public class StudentManager {
private static StudentManager instance = null; private StudentManager() {
} public static synchronized StudentManager getInstance() {
if (instance == null) {
instance = new StudentManager();
}
return instance;
}
.....
}在这个类中使用了单例模式,可是在jsp页面中使用单例报一下错误。org.apache.jasper.JasperException: Unable to compile class for JSP: An error occurred at line: 19 in the jsp file: /sysmgr/student_add.jsp
The method getInstance() is undefined for the type StudentManager
16: String mail = "";
17: String phone = "";
18: if ("bj".equals(request.getParameter(bj))) {
19: if (StudentManager.getInstance().findStudentById(request
20: .getParameter("stuId")) == null) {
21:
22: Student student = new Student();
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<%@ page import="com.qrh.bs.sysmgr.domain.*"%>
<%@ page import="com.qrh.bs.sysmgr.manager.StudentManager"%>
<%@ page import="java.util.*"%>
<%
request.setCharacterEncoding("GB18030");
String bj = request.getParameter("bj");
String stuId = "";
String stuName = "";
String password = "";
String college = "";
String radio = "";
String mail = "";
String phone = "";
if ("bj".equals(request.getParameter(bj))) {
if (StudentManager.getInstance().findStudentById(request
.getParameter("stuId")) == null) { Student student = new Student();
student.setStuId(request.getParameter("stuId"));
student.setStuName(request.getParameter("stuName"));
student.setPassword(request.getParameter("password"));
student.setCollege(request.getParameter("college"));
student.setIsLogin(request.getParameter("radio"));
student.setMail(request.getParameter("mail"));
student.setCreateTime(new Date());
student.setPhone(request.getParameter("phone"));
StudentManager.getInstance().addStudent(student);
} else {
//代码要是重复,就把值取出来在传回网页
out.println("用户代码重复");
stuId = request.getParameter("stuId");
stuName = request.getParameter("stuName");
password = request.getParameter("password");
college = request.getParameter("college");
radio = request.getParameter("radio");
mail = request.getParameter("mail");
phone = request.getParameter("phone");
}
}
%>
public class StudentManager {
private static StudentManager instance = new StudentManager (); private StudentManager() {
} public static synchronized StudentManager getInstance() {
return instance;
}
.....
}
public synchronized static StudentManager getInstance()样试试!
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