为什么java后台无法获取到前台的部分值

                                <input type="email" name="login" class="form-control" placeholder="请输入邮箱">
                            </div>
                        </div>
                        <div class="form-group">
                            <div class="input-group">
                                <div class="input-group-addon">
                                    <i class="fa fa-lock" style="margin:0;"></i>
                                </div>
                                <input type="password" name="password" class="form-control" placeholder="请输入密码">
                            </div>
                        </div>

                        <div class="form-group">
                            <input class="btn btn-primary"  type="submit" value="注册">
                              <input type="hidden" name="status" value="saveStudent"/>

                        </div>
                        <div class="form-group agree-privacy">
                            注册表示您已经同意我们的<a href="privacy/index.html" target="_blank">隐私条款</a>
                        </div>
                        <div class="form-group widget-signup">
                            <span>快速注册</span>
                            <a href="/auth/qq?next="><i class="fa fa-qq"></i></a>
                            <a href="/auth/weibo?next="><i class="fa fa-weibo"></i></a>
                            <a href="/auth/weixin?next="><i class="fa fa-weixin"></i></a>
                            <a href="/auth/github?next="><i class="fa fa-github"></i></a>
                            <a href="/auth/renren?next="><i class="fa fa-renren"></i></a>
                        </div>

                    </form>
                </div>

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2017-11-21 17:35:54 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet StudentSer threw exception
java.lang.NullPointerException
at ser.StudentSer.doPost(StudentSer.java:88)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)

我在控制台试着打印出email password 和status的value值 可是只输出了password值
想了一个下午实在想不出