我正在构建一个程序，并且我尝试使用编辑功能来更新mysql中的某些数据。但是，我收到了一个错误。
我看到的错误可能是在控制器中。
这是我的controller：
package org.assignment.controller;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.assignment.dao.AssignmentDao;
import org.assignment.pojo.Assignment;
import org.assignment.service.AssignmentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;
import java.util.ArrayList;
import java.util.List;
@Controller
public class AssignmentController {
@Autowired
public AssignmentService assignmentService;
@Autowired
public AssignmentDao assignmentDao;
@RequestMapping(value = "/addAssignment", method =RequestMethod.GET)
public ModelAndView showRegister(HttpServletRequest request, HttpServletResponse response) {
ModelAndView mav = new ModelAndView("add_Assignment");
mav.addObject("assignment", new Assignment());
return mav;
}
@RequestMapping(value = "/successAddAssignment", method = RequestMethod.POST)
public ModelAndView addAssignment(HttpServletRequest request, HttpServletResponse response,
@ModelAttribute("assignment") Assignment assignment) {
assignmentService.addAssignment(assignment);
return new ModelAndView("success_Add_Assignment", "code_module", assignment.getCode_module());
}
@RequestMapping(value = "/showAllAssignment", method = RequestMethod.GET)
public ModelAndView showAllAssignment(HttpServletRequest request, HttpServletResponse response) {
List<Assignment> list = new ArrayList<Assignment>();
list = assignmentService.showAllAssignment();
for (Assignment a:list) {
System.out.println(a.getId() +" "+ a.getName_module() +" "+ a. getDate() +" "+ a.getTime());
}
ModelAndView mav = new ModelAndView("show_All_Assignments");
mav.addObject("assignment", list);
return mav;
}
/* It updates model object. */
@RequestMapping(value="/assignment/{id}/edit")
public ModelAndView editAssignment(@PathVariable int id){
Assignment a = assignmentDao.editAssignment(id);
return new ModelAndView("edit_Assignment","command", a);
}
/* It updates model object. */
@RequestMapping(value="/assignment/{id}/saveEditAssignment", method = RequestMethod.POST)
public String editSave(HttpServletRequest request, HttpServletResponse response,
@ModelAttribute("assignment") Assignment assignment, final RedirectAttributes redirectAttributes){
redirectAttributes.addFlashAttribute("css", "Success");
redirectAttributes.addFlashAttribute("msg", "The user is updated");
assignmentDao.update(assignment);
return ("redirect:/showAllAssignment");
}
}
这是我的jsp文件：
<form:form id="regForm" action="saveEditAssignment" method="post">
<table align="center">
<tr>
<td>
<form:label path="code_module">Code Module</form:label>
</td>
<td>
<form:input path="code_module"/>
</td>
</tr>
<tr>
<td>
<form:label path="name_module">Name Module</form:label>
</td>
<td>
<form:input path="name_module"/>
</td>
</tr>
<tr>
<td>
<form:label path="description">Description</form:label>
</td>
<td>
<form:input path="description" />
</td>
</tr>
<tr>
<td>
<form:label path="date">Date</form:label>
</td>
<td>
<form:input type="text" path="date" />
</td>
</tr>
<tr>
<td>
<form:label path="time">Time</form:label>
</td>
<td>
<form:input path="time" name="time" id="time" type="time" step="2"/>
</td>
</tr>
<tr>
<td>
<form:button id="addAssignment" name="addAssignment">Submit</form:button>
</td>
</tr>
</table>
</form:form>
这是我的dao文件：
@Override
public void update(Assignment assignment) {
String sql="update assignment set date='"+ assignment.getDate()+"', " +
"time="+assignment.getTime()+", " +
"code_module='"+assignment.getCode_module()+", " +
"name_module='"+assignment.getName_module()+", " +
"description='"+assignment.getDescription()+
"' where id="+assignment.getId()+"";
jdbcTemplate.update(sql);
}
当我想将编辑数据提交到mysql时，我收到了错误。
这是我的Assignment课程：
public class Assignment {
private int id;
private Time time;
private String date;
private String code_module;
private String name_module;
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
private String description;
public int getId() { return id; }
public void setId(int id) { this.id = id; }
public Time getTime() { return time; }
public void setTime(Time time) { this.time = time; }
public String getDate() { return date; }
public void setDate(String date) { this.date = date; }
public String getCode_module() { return code_module; }
public void setCode_module(String code_module) { this.code_module = code_module; }
public String getName_module() { return name_module; }
public void setName_module(String name_module) { this.name_module = name_module; }
}
这是错误，在我成功更新/编辑mysql中的数据后，又想回到showAllAssignment目录页面：
2018-04-25 08:52:43,884 [org.springframework.web.servlet.DispatcherServlet]-[DEBUG] DispatcherServlet with name 'spring-mvc' processing POST request for [/assignment/30/saveEditAssignment]
2018-04-25 08:52:43,885 [org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping]-[DEBUG] Looking up handler method for path /assignment/30/saveEditAssignment
2018-04-25 08:52:43,886 [org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping]-[DEBUG] Returning handler method [public java.lang.String org.assignment.controller.AssignmentController.editSave(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse,org.assignment.pojo.Assignment,org.springframework.web.servlet.mvc.support.RedirectAttributes)]
2018-04-25 08:52:43,886 [org.springframework.beans.factory.support.DefaultListableBeanFactory]-[DEBUG] Returning cached instance of singleton bean 'assignmentController'
2018-04-25 08:52:43,909 [org.springframework.web.cors.DefaultCorsProcessor]-[DEBUG] Skip CORS processing: request is from same origin
2018-04-25 08:52:43,914 [org.springframework.validation.DataBinder]-[WARN] Skipping URI variable 'id' since the request contains a bind value with the same name.
