CIS 3052 [Part 2] 2014/2015

Transcription

1 Java EE Course Notes Course Notes & Examples for CIS 3052 [Part 2] 2014/2015 These notes belong to Name: Mobile: Prepared and compiled by Matthew Xuereb

2 Contact details Name: Matthew Xuereb Office Telephone: (+356) URL: Office: Room 318 Engineering Building University of Malta Msida Copyright These notes were prepared and compiled by Matthew Xuereb B.Sc. I.T. (Hons.), M.Sc The contents of this course and its modules and related materials, including handouts are Copyright 2014/2015 Matthew Xuereb. Preface Various books and websites were used for the compilation of these notes. The readers of these notes are encouraged to use other books and the web to find more Java examples. Matthew Xuereb 2014/2015 Page 2 of 40

3 Table of contents The Java EE... 4 Java Database Connectivity (JDBC)... 5 Java Servlets and Java Server Pages (JSP)... 8 Servlets and JSP Tutorial Servlets, JSP and JDBC Case Study Java Persistence API (JPA) Java Server Faces (JSF) Matthew Xuereb 2014/2015 Page 3 of 40

4 OVERVIEW The Java EE Developers today increasingly recognize the need for distributed, transactional, and portable applications that leverage the speed, security, and reliability of server-side technology. Enterprise applications provide the business logic for an enterprise. They are centrally managed and often interact with other enterprise software. In the world of information technology, enterprise applications must be designed, built, and produced for less money, with greater speed, and with fewer resources. The aim of the Java EE platform is to provide developers with a powerful set of APIs while shortening development time, reducing application complexity, and improving application performance [Taken from Matthew Xuereb 2014/2015 Page 4 of 40

5 CIS 3052[Part 2] JDBC Java Database Connectivity (JDBC) JDBC stands for Java Database Connectivity. This is an API for the Java programming language that defines how a client may access a (relational oriented) database. It provides methods for querying and updating data in a database. This API enables Java programs to execute SQL statements and to interact with any SQL-compliant database. Since nearly all relational database management systems (DBMSs) support SQL, and because Java itself runs on most platforms, JDBC makes it possible to write a single database application that can run on different platforms and interact with different DBMSs. The MySQL Database Engine MySQL is a relational database management system that runs as a server providing multiuser access to a number of databases. The MySQL development project has made its source code available under the terms of the GNU General Public License, as well as under a variety of proprietary agreements. MySQL was owned and sponsored by a single for-profit firm, the Swedish company MySQL AB, now owned by Sun Microsystems, a subsidiary of Oracle Corporation. Free-software projects that require a full-featured database management system often use MySQL. MySQL is also used in many high-profile, large-scale World Wide Web products including Wikipedia, Google and Facebook. The MySQL community server can be downloaded at no charge from A special interfacing file called the JDBC Driver for MySQL is required to interface the MySQL database engine to JDBC. This file can be downloaded from Connecting to a database using Java via JDBC There are three main steps required to use a database from a Java program. These are: 1. Connect to the data source (database) 2. Send queries and update statements to the database 3. Retrieve and process the results received from the database in answer to your query In this section, examples of how to manipulate databases with JDBC are given. A students table is used as a dummy for the code illustrated below. The database management system that is used for this example is the MySQL Server. This table is illustrated below: Id Name Surname Tel Address Class Subject1 Subject2 Subject3 1 Matthew Xuereb Mosta 3B Italian Computer Studies Chemistry 2 Joe Borg San Gwann 4B French Biology Chemistry 3 Paul Camilleri Luqa 5B Latin Computer Business Studies Studies As the table is stored in a MySQL database server, the JDBC Driver for MySQL is required and should be included in the Libraries section via the NetBeans IDE as explained below: Matthew Xuereb 2014/2015 Page 5 of 40

6 CIS 3052[Part 2] JDBC 1. Right click on the Libraries icon under the Projects section an click on the Add JAR/Folder option as shown in the screen shoot below: 2. Select the MySQL Connector driver and click on open as shown in the screen shoot below: Example The following example illustrates how a database can be queried: public class DBDemo { /** The JDBC driver name */ static final String JDBC_DRIVER = "com.mysql.jdbc.driver"; /** The database URL */ static final String DATABASE_URL = "jdbc:mysql://localhost/school"; /** The database username */ static final String DATABASE_USERNAME = "root"; /** The database password */ static final String DATABASE_PASSWORD = "letmein"; // The main method public static void main(string[] args) { // Create a reference to a connection Connection connection = null; Matthew Xuereb 2014/2015 Page 6 of 40

