吴裕雄--天生自然轻量级JAVA EE企业应用开发Struts2Sping4Hibernate整合开发学习笔记：Hibernate_projection

<?xml version="1.0" encoding="GBK"?>
<project name="hibernate" basedir="." default="">
    <property name="src" value="src"/>
    <property name="dest" value="classes"/>

    <path id="classpath">
        <fileset dir="../../lib">
            <include name="**/*.jar"/>
        </fileset>
        <pathelement path="${dest}"/>
    </path>

    <target name="compile" description="Compile all source code">
        <delete dir="${dest}"/>
        <mkdir dir="${dest}"/>
        <copy todir="${dest}">
            <fileset dir="${src}">
                <exclude name="**/*.java"/>
            </fileset>        
        </copy>
        <javac destdir="${dest}" debug="true" includeantruntime="yes"
            deprecation="false" optimize="false" failonerror="true">
            <src path="${src}"/>
            <classpath refid="classpath"/>
            <compilerarg value="-Xlint:deprecation"/>
        </javac>
    </target>

    <target name="run" description="Run the main class" depends="compile">
        <java classname="lee.ProjectionTest" fork="yes" failonerror="true">
            <classpath refid="classpath"/>
        </java>
    </target>

</project>

drop database if exists hibernate;

create database hibernate;

use hibernate;

CREATE TABLE course_inf (
  course_code varchar(255) NOT NULL,
  name varchar(255) default NULL,
  PRIMARY KEY  (course_code)
);

INSERT INTO course_inf VALUES 
('001','疯狂Java讲义'),
('002','轻量级Java EE企业应用实战'),
('003','疯狂Android讲义');

CREATE TABLE student_inf (
  student_id int NOT NULL,
  name varchar(255) NOT NULL,
  PRIMARY KEY  (student_id)
);

INSERT INTO student_inf VALUES
(20050231,'孙悟空'),
(20050232,'猪八戒'),
(20050233,'牛魔王');



CREATE TABLE enrolment_inf (
  enrolment_id int(11) NOT NULL auto_increment,
  semester int(11) NOT NULL,
  year int(11) NOT NULL,
  student_id int default NULL,
  course_code varchar(255) default NULL,
  PRIMARY KEY  (enrolment_id),
  KEY FKEB4882C47EDE09EE (course_code),
  KEY FKEB4882C4109881D8 (student_id),
  FOREIGN KEY (student_id) REFERENCES student_inf (student_id),
  FOREIGN KEY (course_code) REFERENCES course_inf (course_code)
);

INSERT INTO enrolment_inf VALUES
(1,3,2005,20050232,'001'),
(2,2,2005,20050232,'003'),
(3,2,2005,20050233,'002'),
(4,3,2005,20050233,'003'),
(5,1,2005,20050231,'002');

<?xml version="1.0" encoding="GBK"?>
<!-- 指定Hibernate配置文件的DTD信息 -->
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<!-- hibernate-configuration是配置文件的根元素 -->
<hibernate-configuration>
    <session-factory>
        <!-- 指定连接数据库所用的驱动 -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <!-- 指定连接数据库的url，其中hibernate是本应用连接的数据库名 -->
        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>
        <!-- 指定连接数据库的用户名 -->
        <property name="connection.username">root</property>
        <!-- 指定连接数据库的密码 -->
        <property name="connection.password">32147</property>
        <!-- 指定连接池里最大连接数 -->
        <property name="hibernate.c3p0.max_size">20</property>
        <!-- 指定连接池里最小连接数 -->
        <property name="hibernate.c3p0.min_size">1</property>
        <!-- 指定连接池里连接的超时时长 -->
        <property name="hibernate.c3p0.timeout">5000</property>
        <!-- 指定连接池里最大缓存多少个Statement对象 -->
        <property name="hibernate.c3p0.max_statements">100</property>
        <property name="hibernate.c3p0.idle_test_period">3000</property>
        <property name="hibernate.c3p0.acquire_increment">2</property>
        <property name="hibernate.c3p0.validate">true</property>
        <!-- 指定数据库方言 -->
        <property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
        <!-- 根据需要自动创建数据库 -->
        <property name="hbm2ddl.auto">update</property>
        <!-- 显示Hibernate持久化操作所生成的SQL -->
        <property name="show_sql">true</property>
        <!-- 将SQL脚本进行格式化后再输出 -->
        <property name="hibernate.format_sql">true</property>
        <!-- 罗列所有持久化类的类名 -->
        <mapping class="org.crazyit.app.domain.Enrolment"/>
        <mapping class="org.crazyit.app.domain.Student"/>
        <mapping class="org.crazyit.app.domain.Course"/>
    </session-factory>
</hibernate-configuration>

package org.crazyit.app.domain;

import javax.persistence.*;
/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
@Entity
@Table(name="course_inf")
public class Course
{
    // 代表课程编号的成员变量，将作为标识属性
    @Id @Column(name="course_code")
    private String courseCode;
    // 代表课程名成员变量
    private String name;

