Recent Tips and News on Java, Java EE 6, GlassFish & more :
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• Using Java Persistence API for Java SE 7 Desktop applications in NetBeans 7 (Oracle Learning Library)
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This is the 150th tip published on this blog so decided to make it a collection of all the previous ones. Here is a tag cloud (created from wordle.net/create) from title of all the tips:
As expected GlassFish is the most prominent topic. And then there are several entries on NetBeans, JRuby/Rails, several Java EE 6 technologies like JPA, JAX-WS, JAX-RS, EJB, and JSF, and more entries on Eclipse, OSGi and some other tecnhologies too. Here is a complete collection of all the tips published so far:
Just for fun, here is another tag cloud:
You can access all the tips here. And keep those suggestions coming!
Technorati: totd glassfish netbeans jpa jsf jaxws jersey mysql rails osgi eclipse
Fig. 1 Java access to MySQL Cluster
ClusterJ is part of the MySQL Cluster Connector for Java which is currently in beta as part of MySQL Cluster 7.1. It is designed to provide a high performance method for Java applications to store and access data in a MySQL Cluster database. It is also designed to be easy for Java developers to use and is “in the style of” Hibernate/Java Data Objects (JDO) and JPA. It uses the Domain Object Model DataMapper pattern:
The purpose of ClusterJ is to provide a mapping from the table-oriented view of the data stored in MySQL Cluster to the Java objects used by the application. This is achieved by annotating interfaces representing the Java objects; where each persistent interface is mapped to a table and each property in that interface to a column. By default, the table name will match the interface name and the column names match the property names but this can be overridden using annotations.
Fig. 2 ClusterJ Interface Annotations
If the table does not already exist (for example, this is a brand new application with new data) then the table must be created manually – unlike OpenJPA, ClusterJ will not create the table automatically.
Figure 2 shows an example of an interface that has been created in order to represent the data held in the ‘employee’ table.
ClusterJ uses the following concepts:
Fig. 3 ClusterJ Terminology
SessionFactory: There is one instance per MySQL Cluster instance for each Java Virtual Machine (JVM). The SessionFactory object is used by the application to get hold of sessions. The configuration details for the ClusterJ instance are defined in the Configuration properties which is an artifact associated with the SessionFactory.
ClusterJ will be suitable for many Java developers but it has some restrictions which may make OpenJPA with the ClusterJPA plug-in more appropriate. These ClusterJ restrictions are:
This tutorial uses MySQL Cluster 7.1.2a on Fedora 12. If using earlier or more recent versions of MySQL Cluster then you may need to change the class-paths as explained in http://dev.mysql.com/doc/ndbapi/en/mccj-using-clusterj.html
It is necessary to have MySQL Cluster up and running. For simplicity all of the nodes (processes) making up the Cluster will be run on the same physical host, along with the application.
These are the MySQL Cluster configuration files being used :
config.ini:
[ndbd default]noofreplicas=2
datadir=/home/billy/mysql/my_cluster/data
[ndbd]
hostname=localhost
id=3
[ndbd]
hostname=localhost
id=4
[ndb_mgmd]
id = 1
hostname=localhost
datadir=/home/billy/mysql/my_cluster/data
[mysqld]
hostname=localhost
id=101
[api]
hostname=localhost
my.cnf:
[mysqld]
ndbcluster
datadir=/home/billy/mysql/my_cluster/data
basedir=/usr/local/mysql
This tutorial focuses on ClusterJ rather than on running MySQL Cluster; if you are new to MySQL Cluster then refer to running a simple Cluster before trying this tutorial.
ClusterJ needs to be told how to connect to our MySQL Cluster database; including the connect string (the address/port for the management node), the database to use, the user to login as and attributes for the connection such as the timeout values. If these parameters aren’t defined then ClusterJ will fail with run-time exceptions. This information represents the “configuration properties” shown in Figure 3. These parameters can be hard coded in the application code but it is more maintainable to create a clusterj.properties file that will be imported by the application. This file should be stored in the same directory as your application source code.