7 CIS 3052[Part 2] JDBC // Create a reference to a statement Statement statement = null; try{ //Load the database driver class Class.forName(JDBC_DRIVER); // Establish the connecion to the database connection = DriverManager.getConnection(DATABASE_URL, DATABASE_USERNAME, DATABASE_PASSWORD); // Create a statement for querying database statement = connection.createstatement(); // Query the database ResultSet resultset = statement.executequery( "SELECT name,surname,class FROM students"); // Process the query results ResultSetMetaData metadata = resultset.getmetadata(); int numofcolumns = metadata.getcolumncount(); // Display the column names for(int i = 1;i <= numofcolumns;i++){ System.out.printf("%-8s\t",metaData.getColumnName(i)); System.out.println(); // Display the data while(resultset.next()){ for(int i = 1;i <= numofcolumns;i++){ System.out.printf("%-8s\t",resultSet.getObject(i)); System.out.println(); // Close the connections resultset.close(); statement.close(); connection.close(); catch(exception e){ e.printstacktrace();; In order to add (update) records to a database, a statement as shown in the example below should be used: String updatestatement = "(name,surname,tel,address,class,subject1,subject2,subject3) " + "VALUES ('Joseph','Xuereb',' ','Mosta','3B','Italian', + 'Computer Studies','Chemistry')"); statement.executeupdate(updatestatement); Matthew Xuereb 2014/2015 Page 7 of 40

8 SERVLETS & JSP Java Servlets and Java Server Pages (JSP) In order to develop web pages with JSP and servlets using NetBeans, a Web Application project should be initiated as explained below: 1. Create a new project and select Web Application and click on Next as shown in the screen shots below: 2. Enter the Project Name and click on Next as shown in the screen shot below: Matthew Xuereb 2014/2015 Page 8 of 40

9 SERVLETS & JSP 3. Select the Web Server (In our case GlassFish Server 3) and click on Finish. 4. The NetBeans environment should then look as shown in the screen shot below, with the Projects section (as illustrated on the left hand side of the screen shot) illustrating a web project rather than a Java application. Matthew Xuereb 2014/2015 Page 9 of 40

10 SERVLETS & JSP 5. In order to execute the web application, right click on the source code window and click on Run File as shown in the screen shot below: Note that this time, when the application is executed, first the web server is initiated and the application is executed on the default web browser. Java Servlet Overview The Java Servlet technology provides Web developers with a simple, consistent mechanism for extending the functionality of a Web server and for accessing existing business systems. A servlet can almost be thought of as an applet that runs on the server side however without a face. Java servlets make many Web applications possible. Matthew Xuereb 2014/2015 Page 10 of 40

11 SERVLETS & JSP Servlets are the Java platform technology of choice for extending and enhancing Web servers. Servlets provide a component-based, platform-independent method for building Web-based applications, without the performance limitations of CGI programs. And unlike proprietary server extension mechanisms (such as the Netscape Server API or Apache modules), servlets are server and platform independent. This leaves you free to select a "best of breed" strategy for your servers, platforms, and tools. Servlets have access to the entire family of Java APIs, including the JDBC API to access enterprise databases. Servlets can also access a library of HTTP-specific calls and receive all the benefits of the mature Java language, including portability, performance, reusability, and crash protection. Today servlets are a popular choice for building interactive Web applications. Third-party servlet containers are available for Apache Web Server, Microsoft IIS, and others. Servlet containers are usually a component of Web and application servers, such as BEA WebLogic Application Server, IBM WebSphere, Sun Java System Web Server, Sun Java System Application Server, and others. JSP Overview Java Server Pages (JSP) technology enables Web developers and designers to rapidly develop and easily maintain, information-rich, dynamic Web pages that leverage existing business systems. As part of the Java technology family, JSP technology enables rapid development of Web-based applications that are platform independent. JSP technology separates the user interface from content generation, enabling designers to change the overall page layout without altering the underlying dynamic content. A JSP page can consists of four main elements. These are: 1. Template text. Generally consists of HTML code which consist scripting tags to be interpreted by the browser rather than server. 2. Scripting Elements. Specifically Java code which will be embedded in servlet. 3. JSP Directives. Enable the programmer to control the overall structure of the generated servlet. 4. JSP Actions. Enable the programmer to make use of existing components and to control behavior of the JSP engine. Apart from this, JSP provides access to a number of predefined variables such as request, response and session. JSP Scriptlets There are three main scripting elements in JSP Expressions, Scriptlets and Declarations. These are explained below. Matthew Xuereb 2014/2015 Page 11 of 40

