在JSP中使用Integer.parseInt()报错的问题

本文探讨了在JSP页面中使用Integer.parseInt方法时遇到的NumberFormatException异常问题,并给出了详细的错误堆栈跟踪信息。通过分析发现,该问题是由于尝试将超出int类型范围的字符串转换为整数导致的。

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在JSP中使用xuehaoi = Integer.parseInt(request.getParameter("xuehao"));时候报错。打开页面显示500错误,定位到这一行。报错信息是:
org.apache.jasper.JasperException: An exception occurred processing JSP page /query.jsp at line 49

46: 		System.out.println("娌℃湁鎷垮埌鏁版嵁");
47: 	}
48: 	if(xuehao!=null && ""!=xuehao.trim()){
49: 		xuehaoi = Integer.parseInt(xuehao);
50: 	}
51: 	if(age!=null && ""!=age.trim()){
52: 		agei = Integer.parseInt(age);


Stacktrace:
	org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause

java.lang.NumberFormatException: For input string: "20131103641"
	java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	java.lang.Integer.parseInt(Integer.java:583)
	java.lang.Integer.parseInt(Integer.java:615)
	org.apache.jsp.query_jsp._jspService(query_jsp.java:124)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

上网查资料,网上说使用Integer.valueOf()。其实网上的说法并不对。这里报错是因为将字符串“20131103641”转化为int型,但是int并不能放下这么大的数值。所以这个问题的原因是溢出。如果把xuehao的数值改为“100”就可顺利执行。在设计数据库的时候,一定要考虑到数据的范围,写入数据前应该进行检验,保证健壮性。


package com.hafu.servlet; import com.hafu.model.Student; import com.hafu.service.StudentService; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; @WebServlet("/student") public class StudentServlet extends HttpServlet { private StudentService studentService = new StudentService(); protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String action = request.getParameter("action"); if (action == null) { action = "list"; } try { switch (action) { case "new": showNewForm(request, response); break; case "edit": showEditForm(request, response); break; case "delete": deleteStudent(request, response); break; default: listStudents(request, response); break; } } catch (Exception e) { e.printStackTrace(); } } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String action = request.getParameter("action"); if (action == null) { action = "list"; } try { switch (action) { case "insert": insertStudent(request, response); break; case "update": updateStudent(request, response); break; default: listStudents(request, response); break; } } catch (Exception e) { e.printStackTrace(); } } private void listStudents(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setAttribute("students", studentService.getAllStudents()); request.getRequestDispatcher("student-list.jsp").forward(request, response); } private void showNewForm(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.getRequestDispatcher("student-form.jsp").forward(request, response); } private void showEditForm(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { int id = Integer.parseInt(request.getParameter("id")); Student student = studentService.getStudentById(id); request.setAttribute("student", student); request.getRequestDispatcher("student-form.jsp").forward(request, response); } private void insertStudent(HttpServletRequest request, HttpServletResponse response) throws IOException { Student student = new Student(); student.setName(request.getParameter("name")); student.setGender(request.getParameter("gender")); student.setAge(Integer.parseInt(request.getParameter("age"))); student.setDepartment(request.getParameter("department")); student.setEmail(request.getParameter("email")); student.setPhone(request.getParameter("phone")); studentService.addStudent(student); response.sendRedirect("student"); } private void updateStudent(HttpServletRequest request, HttpServletResponse response) throws IOException { int id = Integer.parseInt(request.getParameter("id")); Student student = studentService.getStudentById(id); student.setName(request.getParameter("name")); student.setGender(request.getParameter("gender")); student.setAge(Integer.parseInt(request.getParameter("age"))); student.setDepartment(request.getParameter("department")); student.setEmail(request.getParameter("email")); student.setPhone(request.getParameter("phone")); studentService.updateStudent(student); response.sendRedirect("student"); } private void deleteStudent(HttpServletRequest request, HttpServletResponse response) throws IOException { int id = Integer.parseInt(request.getParameter("id")); studentService.deleteStudent(id); response.sendRedirect("student"); } }报错
06-03
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