Spring，Facebook登录：Servlet没有被执行登录

我正在开发一个Spring-MVC应用程序，我们希望使用Facebook登录 . 我尝试了一些代码，我被重定向到Facebook页面请求许可，然后当我给予许可时，我可以看到该应用程序已在Facebook的“我的应用程序”中注册 .

问题是servlet中的后端代码没有被执行，这将使我像UserDetails一样发送电子邮件等，我可以用它来登录/注册 . 我不知道为什么 .

此外，是否有任何其他方式来访问数据，而不是使用循环和读取变量，如通过RestTemplate左右的对象 .

代码时间：

公共类FbSignIn扩展HttpServlet {

public void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
    System.out.println("How to know if I was executed");
    String code = req.getParameter("code");
    if (code == null || code.equals("")) {
        System.out.println("No code recieved");
    }

    String token = null;
    try {
        String g = "https://graph.facebook.com/oauth/access_token?client_id=appid&redirect_uri=url&" + URLEncoder.encode("http://myappengineappid.appspot.com/signin_fb.do", "UTF-8") + "&client_secret=clientsecret&code=" + code;
        URL u = new URL(g);
        URLConnection c = u.openConnection();
        BufferedReader in = new BufferedReader(new InputStreamReader(c.getInputStream()));
        String inputLine;
        StringBuffer b = new StringBuffer();
        while ((inputLine = in.readLine()) != null)
            b.append(inputLine + "\n");
        in.close();
        token = b.toString();
        if (token.startsWith("{"))
            throw new Exception("error on requesting token: " + token + " with code: " + code);
    } catch (Exception e) {
        e.printStackTrace();
    }

    String graph = null;
    try {
        String g = "https://graph.facebook.com/me?" + token;
        URL u = new URL(g);
        URLConnection c = u.openConnection();
        BufferedReader in = new BufferedReader(new InputStreamReader(c.getInputStream()));
        String inputLine;
        StringBuffer b = new StringBuffer();
        while ((inputLine = in.readLine()) != null)
            b.append(inputLine + "\n");
        in.close();
        graph = b.toString();
    } catch (Exception e) {
        e.printStackTrace();
        // an error occurred, handle this
    }

    String facebookId;
    String firstName;
    String middleNames;
    String lastName;
    String email;
    //Gender gender;
    try {
        JSONObject json = new JSONObject(graph);
        facebookId = json.getString("id");
        firstName = json.getString("first_name");
        System.out.println("First name is "+firstName);
// I want to avoid this, but access via objects
        if (json.has("middle_name"))
            middleNames = json.getString("middle_name");
        else
            middleNames = null;
        if (middleNames != null && middleNames.equals(""))
            middleNames = null;
        lastName = json.getString("last_name");
        email = json.getString("email");

        if (json.has("gender")) {
            String g = json.getString("gender");
            if (g.equalsIgnoreCase("female")){
                System.out.println("Female");
            }
            //gender = Gender.FEMALE;

            else if (g.equalsIgnoreCase("male")){
                System.out.println("Male");
            }
            //gender = Gender.MALE;
            else{
                System.out.println("Unknown gender");
            }
            //    gender = Gender.UNKNOWN;
        } else {
            System.out.println("Gender unknown");
            //   gender = Gender.UNKNOWN;
        }
    } catch (JSONException e) {
        e.printStackTrace();
    }
}

}

web.xml中的serlvet：

<servlet>
    <servlet-name>FbSignin</servlet-name>
</servlet>
<servlet-mapping>
    <servlet-name>FbSignin</servlet-name>
    <url-pattern>/*</url-pattern>
</servlet-mapping>

JSP文件调用代码：

<%@page import="java.net.URLEncoder" %>
<%
    String fbURL = "http://www.facebook.com/dialog/oauth?client_id=123456&redirect_uri=redirect.com&" + URLEncoder.encode("http://myappengineappid.appspot.com/signin_fb.do") + "&scope=email";
%>

<a href="<%= fbURL %>"><img src="/img/fb.png" border="0" width="300" height="300" /></a>

我做错了什么，我只是想得到详细信息，所以我可以注册用户并登录他 . 下次当用户再次点击按钮时，我将从FB获取电子邮件地址，验证它是否存在在DB中，并登录 .

更新

JSP的新servlet映射：

<servlet>
        <servlet-name>mvc-dispatcher</servlet-name>
        <servlet-class>com.journaldev.spring.Login.FbSignIn</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>mvc-dispatcher</servlet-name>
        <url-pattern>/FbSignin</url-pattern>
    </servlet-mapping>