WebSphere Studio Application Developer Version 5 Programming Guide part 30 pdf

264 WebSphere Studio Application Developer Version 5 Programming Guide The jspsql.jar file contains the tags and dbbeans.jar contains the actual classes used to access the database. Creating a JSP We now create a TestTagLib.jsp file to use tag libraries. See “Working with JSPs” on page 210 for details about creating a new JSP. Open TestTagLib.jsp in Page Designer. You can use the JSP editor to insert the database tags into your page when you are in the Design view. To be able to use the custom tags from the database tag library, you first have to do two things:  Import the tag library into your Web application as described above.  Create the taglib directive in the JSP. To insert the taglib directive, bring up the context menu on the page in the Design view and select Page Properties . In the dialog shown select JSP Tags and JSP Directive - taglib from the Tag Type drop-down menu (Figure 8-16). Figure 8-16 Insert JSP taglib directive Click Add to select the tag library to add, and the dialog shown in Figure 8-17 is displayed. Chapter 8. Developing Web applications with database access 265 Figure 8-17 Selecting a tag library Click Import to locate the jspsql.jar file to import. The Import a Tag Library dialog opens (Figure 8-18). Click Browse to locate the JAR file: <wsadhome>\wstools\eclipse\plugins\com.ibm.etools.dbjars_5.0.1\jars\jspsql.jar Figure 8-18 Importing a tag library 266 WebSphere Studio Application Developer Version 5 Programming Guide Be sure to select Add an alias URI so that the tag library is added to the web.xml file. The entry can be found on the References page. Click OK to close the dialog. Now the tag library has been imported. Select the jspsql check box to add it to the JSP (Figure 8-19). Figure 8-19 Select the jspsql tag library Select OK twice to close the dialog. The following tag is inserted into your JSP: <%@taglib uri="jspsql" prefix="dab"%> The full TestTagLib.jsp is available in: \sg246957\sampcode\dev-webdb Chapter 8. Developing Web applications with database access 267 Building the JSP with custom tags Now you can add tags to the JSP by selecting JSP -> Insert Custom . You should see the following dialog (Figure 8-20). Figure 8-20 Insert custom JSP tags In the following example we create a JSP that displays a list of transaction records. We show you some of the main tags that you would use to access the database. The Application Developer online help contains descriptions for all the tags that are available. First, we have to create the connection to the database. To do this we use the <dab:dataSourceSpec> tag. Select dataSourceSpec in the left list, then click Insert . Click Close , then go to the Source view of the JSP editor. The following new code has been added: <dab:dataSourceSpec dataSource="" id="" /> Figure 8-21 shows the correct parameters and values to use for the <dab:dataSourceSpec> tag. Update the tag in your JSP. Note: Application Developer version 5 offers an improved New JSP wizard, which includes a step to add tag libraries to a newly generated JSP file. 268 WebSphere Studio Application Developer Version 5 Programming Guide Figure 8-21 Establishing a database connection All the parameters for the connection are retrieved from the data source defined in the server. Once you have established a connection, you can execute the query. Click JSP -> Insert Custom again, and this time choose select and click Insert . Update the new select tag to be the same as in Figure 8-22. Figure 8-22 Executing a select statement in a JSP tag Here you use the connection created previously to issue the SQL select statement. The input parameter is specified using the <dab:parameter> tag. Assuming that you have created an HTML table to display the result, you can then use <dab:repeat> and <dab:getColumn> to loop through the result set and display the values. You can either use the insert custom method to get you started, or enter the code shown in Figure 8-23. <dab:dataSourceSpec id="DSConnect" scope="page" dataSource='jdbc/ejbbank'/> Tip: In the Properties view ( Window -> Show View ) you can see the properties of each tag when you place the cursor within the tag. <dab:select id="select_master" scope="request" connectionSpec="DSConnect>"> <dab:sql> SELECT ITSO.TRANSRECORD.TRANSID, ITSO.CUSTOMER.FIRSTNAME, ITSO.CUSTOMER.LASTNAME, ITSO.TRANSRECORD.ACCID, ITSO.TRANSRECORD.TRANSAMT FROM ITSO.CUSTACCT, ITSO.CUSTOMER, ITSO.TRANSRECORD WHERE ITSO.CUSTACCT.CUSTOMERID = ITSO.CUSTOMER.CUSTOMERID AND ITSO.CUSTACCT.ACCID = ITSO.TRANSRECORD.ACCID AND ITSO.TRANSRECORD.TRANSTYPE = 'C' AND ITSO.CUSTOMER.LASTNAME LIKE :lastname </dab:sql> <dab:parameter position = "1" type="CHAR" value="Brown"/> </dab:select> Chapter 8. Developing Web applications with database access 269 Figure 8-23 Displaying result set values As you can see from the discussion above, both the DB Beans and the corresponding JSP tags give you an easy and quick way to access