HIbernate saveorUpdate（）在更新时插入新记录

时间：2016-11-19 12:43:49

标签： java hibernate jsp struts2 struts-tags

我正在使用struts2和hibernate Integration，通过以下链接http://www.tutorials4u.net/struts2-tutorial/struts2_crud_example.html并尝试更新记录，但不是更新它是插入新记录，我已经看到所有hibernate更新问题，然后发布此帖子但没有他们为我工作所以我请求在将其标记为重复之前阅读我的问题，因为我已经从已经发布的问题和答案中尝试了很多......

AddStudentAction.java 

public class AddStudentAction extends ActionSupport implements
        ModelDriven<Student> {

    public AddStudentAction() {
        // TODO Auto-generated constructor stub
    }

    Student student = new Student();

    private String firstName;

    private int id;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstNameSearch(String firstName) {
        this.firstName = firstName;
    }

    List<Student> students = new ArrayList<Student>();

    List<Student> studentFirstNames = new ArrayList<Student>();

    public List<Student> getStudentFirstNames() {
        return studentFirstNames;
    }

    public void setStudentFirstNames(List<Student> studentFirstNames) {
        this.studentFirstNames = studentFirstNames;
    }

    StudentDAO dao = new StudentDAO();

    public Student getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        this.student = student;
    }

    public List<Student> getStudents() {
        return students;
    }

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

    public StudentDAO getDao() {
        return dao;
    }

    public void setDao(StudentDAO dao) {
        this.dao = dao;
    }

    @Override
    public Student getModel() {
        // TODO Auto-generated method stub
        return student;
    }
@Override
public String execute() {
    // TODO Auto-generated method stub
    dao.addStudent(student);
    String f = student.getFirstName();
    String l = student.getLastName();
    int m = student.getMarks();
    System.out.println(f + l + m + "Inside execute method");
    return "success";
}

public String updateStudent() {

    dao.addStudent(student);
    return "success";
}

public String listStudents() {
    students = dao.getStudents();
    return "success";
}
public String editStudent() {
    HttpServletRequest request = (HttpServletRequest) ActionContext
            .getContext().get(ServletActionContext.HTTP_REQUEST);
    student = dao.listStudentById(Integer.parseInt((request
            .getParameter("id"))));

    student.setId(Integer.parseInt((request.getParameter("id"))));

    System.out.println(request.getParameter("id") + "id in editStudent");
    dao.updateStudent(student);

    return SUCCESS;
}

StudentDAO.java 

public class StudentDAO {
@SessionTarget
Session session;

@TransactionTarget
Transaction transaction;
public void addStudent(Student student) {
    try {
        session.saveOrUpdate(student);

    } catch (Exception e) {
        e.printStackTrace();
    }
}

public void updateStudent(Student student) {
    try {

        session.saveOrUpdate(student);
        session.flush();
    } catch (Exception e) {
        e.printStackTrace();
    }
}
public Student listStudentById(int Id) {
    Student student = null;
    try {
        student = (Student) session.get(Student.class, Id);
    } catch (Exception e) {

    }
    return student;
}

}

Student.java 

    package com.struts2hibernatepagination.hibernate;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "student")
public class Student {

    @Id
    @GeneratedValue
    @Column(name = "id")
    private int id;
    @Column(name = "last_name")
    private String lastName;
    @Column(name = "first_name")
    private String firstName;
    private int marks;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public int getMarks() {
        return marks;
    }

    public void setMarks(int marks) {
        this.marks = marks;
    }

}

struts.xml中 

<?xml version="1.0" encoding="UTF-8"?>

    

<package name="default" extends="hibernate-default">
<action name="addStudent" method="execute"
        class="com.struts2hibernatepagination.action.AddStudentAction">
        <interceptor-ref name="defaultStackHibernateStrutsValidation">
            <param name="validation.excludeMethods">listStudents</param>
            <param name="validation.excludeMethods">fetchStudentList</param>
        </interceptor-ref>
        <result name="success" type="redirect">
            listStudents
        </result>
        <result name="input">/student.jsp</result>
    </action>
<action name="editStudent"
        class="com.struts2hibernatepagination.action.AddStudentAction"
        method="editStudent">
        <interceptor-ref name="basicStackHibernate" />
        <result name="success">/student.jsp</result>
    </action>
</package>

