将 PNG 图像转换为 JPEG 的Java程序

PNG 和 JPG格式用于图像插图。这两种格式都用于为某些类型的图像提供良好的兼容性，例如 PNG 对线条图和图标图形效果更好，而 JPG 对照片效果很好。然而，对于媒体和图片的使用和存储，两者相对于彼此是可相互转换的。

在Java，write() 方法用于将图像从 gif 类型的格式转换为 jpg，使用javax.imageio 包下 ImageIO 类提供的静态方法 write()。下面的实用程序类实现了一个称为converImg()的静态方法，它以输入和输出图像路径作为参数并格式化输出图像。

句法：

boolean write(RenderedImage image, String formatName, OutputStream output)

参数： write() 方法接受 3 个参数，即图像、格式名称和输出。

Image：输入图像作为RenderedImage接口的子类，如BufferedImage。要从输入图像文件中获取BufferedImage对象，我们可以使用ImageIO类也提供的read(InputStream)。
formatName：指定输出图像的格式类型。
output指定输出图像将写入的 OutputStream。

返回类型：布尔值，如果可以找到 ImageWriter 并成功执行转换，则返回 true，否则返回 false。

异常：如果在执行过程中发生错误，它将抛出 IOException。它在稍后的实现部分中显示。

执行：

Note: For input and output images path, Input and input images been passed are present on the desktop of the machine

Input image with name “demoImage.png”
Output Image with name “demoImage.jpeg”

Code is present at the directory mentioned below

/Users/mayanksolanki/Desktop/Job/Coding/GFG/Folder/

编程需要懂一点英语

例子

Java

// Java Program to Convert PNG Image to JPEG Image
 
// Importing BufferdImage 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 occured
            ex.printStackTrace();
        }
    }
}

输出：

情况一：抛出错误时

情况二：编译成功但运行时抛出异常（无法正常运行）

案例三：编译成功并成功运行

Image converted to jpeg successfully.

执行后会显示Image转换为jpeg成功，我们可以在console上找到，文件中新建了一个jpeg图片