Java PNG Images转JPEG用法及代码示例

// Java Program to Convert PNG Image to JPEG Image
// Importing BufferedImage class from java.awt package
// to describe an image with accessible buffer of image
import java.awt.image.BufferedImage;
// Importing all input output classes
import java.io.*;
// Importing an interface
// to determine the setting of IIOParam object
import javax.imageio.ImageIO;
// Class 1
// helper class
class HelperClass {
    // Method
    // To convert image format
    public static boolean convertImg(String inputImgPath,
                                     String outputImgPath,
                                     String formatType)
        throws IOException
    {
        // Creating an object  of FileInputStream to read
        FileInputStream inputStream
            = new FileInputStream(inputImgPath);
        // Creating an object  of FileOutputStream to write
        FileOutputStream outputStream
            = new FileOutputStream(outputImgPath);
        // Reading the  input image from file
        BufferedImage inputImage
            = ImageIO.read(inputStream);
        // Writing to the output image in specified format
        boolean result = ImageIO.write(
            inputImage, formatType, outputStream);
        // Closing the streams in order to avoid read write
        // operations
        outputStream.close();
        inputStream.close();
        return result;
    }
}
// Class 2
// Main class
public class GFG {
    // Main class
    public static void main(String[] args)
    {
        // Here, the local directories from machine
        //  is passed as in strings
        // Creating a string to store the path of image
        // to be converted
        String inputImage
            = "/Users/mayanksolanki/Desktop/demoImage.png";
        // Creating a string to
        // store path of converted image
        String outputImage
            = "/Users/mayanksolanki/Desktop/demoImage.jpeg";
        // Creating another string that will be
        // store format of converted image
        // Simply creating  creating just to hold the format
        // type
        String formatType = "JPEG";
        // Try block to check for exceptions
        try {
            // result will store boolean value whether image
            // is converted successfully or not
            boolean result = HelperClass.convertImg(
                inputImage, outputImage, formatType);
            if (result) {
                // Display message when image is converted
                // successfully
                System.out.println(
                    "Image converted to jpeg successfully.");
            }
            else {
                // Display message when image is not
                // converted successfully
                System.out.println(
                    "Could not convert image.");
            }
        }
        // Catch block to handle the exceptions
        catch (IOException ex) {
            // Display message when exception is thrown
            System.out.println(
                "Error during converting image.");
            // Print the line number
            // where the exception occurred
            ex.printStackTrace();
        }
    }
}