Lookup Applet
This applet does searches of simple databases, like Phone Books.
You can use this applet without any knowledge of Java by calling
it
from your HTML code. The database is a stored as a simple text
file in your web
directory. The applet down-loads this file into memory as it
starts, so if you have
a huge file this may take un-acceptably long.
The number of fields in each record and the names to give them
are defined in the APPLET tag in your html code.
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Simple Phone Book
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Complex Phone Book
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Other Examples
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How to use this Applet
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Java Source Code, and complied Class files
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Detailed explanation of Applet Parameters
Heres a simple phone book
example of a page that uses
this applet.
This is the HTML code that calls the above example:
<![CDATA[
<HTML>
<BODY>
<BODY TEXT="#000000" BGCOLOR="#FFFFFF">
<CENTER><H2>Search Springfield Phone Book</H2></CENTER>
<APPLET CODE="Lookup.class" WIDTH=580 HEIGHT=110>
<param name="UrlOfDataFile"
value="http://www.jdonohue.com/java/lookup/simple-phone.html">
<param name="fieldNames" value="Search for:,40">
<param name="fieldSeparatorCharacter" value="|">
<param name="foregroundColor" value="000000">
<param name="backgroundColor" value="FFFFFF">
</APPLET>
<BR>
<I>Click "Search" to see all the names, or enter a search term in
one, or more, of the </I>
<I>text boxes to constrain the results to only names that match
it.</I>
<!The Following is the Phone book data!>
<B>This is the Springfield phone book data</B>
<PRE>
Homer Simpson 555-6528
Lisa Simpson 555-6528
..... Stuff deleted ......
Dr. Nick Riviera 555-6022
Pr. John Frink 555-6024
</PRE>
</BODY></HTML>
]]>
This example defines only one field for each line. This is the
simplist way to use the
applet- because you don't need to put field separators in your
data. The drawback is that
you can only search the entire line of data for matches.
The "APPLET CODE" tag loads the "Lookup.class" Java
applet and runs it.
The "param name" tags supply information to the applet about
where your file with the
names and phone numbers is, and how to search and display the
data.
In the example above the line
"Homer Simpson 555-6528"
defines one record with that will be searched and displayed as a
whole.
The parameter "UrlOfDataFile" is set to the same html file
that calls
the applet. The applet will ignore any lines in the data file
that are blank or
that contain at least one HTML tags. You can therefore put HTML
code above,
and below your data. The parameter "fieldNames" specifies
how the text box where
search strings are entered is labeled.
The "foregroundColor" and "backgroundColor"
parameters define what color the applet should be. These should
be the same as those
defined in the HTML "BODY TEXT="#000000"
BGCOLOR="#FFFFFF"" tag if
you want the applet to blend into the page.
The parameter "fieldSeparatorCharacter" is ignored in this
case.
Complex Phone Book
Heres an complex phone book example
where you can search
individual fields, like first name or last name separately.
This is the HTML code that calls the above example:
<![CDATA[
<HTML>
<BODY TEXT="#000000" BGCOLOR="#FFFFFF">
<CENTER><H2>Search Springfield Phone Book</H2></CENTER>
<APPLET CODE="Lookup.class" WIDTH=620 HEIGHT=220>
<param name="UrlOfDataFile"
value="http://www.jdonohue.com/java/lookup/phone.html">
<param name="fieldNames" value="First Name,25,Last Name,30,Phone
#,15">
<param name="fieldSeparatorCharacter" value=",">
<param name="foregroundColor" value="000000">
<param name="backgroundColor" value="FFFFFF">
</APPLET>
<PRE>
Homer,Simpson,555-6528
Lisa,Simpson,555-6528
..... Stuff deleted ......
Dr. Nick,Riviera,555-6022
Pr. John,Frink,555-6024
</PRE>
</BODY></HTML>
]]>
This example requires that the file has one record per line, and
the fields in each
line are delimited with a field separator character (like comma
or "|").
The line "Homer,Simpson,555-6528"
defines one record with three fields separated by a comma.
The parameter
"fieldNames" specifies that the first field is labeled
"First Name", the second
"Last Name", and the third "Phone #". The number following each
name determines
how many characters of that field will display on screen before
truncating. Set this
number to the maximum expected field size unless things are
getting squeezed.
The number of field names, and lengths specified in the
"fieldNames" parameter
has to match whats in your data or the Applet won't work.
The parameter "fieldSeparatorCharacter" tells the applet
that the fields are
separated by commas.
Other Examples
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A US
Telephone Area Codes data base.
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A
Library
data base.
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A 2 letter ISO Country Codes data base.
How to use this Applet
Copy the two required Java "*.class" files to the
same directory on your web
server as the HTML page that is going to call them. The class
files are
Lookup
.class
and
Field.class
Create the HTML page that will have the applet embedded in it.
Create the
file that will have your data. These two can be the same if you
wish.
Make sure the "UrlOfDataFile" parameter points to the full URL of
your
data file. Adjust the APPLET WIDTH, and HEIGHT tags so that all
the
GUI components fit, without too much empty space in the middle.
Java Source Code, and compilied Class files
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Java Source Code:
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Lookup.java
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Field.java
Java Class files:
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Lookup.class
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Field.class
Note: Netscape does not download these files as binary. Use
Internet Explore to download the class files.
Detailed explaination of Applet Parameters
UrlOfDataFile
Is the flat file with the records to search.
This must be a URL of a file that the browser running the
applet is allowed
to retrieve (i.e. on the same web server as the applet).
You can make this the same html file that calls the applet.
This will
give you a web page with a search applet at the top of the
page, and a list of
all the data below. When reading the flat file the applet
only uses lines
that do not contain the "<". You can therefore put html code
in this file
above and below the actual lines of data.
This applet was meant to be used with a Web Server, and not
run from your PC's
hard-drive. Allthough it can sometimes work that way.
fieldNames
This is a list of the fields in each line of the data file.
Each field is given a name to label it with. Following each
field name is a
number that specifies the number of characters to display in
the results box
for this field before truncation.
fieldSeparatorCharacter
This the character that delimites each field in the data file.
Pick something
that isn't likely to be in inside a field in your data file.
If only one field
name is given in the "fieldNames" parameter then this
parameter is ignored.
If only one fieldName parameter was given this parameter is
ignored.
foregroundColor/backgroundColor
This is the colors to use for the foreground(text) and
background in the applet
The colors are specifed using the same notation as the HTML
BODY tag.
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Last Updated 09/2/97