12 SERVLETS & JSP Expressions An expression is a term which can be evaluated and which has a return of some type. Java expressions can be inserted into a JSP such that this expression is evaluated at the moment when the page is being serviced to a client. The syntax for a JSP expression is: <%=..expression.. %> Example: Note the use of predefined variable request used to get the host name of client in the JSP expression. A JSP page provides access to a number of variables which are usually available in a servlet. These are request, response and session. Matthew Xuereb 2014/2015 Page 12 of 40

13 SERVLETS & JSP Scriptlets A scriptlet enable the programmer to insert arbitrary code, possibly more complex than expressions into the service method. The syntax for a JSP scriptlets is: <%..java code.. %> Example: Matthew Xuereb 2014/2015 Page 13 of 40

14 SERVLETS & JSP Declarations A JSP declaration enables the programmer to define methods or fields outside the service method of the servlet. The syntax for a JSP declaration is: <%!..java code.. %> Example: Matthew Xuereb 2014/2015 Page 14 of 40

15 SERVLETS & JSP TUTORIAL Servlets and JSP Tutorial Java Servlets Example 1 (Plain Servlet) SERVLET CODE import java.io.ioexception; import java.io.printwriter; import javax.servlet.servletexception; import javax.servlet.annotation.webservlet; import javax.servlet.http.httpservlet; import javax.servlet.http.httpservletrequest; import = "Servlet1", urlpatterns = {"/Servlet1") public class Servlet1 extends HttpServlet protected void doget(httpservletrequest request, HttpServletResponse response) throws ServletException, IOException { response.setcontenttype("text/html"); PrintWriter out = response.getwriter(); out.println("<html>"); out.println("<head> <title>my first servlet</title> </head>"); out.println("<body>"); out.println("<h1>welcome to Servlets!</h1>"); out.println("</body>"); out.println("</html>"); out.close(); Matthew Xuereb 2014/2015 Page 15 of 40

16 SERVLETS & JSP TUTORIAL HTML PAGE CODE <html> <head> <title>an HTML page to invoke the welcome Servlet</title> <meta http-equiv="content-type" content="text/html; charset=utf-8"> </head> <body> <form action="servlet1" method="get"> <label> Click on the button to invoke the servlet</label> <input type="submit" value="click HERE"/> </form> </body> </html> Matthew Xuereb 2014/2015 Page 16 of 40

17 SERVLETS & JSP TUTORIAL Example 2 (Servlet with form data using GET) SERVLET CODE import java.io.ioexception; import java.io.printwriter; import javax.servlet.servletexception; import javax.servlet.annotation.webservlet; import javax.servlet.http.httpservlet; import javax.servlet.http.httpservletrequest; import = "Servlet2", urlpatterns = {"/Servlet2") public class Servlet2 extends HttpServlet protected void doget(httpservletrequest request, HttpServletResponse response) throws ServletException, IOException { response.setcontenttype("text/html"); PrintWriter out = response.getwriter(); out.println("<html>"); out.println("<head>"); out.println("<title>my second servlet</title>"); out.println("</head>"); out.println("<body>"); out.println("<h1>extracting data using get request</h1>"); // Get the data String name = request.getparameter("name"); String surname = request.getparameter("surname"); String age = request.getparameter("age"); out.println("hello " + name + " " + surname + "!<br/>"); try{ Matthew Xuereb 2014/2015 Page 17 of 40

18 SERVLETS & JSP TUTORIAL int ageint = Integer.parseInt(age); if(ageint < 18){ out.println("you cannot drive"); else{ out.println("you can drive"); catch(exception e){ // Do nothing out.println("</body>"); out.println("</html>"); out.close(); HTML PAGE CODE <html> <head> <title>an HTML page to invoke the Servlet using a get</title> <meta http-equiv="content-type" content="text/html; charset=utf-8"> </head> <body> <h1>fill in the following form</h1> <form action="servlet2" method="get"> <label>name: </label> <input type="text" name="name"/> <br/> <br/> <label>surname: </label> <input type="text" name="surname"/> <br/><br/> <label>age: </label> <input type="text" name="age"/> <br/><br/> <input type="submit" value="submit"/> </form> Matthew Xuereb 2014/2015 Page 18 of 40

