SpringMVC框架

发布日期：2018-12-19 作者：atguigu 1366人浏览

7.4 RESTRUL_CRUD_添加操作

在jsp上增加连接

<a href="empInput">Add Employee</a>

增加处理器方法

@RequestMapping(value="/empInput",method=RequestMethod.GET)

public String empInput(Map<String,Object> map){

map.put("deptList", departmentDao.getDepartments());

//解决错误：java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'command' available as request attribute

Employee employee = new Employee();

//map.put("command", employee);

map.put("employee", employee);

return "add";

}

显示添加页面

<%@ page language="java" contentType="text/html; charset=UTF-8"

pageEncoding="UTF-8" import="java.util.*"%>

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01

Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Insert title here</title>

</head>

<body>

<!--

1.为什么使用SpringMVC的form标签

① 快速开发

② 表单回显

2.可以通过modelAttribute指定绑定的模型属性，

若没有指定该属性，则默认从request域中查找command的表单的bean

如果该属性也不存在，那么，则会发生错误。

-->

<form:form action="empAdd" method="POST" modelAttribute="employee">

LastName : <form:input path="lastName"/><br><br>

Email : <form:input path="email"/><br><br>

Map<String,String> map = new HashMap<String,String>();

map.put("1", "Male");

map.put("0","Female");

request.setAttribute("genders", map);

Gender : <br><form:radiobuttons path="gender" items="${genders }" delimiter="<br>"/><br><br>

DeptName :

<form:select path="department.id"

items="${deptList }"

itemLabel="departmentName"

itemValue="id"></form:select><br><br>

<input type="submit" value="Submit"><br><br>

</form:form>

</body>

</html>

显示表单信息时，会报错：

HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: An exception occurred processing JSP page /WEB-INF/views/add.jsp at line 18

15:                         ② 表单回显
16:          -->
17:          <form:form action="empAdd" method="POST">
18:                  LastName : <form:input path="lastName"/>
19:                  Email : <form:input path="email"/>
20:                  <%
21:                          Map<String,String> map = new HashMap<String,String>();

Stacktrace:
        org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:505)
        org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:410)
        org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:337)
        org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:209)
        org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:266)
        org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1225)
        org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1012)
        org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
        org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:876)
        org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:931)
        org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:822)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
        org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:807)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
        org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)

root cause

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'command' available as request attribute
org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:141)

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