hibernate.cfg.xml中 

 <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.password">admin12345</property>
        <property name="hibernate.connection.url">jdbc:mysql://192.168.1.3:3306/nupur</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="show_sql">true</property>
        <property name="hibernate.hbm2ddl.auto">update</property>
        <mapping class="com.struts2hibernatepagination.hibernate.Student" />
    </session-factory>
</hibernate-configuration>

student.jsp 

   <%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>

<html>
<head>
<title>Hello World</title>
<s:head />
</head>
<body>
    <a href="searchStudent.jsp">Search</a>
    <s:form action="addStudent">
        <s:actionerror />
        <s:textfield name="firstName" label="First Name" />
        <s:textfield name="lastName" label="Last Name" />
        <s:textfield name="marks" label="Marks" />
        <s:submit value="Save" />
        <hr />
        <table border="2">
            <tr bgcolor="cyan">
                <th><u>First Name</u></th>
                <th><u>Last Name</u></th>
                <th><u>Marks</u></th>
                <th><u>Edit</u></th>
                <th><u>Delete</u></th>
            </tr>
            <s:iterator value="students">
                <tr>
                    <td><s:property value="firstName" /></td>
                    <td><s:property value="lastName" /></td>
                    <td><s:property value="marks" /></td>
                    <td><s:url id="editURL" action="editStudent">
                            <s:param name="id" value="%{id}"></s:param>
                        </s:url> <s:a href="%{editURL}">Edit</s:a></td>
                    <td><s:url id="deleteURL" action="deleteStudent">
                            <s:param name="id" value="%{id}"></s:param>
                        </s:url> <s:a href="%{deleteURL}">Delete</s:a></td>
                </tr>
            </s:iterator>
        </table>

    </s:form>

    <s:form action="fetchStudentList">
        <s:submit value="Show"></s:submit>

    </s:form>


</body>
</html>

请帮助我...当我尝试各种方式时，无论是使用session.flush（）还是删除@GeneratedValue注释

我没有加入addStudent（） 

public String editStudent() {
HttpServletRequest request = (HttpServletRequest) ActionContext
                        .getContext().get(ServletActionContext.HTTP_REQUEST);
                dao.listStudentById(Integer.parseInt((request.getParameter("id"))));                return SUCCESS;
            } //AddStudetnAction class method

                                                                         public void addStudent(Student student) {
                try {  
                System.out.println(student.getId() + "In DAO addStudent");// returning null
                 session.saveOrUpdate(student);

                } catch (Exception e) {
                    e.printStackTrace();
                }

  //StudentDAO class method

addStudent()的{​​{1}}获得了StudentDAO的{​​{1}}值，如何设置null的ID，以便它调用update方法而不是保存

4 个答案:

答案 0 :(得分：1)

花了将近2-3天后，我得到了解决方案，我在JSP中提到了<s:hidden>标签，我将id传递给了 <s:hidden name="id" />，为了更新Hibernate应该得到id，如果不能这样做，它将调用save方法。

答案 1 :(得分：0)

如果你想要更新记录你需要拥有它的id，SaveOrUpdate会查找你的表中的id然后它会更新，如果不是那么它会添加一个新的记录。

我不确定你是如何创建学生的，但如果你想要更新，你需要从数据库中获取对象以获得id（或者你知道id只是设置它）然后在对象时更新你想要的内容是在持久性背景和冲洗。

答案 2 :(得分：0)

这是我的编辑方法。

StudentAction.java 

public String edit()
{
    HttpServletRequest request = (HttpServletRequest) ActionContext.getContext().get(ServletActionContext.HTTP_REQUEST);
    student = studentDAO.listStudentsById(Long.parseLong(request.getParameter("id")));

    return SUCCESS;
}

StudentList.jsp 

<s:url id="editURL" action="edit">
                        <s:param name="id" value="%{id}"></s:param>
                    </s:url> 
                    <s:a href="%{editURL}">Edit</s:a>

答案 3 :(得分：0)

s:form代码不允许您使用网址中的任何参数，但您可以使用hidden输入字段。 s:form代码默认为POST方法。

<s:form action="addStudent">
    <s:actionerror />
    <s:textfield name="firstName" label="First Name" />
    <s:textfield name="lastName" label="Last Name" />
    <s:textfield name="marks" label="Marks" />
    <s:hidden name="id"/>
    <s:submit value="Save" />
    ...
</s:form>
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