"Java打印方法详解与实践"

The PrintDemo class is a demonstration of printing text and graphics in Java. By default, the print() method calls the paint() method to complete its work. This method selects a font and size, determines the position of the string on the page, and uses the Graphics.drawString() method to draw the string on the page. It is essential to accurately calculate the position of each line of text on the page and ensure that the text does not go beyond the page bottom or conflict with other lines. The PrintDemo class extends the Frame class and includes buttons for printing text and graphics, a text field for entering the number of rings, a choice for selecting different fonts, and a plot object for plotting graphics. The Plot class is an interface that can be implemented with different plot types. The PrintDemo constructor initializes the GUI components, sets the default ring number to 3, adds a text listener for the ring number, creates a panel with buttons for printing text and graphics, a label for selecting the font, and adds action listeners to the buttons for printing text and graphics. Overall, the PrintDemo class provides a simple yet effective demonstration of printing text and graphics in Java. By allowing users to select a font, size, and plot type, it showcases the versatility and flexibility of Java's graphics capabilities. With accurate positioning and careful design, the PrintDemo class can produce professional-looking printed output that meets the requirements of various printing tasks.