    // 无参数的构造器
    public Course()
    {
    }
    // 初始化全部成员变量的构造器
    public Course(String courseCode , String name)
    {
        this.courseCode = courseCode;
        this.name = name;
    }

    // courseCode的setter和getter方法
    public void setCourseCode(String courseCode)
    {
        this.courseCode = courseCode;
    }
    public String getCourseCode()
    {
        return this.courseCode;
    }

    // name的setter和getter方法
    public void setName(String name)
    {
        this.name = name;
    }
    public String getName()
    {
        return this.name;
    }

}

package org.crazyit.app.domain;

import javax.persistence.*;
/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
@Entity
@Table(name="enrolment_inf")
public class Enrolment

{
    // 定义标识属性
    @Id @Column(name="enrolment_id")
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer enrolmentId;
    // 定义选课记录所属的学年
    private int year;
    
// 定义选课记录所属的学期
    private int semester;
    // 定义选课记录关联的学生实体
    @ManyToOne(targetEntity=Student.class)
    @JoinColumn(name="student_id")
    private Student student;
    // 定义选课记录关联的课程实体
    @ManyToOne(targetEntity=Course.class)
    @JoinColumn(name="course_code")
    private Course course;

    // enrolmentId的setter和getter方法
    public void setEnrolmentId(Integer enrolmentId)
    {
        this.enrolmentId = enrolmentId;
    }
    public Integer getEnrolmentId()
    {
        return this.enrolmentId;
    }

    // year的setter和getter方法
    public void setYear(int year)
    {
        this.year = year;
    }
    public int getYear()
    {
        return this.year;
    }

    // semester的setter和getter方法
    public void setSemester(int semester)
    {
        this.semester = semester;
    }
    public int getSemester()
    {
        return this.semester;
    }

    // student的setter和getter方法
    public void setStudent(Student student)
    {
        this.student = student;
    }
    public Student getStudent()
    {
        return this.student;
    }

    // course的setter和getter方法
    public void setCourse(Course course)
    {
        this.course = course;
    }
    public Course getCourse()
    {
        return this.course;
    }
}

package org.crazyit.app.domain;

import java.util.*;
import javax.persistence.*;
/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
@Entity
@Table(name="student_inf")
public class Student
{
    // 代表学生学号的成员变量，将作为标识属性
    @Id @Column(name="student_id")
    private Integer studentNumber;
    // 代表学生姓名的成员变量
    private String name;
    // 该学生的所有选课记录对应的关联实体
    @OneToMany(targetEntity=Enrolment.class
        , mappedBy="student" , cascade=CascadeType.REMOVE)
    private Set<Enrolment> enrolments
        = new HashSet<>();

    // 无参数的构造器
    public Student()
    {
    }
    // 初始化全部成员变量的构造器
    public Student(Integer studentNumber , String name)
    {
        this.studentNumber = studentNumber;
        this.name = name;
    }

    // studentNumber的setter和getter方法
    public void setStudentNumber(Integer studentNumber)
    {
        this.studentNumber = studentNumber;
    }
    public Integer getStudentNumber()
    {
        return this.studentNumber;
    }

    // name的setter和getter方法
    public void setName(String name)
    {
        this.name = name;
    }
    public String getName()
    {
        return this.name;
    }

    // enrolments的setter和getter方法
    public void setEnrolments(Set<Enrolment> enrolments)
    {
        this.enrolments = enrolments;
    }
    public Set<Enrolment> getEnrolments()
    {
        return this.enrolments;
    }
}

package lee;

import org.hibernate.*;
import org.hibernate.cfg.*;
import org.hibernate.service.*;
import org.hibernate.boot.registry.*;
/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
public class HibernateUtil
{
    public static final SessionFactory sessionFactory;

    static
    {
        try
        {
            // 使用默认的hibernate.cfg.xml配置文件创建Configuration实例
            Configuration cfg = new Configuration()
                .configure();
            // 以Configuration实例来创建SessionFactory实例
            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                .applySettings(cfg.getProperties()).build();
            sessionFactory = cfg.buildSessionFactory(serviceRegistry);
        }
        catch (Throwable ex)
        {
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    // ThreadLocal可以隔离多个线程的数据共享，因此不再需要对线程同步
    public static final ThreadLocal<Session> session
        = new ThreadLocal<Session>();

    public static Session currentSession()
        throws HibernateException
    {
        Session s = session.get();
        // 如果该线程还没有Session,则创建一个新的Session
        if (s == null)
        {
            s = sessionFactory.openSession();
            // 将获得的Session变量存储在ThreadLocal变量session里
            session.set(s);
        }
        return s;
    }

    public static void closeSession()
        throws HibernateException
    {
        Session s = session.get();
        if (s != null)
            s.close();
        session.set(null);
    }
}

package lee;

import org.hibernate.*;
import org.hibernate.criterion.*;

import java.util.*;

import org.crazyit.app.domain.*;