19 SERVLETS & JSP TUTORIAL </body> </html> Matthew Xuereb 2014/2015 Page 19 of 40

20 SERVLETS & JSP TUTORIAL Example 3 (Servlet with form data using POST) SERVLET CODE import java.io.ioexception; import java.io.printwriter; import javax.servlet.servletexception; import javax.servlet.annotation.webservlet; import javax.servlet.http.httpservlet; import javax.servlet.http.httpservletrequest; import = "Servlet3", urlpatterns = {"/Servlet3") public class Servlet3 extends HttpServlet protected void dopost(httpservletrequest request, HttpServletResponse response) throws ServletException, IOException { response.setcontenttype("text/html"); PrintWriter out = response.getwriter(); out.println("<html>"); out.println("<head>"); out.println("<title>my second servlet</title>"); out.println("</head>"); out.println("<body>"); out.println("<h1>extracting data using post request</h1>"); // Get the data String name = request.getparameter("name"); String surname = request.getparameter("surname"); String age = request.getparameter("age"); out.println("hello " + name + " " + surname + "!<br/>"); try{ int ageint = Integer.parseInt(age); Matthew Xuereb 2014/2015 Page 20 of 40

21 SERVLETS & JSP TUTORIAL if(ageint < 18){ out.println("you cannot drive"); else{ out.println("you can drive"); catch(exception e){ // Do nothing out.println("</body>"); out.println("</html>"); out.close(); HTML PAGE CODE <html> <head> <title>an HTML page to invoke the Servlet using a post</title> <meta http-equiv="content-type" content="text/html; charset=utf-8"> </head> <body> <h1>fill in the following form</h1> <form action="servlet3" method="post"> <label>name: </label> <input type="text" name="name"/> <br/> <br/> <label>surname: </label> <input type="text" name="surname"/> <br/><br/> <label>age: </label> <input type="text" name="age"/> <br/><br/> <input type="submit" value="submit"/> </form> </body> </html> Matthew Xuereb 2014/2015 Page 21 of 40

22 SERVLETS & JSP TUTORIAL Matthew Xuereb 2014/2015 Page 22 of 40

23 SERVLETS & JSP TUTORIAL Java Server Pages (JSP) Example 1 JSP Code <%@page import="java.text.simpledateformat"%> <%@page import="java.util.date" %> <html> <head> <title>jsp Page showing the current date and time</title> </head> <body> <h1>date and time</h1> Current time: <%= new Date() %> <br/><br/> Date only: <% Date now = new Date(); String fulldateandtime = now.tostring(); SimpleDateFormat dateformat = new SimpleDateFormat("dd/MM/yyyy"); out.println(dateformat.format(now)); %> </body> </html> Matthew Xuereb 2014/2015 Page 23 of 40

24 SERVLETS & JSP TUTORIAL Generated HTML code <html> <head> <title>jsp Page showing the current date and time</title> </head> <body> <h1>date and time</h1> Current time: Fri Aug 17 11:40:31 CEST 2012 <br/><br/> Date only: 17/08/2012 </body> </html> Matthew Xuereb 2014/2015 Page 24 of 40

25 SERVLETS & JSP TUTORIAL Example 2 HTML Code <html> <head> <title>an HTML page to invoke a JSP page</title> </head> <body> <h1>times table</h1> <form action="timestable.jsp" method="get"> <label>enter a number to display it's times table: </label> <input type="text" name="num"/> <br/><br/> <input type="submit" value="submit"/> </form> </body> </html> Matthew Xuereb 2014/2015 Page 25 of 40

26 SERVLETS & JSP TUTORIAL JSP Code <html> <head> <title>jsp Page showing the times table</title> </head> <body> <%! int num = 1; %> <% %> String snum = request.getparameter("num"); try{ num = Integer.parseInt(sNum); catch(exception e){ // Do nothing <h1>the <%=num%> times table</h1> <% %> </body> </html> for(int i = 1;i <= 10;i++){ out.println("<br/>" + num + " x " + i + " = " + num*i); Matthew Xuereb 2014/2015 Page 26 of 40