clusterj.properties:
com.mysql.clusterj.connectstring=localhost:1186
com.mysql.clusterj.database=clusterdb
com.mysql.clusterj.connect.retries=4
com.mysql.clusterj.connect.delay=5
com.mysql.clusterj.connect.verbose=1
com.mysql.clusterj.connect.timeout.before=30
com.mysql.clusterj.connect.timeout.after=20
com.mysql.clusterj.max.transactions=1024
com.mysql.clusterj.username=
com.mysql.clusterj.password=
As ClusterJ will not create tables automatically, the next step is to create ‘clusterdb’ database (referred to in clusterj.properties) and the ‘employee’ table:
[billy@ws1 ~]$ mysql -u root -h 127.0.0.1 -P 3306 -u root
mysql> create database clusterdb;use clusterdb;
mysql> CREATE TABLE employee (
-> id INT NOT NULL PRIMARY KEY,
-> first VARCHAR(64) DEFAULT NULL,
-> last VARCHAR(64) DEFAULT NULL,
-> municipality VARCHAR(64) DEFAULT NULL,
-> started VARCHAR(64) DEFAULT NULL,
-> ended VARCHAR(64) DEFAULT NULL,
-> department INT NOT NULL DEFAULT 1,
-> UNIQUE KEY idx_u_hash (first,last) USING HASH,
-> KEY idx_municipality (municipality)
-> ) ENGINE=NDBCLUSTER;
The next step is to create the annotated interface:
Employee.java:
import com.mysql.clusterj.annotation.Column;
import com.mysql.clusterj.annotation.Index;
import com.mysql.clusterj.annotation.PersistenceCapable;
import com.mysql.clusterj.annotation.PrimaryKey;
@PersistenceCapable(table="employee")
@Index(name="idx_uhash")
public interface Employee {
@PrimaryKey
int getId();
void setId(int id);
String getFirst();
void setFirst(String first);
String getLast();
void setLast(String last);
@Column(name="municipality")
@Index(name="idx_municipality")
String getCity();
void setCity(String city);
String getStarted();
void setStarted(String date);
String getEnded();
void setEnded(String date);
Integer getDepartment();
void setDepartment(Integer department);
}
The name of the table is specified in the annotation @PersistenceCapable(table=”employee”) and then each column from the employee table has an associated getter and setter method defined in the interface. By default, the property name in the interface is the same as the column name in the table – the column name has been overridden for the City property by explicitly including the @Column(name=”municipality”) annotation just before the associated getter method. The @PrimaryKey annotation is used to identify the property whose associated column is the Primary Key in the table. ClusterJ is made aware of the existence of indexes in the database using the @Index annotation.
The next step is to write the application code which we step through here block by block; the first of which simply contains the import statements and then loads the contents of the clusterj.properties defined above (Note – refer to section 3.2.1 for details on compiling and running the tutorial code):
Main.java (part 1):
import com.mysql.clusterj.ClusterJHelper;
import com.mysql.clusterj.SessionFactory;
import com.mysql.clusterj.Session;
import com.mysql.clusterj.Query;
import com.mysql.clusterj.query.QueryBuilder;
import com.mysql.clusterj.query.QueryDomainType;
import java.io.File;
import java.io.InputStream;
import java.io.FileInputStream;
import java.io.*;
import java.util.Properties;
import java.util.List;
public class Main {
public static void main (String[] args) throws java.io.FileNotFoundException,java.io.IOException {
// Load the properties from the clusterj.properties file
File propsFile = new File("clusterj.properties");
InputStream inStream = new FileInputStream(propsFile);
Properties props = new Properties();
props.load(inStream);
//Used later to get userinput
BufferedReader br = new BufferedReader(new
InputStreamReader(System.in));
The next step is to get a handle for a SessionFactory from the ClusterJHelper class and then use that factory to create a session (based on the properties imported from clusterj.properties file.
Main.java (part 2):
// Create a session (connection to the database)
SessionFactory factory = ClusterJHelper.getSessionFactory(props);
Session session = factory.getSession();
Now that we have a session, it is possible to instantiate new Employee objects and then persist them to the database. Where there are no transaction begin() or commit() statements, each operation involving the database is treated as a separate transaction.
Main.java (part 3):
// Create and initialise an Employee
Employee newEmployee = session.newInstance(Employee.class);
newEmployee.setId(988);
newEmployee.setFirst("John");
newEmployee.setLast("Jones");
newEmployee.setStarted("1 February 2009");
newEmployee.setDepartment(666);
// Write the Employee to the database
session.persist(newEmployee);
At this point, a row will have been added to the ‘employee’ table. To verify this, a new Employee object is created and used to read the data back from the ‘employee’ table using the primary key (Id) value of 998:
Main.java (part 4):
// Fetch the Employee from the database
Employee theEmployee = session.find(Employee.class, 988);
if (theEmployee == null)
{System.out.println("Could not find employee");}
else
{System.out.println ("ID: " + theEmployee.getId() + "; Name: " +
theEmployee.getFirst() + " " + theEmployee.getLast());
System.out.println ("Location: " + theEmployee.getCity());
System.out.println ("Department: " + theEmployee.getDepartment());
System.out.println ("Started: " + theEmployee.getStarted());
System.out.println ("Left: " + theEmployee.getEnded());
}
This is the output seen at this point:
ID: 988; Name: John Jones
Location: null
Department: 666
Started: 1 February 2009
Left: null
Check the database before I change the Employee - hit return when you are done
The next step is to modify this data but it does not write it back to the database yet:
Main.java (part 5):
// Make some changes to the Employee & write back to the database
theEmployee.setDepartment(777);
theEmployee.setCity("London");
System.out.println("Check the database before I change the Employee -
hit return when you are done");
String ignore = br.readLine();
The application will pause at this point and give you chance to check the database to confirm that the original data has been added as a new row but the changes have not been written back yet:
mysql> select * from clusterdb.employee;
+-----+-------+-------+--------------+-----------------+-------+------------+
| id | first | last | municipality | started | ended | department |
+-----+-------+-------+--------------+-----------------+-------+------------+
| 988 | John | Jones | NULL | 1 February 2009 | NULL | 666 |
+-----+-------+-------+--------------+-----------------+-------+------------+
After hitting return, the application will continue and write the changes to the table, using an automatic transaction to perform the update.
Main.java (part 6):
session.updatePersistent(theEmployee);
System.out.println("Check the change in the table before I bulk add
Employees - hit return when you are done");
ignore = br.readLine();
The application will again pause so that we can now check that the change has been written back (persisted) to the database:
mysql> select * from clusterdb.employee;
+-----+-------+-------+--------------+-----------------+-------+------------+
| id | first | last | municipality | started | ended | department |
+-----+-------+-------+--------------+-----------------+-------+------------+
| 988 | John | Jones | London | 1 February 2009 | NULL | 777 |
+-----+-------+-------+--------------+-----------------+-------+------------+
The application then goes onto create and persist 100 new employees. To improve performance, a single transaction is used to that all of the changes can be written to the database at once when the commit() statement is run:
Main.java (part 7):
// Add 100 new Employees - all as part of a single transaction
newEmployee.setFirst("Billy");
newEmployee.setStarted("28 February 2009");
session.currentTransaction().begin();
for (int i=700;i<800;i++) {
newEmployee.setLast("No-Mates"+i);
newEmployee.setId(i+1000);
newEmployee.setDepartment(i);
session.persist(newEmployee);
}
session.currentTransaction().commit();
The 100 new employees will now have been persisted to the database. The next step is to create and execute a query that will search the database for all employees in department 777 by using a QueryBuilder and using that to build a QueryDomain that compares the ‘department’ column with a parameter. After creating the, the department parameter is set to 777 (the query could subsequently be reused with different department numbers). The application then runs the query and iterates through and displays each of employees in the result set:
Main.java (part 8):
// Retrieve the set all of Employees in department 777
QueryBuilder builder = session.getQueryBuilder();
QueryDomainType<Employee> domain =
builder.createQueryDefinition(Employee.class);
domain.where(domain.get("department").equal(domain.param(
"department")));
Query<Employee> query = session.createQuery(domain);
query.setParameter("department",777);
List<Employee> results = query.getResultList();
for (Employee deptEmployee: results) {
System.out.println ("ID: " + deptEmployee.getId() + "; Name: " +
deptEmployee.getFirst() + " " + deptEmployee.getLast());
System.out.println ("Location: " + deptEmployee.getCity());
System.out.println ("Department: " + deptEmployee.getDepartment());
System.out.println ("Started: " + deptEmployee.getStarted());
System.out.println ("Left: " + deptEmployee.getEnded());
}
System.out.println("Last chance to check database before emptying table
- hit return when you are done");
ignore = br.readLine();
At this point, the application will display the following and prompt the user to allow it to continue:
ID: 988; Name: John Jones
Location: London
Department: 777
Started: 1 February 2009
Left: null
ID: 1777; Name: Billy No-Mates777
Location: null
Department: 777
Started: 28 February 2009
Left: null
We can compare that output with an SQL query performed on the database:
mysql> select * from employee where department=777;
+------+-------+-------------+--------------+------------------+-------+------------+
| id | first | last | municipality | started | ended | department |
+------+-------+-------------+--------------+------------------+-------+------------+
| 988 | John | Jones | London | 1 February 2009 | NULL | 777 |
| 1777 | Billy | No-Mates777 | NULL | 28 February 2009 | NULL | 777 |
+------+-------+-------------+--------------+------------------+-------+------------+
Finally, after pressing return again, the application will remove all employees:
Main.java (part 9):
session.deletePersistentAll(Employee.class);
}
}
As a final check, an SQL query confirms that all of the rows have been deleted from the ‘employee’ table.
