Week8 Jsp Final Remarks
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Transcript of Week8 Jsp Final Remarks
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Server-Side Web Development
Server-Side Web Development
JSP Final Remarks
09thMarch 2006
Bogdan L. Vrusias
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Server-Side Web Development
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Contents
Java Collections API and Casting
Server-Side Dynamic Construction of JavaScript
Login Pattern Example
Importing and Using JavaBeans within JavaBeans
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Java Collection API
Array
Vector
Hashtable
ArrayList
LinkedList
...
import java.util.*;
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Array Example
int[] anArray;
anArray = new int[10];
for (int i = 0; i < anArray.length; i++) {
anArray[i] = i;
System.out.print(anArray[i] + " ");
}
boolean[] answers = { true, false, true, false };
MyObject[] anObjectArray = new MyObject[5];
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Multidimensional Array Example
int[][] aMatrix = new int[4][];
for (int i = 0; i < aMatrix.length; i++) {
aMatrix[i] = new int[5];
for (int j = 0; j < aMatrix[i].length; j++) {aMatrix[i][j] = i + j;
}
}
for (int i = 0; i < aMatrix.length; i++) {
for (int j = 0; j < aMatrix[i].length; j++) {
System.out.print(aMatrix[i][j] + " ");
}
System.out.println();
}
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Hashtable Example
Hashtable nums = new Hashtable();
nums.put("one", new Integer(1));
nums.put("two", new Integer(2));
Integer n = (Integer)nums.get("two");
if (n != null) {
System.out.println("two = " + n);
}
for (Enumeration e = nums.keys(); e.hasMoreElements();)
{
System.out.println(e.nextElement().toString());
}
if (nums.containsKey("one")) {...}
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Java Type Conversion / Casting
If vis a Vectortype collection object then:
Getting a String from Vector
String s = (String)v.elementAt(x);
Vector of Vector objects
Vector v = (Vector)v.elementAt(x);
Getting a String from Vector of Vector objectsString s =
((Vector)v.elementAt(x)).elementAt(y).toString();
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Server-Side Dynamic Construction of JavaScript
Target output (for the client machine):
...
function doit() {
var names = new Array(5);
names[0] = "Tony";
names[1] = "Mike";
names[2] = "Sarah";
names[3] = "Helen";
names[4] = "Alex";
for (i = 0; i < names.length; i++) {
alert(names[i]);
}
}
...
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Server-Side Dynamic Construction of JavaScript
JSP processed on the server side:
...
function doit() {
var names = new Array();
names[] = "";
for (i = 0; i < names.length; i++) alert(names[i]);
}
...
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Server-Side Dynamic Construction of JavaScript
Follow the class demo
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Login Pattern Example
First we create a JavaBean that checks the username and password of auser, and then stores the status of the login.
Usernames and password can be stored either within a database (mostcommon) or within a file that is not accessible externally.
Use the JavaBean within the login page to check the password. If thelogin is incorrect then keep the user within the login page, otherwiseredirect to the desired page.
Each consequent page that should only be accessed by logged in usersshould first of all (at the top of the page) use the previous loginJavaBean to check the status of the login. If the user is logged in thenthe page is displayed, otherwise the user is redirected to the login page.
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Login Pattern Example
login.jsp
securePage.jsp
check
login
loginBean
correct
incorrect
submit formaccess page
get login
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Login Pattern Example
Follow the class demo
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Importing & Using JavaBeans within JavaBeans
To invoke and use a JavaBean from another JavaBean just follow the standard
Java approach of calling any other Java Class:
Import the appropriate library (not necessary if the class is in the same package)
import webtech.lab5.MyClass;
If the class has a state (is an object) then instantiate it.
MyClass mc = new MyClass();
Call the methods within the new object
mc.setMethod(abc);
String v = mc.getMethod();
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Importing & Using JavaBeans within JavaBeans
Follow the class demo
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Closing
Questions???
Remarks???
Comments!!!
Evaluation!