Java             3GL - .   4GL -     DB-

JAVA

Java

, Internet, , , HTML. , .

HelloWorld, :

import java.awt.*;
import java.applet.*;
public class HelloWorldApplet extends Applet {
public void paint(Graphics g) {
g.drawString("Hello World!", 20, 20);
} }

, java.applet java.awt. paint, Applet. , Graphics. . drawString, Graphics, (20,20) Hello World.

, , html-.

<applet code="HelloWorldApplet" width=200 height=40>
</applet>

html-, appletviewer .

HTML <Applet>

<applet> HTML-, appletviewer. appletviewer <applet> , . <APPLET> :

<APPLET

CODE = appletFile
OBJECT = appletSerialFile
WIDTH = pixels
HEIGHT = pixels
[ARCHIVE = jarFiles]
[CODEBASE = codebaseURL]
[ALT = alternateText]
[NAME = appletInstanceName]
[ALIGN = alignment]
[VSPACE = pixels]
[HSPACE = pixels]
>
[< PARAM NAME = AttributeNamel VALUE = AttributeValuel >]
[< PARAM NAME = AttributeName2 VALUE = AttributeValue2 >]
[HTML-, Java]
</APPLET>

CODE = appletClassFile

CODE , , . codebase, , , CODEBASE. Java 1.1 OBJECT.

OBJECT = appletClassSerialFile

, , . init(), start(). CODE, OBJECT, .

WIDTH = pixels

HEIGHT = pixels

WIDTH HEIGHT , .

ARCHIVE = jarFiles

jar- ( ), Web-. , , , . JAR, TAR Unix ( 1):

c:\> jar cf soundmap.jar *.class image.gif sound.wav

, jar- . (Lotus JavaBeans, Borland JBuilder) jar-.

CODEBASE = codebaseURL

CODEBASE , URL , , ( CODE). , HTML-. CODEBASE , HTML-.

ALT = alternateAppletText

ALT , , , <applet>, . , HTML-, <applet> </applet> , .

NAME = appletInstanceName

NAME , . , . , MyApplet Applet Duke, :

MyApplet a = getAppletContext().getApplet("Duke");

, , , .

ALIGN = alignment

ALIGN , . , IMG, LEFT, RIGHT, TOP, TEXTTOP, MIDDLE, ABSMIDDLE, BASELINE, BOTTOM, ABSBOTTOM.

VSPACE = pixels

HSPACE = PIXELS

(VSPACE), (HSPACE). , IMG.

PARAM NAME = appletAttribute1 VALUE = value1

HTML- . , getParameter(), .

getParameter(String)

getParameter String, . - , - . getParameter :

<applet code=Testing width=40 height=40>
<param name=fontName value=Univers>
<param name=fontSize value=14>
<param name=leading value=2>
<param name=accountEnabled value=true>

, :

String FontName = getParameter("fontName");
String FontSize = Integer.parseInt(getParameter("fontSize"));
String Leading = Float.valueOf(getParameter("leading"));
String PaidUp = Boolean.valueOf(getParameter("accountEnabled"));

getDocumentBase getCodeBase

, , . Java , HTML-, ( - getDocumentBase), , class- ( - getCodeBase).

AppletContext showDocument

AppletContext , . showDocument , .

: . , , :

System.out.println(Hello there, welcome to Java);

, , . Netscape Java Options, Show Java Console.

showStatus pletviewer Java. .

, Applet, , .

init

init . .

start

start init. , . , init , start HTML-, , . , , WWW-, , start.

paint

paint . AWT , , , . , , , paint.

update

update Applet , paint. paint , update , , . , update. update, paint, AWT, update.

stop

stop , HTML-, . stop . , . , , start.

destroy

destroy , (, Netscape) , . , .

HelloWorldApplet. paint, . Applet , . , update . update repaint.

repaint

repaint . , , update. , , update . AWT, update . , repaint(time) , .

repaint(time)

repaint, ( repaint).

repaint(x, y, w, h)

, , .

repaint(time, x, , w, h)

.

