Create PNG Image Compress

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>top.gtb520.java.gnu</groupId>
     <artifactId>gnu_java_utils_library</artifactId>
-    <version>1.5-SNAPSHOT</version>
+    <version>1.6-SNAPSHOT</version>
 
     <properties>
         <maven.compiler.source>25</maven.compiler.source>

src/main/java/top/gtb520/java/gnu/java/utils/library/main.java

@@ -1,6 +1,7 @@
 package top.gtb520.java.gnu.java.utils.library;
 
 import top.gtb520.java.gnu.java.utils.library.utils.print.ColorNameEnum;
+import top.gtb520.java.gnu.java.utils.library.utils.compress.CompressPNG.PNGThreshold;
 
 import java.io.File;
 import java.nio.file.Path;
@@ -31,6 +32,11 @@ public interface main {
         static void UnZip(String sourceFilePanth, String destFilePanth) throws Exception {
             top.gtb520.java.gnu.java.utils.library.utils.compress.compress.UnZip(sourceFilePanth, destFilePanth);
         }
+
+        // 压缩png图片
+        static File CompressPNG(File pngFile, PNGThreshold threshold) {
+            return top.gtb520.java.gnu.java.utils.library.utils.compress.CompressPNG.PNG(pngFile, threshold);
+        }
     }
 
     // 终端打印接口与方法

src/main/java/top/gtb520/java/gnu/java/utils/library/utils/compress/CompressPNG.java

@@ -0,0 +1,82 @@
+package top.gtb520.java.gnu.java.utils.library.utils.compress;
+
+import javax.imageio.IIOImage;
+import javax.imageio.ImageIO;
+import javax.imageio.ImageWriteParam;
+import javax.imageio.ImageWriter;
+import javax.imageio.stream.ImageOutputStream;
+import java.io.File;
+import java.awt.image.BufferedImage;
+import java.util.Iterator;
+
+public class CompressPNG {
+    /***
+     * 压缩PNG图片
+     * 传入未压缩的PNG图片文件，和压缩阈值，返回压缩后的PNG图片文件
+     * 5个等级的压缩阈值，从低到高，THRESHOLD_1 最低，THRESHOLD_5 最高
+     *
+     * @param pngFile 未压缩的PNG图片文件
+     * @param threshold 压缩阈值
+     * @return 压缩后的PNG图片文件
+     */
+    public static File PNG(File pngFile, PNGThreshold threshold) {
+        if (!pngFile.exists()) {
+            System.out.println("文件不存在");
+            return null;
+        }
+        if (pngFile.getName().endsWith(".png") || pngFile.getName().endsWith(".PNG")) {
+            try {
+                BufferedImage image = ImageIO.read(pngFile);
+                if (image == null) {
+                    System.out.println("无法读取PNG文件");
+                    return null;
+                }
+
+                Iterator<ImageWriter> writers = ImageIO.getImageWritersByFormatName("png");
+                if (!writers.hasNext()) {
+                    System.out.println("未找到PNG写入器");
+                    return null;
+                }
+                ImageWriter writer = writers.next();
+
+                try (ImageOutputStream ios = ImageIO.createImageOutputStream(pngFile)) {
+                    writer.setOutput(ios);
+
+                    ImageWriteParam param = writer.getDefaultWriteParam();
+                    param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
+                    param.setCompressionQuality(getCompressionQuality(threshold));
+
+                    writer.write(null, new IIOImage(image, null, null), param);
+                } finally {
+                    writer.dispose();
+                }
+
+                return pngFile;
+            } catch (Exception e) {
+                e.printStackTrace();
+                return null;
+            }
+        } else {
+            System.out.println("文件不是PNG格式，无法压缩");
+        }
+        return null;
+    }
+
+    private static float getCompressionQuality(PNGThreshold threshold) {
+        return switch (threshold) {
+            case THRESHOLD_1 -> 0.7f;
+            case THRESHOLD_2 -> 0.5f;
+            case THRESHOLD_3 -> 0.3f;
+            case THRESHOLD_4 -> 0.1f;
+            case THRESHOLD_5 -> 0.0f;
+        };
+    }
+
+    public enum PNGThreshold {
+        THRESHOLD_1,
+        THRESHOLD_2,
+        THRESHOLD_3,
+        THRESHOLD_4,
+        THRESHOLD_5;
+    }
+}

src/test/java/top/gtb520/java/gnu/java/utils/library/utils/compress/CompressPNGTest.java