/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
public class ProjectionTest
{
    public static void main(String[] args)
    {
        ProjectionTest pt = new ProjectionTest();
        pt.queryForProperty2();
        HibernateUtil.sessionFactory.close();
    }

    private void query()
    {
        // 打开Session和事务
        Session session = HibernateUtil.currentSession();
        Transaction tx = session.beginTransaction();
        // 使用createCriteria开始条件查询
        List list = session.createCriteria(Enrolment.class)
            .createAlias("student", "s")
            .setProjection(Projections.projectionList()
                // 统计记录条数
                .add(Projections.rowCount())
                // 统计选择该课程里最大的学生姓名
                .add(Projections.max("s.name"))
                // 按course进行分组
                .add(Projections.groupProperty("course"))
            ).list();
        for(Object ele : list)
        {
            Object[] objs = (Object[])ele;
            Course c = (Course)objs[2];
            System.out.println("=====<" + c.getName()
                + ">课程的选课统计=====");
            System.out.println("选课人数:" + objs[0]);
            System.out.println("选课的姓名最大的学生为：" + objs[1]);
        }
        tx.commit();
        HibernateUtil.closeSession();
    }


    private void aliasQuery()
    {
        // 打开Session和事务
        Session session = HibernateUtil.currentSession();
        Transaction tx = session.beginTransaction();
        List list = session.createCriteria(Enrolment.class)
            .setProjection(Projections.projectionList()
            // 按course进行分组
            .add(Projections.groupProperty("course"))
            // 统计记录条数，并为统计结果指定别名c
            .add(Projections.alias(Projections.rowCount(), "c")))
            .addOrder(Order.asc("c"))
            .list();
        for(Object ele : list)
        {
            System.out.println(java.util.Arrays.toString((Object[])ele));
        }
        tx.commit();
        HibernateUtil.closeSession();
    }

    private void aliasQuery2()
    {
        // 打开Session和事务
        Session session = HibernateUtil.currentSession();
        Transaction tx = session.beginTransaction();
        List list = session.createCriteria(Enrolment.class)
            .setProjection(Projections.projectionList()
            // 按course进行分组，并为分组结果指定别名c
            .add(Projections.groupProperty("course").as("c"))
            // 统计记录条数
            .add(Projections.rowCount()))
            .addOrder(Order.asc("c"))
            .list();
        for(Object ele : list)
        {
            System.out.println(java.util.Arrays.toString((Object[])ele));
        }
        tx.commit();
        HibernateUtil.closeSession();
    }

    private void aliasQuery3()
    {
        // 打开Session和事务
        Session session = HibernateUtil.currentSession();
        Transaction tx = session.beginTransaction();
        List list = session.createCriteria(Enrolment.class)
            .setProjection(Projections.projectionList()
            // 按course进行分组，指定别名为c
            .add(Projections.groupProperty("course") , "c")
            // 统计每组记录的条数，指定别名为rc
            .add(Projections.rowCount(), "rc"))
            .addOrder(Order.asc("rc"))
            .list();
        for (Object ele : list)
        {
            System.out.println(java.util.Arrays.toString((Object[])ele));
        }
        tx.commit();
        HibernateUtil.closeSession();
    }

    private void queryForProperty()
    {
        // 打开Session和事务
        Session session = HibernateUtil.currentSession();
        Transaction tx = session.beginTransaction();
        // 使用Property只选出指定列
        List list = session.createCriteria(Student.class)
            .setProjection(Property.forName("name"))
            .list();
        for (Object ele : list)
        {
            System.out.println(ele);
        }
        tx.commit();
        HibernateUtil.closeSession();
    }

    private void queryForProperty2()
    {
        // 打开Session和事务
        Session session = HibernateUtil.currentSession();
        Transaction tx = session.beginTransaction();
        // 使用Property选出指定列，并根据指定列过滤数据
        List list = session.createCriteria(Enrolment.class)
            .createAlias("student", "s")
            .setProjection(Projections.projectionList()
            .add(Property.forName("course"))
            .add(Property.forName("s.name")))
            .add(Property.forName("s.name").eq("孙悟空"))       // ①
            .list();
        for (Object ele : list)
        {
            System.out.println(java.util.Arrays.toString((Object[])ele));
        }
        tx.commit();
        HibernateUtil.closeSession();
    }
}