實現Servle簡易驗證碼

老規矩，先上效果圖

這是一款比較簡單的驗證碼的實現，只需弄清其原理即可

實現驗證碼只需分三步走

• 創建字節流驗證碼

 //在doPost方法中定義寬高 
		int width = 200;
		int height = 100;
		BufferedImage imge = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

• 美化驗證碼

//美化分幾步走
//改變背景色
				Graphics graphics = imge.getGraphics();
				graphics.setColor(Color.PINK);
				graphics.fillRect(0, 0, width, height);
``

	
				//邊框
				graphics.setColor(Color.BLUE);
				graphics.drawRect(0, 0, width - 1, height - 1);`




//寫出驗證碼
				
				
				String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
				
				Random r = new Random();
				for (int j = 1; j <= 4; j++) {
					int index = r.nextInt(str.length());
					char chars = str.charAt(index);
					session_str += chars;
					graphics.drawString(chars+"", width/5 * j, height/5 * j);
				}

		//畫線
				graphics.setColor(Color.black);
				
			for (int i = 0; i < 10; i++) {
				
				int x1 = r.nextInt(width);
				
				int x2 = r.nextInt(width);
				
				
				int y1 = r.nextInt(height);
				int y2 = r.nextInt(height);

				graphics.drawLine(x1, y1, x2, y2);
				
			}

		//使用輸出流，將驗證碼顯示
	ImageIO.write(imge, "jpg", response.getOutputStream());
	

這裏就是最原始的驗證碼實現原理了，希望能給大家帶來幫助