| 21. 15. 3. 投影：最小 |
|
|
File: Main.java |
|
import java.util.Date;
import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.criterion.ProjectionList;
import org.hibernate.criterion.Projections;
public class Main {
public static void main(String[] args) throws Exception {
HibernateUtil hibernateUtil = new HibernateUtil();
hibernateUtil
.executeSQLCommand("create table survey (id int,name varchar, purchasedate date);");
Session session = hibernateUtil.getSession();
Survey survey = new Survey();
survey.setName("Survey");
survey.setPurchaseDate(new Date());
session.save(survey);
survey = new Survey();
survey.setName("Survey1");
survey.setPurchaseDate(new Date());
session.save(survey);
session.flush();
Criteria crit = session.createCriteria(Survey.class);
ProjectionList projList = Projections.projectionList();
projList.add(Projections.min("Id"));
crit.setProjection(projList);
List results = crit.list();
System.out.println(results);
session.close();
hibernateUtil.checkData("select * from survey");
}
}
|
|
File: Survey.hbm.xml |
|
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="Survey" table="SURVEY" dynamic-update="false" dynamic-insert="false">
<cache usage="read-write"/>
<id name="Id" type="int" unsaved-value="0">
<column name="ID" sql-type="int" not-null="true"/>
<generator class="increment"></generator>
</id>
<property name="name" type="java.lang.String" update="true" insert="true" access="property" column="name"/>
<property name="purchaseDate" type="date" column="purchasedate" />
</class>
</hibernate-mapping>
|
|
File: Survey.java |
|
import java.util.Date;
public class Survey {
private int id;
private String name;
private Date purchaseDate;
public Date getPurchaseDate() {
return purchaseDate;
}
public void setPurchaseDate(Date purchaseDate) {
this.purchaseDate = purchaseDate;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}
|
|
File: HibernateUtil.java |
|
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtil {
Session session;
Statement st;
public HibernateUtil() throws Exception{
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
session = sessionFactory.openSession();
// Load the JDBC driver.
Class.forName("org.hsqldb.jdbcDriver");
System.out.println("Driver Loaded.");
// Establish the connection to the database.
String url = "jdbc:hsqldb:data/tutorial";
Connection conn = DriverManager.getConnection(url, "sa", "");
System.out.println("Got Connection.");
st = conn.createStatement();
}
public Session getSession(){
return session;
}
public void executeSQLCommand(String sql) throws Exception {
st.executeUpdate(sql);
}
public void checkData(String sql) throws Exception {
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData metadata = rs.getMetaData();
for (int i = 0; i < metadata.getColumnCount(); i++) {
System.out.print("\t"+ metadata.getColumnLabel(i + 1));
}
System.out.println("\n----------------------------------");
while (rs.next()) {
for (int i = 0; i < metadata.getColumnCount(); i++) {
Object value = rs.getObject(i + 1);
if (value == null) {
System.out.print("\t ");
} else {
System.out.print("\t"+value.toString().trim());
}
}
System.out.println("");
}
}
}
|
|
File: hibernate.cfg.xml |
|
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">org.hsqldb.jdbcDriver</property>
<property name="connection.url">jdbc:hsqldb:data/tutorial</property>
<property name="connection.username">sa</property>
<property name="connection.password"></property>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.HSQLDialect</property>
<!-- Enable Hibernate's current session context -->
<property name="current_session_context_class">org.hibernate.context.ManagedSessionContext</property>
<property name="hibernate.cache.use_second_level_cache">false</property>
<property name="hibernate.cache.use_query_cache">false</property>
<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Mapping files -->
<mapping resource="Survey.hbm.xml"/>
</session-factory>
</hibernate-configuration>
|
|
 Download: HibernateMinProjection.zip( 4,860 k) |