.

, , . size, Dimension. Dimension, width height:

Dimension d = size();
System.out.println(d. width + "," + d.height);

Graphics

Graphics . , . drawRect, drawOval, fillRect fillOval : int x, int y, int width int height. , width height .

drawLine

drawline(int x1, int 1, int 2, int 2)

(1,1) (2,2). 1 . .

drawArc fillArc

drawArc fillArc :

drawArc(int x, int , int width, int height, int startAngle, int sweepAngle)

(fillArc ) , (x,y,width, height), startAngle sweepAngle. 3 , (, 90 12 , 180 9 , ).

drawPolyson fillPolyson

:

drawPolygon(int[], int[], int)

fillPolygon(int[], int[], int)

drawPolygon ( ), , , . drawPolygon . , , .

AWT , . , , Java , . , , , , . Color.black - - black, white, red, green, blue, cyan, yellow, magenta, orange, pink, gray, darkGray lightGray.

.

Color(int, int, int)

0 255 , .

Color(int)

, , . 16-23, 8-15, 0-7.

Color(float, float, float)

, Color(float, float, float), float ( 0.0 1.0) , .

Color

HSBtoRGB(float, float, float)
RGBtoHSB(int, int, int, float[1)

HSBtoRGB , , (HSB), RGB, Color(int). RGBtoHSB , , float HSB, .

HSB (Hue-Saturation-Brightness, --) Red-Green-Blue . ( 0.0 1.0, , , , , , , , ). ( 0.0 1.0) - , . - 0.0 1.0, , - .

getRedQ, getGreenO, setBlue()

.

getRGB()

, ,

red = Oxff & (getRGB() >> 16);
green = Oxff & (getRGB() >> 8);
blue = Oxff & getRGB();

setPaintMode() setXORMode(Color)

paint , . XOR , XOR ( ) ( ).

AWT . , Java .

/*
* <applet code="WhatFontsAreHere" width=100 height=40>
* </applet>
*
*/
import java.applet.*;
import java.awt.*;
public class WhatFontsAreHere extends Applet {
public void init() {
String FontList[];
FontList = getToolkit().getFontList();
for (int i=0; i < FontList.length; i++) {
System.out.println(i + ": " + FontList[i]);
}
} }

drawString

drawString(String, x, ). . (,) , , . , , , .

Font , :

Font StrongFont = new Font("Helvetica", Font.BOLD|Font.ITALIC, 24);

: Dialog, Helvetica, TimesRoman, Courier Symbol. . Font.PLAIN, Font.BOLD Font.ITALIC, , .

.

getFamily getName

getFamily . getName .

getSize

, .

getStyle

, . Font: PLAIN, BOLD ITALIC.

isBold, isItalic, isPlain

true , (bold), (italic) (plain), .

: FontMetrics

Java , FontMetrics . - , :

FontMetrics

FontMetrics:

stringWidth

.

bytesWidth, charsWidth

.

getAscent, getDescent, getHeight

, . . g . ..

getMaxAscent getMaxDescent

.

FontMetrics , , , .

/*
* <applet code="HelloWorld" width=200 height=100> * </applet> * */ import java.applet.*; import java.awt.*; public class HelloWorld extends Applet { final Font f = new Font("Helvetica", Font.BOLD, 18); public void paint(Graphics g) { Dimension d = this.size(); g.setColor(Color.white); g.fillRect(0,0,d.width,d.height); g.setColor(Color.black); g.setFont(f); drawCenteredString("Hello World!", d.width, d.height, g); g.drawRect(0,0,d.width-1,d.height-1); } public void drawCenteredString(String s, int w, int h, Graphics g) { FontMetrics fm = g.getFontMetrics(); int x = (w - fm.stringWidth(s)) / 2; int y = (fm.getAscent() + (h - (fm.getAscent() + fm.getDescent()))/2); g.drawString(s, x, y); } }
Java             3GL - .   4GL -     DB-


, - - , , , , , .




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