35hibernate_fetch_6_batch_size

hibernate抓取策略，,batch-szie在<class>上的应用

batch-size属性，可以批量加载实体类，参见：Classes.hbm.xml
<class name="Classes" table="t_classes" batch-size="3">
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public void testFetch1() {
        Session session = null;
        try {
            session = HibernateUtils.getSession();
            session.beginTransaction();
            
            List students = session.createQuery("select s from Student s where s.id in(:ids)")
                   .setParameterList("ids", new Object[]{1, 11, 21, 31, 41, 51, 61, 71, 81, 91})
                   .list();
            for (Iterator iter=students.iterator(); iter.hasNext();) {
                Student  student = (Student)iter.next();
                System.out.println("student.name=" + student.getName());
                System.out.println("classes.name=" + student.getClasses().getName());
            }
            session.getTransaction().commit();
        }catch(Exception e) {
            e.printStackTrace();
            session.getTransaction().rollback();
        }finally {
            HibernateUtils.closeSession(session);
        }
    }
配置batch-size="3"时：<class name="Classes" table="t_classes" batch-size="3">
Hibernate: select student0_.id as id1_, student0_.name as name1_, student0_.classesid as classesid1_ from t_student student0_ where student0_.id in (? , ? , ? , ? , ? , ? , ? , ? , ? , ?)
student.name=班级0的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id in (?, ?, ?)
classes.name=班级0
student.name=班级1的学生0
classes.name=班级1
student.name=班级2的学生0
classes.name=班级2
student.name=班级3的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id in (?, ?, ?)
classes.name=班级3
student.name=班级4的学生0
classes.name=班级4
student.name=班级5的学生0
classes.name=班级5
student.name=班级6的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id in (?, ?, ?)
classes.name=班级6
student.name=班级7的学生0
classes.name=班级7
student.name=班级8的学生0
classes.name=班级8
student.name=班级9的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级9

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什么都不配置时：发10条<class name="Classes" table="t_classes">
Hibernate: select student0_.id as id1_, student0_.name as name1_, student0_.classesid as classesid1_ from t_student student0_ where student0_.id in (? , ? , ? , ? , ? , ? , ? , ? , ? , ?)
student.name=班级0的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级0
student.name=班级1的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级1
student.name=班级2的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级2
student.name=班级3的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级3
student.name=班级4的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级4
student.name=班级5的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级5
student.name=班级6的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级6
student.name=班级7的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级7
student.name=班级8的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级8
student.name=班级9的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id=?
classes.name=班级9
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配置batch-size="5"时：发2条
<class name="Classes" table="t_classes" batch-size="5">
Hibernate: select student0_.id as id1_, student0_.name as name1_, student0_.classesid as classesid1_ from t_student student0_ where student0_.id in (? , ? , ? , ? , ? , ? , ? , ? , ? , ?)
student.name=班级0的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id in (?, ?, ?, ?, ?)
classes.name=班级0
student.name=班级1的学生0
classes.name=班级1
student.name=班级2的学生0
classes.name=班级2
student.name=班级3的学生0
classes.name=班级3
student.name=班级4的学生0
classes.name=班级4
student.name=班级5的学生0
Hibernate: select classes0_.id as id0_0_, classes0_.name as name0_0_ from t_classes classes0_ where classes0_.id in (?, ?, ?, ?, ?)
classes.name=班级5
student.name=班级6的学生0
classes.name=班级6
student.name=班级7的学生0
classes.name=班级7
student.name=班级8的学生0
classes.name=班级8
student.name=班级9的学生0
classes.name=班级9