27 SERVLETS & JSP TUTORIAL Generated HTML code <html> <head> <meta http-equiv="content-type" content="text/html; charset=utf-8"> <title>jsp Page showing the times table</title> </head> <body> <h1>the 5 times table</h1> <br/>5 x 1 = 5 <br/>5 x 2 = 10 <br/>5 x 3 = 15 <br/>5 x 4 = 20 <br/>5 x 5 = 25 <br/>5 x 6 = 30 <br/>5 x 7 = 35 <br/>5 x 8 = 40 <br/>5 x 9 = 45 <br/>5 x 10 = 50 </body> </html> Matthew Xuereb 2014/2015 Page 27 of 40

28 SERVLETS, JSP & JDBC CASE STUDY Servlets, JSP and JDBC Case Study You have been hired to write a [very basic] web application that is going to be used by travel agents to book flights. A central database named flightsdb is used. This database contains two tables, one named users that holds the Travel Agents credentials and another table called flights that holds the flight details including the remaining seats on a particular flight. Samples of these two tables are displayed below. Table: users username password SkyTours qqqwww FlyAway gggxxx itours kkkooo Table: flights id flight_num flight_date seats_left 1 KM102 20/01/ KM100 20/01/ KM102 21/01/ EY /01/ FR /01/ Develop this system by answering the following questions: 1. Create on your local host computer the fligthsdb database and fill it with some sample data as shown above. 2. Write an HTML page LoginPage.html that allows the user to enter the username and password so that the user can login to the system. 3. Write a servlet LoginServlet that accepts the username and password and check whether these are valid or not. If these are valid, the servlet should automatically redirect to the BookFlights.jsp page. 4. Write the JSP page BookFlights.jsp. This web page should allow the user to enter the flight number, flight date and amount of seats to book. When the user clicks on the Book Flights button, the JSP page should redirect to the servlet CommitBookingServlet. 5. Write a servlet CommitBookingServlet that will perform the actual flights booking by subtracting the number of seats left from the flights table. Note that you should include all the necessary data validation and a session should be kept to make sure that only logged in users can book a flight. Matthew Xuereb 2014/2015 Page 28 of 40

29 JPA Java Persistence API (JPA) An entity class is a conventional Java class Plan Old Java Object (POJO) that is used to be mapped to a particular database table. An entity can either be mapped to an existing table or else it can be used to actually generate a new SQL table in a database. Creating an entity class from a database table In this tutorial the flightsdb database that was created for the Servets/JSP tutorial is going to be used. This database is implemented using MySQL therefore it is important that the MySQL JDBC Connector library is included in the project. 1. Create a new entity class by selecting the option Entity Classes from Database as shown in the screen shot below: 2. A dialog box as shown below is displayed on the screen. You have to either select a stored connection (if you have already created other entities for the same project) or else select New Database Connection and follow the wizard to create a new database connection. Matthew Xuereb 2014/2015 Page 29 of 40

30 JPA 3. It is very important that when a new database connection is created, the appropriate database is selected as shown in the screen shot below: 4. When the database connection is established, a dialog box as shown below is displayed on the screen. Select the tables from the database that you want to map to an entity class and click on the Next button. Matthew Xuereb 2014/2015 Page 30 of 40

31 JPA 5. Select or type in a package where to store the entity classes and click on finish. 6. When you click on finish notice that an entity class is created together with a persistence.xml file in a META-INF sub-directory directory under the source package directory as shown in the screen shot below. This file will be explained later in this tutorial. The entity class When an entity class is created, apart from the usual Java code, the class is also populated with special annotations. These annotations are used to provide information about the mapping between the entity POJO and the SQL table. When an entity is mapped from an existing table using an IDE such as NetBeans or eclipse there is no need to add any other special annotations. The following is the code (excluding the package declaration and the imports) that was generated in the above example for the @NamedQuery(name = "Flights.findAll", query = "SELECT f FROM Flights = "Flights.findById", query = "SELECT f FROM Flights f WHERE f.id = = "Flights.findByFlightNum", query = "SELECT f FROM Flights f WHERE f.flightnum = = "Flights.findByFlightDate", query = "SELECT f FROM Flights f WHERE f.flightdate = = "Flights.findBySeatsLeft", query = "SELECT f FROM Flights f WHERE f.seatsleft = :seatsleft")) public class Flights implements Serializable { Matthew Xuereb 2014/2015 Page 31 of 40

