Java by API/javax.persistence/NamedQuery

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NamedQuery.hints()

   <source lang="java">

File: Professor.java

import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.NamedQuery; import javax.persistence.QueryHint; @Entity @NamedQuery(name="findProfessorNoCache", 

           query="SELECT e FROM Professor e WHERE e.id = ?1",
           hints={@QueryHint(name="toplink.cache-usage", value="DoNotCheckCache")})

public class Professor { 

   @Id
   private int id;
   private String name;
   private long salary;
   public int getId() {
       return id;
   }
   
   public String getName() {
       return name;
   }
   public long getSalary() {
       return salary;
   }
   
   public String toString() {
       return "Professor " + getId() + 
              ": name: " + getName() +
              ", salary: " + getSalary();
   }

}

File: ProfessorService.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.NoResultException; import javax.persistence.Query; public class ProfessorService { 

 protected EntityManager em;
 public ProfessorService(EntityManager em) {
   this.em = em;
 }
 public Professor findProfessor(int empId) {
   Query q = em.createQuery("SELECT e FROM Professor e WHERE e.id =  ?1");
   q.setParameter(1, empId);
   try {
     return (Professor) q.getSingleResult();
   } catch (NoResultException e) {
     return null;
   }
 }
 public Professor findProfessorNoCache(int empId) {
   Query q = em.createQuery("SELECT e FROM Professor e WHERE e.id = ?1");
   // force read from database
   q.setHint("cacheUsage", oracle.toplink.essentials.queryframework.ObjectLevelReadQuery.DoNotCheckCache);
   q.setParameter(1, empId);
   try {
     return (Professor) q.getSingleResult();
   } catch (NoResultException e) {
     return null;
   }
 }
 public Professor findProfessorNoCacheNamed(int empId) {
   Query q = em.createNamedQuery("findProfessorNoCache");
   q.setParameter(1, empId);
   try {
     return (Professor) q.getSingleResult();
   } catch (NoResultException e) {
     return null;
   }
 }
 public Collection<Professor> findAllProfessors() {
   return (Collection<Professor>) em.createQuery("SELECT e FROM Professor e").getResultList();
 }

}

File: JPAUtil.java import java.io.Reader; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class JPAUtil { 

 Statement st;
 
 public JPAUtil() throws Exception{
   Class.forName("org.hsqldb.jdbcDriver");
   System.out.println("Driver Loaded.");
   String url = "jdbc:hsqldb:data/tutorial";
   Connection conn = DriverManager.getConnection(url, "sa", "");
   System.out.println("Got Connection.");
   st = conn.createStatement();
 }
 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: Main.java import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; public class Main { 

 public static void main(String[] a) throws Exception {
   JPAUtil util = new JPAUtil();
   EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
   EntityManager em = emf.createEntityManager();
   ProfessorService service = new ProfessorService(em);
   em.getTransaction().begin();

   //service.removeDepartment2();
   
   util.checkData("select * from Professor");
   util.checkData("select * from Department");
   em.getTransaction().rumit();
   em.close();
   emf.close();
 }

}


File: persistence.xml <persistence xmlns="http://java.sun.ru/xml/ns/persistence" 

            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
 <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
   <properties>
     <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
     <property name="hibernate.hbm2ddl.auto" value="update"/>
     <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
     <property name="hibernate.connection.username" value="sa"/>
     <property name="hibernate.connection.password" value=""/>
     <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
   </properties>
 </persistence-unit>

</persistence> 


 </source>



NamedQuery.name()

   <source lang="java">

File: Professor.java

import java.util.ArrayList; import java.util.Collection; import java.util.Date; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.ManyToMany; import javax.persistence.ManyToOne; import javax.persistence.NamedQueries; import javax.persistence.NamedQuery; import javax.persistence.OneToMany; import javax.persistence.Temporal; import javax.persistence.TemporalType; @Entity @NamedQuery(name="findSalaryForNameAndDepartment", 

       query="SELECT e.salary " +
             "FROM Professor e " +
             "WHERE e.department.name = :deptName AND " +
             "      e.name = :empName")

public class Professor { 

   @Id
   private int id;
   private String name;
   private long salary;
   @Temporal(TemporalType.DATE)
   private Date startDate;
   
   @ManyToOne
   private Professor manager;
   
