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Object Oriented Programming Articles
Page 558 of 589
How to write a JDBC application which connects to multiple databases simultaneously?
To connect with a database, you need toRegister the Driver: Select the required database, register the Driver class of the particular database using the registerDriver() method of the DriverManager class or, the forName() method of the class named Class.DriverManager.registerDriver(new com.mysql.jdbc.Driver());Get connection: Create a connection object by passing the URL of the database, username and password (of a user in the database) in string format, as parameters to the getConnection() method of the DriverManager class.Connection mysqlCon = DriverManager.getConnection(mysqlUrl, "root", "password");To connect to multiple databases in a single JDBC program you need to connect to the two (or more) databases simultaneously using ...
Read MoreHow to setup a Web server like Tomcat to test JSP pages?
Apache Tomcat is an open source software implementation of the JavaServer Pages and Servlet technologies and can act as a standalone server for testing JSP and Servlets, and can be integrated with the Apache Web Server. Here are the steps to set up Tomcat on your machine −Download the latest version of Tomcat from https://tomcat.apache.org/.Once you downloaded the installation, unpack the binary distribution into a convenient location. For example, in C:\apache-tomcat-5.5.29 on windows, or /usr/local/apache-tomcat-5.5.29 on Linux/Unix and create CATALINA_HOME environment variable pointing to these locations.Tomcat can be started by executing the following commands on the Windows machine −%CATALINA_HOME%\bin\startup.bat ...
Read MoreHow to write a JDBC program to extract data from multiple databases?
To connect with a data base, you need toRegister the DriverSelect the required database register the Driver class of the particular database using the registerDriver() method of the DriverManager class or, the forName() method of the class named Class.DriverManager.registerDriver(new com.mysql.jdbc.Driver());Get connectionCreate a connection object by passing the URL of the database, username and password of a user in the database (in string format) as parameters to the getConnection() method of the DriverManager class.Connection mysqlCon = DriverManager.getConnection(mysqlUrl, "root", "password");And, to extract data you need to execute the select query as:ResultSet rs = stmt.executeQuery("Select * from Employee");To print the contents of the ...
Read MoreWhat do the id and scope attribute mean in the action elements in JSP?
These are two attributes that are common to all Action elements: the id attribute and the scope attribute.Id attributeThe id attribute uniquely identifies the Action element and allows the action to be referenced inside the JSP page. If the Action creates an instance of an object, the id value can be used to reference it through the implicit object PageContext.Scope attributeThis attribute identifies the lifecycle of the Action element. The id attribute and the scope attribute are directly related, as the scope attribute determines the lifespan of the object associated with the id. The scope attribute has four possible values:(a) ...
Read MoreWhat is the function of action in JSP?
This action lets you insert files into the page being generated. The syntax looks like this −Unlike the include directive, which inserts the file at the time the JSP page is translated into a servlet, this action inserts the file at the time the page is requested.Following table lists out the attributes associated with the include action −S.No.Attribute & Description1pageThe relative URL of the page to be included.2flushThe boolean attribute determines whether the included resource has its buffer flushed before it is included.ExampleLet us define the following two files (a)date.jsp and (b) main.jsp as follows −Following is the content of ...
Read MoreWhat are JSP declarations? In how many ways we can write JSP declarations?
A declaration declares one or more variables or methods that you can use in Java code later in the JSP file. You must declare the variable or method before you use it in the JSP file.Following is the syntax for JSP Declarations −You can write the XML equivalent of the above syntax as follows − code fragment Following is an example for JSP Declarations −
Read MoreHow to declare an object of a class using JSP declarations?
A declaration declares one or more variables or methods that you can use in Java code later in the JSP file. You must declare the variable or method before you use it in the JSP file.Following is the syntax for JSP Declarations −You can write the XML equivalent of the above syntax as follows − code fragment Following is an example of Object declaration in JSP Declarations −
Read MoreWhat are JSP comments?
JSP comment marks text or statements that the JSP container should ignore. A JSP comment is useful when you want to hide or "comment out", a part of your JSP page.Following is the syntax of the JSP comments −Following example shows the JSP Comments − A Comment Test A Test of Comments The above code will generate the following result −A Test of Comments
Read MoreHow to use action in JSP?
The getProperty action is used to retrieve the value of a given property and converts it to a string, and finally inserts it into the output.The getProperty action has only two attributes, both of which are required. The syntax of the getProperty action is as follows − ... Following table lists out the required attributes associated with the getProperty action −Sr.No.Attribute & Description1nameThe name of the Bean that has a property to be retrieved. The Bean must have been previously defined.2propertyThe property attribute is the name of the Bean property to be retrieved.ExampleLet us define a test bean that will ...
Read MoreHow many types of directive tags JSP supports?
A JSP directive affects the overall structure of the servlet class. It usually has the following form −Directives can have a number of attributes which you can list down as key-value pairs and separated by commas.The blanks between the @ symbol and the directive name, and between the last attribute and the closing %>, are optional.There are three types of directive tag −S.No.Directive & Description1Defines page-dependent attributes, such as scripting language, error page, and buffering requirements.2Includes a file during the translation phase.3Declares a tag library, containing custom actions, used in the page
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