java - Spring MVC @ResponseBody错误

我有实体类GroupStudent，Spring Controller和带有Ajax函数的JSP页面。在控制器中，我尝试使用@ResponseBody将实体GroupStudent对象传递到JSP页面。但是我总是从浏览器中得到错误：Error [object Object]。我发现我需要在项目jackson-core-asl和jackson-mapper-asl jars中添加到lib文件夹。我添加了它们（版本1.9.7）并放入spring-servlet.xml，以便它可以自动将GroupStudent对象转换为json格式并将其传递回ajax函数。但这并没有帮助，我在浏览器中始终有相同的错误对话框。如果有人知道如何使用@ResponseBody将实体对象传递给Ajax，我将不胜感激。

谢谢。

GroupStudent类

@Entity
@Table(name = "GroupStudent")
@NamedQueries({
@NamedQuery(name = "GroupStudent.getAllGroups", // get all groups
            query = "select g from GroupStudent g"),
@NamedQuery(name = "GroupStudent.getGroupByName", // get group by name
            query = "select g from GroupStudent g where g.groupStudentNumber = :name")
})
public class GroupStudent implements Serializable {
public GroupStudent() {}

public GroupStudent(String groupStudentNumber) {
    this.groupStudentNumber = groupStudentNumber;
}

// create connectivity with table Student
private Set<Student> students = new HashSet<Student>();

@OneToMany(mappedBy = "groupStudent", cascade = CascadeType.ALL, orphanRemoval = true)
public Set<Student> getStudents() {
    return this.students;
}

public void setStudents(Set<Student> students) {
    this.students = students;
}

@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "group_id_seq")
@SequenceGenerator(name = "group_id_seq", sequenceName = "GroupStudent_seq", allocationSize = 1)
@Column(name = "GroupStudentId")
public Long getGroupStudentId() {
    return this.groupStudentId;
}

public void setGroupStudentId(Long groupStudentId) {
    this.groupStudentId = groupStudentId;
}

@Column(name = "GroupStudentNumber")
public String getGroupStudentNumber() {
    return this.groupStudentNumber;
}

public void setGroupStudentNumber(String groupStudentNumber) {
    this.groupStudentNumber = groupStudentNumber;
}

// table GroupStudent fields
private Long groupStudentId;
private String groupStudentNumber;

}

控制者

@RequestMapping(value = "/addData.html", method = RequestMethod.POST)
public @ResponseBody GroupStudent addNewGroup(@RequestBody GroupStudent group) {

    return group;
}

}

Ajax功能

function addGroupAjax() {
            var groupStudentNumber = $('#groupStudentNumber').val();

            $.ajax({
                type: "POST",
                url: "/IRSystem/addData.html",
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                mimeType: "application/json",
                data: "{\"groupStudentNumber\":" + "\"" + groupStudentNumber + "\"}",
                success: function(response) {

                },
                error: function(e) {
                    alert("Error" + e);
                }
            });
        }

最佳答案

您可以尝试将produces="application/json"添加到您的@RequestMapping中，使其看起来像@RequestMapping(value = "/addData.html", method = RequestMethod.POST, produces="application/json")。

另外，我最初没有看到它，您在POST方法上缺少@ResponseBody批注。在此博文http://www.javacodegeeks.com/2013/07/spring-mvc-requestbody-and-responsebody-demystified.html中，您可以看到它的作用。简短的回答：它可以帮助您进行序列化/反序列化，并将序列化的对象直接写入响应流，因此您不必手动进行。

另外，检查登录服务器上是否有错误（如果没有）（如果您使用的是Chrome），请打开“设置”->“工具”->“开发人员工具”->“网络”，然后再次触发您的呼叫。从显示您的呼叫的列表中选择元素，在那里您可以确切地看到哪个服务器返回了您。

关于java - Spring MVC @ResponseBody错误，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/19914773/