java - 使用 hibernate 时在POJO中使用构造函数有哪些限制？

我正在尝试一个简单的休眠填充数据库示例。有两个POJO的Employee和Address。当我尝试使用带参数的Employee和Address构造函数来创建两个实例时，抛出了错误could not get constructor for org.hibernate.persister.entity.singletableentitypersister，但属性访问器方法运行良好。为什么会出现错误？

好的，因为我现在没有堆栈跟踪，所以我将重新表述我的问题：与休眠中的构造方法相比，属性访问器方法更受欢迎吗？

员工PO​​JO：

package many2one;

public class Employee {

    public int id;
    public String firstName;
    public String lastName;
    public int salary;
    public Address address;

    public Employee(){}
    public Employee(String firstName,String lastName,int salary,Address address){
        this.firstName = firstName;
        this.lastName = lastName;
        this.salary = salary;
        this.address = address;
    }

    public int getId(){
        return id;
    }

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

    public String getFirstName(){
        return firstName;
    }

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

    public String getLastName(){
        return lastName;
    }

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

    public int getSalary(){
        return salary;
    }

    public void setSalary(int salary){
        this.salary = salary;
    }

    public Address getAddress(){
        return address;
    }

    public void setAddress(Address address){
        this.address = address;
    }
    @Override
    public String toString(){
        return id+","+firstName+","+lastName+","+salary+","+address.getStreetName()+","+address.getCityName()+","+address.getStateName()+","+address.getZipcode();
    }

}

地址POJO：

package many2one;

public class Address {
    public int id;
    public String streetName;
    public String cityName;
    public String stateName;
    public String zipcode;

    public Employee employee;

    public Address(){

    }

    public Address(String sname,String cname,String statename,String zipcode){
        this.streetName = sname;
        this.cityName = cname;
        this.stateName = statename;
        this.zipcode = zipcode;
    }

    public int getId(){
        return id;
    }

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

    public String getStreetName(){
        return streetName;
    }

    public void setStreetName(String streetname){
        this.streetName = streetname;
    }

    public String getCityName(){
        return cityName;
    }

    public void setCityName(String cname){
        this.cityName = cname;
    }

    public String getStateName(){
        return stateName;
    }

    public void setStateName(String statename){
        this.stateName = statename;
    }

    public String getZipcode(){
        return zipcode;
    }

    public void setZipcode(String zipcode){
        this.zipcode = zipcode;
    }

    public Employee getEmployee(){
        return employee;
    }

    public void setEmployee(Employee employee){
        this.employee = employee;
    }

}

`

最佳答案

您的类应具有不带任何参数的默认公共构造函数。这是使用Hibernate时对构造函数的唯一约束。

至于例外情况，您可能缺少某个字段的设置器，或者这些设置器未遵循Hibernate期望的约定。但这只能在您提供完整堆栈跟踪的情况下才能确认。


  是属性访问器方法而不是构造函数中的首选方法
  冬眠？


你是什​​么意思？如果您的意思是属性方法是可选的，那么答案是否定的。 （首先可能是例外的原因之一）