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This example demonstrates how to implement the applet so that the graph data
is acquired from a database. Here we set up the applet to acquire the configuration data from a text file and the graph data from
a server side process which in turn acquires the data from a database.
The Graphing Software provides several methods by which data can be acquired
from databases. For a full discussion on the various methods and Template Scripts please see the
Tutorial Section.
The configuration data is acquired from the text file ../../../bar_graph/shbarchart/Examples/barprops.txt
(click here to view)
The DatabaseServletSHbar is designed
to retrieve product sales data from a MySQL database, from a table with the following structure,
| Table Name : SalesBar |
|
|
| ProductName |
Character |
| Year |
Integer |
| Month |
Integer |
| Value |
double |
Our servlet will pick out the sales figures for three products ( ProductX,
ProductY and ProductZ) and return the data in the correct format for the graph.
The method is as follows,
- Set the output characteristics for the return data
- Establish the database connection
- Build the query statement and retrieve the database records
- Process the database records and return the Data
- All finished so close the database connection
The full servlet code is contained in the DatabaseServletSHbar
file.
(Click here to view the code).
As you will see from the code the servlet connects to the database via JDBC
and as such it is essential to have the correct JDBC drivers for your database. ( For further information on JDBC drivers please
see http://industry.java.sun.com/products/JDBC/drivers
)
For a full explanation of and range of values for the above parameters please
see the Documentation - Configuration Options».
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