCache.TICKET_AND_NAME.put(timeString, username);
            StringBuilder url = new StringBuilder();
            url.append(service);
            if (0 <= service.indexOf("?")) {
                url.append("&");
            } else {
                url.append("?");
            }
            url.append("ticket=").append(timeString);
            response.sendRedirect(url.toString());
        } else {
            filterChain.doFilter(servletRequest, servletResponse);
        }
    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
    }

}

兩個servlet:

LoginServlet.java

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");

        if ("cloud".equals(username) && "cloud".equals(password)) {
            Cookie cookie = new Cookie("sso", username);
            cookie.setPath("/");
            response.addCookie(cookie);

            long time = System.currentTimeMillis();
            String timeString = username + time;
            JVMCache.TICKET_AND_NAME.put(timeString, username);

            if (null != service) {
                StringBuilder url = new StringBuilder();
                url.append(service);
                if (0 <= service.indexOf("?")) {
                    url.append("&");
                } else {
                    url.append("?");
                }
                url.append("ticket=").append(timeString);
                response.sendRedirect(url.toString());
            } else {
                response.sendRedirect("/sso/index.jsp");
            }
        } else {
            response.sendRedirect("/sso/index.jsp?service=" + service);
        }
    }

}

TicketServlet.java

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;

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);
        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 {

    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系統中的代碼：

pom.xml

（注意：端口爲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>
              <stopKey>stop</stopKey>
              <stopPort>6000</stopPort>
              <webAppConfig>
                  <contextPath>/oa</contextPath>
              </webAppConfig>
              <scanIntervalSeconds>4</scanIntervalSeconds>
              <connectors>
                  <connector implementation="org.eclipse.jetty.server.nio.SelectChannelConnector">
                      <port>8082</port>
                      <maxIdleTime>60000</maxIdleTime>
                  </connector>
              </connectors>
          </configuration>
      </plugin>
    </plugins>
  </build>
</project>

OA系統中的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");

        if (null == username) {
            if (null != ticket && !"".equals(ticket)) {
                PostMethod postMethod = new PostMethod("http://localhost:8081/sso/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/index.jsp?service=" + url);
                }
            } else {
                response.sendRedirect("http://localhost:8081/sso/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系統的代碼：

pom.xml

（注意：端口爲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>
              <stopKey>stop</stopKey>
              <stopPort>6000</stopPort>
              <webAppConfig>
                  <contextPath>/pro</contextPath>
              </webAppConfig>
              <scanIntervalSeconds>4</scanIntervalSeconds>
              <connectors>
                  <connector implementation="org.eclipse.jetty.server.nio.SelectChannelConnector">
                      <port>8083</port>
                      <maxIdleTime>60000</maxIdleTime>
                  </connector>
              </connectors>
          </configuration>
      </plugin>
    </plugins>
  </build>
</project>

PRO系統中的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/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/index.jsp?service=" + url);
                }
            } else {
                response.sendRedirect("http://localhost:8081/sso/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>

運行結果：

1：分別啓動這三個工程。

2：訪問OA系統，URL：http://localhost:8082/oa/list

3：這樣到登錄頁面，如圖：