WebSphere Studio Application Developer Version 5 Programming Guide part 30 pdf

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.. Figure 8-16 Inse

The jspsql.jar file contains the tags anddbbeans.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

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

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

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

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>

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>

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

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.

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

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