relational data directly from a JSP. As was mentioned earlier, you have to be aware of the potential problems of combining presentation and business logic in one JSP. From a model-view-controller perspective, a JSP should ideally only implement the presentation layer of your application, while the database access should be handled by JavaBeans. However, if your application is small, or if you are building a prototype, using the database access facilities described here may be a good solution. <TABLE border="1"> <TR> <TH>TransID</TH><TH>Firstname</TH><TH>Lastname</TH> <TH>Account</TH><TH>Amount</TH> </TR> <dab:repeat name="select_master" index="rowNum" over="rows" > <TR> <TD> <dab:getColumn index="1"/> <INPUT TYPE="hidden" NAME="ITSO_TRANSRECORD_TRANSID<%=rowNum%>" VALUE='<dab:getColumn index="1"/>'/> </TD> <TD> <dab:getColumn index="2"/> </TD> <TD> <dab:getColumn index="3"/> </TD> <TD> <dab:getColumn index="4"/> </TD> <TD> <dab:getColumn index="5"/> </TD> </TR> <%select_master.next();%> </dab:repeat> </TABLE> 270 WebSphere Studio Application Developer Version 5 Programming Guide Running the JSP Figure 8-24 shows the output of the JSP run execution. Figure 8-24 JSP with DB Beans run Summary In this chapter we used the wizards within Application Developer to create dynamic Web pages using SQL queries. We showed how to access databases from a Web application, both by using the database Web page wizard and by creating your own JSPs using tag libraries. We also described the configuration of a test server with a data source. © Copyright IBM Corp. 2003. All rights reserved. 271 Chapter 9. Developing applications with stored procedures In this chapter, we discusses the following topics:  What is a stored procedure?  Creating a Java stored procedure  Accessing a Java stored procedure  Creating a stored procedure with multiple statements 9 Tip: When building stored procedures with DB2 be sure to use the DB2 app JDBC driver. Using the BD2 net JDBC driver is unstable and may not work. 272 WebSphere Studio Application Developer Version 5 Programming Guide What is a stored procedure? A stored procedure is a block of procedural constructs and embedded SQL statements that are stored in a database and can be called by name. Stored procedures allow an application program to be run in two parts, one on the client and the other on the server, so that one client-server call can produce several accesses to the database. This is good for performance because the traffic between the client and the server is minimized. Stored procedures can be written as SQL procedures, or as C, COBOL, PL/I, or Java programs. In the following sections we will look at how to write and use a Java stored procedure. Creating a Java stored procedure In this section we create a simple stored procedure that takes a customer ID and returns all customer information. Later we create a Web application that uses the stored procedure. Importing the database definition into a Web project We use a new Web project ItsoProGuideStoredProcWeb for the stored procedure examples. Create the project by following the instructions in “Creating a Web project” on page 248.  Open the Data perspective and go to the DB Servers view.  Select the existing connection Con2 and Reconnect (context). Alternatively, create a new connection as described in “Creating a database connection” on page 145 (without a filter to get all the tables).  Import the EJBBANK database into the ItsoProGuideStoredProcWeb project. – Select the EJBBANK and Import to Folder , then select the ItsoProGuideStoredProcWeb project and click Finish . – The database is imported into Web Content/WEB-INF/databases.  Figure 9-1 shows the Data Definition view in the Data perspective after the EJBBANK database has been imported. Note: The support for stored procedures varies between different data base management systems. We are using DB2 stored procedures in the example. Chapter 9. Developing applications with stored procedures 273 Figure 9-1 Data Definition view after importing EJBBANK database Using the Stored Procedure Wizard We are now ready to create the stored procedure. Select the Stored Procedures folder and New -> Java Stored Procedure (or by selecting File -> New -> Other -> Data -> Java Stored Procedure ). Enter getCustomer as the name of the stored procedure (Figure 9-2). Figure 9-2 Specify stored procedure name folder for stored procedures imported database . file: <wsadhome>wstoolseclipsepluginscom.ibm.etools.dbjars _5. 0.1jarsjspsql.jar Figure 8-18 Importing a tag library 266 WebSphere Studio Application Developer Version 5 Programming Guide Be sure to select Add an alias. JSP. Note: Application Developer version 5 offers an improved New JSP wizard, which includes a step to add tag libraries to a newly generated JSP file. 268 WebSphere Studio Application Developer Version. index=" ;5& quot;/> </TD> </TR> <%select_master.next();%> </dab:repeat> </TABLE> 270 WebSphere Studio Application Developer Version 5 Programming Guide Running