用Java编写随机验证码生成器
用Java编写随机验证码生成器
很多GUI程序都需要在组件上绘制图形，在java.awt包中提供了一个专门的Graphics类，它相当于画布，提供各种绘制方法。
随机验证码生成器用了其中的几种方法
①setColor( )用于指定上下文颜色，方法中接收一个Color类型的参数，如Color.WHITE等。
声明
public abstract void setColor(Color c);
/**
* Sets the paint mode of this graphics context to overwrite the
* destination with this graphics context's current color.
* This sets the logical pixel operation function to the paint or
* overwrite mode. All subsequent rendering operations will
* overwrite the destination with the current color.
*/
②setFont( )方法用于指定上下文字体，方法中接收一个Font类型的参数，Font类第一个参数是String类型，表示字体名称，如“黑体”；第二个参数表示int类型，表示字体样式，如Font.PLAINT；第三个参数也是int类型，表示字体大小。
声明
public abstract void setPaintMode();
/**
* Sets the paint mode of this graphics context to alternate between
* this graphics context's current color and the new specified color.
* This specifies that logical pixel operations are performed in the
* XOR mode, which alternates pixels between the current color and
* a specified XOR color.
*
* When drawing operations are performed, pixels which are the
* current color are changed to the specified color, and vice versa.
*
* Pixels that are of colors other than those two colors are changed
* in an unpredictable but reversible manner; if the same figure is
* drawn twice, then all pixels are restored to their original values.
* @param c1 the XOR alternation color
*/
③drawRect( )方法和drawOval( )方法用于绘制矩形和椭圆形的边框，fillRect( )和fillOval( )方法用于使用当前颜色填充绘制完成的矩形和椭圆形。
声明
public abstract void fillRect(int x, int y, int width, int height);
/**
* Draws the outline of the specified rectangle.
* The left and right edges of the rectangle are at
* x and x + width.
* The top and bottom edges are at
* y and y + height.
* The rectangle is drawn using the graphics context's current color.
* @param x the x coordinate
* of the rectangle to be drawn.
* @param y the y coordinate
* of the rectangle to be drawn.
* @param width the width of the rectangle to be drawn.
* @param height the height of the rectangle to be drawn.
* @see java.awt.Graphics#fillRect
* @see java.awt.Graphics#clearRect
*/
public void drawRect(int x, int y, int width, int height) {
if ((width < 0) || (height < 0)) {
return;
}
if (height == 0 || width == 0) {
drawLine(x, y, x + width, y + height);
} else {
drawLine(x, y, x + width - 1, y);
drawLine(x + width, y, x + width, y + height - 1);
drawLine(x + width, y + height, x + 1, y + height);
drawLine(x, y + height, x, y + 1);
}
}
public abstract void drawOval(int x, int y, int width, int height);
/**
* Fills an oval bounded by the specified rectangle with the
* current color.
* @param x the x coordinate of the upper left corner
* of the oval to be filled.
* @param y the y coordinate of the upper left corner
* of the oval to be filled.
* @param width the width of the oval to be filled.
* @param height the height of the oval to be filled.
* @see java.awt.Graphics#drawOval
*/
④drawString( )方法用于绘制一段文本，第一个参数为绘制文本的内容，第二个，第三个参数表示绘制的左下角坐标x,y；
声明
public abstract void drawString(String str, int x, int y);
/**
* Renders the text of the specified iterator applying its attributes
* in accordance with the specification of the
* {@link java.awt.font.TextAttribute TextAttribute} class.
*
* The baseline of the leftmost character is at position
* (x, y) in this graphics context's coordinate system.
* @param iterator the iterator whose text is to be drawn
* @param x the x coordinate.
* @param y the y coordinate.
* @throws NullPointerException if iterator is
* null.
* @see java.awt.Graphics#drawBytes
* @see java.awt.Graphics#drawChars
*/
最后贴上完整代码
package GUI;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class AWT绘图 {
public static void main(String[] args){
final Frame frame = new Frame("验证码");
final Panel panel = new Mypanel();
frame.add(panel);
frame.setSize(200,100);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
MypanelListener ml = new MypanelListener();
frame.addWindowListener(ml);
}
}
class Mypanel extends Panel {
public void paint(Graphics g){
int width = 160;
int height = 40;
g.setColor(Color.LIGHT_GRAY);
g.fillRect(0, 0, width, height);
g.setColor(Color.BLACK);
g.drawRect(0, 0, width-1, height-1);
Random r = new Random();
for(int i=0;i<100;i++){
int x = r.nextInt(width)-2;
int y = r.nextInt(height)-2;
g.drawOval(x, y, 2, 2);
}
g.setFont(new Font("黑体",Font.BOLD,30));
g.setColor(Color.BLUE);
char [] chars = ("0123456789abcdefghijklmnopqrstuvwxyzABCDEFG"+"HIJKLMNPQRSTUVWXYZ").toCharArray();
StringBuilder sb = new StringBuilder();
for(int i=0;i<4;i++){
int pos = r.nextInt(chars.length);
char c = chars[pos];
sb.append(c+" ");
}
g.drawString(sb.toString(), 20, 30);
}
}
class MypanelListener implements WindowListener{
public void windowClosing(WindowEvent e){
Window window = e.getWindow();
window.setVisible(false);
window.dispose();
}
public void windowActivated(WindowEvent e){
}
public void windowClosed(WindowEvent e){
}
public void windowDeactivated(WindowEvent e){
}
public void windowDeiconified(WindowEvent e){
}
public void windowIconified(WindowEvent e){
}
public void windowOpened(WindowEvent e){
}
}
先填充一个浅灰色的矩形，再填充一个黑色的矩形边框，然后随机在矩形中绘制100个椭圆作为验证码干扰，最后生成随机数。
效果图
