java.sql.SQLException : ResultSet may only be accessed in a forward direction

Question

我有一个可以在 MySQL 数据库上顺利运行的程序。现在由于外部需求，我必须切换到 SQL Server。感谢 Hibernate，除了错误之外，切换很顺利:

java.sql.SQLException: ResultSet may only be accessed in a forward direction.

对从数据库获取的数据执行自定义分页时出现此错误。下面是一个尝试获取数据库中存储的用户并对其进行分页的最小示例(以下示例假设表中至少有 3 行)。

自定义分页:

import org.hibernate.Query;
import org.hibernate.Session;

public class newMain1 {

    public static void main(String[] args) {
        getList(1, getSession());
        getList(2, getSession());
    }

    private static void getList(int page, Session s) {
        int rowsPerPage = 2;
        String hql = "FROM User u ";

            try {
                Query query = s.createQuery(hql);
                int start = (page - 1) * rowsPerPage;
                query.setFirstResult(start);
                query.setMaxResults(rowsPerPage);
                //line that throws exception when int page is 2
                query.list();
                //line that throws exception when int page is 2
            } finally {
                if (s.isOpen()) {
                    s.close();
                }
            }
    }

    private Session getSession(){
        //gets org.hibernate.Session
    }
}

用户 Java POJO:

public class User {    
    private Long id;
    private String username;
    private String password;
    private String email;

    public User() {
    }

    public Long getId() {
        return id;
    }

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


    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}

SQL Server 的用户表:

CREATE TABLE [USER] (
  ID bigint NOT NULL,
  USERNAME varchar(150) NOT NULL UNIQUE,
  PASSWORD varchar(150) NOT NULL,
  EMAIL varchar(150) NOT NULL UNIQUE,
  PRIMARY KEY (ID)
);

用户 POJO 的 Hibernate 映射:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="product.model.User" table="USER">
        <id column="ID" name="id" type="long">
            <generator class="increment"/>
        </id>
        <property column="EMAIL" name="email" type="string"/>
        <property column="USERNAME" name="username" type="string"/>
        <property column="PASSWORD" name="password" type="string"/>
    </class>
</hibernate-mapping>

Hibernate cfg xml:

<session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.SQLServerDialect</property>
    <property name="hibernate.connection.driver_class">net.sourceforge.jtds.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:jtds:sqlserver://127.0.0.1:1433;DatabaseName=myDB;prepareSQL=3;sendStringParametersAsUnicode=false;</property>
    <property name="hibernate.connection.username">sa</property>
    <property name="hibernate.connection.password">myPassword</property>
    <property name="hibernate.show_sql">true</property>
    <property name="hibernate.globally_quoted_identifiers">true</property>
    <mapping resource="product_mapping/user.hbm.xml"/>
  </session-factory>

我使用的是 SQL Server 2012、JDK 1.8、Hibernate 4.0.1.Final、jtds 驱动程序 1.3.1

请注意，getList(1, getSession()) 不会引发异常，而 getList(2, getSession()) 则会引发异常。

Answer 1

经过几个小时的调查，我发现这个问题是由于我使用的 hibernate 方言造成的。

考虑到我需要使用的 hibernate 版本，正确的方言是:org.hibernate.dialect.SQLServer2008Dialect

来源:https://forum.hibernate.org/viewtopic.php?p=2452163