32 JPA private static final long serialversionuid = = = "id") private Integer = = "flight_num") private String = = private Date = "seats_left") private Integer seatsleft; public Flights() { public Flights(Integer id) { this.id = id; public Flights(Integer id, String flightnum, Date flightdate) { this.id = id; this.flightnum = flightnum; this.flightdate = flightdate; public Integer getid() { return id; public void setid(integer id) { this.id = id; public String getflightnum() { return flightnum; public void setflightnum(string flightnum) { this.flightnum = flightnum; public Date getflightdate() { return flightdate; public void setflightdate(date flightdate) { this.flightdate = flightdate; public Integer getseatsleft() { return seatsleft; public void setseatsleft(integer seatsleft) { this.seatsleft = seatsleft; Matthew Xuereb 2014/2015 Page 32 of 40

33 public int hashcode() { int hash = 0; hash += (id!= null? id.hashcode() : 0); return public boolean equals(object object) { if (!(object instanceof Flights)) { return false; Flights other = (Flights) object; if ((this.id == null && other.id!= null) (this.id!= null &&!this.id.equals(other.id))) { return false; return public String tostring() { return "entities.flights[ id=" + id + " ]"; The following is the SQL code that was used to create the flights database table on the MySQL server: create table flights( id int primary key not null auto_increment, flight_num varchar(8) not null, flight_date date not null, seats_left int ); The entity class is following the rules of encapsulation and therefore all attributes are set to be private and getters and setters are used to provide access to them. An empty and parameter less constructor is included and the entity class is also implementing the Serializable interface. Note that although every item in the table is mapped to a Java POJO, the Java naming convention is used in the Java entity. For this reason, fields such as flight_num where written as flightnum in the Java entity class. To indicate the mapping (as different naming convention is used) notice the use of the both with the name field for the table fields and table name respectively. Other tags such as used to indicate which are the primary fields and the method of auto filling them with values. There are a lot of annotations that can be used with JPA 2.0. For a full list of annotations and their respective explanation, consult with the official Oracle Java EE 6 tutorial Matthew Xuereb 2014/2015 Page 33 of 40

34 JPA Creating an entity class and automatically creating an SQL table in database With JPA it is also possible to first create an entity class and then it JPA will automatically create it respective SQL table in the database. 1. Create a new entity class by selecting the Entity Class option. 2. Type in the name of the entity and the appropriate primary key type as shown in the screen shot below. 3. The outline of the entity class is automatically generated. The attributes of this entity should now be coded including the relevant JPA annotations, getters, setter and constructors. The following source code illustrates and example of an entity (excluding the package declaration and the imports) that was created from scratch and it will be used to create a new SQL table in the database. Notice that only few annotations were used in this example: Matthew Xuereb 2014/2015 Page 34 of 40

35 JPA public class Passenger implements Serializable { private static final long serialversionuid = GenerationType.AUTO) private Long id; private String name; private String private String passportnum; public Passenger(){ // Empty parameter less constructor public Passenger(String name,string surname,string passportnum){ this.name = name; this.surname = surname; this.passportnum = passportnum; public Long getid() { return id; public void setid(long id) { this.id = id; public String getname() { return name; public void setname(string name) { this.name = name; public String getsurname() { return surname; public void setsurname(string surname) { this.surname = surname; public String getpassportnum() { return passportnum; public void setpassportnum(string passportnum) { this.passportnum = public int hashcode() { int hash = 0; hash += (id!= null? id.hashcode() : 0); return hash; Matthew Xuereb 2014/2015 Page 35 of 40

36 public boolean equals(object object) { if (!(object instanceof Passenger)) { return false; Passenger other = (Passenger) object; if ((this.id == null && other.id!= null) (this.id!= null &&!this.id.equals(other.id))) { return false; return public String tostring() { return "entities.passenger[ id=" + id + " ]"; The persistence.xml file The persistence.xml file is usually generated automatically by the IDE. It is a very important file that is used to configure the persistence unit. The following is a screen shot of this file when opened by the NetBeans IDE after the above two entities are created: The above screen shot represents a simple GUI that can be used to configure the persistence.xml file. This GUI is a mapping to an xml file (click on source to view the file) that is shown below: <?xml version="1.0" encoding="utf-8"?> <persistence version="2.0" xmlns=" xmlns:xsi=" xsi:schemalocation=" <persistence-unit name="jpa_demopu" transaction-type="resource_local"> <provider>org.eclipse.persistence.jpa.persistenceprovider</provider> <class>entities.flights</class> <class>entities.passenger</class> <properties> <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/flightsdb"/> <property name="javax.persistence.jdbc.password" value="letmein"/> <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.driver"/> Matthew Xuereb 2014/2015 Page 36 of 40