   @OneToMany(mappedBy="manager")
   private Collection<Professor> directs;
   @ManyToOne
   private Department department;
   
   @ManyToMany 
   private Collection<Project> projects;
   public Professor() {
       projects = new ArrayList<Project>();
       directs = new ArrayList<Professor>();
   }
   public int getId() {
       return id;
   }
   
   public String getName() {
       return name;
   }
   public long getSalary() {
       return salary;
   }
   public Date getStartDate() {
       return startDate;
   }
   
   public Department getDepartment() {
       return department;
   }
   
   public Collection<Professor> getDirects() {
       return directs;
   }
   
   public Professor getManager() {
       return manager;
   }
   public Collection<Project> getProjects() {
       return projects;
   }
   
   public String toString() {
       return "Professor " + getId() + 
              ": name: " + getName() +
              ", salary: " + getSalary() +
              ", dept: " + ((getDepartment() == null) ? null : getDepartment().getName());
   }

}

File: ProfessorService.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.NoResultException; public class ProfessorService { 

 protected EntityManager em;
 public ProfessorService(EntityManager em) {
   this.em = em;
 }

 public long findSalaryForNameAndDepartment(String deptName, String empName) {
   try {
     return (Long) em.createNamedQuery("findSalaryForNameAndDepartment").setParameter("deptName",
         deptName).setParameter("empName", empName).getSingleResult();
   } catch (NoResultException e) {
     return 0;
   }
 }

}

File: Project.java

import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.ManyToMany; @Entity public class Project { 

   @Id
   protected int id;
   protected String name;
   @ManyToMany(mappedBy="projects")
   private Collection<Professor> employees;
   public Project() {
       employees = new ArrayList<Professor>();
   }
   public int getId() {
       return id;
   }
   
   public String getName() {
       return name;
   }
   
   public Collection<Professor> getProfessors() {
       return employees;
   }
   
   public String toString() {
       return "Project id: " + getId() + ", name: " + getName();
   }

}

File: Department.java

import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToMany; @Entity public class Department { 

   @Id
   private int id;
   private String name;
   @OneToMany(mappedBy="department")
   private Collection<Professor> employees;
   public Department() {
       employees = new ArrayList<Professor>();
   }
   
   public int getId() {
       return id;
   }
   
   public String getName() {
       return name;
   }
   
   public Collection<Professor> getProfessors() {
       return employees;
   }
   public String toString() {
       return "Department no: " + getId() + 
              ", name: " + getName();
   }

}

File: JPAUtil.java import java.io.Reader; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class JPAUtil { 

 Statement st;
 
 public JPAUtil() throws Exception{
   Class.forName("org.hsqldb.jdbcDriver");
   System.out.println("Driver Loaded.");
   String url = "jdbc:hsqldb:data/tutorial";
   Connection conn = DriverManager.getConnection(url, "sa", "");
   System.out.println("Got Connection.");
   st = conn.createStatement();
 }
 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: Main.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; public class Main { 

 public static void main(String[] a) throws Exception {
   JPAUtil util = new JPAUtil();
   EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
   EntityManager em = emf.createEntityManager();
   ProfessorService service = new ProfessorService(em);
   em.getTransaction().begin();
   long l = service.findSalaryForNameAndDepartment("deptName", "empName");
   
   
   util.checkData("select * from Professor");
   util.checkData("select * from Department");
   
   em.getTransaction().rumit();
   em.close();
   emf.close();
 }

}


File: persistence.xml <persistence xmlns="http://java.sun.ru/xml/ns/persistence" 

            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
 <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
   <properties>
     <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
     <property name="hibernate.hbm2ddl.auto" value="update"/>
     <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
     <property name="hibernate.connection.username" value="sa"/>
     <property name="hibernate.connection.password" value=""/>
     <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
   </properties>
 </persistence-unit>

</persistence> 


 </source>



NamedQuery.query()

   <source lang="java">


File: Professor.java

import java.util.ArrayList; import java.util.Collection; import java.util.Date; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.ManyToMany; import javax.persistence.ManyToOne; import javax.persistence.NamedQueries; import javax.persistence.NamedQuery; import javax.persistence.OneToMany; import javax.persistence.Temporal; import javax.persistence.TemporalType; @Entity @NamedQuery(name="findSalaryForNameAndDepartment", 

       query="SELECT e.salary " +
             "FROM Professor e " +
             "WHERE e.department.name = :deptName AND " +
             "      e.name = :empName")

public class Professor { 

   @Id
   private int id;
   private String name;
   private long salary;
   @Temporal(TemporalType.DATE)
   private Date startDate;
   