2018-04-25 08:52:43,918 [org.springframework.core.annotation.AnnotationUtils]-[DEBUG] Failed to meta-introspect annotation [interface org.springframework.web.bind.annotation.ModelAttribute]: java.lang.NullPointerException
2018-04-25 08:52:43,919 [org.springframework.jdbc.core.JdbcTemplate]-[DEBUG] Executing prepared SQL update
2018-04-25 08:52:43,919 [org.springframework.jdbc.core.JdbcTemplate]-[DEBUG] Executing prepared SQL statement [update assignment set date=?, time=?, code_module=?, name_module=?, description=? where id=?]
2018-04-25 08:52:43,919 [org.springframework.jdbc.datasource.DataSourceUtils]-[DEBUG] Fetching JDBC Connection from DataSource
2018-04-25 08:52:43,919 [org.springframework.jdbc.datasource.DriverManagerDataSource]-[DEBUG] Creating new JDBC DriverManager Connection to [jdbc:mysql://143.167.9.232:3306/db_assignment]
2018-04-25 08:52:44,231 [org.springframework.jdbc.core.JdbcTemplate]-[DEBUG] SQL update affected 1 rows
2018-04-25 08:52:44,258 [org.springframework.jdbc.datasource.DataSourceUtils]-[DEBUG] Returning JDBC Connection to DataSource
2018-04-25 08:52:44,264 [org.springframework.beans.factory.support.DefaultListableBeanFactory]-[DEBUG] Invoking afterPropertiesSet() on bean with name 'redirect:/show_All_Assignments/'
2018-04-25 08:52:44,264 [org.springframework.web.servlet.DispatcherServlet]-[DEBUG] Rendering view [org.springframework.web.servlet.view.RedirectView: name 'redirect:/show_All_Assignments/'; URL [/show_All_Assignments/]] in DispatcherServlet with name 'spring-mvc'
2018-04-25 08:52:44,267 [org.springframework.web.servlet.support.SessionFlashMapManager]-[DEBUG] Saving FlashMap=FlashMap [attributes={msg=The user is updated, css=Success}, targetRequestPath=/show_All_Assignments/, targetRequestParams={}]
2018-04-25 08:52:44,268 [org.springframework.web.servlet.DispatcherServlet]-[DEBUG] Successfully completed request
2018-04-25 08:52:44,274 [org.springframework.web.servlet.DispatcherServlet]-[DEBUG] DispatcherServlet with name 'spring-mvc' processing GET request for [/show_All_Assignments/]
2018-04-25 08:52:44,274 [org.springframework.web.servlet.support.SessionFlashMapManager]-[DEBUG] Retrieved FlashMap(s): [FlashMap [attributes={msg=The user is updated, css=Success}, targetRequestPath=/show_All_Assignments/, targetRequestParams={}]]
2018-04-25 08:52:44,276 [org.springframework.web.servlet.support.SessionFlashMapManager]-[DEBUG] Found matching FlashMap(s): [FlashMap [attributes={msg=The user is updated, css=Success}, targetRequestPath=/show_All_Assignments/, targetRequestParams={}]]
2018-04-25 08:52:44,276 [org.springframework.web.servlet.support.SessionFlashMapManager]-[DEBUG] Removing FlashMap(s): [FlashMap [attributes={msg=The user is updated, css=Success}, targetRequestPath=/show_All_Assignments/, targetRequestParams={}]]
2018-04-25 08:52:44,276 [org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping]-[DEBUG] Looking up handler method for path /show_All_Assignments/
2018-04-25 08:52:44,278 [org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping]-[DEBUG] Did not find handler method for [/show_All_Assignments/]
2018-04-25 08:52:44,278 [org.springframework.web.servlet.PageNotFound]-[WARN] No mapping found for HTTP request with URI [/show_All_Assignments/] in DispatcherServlet with name 'spring-mvc'
2018-04-25 08:52:44,278 [org.springframework.web.servlet.DispatcherServlet]-[DEBUG] Successfully completed request
答案 0 :(得分：0)
尝试修改您的SQL代码：
"' where id="+assignment.getId()+"";
要像这样：
"'where id="+assignment.getId()+"'";
有时我们需要小心在SQL上加上引号。
此外，
尝试将modelAttribute="assignment"添加到form：form标记中。将操作attribute从form到id的值作为Assignment对象的属性，将很有用