mysql> select * from employee;
Empty set (0.00 sec)
javac -classpath /usr/local/mysql/share/mysql/java/clusterj-api.jar:. Main.java Employee.java
java -classpath /usr/local/mysql/share/mysql/java/clusterj.jar:. -Djava.library.path=/usr/local/mysql/lib Main
Download the source code for this tutorial from here (together with the code for the up-coming ClusterJPA tutorial).
If you want to try out the beta features in MySQL Cluster 7.1 then you can either use the appropriate binaries or you can build it for yourself from source. Here I explain how to do this on LINUX.
Note that if you want to make use of OpenJPA then you first need to install OpenJPA and Connector/J.
The example here was on Fedora12 with the MySQL Cluster 7.1.2 source:
CFLAGS=”-O3″ CXX=gcc CXXFLAGS=”-O3 -felide-constructors -fno-exceptions -fno-rtti” ./configure -prefix=/usr/local/mysql –enable-assembler –with-mysqld-ldflags=-all-static –with-plugins=max –with-openjpa –with-classpath=/usr/local/openjpa/openjpa-1.2.1.jar:/usr/local/openjpa/lib/geronimo-jpa_3.0_spec-1.0.jar:/usr/local/openjpa/lib/geronimo-jta_1.1_spec-1.1.jar –with-extra-charsets=all
make
make install
That’s it! Obviously, the exact location of the OpenJPA jars will depend on where you installed it. Note that for ‘make install’ you need to run it from an account that has access to /usr/local
I’ll follow up a little later with a post with example applications (in the mean time refer to this tutorial or the MySQL Cluster for Java on-line documentation) but FYI these are the options I use to compile and run my test aps:
ClusterJ:
javac -classpath /usr/local/mysql/share/mysql/java/clusterj-api.jar:. Main.java Employee.java
java -classpath /usr/local/mysql/share/mysql/java/clusterj.jar:. -Djava.library.path=/usr/local/mysql/lib/mysql/ Main
ClusterJPA:
javac -classpath /usr/local/mysql/share/mysql/java/clusterjpa.jar:/usr/local/openjpa/openjpa-1.2.1.jar:/usr/local/openjpa/lib/geronimo-jpa_3.0_spec-1.0.jar:. Main.java Employee.java Department.java
java -Djava.library.path=/usr/local/mysql/lib/mysql/ -classpath /usr/local/mysql/share/mysql/java/clusterjpa.jar:/usr/local/openjpa/openjpa-1.2.1.jar:/usr/local/openjpa/lib/*:/usr/local/connectorj/mysql-connector-java-5.1.12-bin.jar:. Main
Taking TOTD #121 forward, this blog explains how to create a JPA Persistence Unit for a MySQL sample database and package it as a library. This JAR file can then be easily included in other web applications.
Lets get started!
| Class | Field |
|---|---|
| sakila.SalesByFilmCategory | category |
| sakila.ActorInfo | actorId |
| sakila.FilmList | fid |
| sakila.CustomerList | id |
| sakila.NicerButSlowerFilmList | fid |
| sakila.StaffList | id |
| sakila.SalesByStore | store |
Right-click on the project and select "Clean & Build". This generates "dist/SakilaPU.jar" and the structure looks like:
This JAR file can now be included in any web application. The pre-built JAR file can also be downloaded here. The key items to note about this pre-built JAR:
Even though this blog uses a MySQL sample database, these steps can be easily followed for any other database such as Oracle or JavaDB.
