LOVELY PROFESSIONAL UNIVERSITY

HOME WORK – I
DOA: 9/7/2012 DoS: 9/17/2012

-------------------------------------------------------------------------------------------------------------------

Assignment

COURSE- Modern Web Programming Tools and Techniques-I

COURSE CODE- CAP618T

SUBMITTED BY: SUBMITTED TO:

Anil Kumar Miss. MANDEEP KAUR

Roll-A24

Reg. - 11013165

Sec- D1R05

Q: 1 Take a JavaBeans Object named “Profession” with properties domain and expertise. Show the use of all 4 scope types on this object.

Ans:- You just need to create a domain object as a JavaBeans property and the corresponding getter and setter methods.

The framework will automatically initialize the domain object and transfers the form data. The UserAction class contains the following code.

Public class UserAction extends ActionSupport

{

Private User user;

Public UserAction()

{

Public String execute()

{

Return SUCCESS;

}

Public User getUser()

{

Return user;

}

Public void setUser(User user)

{

this. user=user;

}

}

To refer the user attributes like name, age etc. we need to first get the user object and then access its properties. For example to access the user's age in the Action you need to use the following syntax.

getUser().getAge();

public class User { private String name; private int age; private String sex; private String[] hobby; private String country; public String getName() { return name;
}
public void setName(String name) { this.name = name;
}
public int getAge() { return age;
}

public void setAge(int age) { this.age = age;
}

public String getSex() { return sex;
}

public void setSex(String sex) { this.sex = sex;
}
public String[] getHobby() { return hobby;
}

public void setHobby(String[] hobby) { this.hobby = hobby;
}

public String getCountry() { return country;
}

public void setCountry(String country) { this.country = country;
}
}
In the jsp page the user attributes cannot be directly referenced. Since the attributes we refer in the jsp page belongs to the User object we need to go one level deeper to reference the attributes. To refer the user's age, the value of the name attribute should be

name="user.age"

Scope is the idea that an object belongs to a certain part of an application. The five main scopes of a web application are request, response, page, session, and application. This means that an object may be a part of a request, a response, an individual page, a session, or an instance of the application. For example, if we said, "the employee object has session scope," we would mean that the employee object only existed within a certain session.

Page Count = Session count = Application count = Time =

[5]

Q: 2 discuss and demonstrate the use of all page directive attributes. Give minimum 2 separate types of examples for each attribute, to make it clear that how that attribute is effecting output.

Ans: - The page directive is used to provide instructions to the container that pertain to the current JSP page. You may code page directives anywhere in your JSP page. By convention, page directives are coded at the top of the JSP page.
Following is the basic syntax of page directive:

You can write XML equivalent of the above syntax as follows:

Attributes:
Following is the list of attributes associated with page directive:

|Attribute |Purpose |
|buffer |Specifies a buffering model for the output stream. |
|autoFlush |Controls the behavior of the servlet output buffer. |
|contentType |Defines the character encoding scheme. |
|errorPage |Defines the URL of another JSP that reports on Java unchecked runtime exceptions. |
|isErrorPage |Indicates if this JSP page is a URL specified by another JSP page's errorPage attribute. |
|extends |Specifies a superclass that the generated servlet must extend |
|import |Specifies a list of packages or classes for use in the JSP as the Java import statement does for |
| |Java classes. |
|info |Defines a string that can be accessed with the servlet's getServletInfo() method. |
|isThreadSafe |Defines the threading model for the generated servlet. |
|language |Defines the programming language used in the JSP page. |
|session |Specifies whether or not the JSP page participates in HTTP sessions |
|isELIgnored |Specifies whether or not EL expression within the JSP page will be ignored. |
|isScriptingEnabled |Determines if scripting elements are allowed for use. |

The buffer Attribute:

The buffer attribute specifies buffering characteristics for the server output response object.
You may code a value of "none" to specify no buffering so that all servlet output is immediately directed to the response object or you may code a maximum buffer size in kilobytes, which directs the servlet to write to the buffer before writing to the response object.
To direct the servlet to write output directly to the response output object, use the following:

Use the following to direct the servlet to write output to a buffer of size not less than 8 kilobytes:

The autoFlush Attribute:

The autoFlush attribute specifies whether buffered output should be flushed automatically when the buffer is filled, or whether an exception should be raised to indicate buffer overflow.
A value of true (default) indicates automatic buffer flushing and a value of false throws an exception.
The following directive causes the servlet to throw an exception when the servlet's output buffer is full:

This directive causes the servlet to flush the output buffer when full:

Usually, the buffer and autoFlush attributes are coded on a single page directive as follows:

The contentType Attribute:

The contentType attribute sets the character encoding for the JSP page and for the generated response page. The default content type is text/html, which is the standard content type for HTML pages.
If you want to write out XML from your JSP, use the following page directive:

The following statement directs the browser to render the generated page as HTML:

The following directive sets the content type as a Microsoft Word document:

You can also specify the character encoding for the response. For example, if you wanted to specify that the resulting page that is returned to the browser uses ISO Latin 1, you would use the following page directive:

The errorPage Attribute:

The errorPage attribute tells the JSP engine which page to display if there is an error while the current page runs. The value of the errorPage attribute is a relative URL.
The following directive displays MyErrorPage.jsp when all uncaught exceptions are thrown:

The isErrorPage Attribute:

The isErrorPage attribute indicates that the current JSP can be used as the error page for another JSP.
The value of isErrorPage is either true or false. The default value of the isErrorPage attribute is false.
For example, the handleError.jsp sets the isErrorPage option to true because it is supposed to handle errors:

The extends Attribute:

The extends attribute specifies a superclass that the generated servlet must extend.
For example, the following directive directs the JSP translator to generate the servlet such that the servlet extends somePackage.SomeClass:

The import Attribute:

The import attribute serves the same function as, and behaves like, the Java import statement. The value for the import option is the name of the package you want to import.
To import java.sql.*, use the following page directive:

To import multiple packages you can specify them separated by comma as follows:

By default, a container automatically imports java.lang.*, javax.servlet.*, javax.servlet.jsp.*, and javax.servlet.http.*.

The info Attribute:

The info attribute lets you provide a description of the JSP. The following is a coding example:

The isThreadSafe Attribute:

The isThreadSafe option marks a page as being thread-safe. By default, all JSPs are considered thread-safe. If you set the isThreadSafe option to false, the JSP engine makes sure that only one thread at a time is executing your JSP.
The following page directive sets the isThreadSafe option to false: