Spring Controller 在使用 Ajax/Post 传递整数数据时抛出 NullPointerException

Question

我正在尝试以 html 形式传递一组数据；

<form class="form-inline" id="createjobform" method="POST" th:action="@{/createJob}">
...
<div class="form-group">
    <input type="text" class="form-control" id="nopth"
    placeholder="Number Of People To Hire" name="nopth" />
</div>
<div class="form-group">
    <input type="text" readonly="readonly" class="form-control"
    id="listid" placeholder="ID" name="listid"
    title="ID of the list which associated" 
    th:value="${findOneList.id}"/>
</div>

这里的listid，来自另一个表（manytoone-onetomany），我想用这个listid添加新记录。当我在 phpmyadmin 上执行此操作时，它正在工作。但我想用 ajax 发布请求或不用 ajax 来做，不管实际上。两种方法都试过了，还是一样的错误。

这是我的控制器；

@RequestMapping(value = "/createJob", method = RequestMethod.POST)
public @ResponseBody void createJob(@RequestBody Jobs jobs,
        @RequestParam(value = "title", required = false) String title,
        @RequestParam(value = "description", required = false) String description,
        @RequestParam(value = "nopth", required = false) Integer nopth,
        @RequestParam(value = "lastDate", required = false) Date lastDate,
        @RequestParam(value = "listid", required = false) Long listid,
        HttpServletResponse hsr) throws IOException {

    // if I do String nopth above and then
    //jobs.setNopth(Integer.valueOf(nopth));
    // error is NumberFormatException (cannot cast string to int)

    jobs.setLastDate(lastDate);
    jobs.setTitle(title);
    jobs.setDescription(description);
    jobs.setNopth(nopth);
    Lists listttt = listsService.findOne(listid);
    jobs.setLists(listttt);

    jobsService.save(jobs);
    mavHomepage.addObject("findOneList", listsService.findOne(jobs.getId()));
    mavHomepage.addObject("mod", "VIEW_ONELIST");
    hsr.sendRedirect("/oneList?id=" + listid);
}

所以错误是；

error: "Internal Server Error"
exception: "java.lang.NullPointerException"
message: "No message available"
path: "/createJob"
status: 500

在线jobs.setNopth(nopth);

还有错误；

error: "Internal Server Error"
exception: "org.springframework.dao.InvalidDataAccessApiUsageException"
message: "The given id must not be null!; nested exception is 
java.lang.IllegalArgumentException: The given id must not be null!"
path: "/createJob"
status: 500

在行列表 listttt = listsService.findOne(listid);

这不适用于 ajax/post。当我这样做时；

public @ResponseBody void createJob(@RequestBody Jobs jobs,
    @RequestParam(value="listid, required="false") listid,
    HttpServletResponse hsr){

        Lists listttt = listsService.findOne(listid);
        jobs.setLists(listttt);
         ...
}

和ajax；

var formData = {
    title : $("#title").val(),
    description : $("#description").val(),
    nopth : $("#nopth").val(),
    lastDate : $("#lastDate").val(),
    listid : $("#listid").val(),
}
...
$.ajax({
        type : "POST",
        contentType : "application/json",
        url : "/createJob",
        data : JSON.stringify(formData),
....

同样的错误（给定的id不能为空！）

那么我必须如何从整数/长值形式传递数据？使用 AJAX 会更好。并且那个 listid 是 FOREIGN KEY。

模型类；

@Entity(name = "jobs")
public class Jobs {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

@Column(name = "Title")
private String title;

@Column(name = "Description")
private String description;

@Column(name = "Number_Of_People_To_Hire")
private Integer nopth;

@Column(name = "Last_Application_Date")
private Date lastDate;

@ManyToOne(fetch=FetchType.LAZY)
@JoinColumn(name="listid")
private Lists lists;

...

@Entity(name = "lists")
public class Lists implements Serializable {

private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
public Long id;

@Column(name = "List_Name")
public String listname;

@OneToMany(mappedBy = "lists", cascade = CascadeType.ALL)
private List<Jobs> jobs;

我尝试将 nopth 的类型更改为 String、Integer 等并输入 type="text or number" 没有变化。

Answer 1

• @RequestBody这个注解表示方法参数应该绑定到web请求的body上

• 所以你必须像这样修复你的控制器：

  @RequestMapping(value = "/createJob", method = RequestMethod.POST)
  @ResponseBody
  public void createJob(
      @RequestBody Jobs jobs,
      @RequestParam("listid") Long listid
      HttpServletResponse hsr) throws IOException {
  
     Lists listttt = listsService.findOne(listid);
     jobs.setLists(listttt);
  
     jobsService.save(jobs);
  
     ...
  
  }
  

• 您的 jquery 请求：

  var formData = {
      title : $("#title").val(),
      description : $("#description").val(),
      nopth : $("#nopth").val(),
      lastDate : $("#lastDate").val()
  }
  
  var listid : $("#listid").val(),
  
  var settings = {
    "url": "http://localhost:8080/createJob?listid="+listid,
    "method": "POST",
    "data": JSON.stringify(formData)
    "headers": {
      "Content-Type": "application/json"
    }
   }
  
   $.ajax(settings).done(function (response) {
     console.log(response);
   });