   @ManyToOne
   private Professor manager;
   
   @OneToMany(mappedBy="manager")
   private Collection<Professor> directs;
   @ManyToOne
   private Department department;
   
   @ManyToMany 
   private Collection<Project> projects;
   public Professor() {
       projects = new ArrayList<Project>();
       directs = new ArrayList<Professor>();
   }
   public int getId() {
       return id;
   }
   
   public String getName() {
       return name;
   }
   public long getSalary() {
       return salary;
   }
   public Date getStartDate() {
       return startDate;
   }
   
   public Department getDepartment() {
       return department;
   }
   
   public Collection<Professor> getDirects() {
       return directs;
   }
   
   public Professor getManager() {
       return manager;
   }
   public Collection<Project> getProjects() {
       return projects;
   }
   
   public String toString() {
       return "Professor " + getId() + 
              ": name: " + getName() +
              ", salary: " + getSalary() +
              ", dept: " + ((getDepartment() == null) ? null : getDepartment().getName());
   }

}

File: ProfessorService.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.NoResultException; public class ProfessorService { 

 protected EntityManager em;
 public ProfessorService(EntityManager em) {
   this.em = em;
 }

 public long findSalaryForNameAndDepartment(String deptName, String empName) {
   try {
     return (Long) em.createNamedQuery("findSalaryForNameAndDepartment").setParameter("deptName",
         deptName).setParameter("empName", empName).getSingleResult();
   } catch (NoResultException e) {
     return 0;
   }
 }

}

File: Project.java

import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.ManyToMany; @Entity public class Project { 

   @Id
   protected int id;
   protected String name;
   @ManyToMany(mappedBy="projects")
   private Collection<Professor> employees;
   public Project() {
       employees = new ArrayList<Professor>();
   }
   public int getId() {
       return id;
   }
   
   public String getName() {
       return name;
   }
   
   public Collection<Professor> getProfessors() {
       return employees;
   }
   
   public String toString() {
       return "Project id: " + getId() + ", name: " + getName();
   }

}

File: Department.java

import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToMany; @Entity public class Department { 

   @Id
   private int id;
   private String name;
   @OneToMany(mappedBy="department")
   private Collection<Professor> employees;
   public Department() {
       employees = new ArrayList<Professor>();
   }
   
   public int getId() {
       return id;
   }
   
   public String getName() {
       return name;
   }
   
   public Collection<Professor> getProfessors() {
       return employees;
   }
   public String toString() {
       return "Department no: " + getId() + 
              ", name: " + getName();
   }

}

File: JPAUtil.java import java.io.Reader; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class JPAUtil { 

 Statement st;
 
 public JPAUtil() throws Exception{
   Class.forName("org.hsqldb.jdbcDriver");
   System.out.println("Driver Loaded.");
   String url = "jdbc:hsqldb:data/tutorial";
   Connection conn = DriverManager.getConnection(url, "sa", "");
   System.out.println("Got Connection.");
   st = conn.createStatement();
 }
 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: Main.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; public class Main { 

 public static void main(String[] a) throws Exception {
   JPAUtil util = new JPAUtil();
   EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
   EntityManager em = emf.createEntityManager();
   ProfessorService service = new ProfessorService(em);
   em.getTransaction().begin();
   long l = service.findSalaryForNameAndDepartment("deptName", "empName");
   
   
   util.checkData("select * from Professor");
   util.checkData("select * from Department");
   
   em.getTransaction().rumit();
   em.close();
   emf.close();
 }

}


File: persistence.xml <persistence xmlns="http://java.sun.ru/xml/ns/persistence" 

            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
 <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
   <properties>
     <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
     <property name="hibernate.hbm2ddl.auto" value="update"/>
     <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
     <property name="hibernate.connection.username" value="sa"/>
     <property name="hibernate.connection.password" value=""/>
     <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
   </properties>
 </persistence-unit>

</persistence> 


 </source>
Источник — «http://jexp.ru/index.php?title=Java_by_API/javax.persistence/NamedQuery&oldid=1668»