struts页面跳转，老是空白页，什么也不显示，也没有报错

struts页面跳转，总是空白页，什么也不显示，也没有报错
在Action的执行方法中
return null;
就会一片空白

正确的代码public String batchAddStudents() {HomeMember homeMember = new HomeMember();for (int i = 0; i < totalnumber; i++) {int temp = numberstart + i;int j = studentService.findUserByName(uprefix + temp);if (j == -1) {homeMember.setUsername(uprefix + temp);homeMember.setPassword("123456");studentService.batchAddStudents(homeMember);} else {addActionError(uprefix + temp + "already existed!!");}}return SUCCESS;}