Technorati: totd javaee glassfish v3 jpa eclipselink persistenceunit mysql sakila netbeans
This blog clearly explains how to configure the MySQL sample database (sakila) with GlassFish. Even though the instructions use a specific database but should work for other databases (such as Oracle, JavaDB, PostgreSQL, and others) as well. The second half of the blog provide specific syntax for the Oracle sample database.
CREATE USER glassfish IDENTIFIED BY 'glassfish'; GRANT ALL PRIVILEGES ON *.* TO 'glassfish'@'localhost' IDENTIFIED BY 'glassfish'; FLUSH PRIVILEGES;
source sakila-schema.sql; source sakila-data.sql;
asadmin start-domain
asadmin create-jdbc-connection-pool --datasourceclassname com.mysql.jdbc.jdbc2.optional.MysqlConnectionPoolDataSource --restype javax.sql.DataSource --property "User=glassfish:Password=glassfish:URL=jdbc\:mysql\://localhost/sakila" jdbc/sakilaPool
asadmin ping-connection-pool jdbc/sakilaPool
asadmin create-jdbc-resource --connectionpoolid jdbc/sakilaPool jdbc/sakila
That's it!
Creating a JDBC resource for any other database requires the following updates to the steps mentioned above. Lets consider modifying these steps for the Oracle sample database.
sqlplus "/ as sysdba"
CREATE USER glassfish IDENTIFIED BY glassfish DEFAULT tablespace users TEMPORARY tablespace temp; GRANT CONNECT TO glassfish IDENTIFIED BY glassfish; GRANT UNLIMITED TABLESPACE TO glassfish; GRANT CREATE TABLE TO glassfish; GRANT CREATE SEQUENCE TO glassfish;
asadmin create-jdbc-connection-pool --datasourceclassname oracle.jdbc.pool.OracleDataSource --restype javax.sql.DataSource --property "User=hr:Password=hr:URL=jdbc\:oracle\:thin\:@localhost\:1521\:orcl" jdbc/hr asadmin ping-connection-pool jdbc/hr asadmin create-jdbc-resource --connectionpoolid jdbc/hr jdbc/hr
Here are a few other related entries:
RESTful representation of sakila using NetBeans and GlassFish
JSF + JPA + EJB Application using Oracle, NetBeans, and GlassFish
Technorati: totd javaee glassfish v3 jpa mysql sakila oracle
TOTD #98 showed how to create a simple Metro/JAX-WS compliant Web service using that bundle and deploy on GlassFish.
This Tip Of The Day (TOTD) shows how to create a simple Java EE 6 application that reads data from a MySQL database using JPA 2.0 and Servlet 3.0 and display the results. A more formal support of Java EE 6/Servlet 3.0 is coming but in the meanwhile the approach mentioned below will work.
Lets get started!
@WebServlet(urlPatterns="/ServletClient")
public class ServletClient extends HttpServlet {
@PersistenceUnit
EntityManagerFactory factory;
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
ServletOutputStream out = resp.getOutputStream();
List list = factory.createEntityManager().createQuery("select f from Film f where f.title like 'GL%';").getResultList();
out.println("<html><table>");
for (Object film : list) {
out.print("<tr><td>" + ((Film)film).getTitle() + "</tr></td>");
}
out.println("</table></html>");
}
}
import java.io.IOException; import java.util.List; import javax.persistence.EntityManagerFactory; import javax.persistence.PersistenceUnit; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import model.Film;Basically, this is a Servlet 3.0 specification compliant Servlet that uses @WebServlet annotation. It uses @PersistenceUnit to inject the generated JPA Persistence Unit which is then used to query the database. The database query return all the movies whose title start with "GL" and the response is displayed in an HTML formatted table.
Simple, easy and clean!
How are you using Eclipse and GlassFish - the consolidated bundle or standalone Eclipse + GlassFish plugin ?
Download GlassFish Tools Bundle for Eclipse now.
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