37 JPA <property name="javax.persistence.jdbc.user" value="root"/> <property name="eclipselink.ddl-generation" value="create-tables"/> </properties> </persistence-unit> </persistence> The tag persistence-unit name is used to define an identifier for this particular persistence application. The provider tag is used to indicate the persistence unit provider. In the above example the provider is the EclipseLink however other such as Hibernate can be used. The list of class tags lists the entity classes. The property tag includes a number of very important properties such as the database url, username, password and driver. The property <property name="eclipselink.ddl-generation" value="create-tables"/> is used to allow the persistence unit to create new SQL tables in the database from a given entity class. Using entity classes The following are some examples of how to use entity classes and JPA to work with databases. Adding a new record Passenger passenger = new Passenger("Matthew","Xuereb","123456"); EntityManagerFactory emfactory = Persistence.createEntityManagerFactory("JPA_DemoPU"); EntityManager em = emfactory.createentitymanager(); em.gettransaction().begin(); em.persist(passenger); em.gettransaction().commit(); em.close(); Querying a table using the Java Persistence Query Language EntityManagerFactory emfactory = Persistence.createEntityManagerFactory("JPA_DemoPU"); EntityManager em = emfactory.createentitymanager(); Query query = em.createquery("select f from Flights f where f.flightnum='km102'"); List<Flights> result = query.getresultlist(); //... em.close(); Querying a table using Named queries Named queries are queries that can be written using JPU annotations as shown in the Flights entity example above. Note that when an entity is generated automatically from a table, such named queries are also generated automatically. EntityManagerFactory emfactory = Persistence.createEntityManagerFactory("JPA_DemoPU"); EntityManager em = emfactory.createentitymanager(); Query query = em.createnamedquery("flights.findbyflightnum"); query.setparameter("flightnum","km102"); List<Flights> result = query.getresultlist(); //... em.close(); Matthew Xuereb 2014/2015 Page 37 of 40

38 JPA Updating a table record EntityManagerFactory emfactory = Persistence.createEntityManagerFactory("JPA_DemoPU"); EntityManager em = emfactory.createentitymanager(); em.gettransaction().begin(); Passenger passenger = em.find(passenger.class,new Long(1)); passenger.setpassportnum("56789"); em.gettransaction().commit(); em.close(); Matthew Xuereb 2014/2015 Page 38 of 40

39 JSF Java Server Faces (JSF) Designed to be flexible, JavaServer Faces technology leverages existing, standard UI and web-tier concepts without limiting developers to a particular mark-up language, protocol, or client device. The UI component classes included with JavaServer Faces technology encapsulate the component functionality, not the client-specific presentation, thus enabling JavaServer Faces UI components to be rendered to various client devices. By combining the UI component functionality with custom renderers, which define rendering attributes for a specific UI component, developers can construct custom tags to a particular client device. As a convenience, JavaServer Faces technology provides a custom renderer and a JSP custom tag library for rendering to an HTML client, allowing developers of Java Platform, Enterprise Edition (Java EE) applications to use JavaServer Faces technology in their applications. Creating a JSF Web application 1. Create a new Java Web application. 2. Make sure to click on the Next button when creating a new web application until you are asked to select the frameworks that you would like to use. Select the Java Server Faces framework and click Finish. Matthew Xuereb 2014/2015 Page 39 of 40

40 JSF 3. A new project is created and a default index.xhtml file is also generated as shown in the screen shot below. Notice that when creating JSF pages, xhtml files are used. The reason for this is that a JSF file is basically an XML based HTML file that can be mapped to Java classes. Notice that even the html tags are written in an XML fashion via a JSF label that by default is set h to refer to html tags. The web.xml file The web.xml file is generated automatically by the IDE and is found under the WEB-INF directory. This is a very important file as it is used to configure the JSF framework. The web.xml file stores in it information such as session timeouts, the JSF framework and more. A very important filed in this file is the welcome-file field that is used to indicate which file should be loaded first when the JSF web application is loaded. By default it is set to load first the index.xhtml web page. Example The usual flight booking system will be implemented during the lecture and subsequently uploaded on the website. Matthew Xuereb 2014/2015 Page 40 of 40