@@ -0,0 +1,205 @@
+package top.gtb520.java.gnu.java.utils.library.utils.compress;
+
+import javax.imageio.ImageIO;
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+
+public class CompressPNGTest {
+
+    static int passed = 0;
+    static int failed = 0;
+
+    public static void main(String[] args) {
+        System.out.println("========== CompressPNG 测试开始 ==========");
+
+        testCompressWithEachThreshold();
+        testNonPNGFile();
+        testNonExistentFile();
+        testCompressedFileIsValidPNG();
+        testCompressedFileSmallerOrEqual();
+
+        System.out.println("========================================");
+        System.out.println("测试完成: 通过 " + passed + ", 失败 " + failed);
+        if (failed > 0) {
+            System.exit(1);
+        }
+    }
+
+    /**
+     * 测试每个压缩阈值均能正常压缩并返回原文件
+     */
+    static void testCompressWithEachThreshold() {
+        String testName = "testCompressWithEachThreshold";
+        for (CompressPNG.PNGThreshold threshold : CompressPNG.PNGThreshold.values()) {
+            File pngFile = null;
+            try {
+                pngFile = createTestPNG("test_threshold_" + threshold.name());
+                long originalSize = pngFile.length();
+
+                File result = CompressPNG.PNG(pngFile, threshold);
+
+                boolean returnedSameFile = result != null && result.equals(pngFile);
+                assertCondition(testName + " [" + threshold.name() + "] - 应返回原文件引用", returnedSameFile);
+
+                boolean fileExists = result != null && result.exists() && result.length() > 0;
+                assertCondition(testName + " [" + threshold.name() + "] - 压缩后文件应存在且非空", fileExists);
+
+                System.out.println("  [" + threshold.name() + "] 原始: " + originalSize + " bytes, 压缩后: " + (result != null ? result.length() : "N/A") + " bytes");
+            } catch (Exception e) {
+                assertCondition(testName + " [" + threshold.name() + "] - 不应抛出异常: " + e.getMessage(), false);
+            } finally {
+                deleteTestFile(pngFile);
+            }
+        }
+    }
+
+    /**
+     * 测试传入非PNG文件应返回null
+     */
+    static void testNonPNGFile() {
+        String testName = "testNonPNGFile";
+        File txtFile = null;
+        try {
+            txtFile = File.createTempFile("test_not_png", ".txt");
+            java.nio.file.Files.writeString(txtFile.toPath(), "this is not a png");
+
+            File result = CompressPNG.PNG(txtFile, CompressPNG.PNGThreshold.THRESHOLD_3);
+            assertCondition(testName + " - 非PNG文件应返回null", result == null);
+        } catch (Exception e) {
+            assertCondition(testName + " - 不应抛出异常: " + e.getMessage(), false);
+        } finally {
+            deleteTestFile(txtFile);
+        }
+    }
+
+    /**
+     * 测试传入不存在的文件应返回null
+     */
+    static void testNonExistentFile() {
+        String testName = "testNonExistentFile";
+        try {
+            File nonExistent = new File(System.getProperty("java.io.tmpdir"), "non_existent_file.png");
+            File result = CompressPNG.PNG(nonExistent, CompressPNG.PNGThreshold.THRESHOLD_3);
+            assertCondition(testName + " - 不存在的文件应返回null", result == null);
+        } catch (Exception e) {
+            assertCondition(testName + " - 不应抛出异常: " + e.getMessage(), false);
+        }
+    }
+
+    /**
+     * 测试压缩后的文件仍然是有效的PNG图片
+     */
+    static void testCompressedFileIsValidPNG() {
+        String testName = "testCompressedFileIsValidPNG";
+        File pngFile = null;
+        try {
+            pngFile = createTestPNG("test_valid_png");
+            CompressPNG.PNG(pngFile, CompressPNG.PNGThreshold.THRESHOLD_3);
+
+            BufferedImage compressed = ImageIO.read(pngFile);
+            boolean isValidPNG = compressed != null;
+            assertCondition(testName + " - 压缩后的文件应是有效的PNG图片", isValidPNG);
+
+            if (isValidPNG) {
+                assertCondition(testName + " - 压缩后图片宽度应一致", compressed.getWidth() == 100);
+                assertCondition(testName + " - 压缩后图片高度应一致", compressed.getHeight() == 100);
+            }
+        } catch (Exception e) {
+            assertCondition(testName + " - 不应抛出异常: " + e.getMessage(), false);
+        } finally {
+            deleteTestFile(pngFile);
+        }
+    }
+
+    /**
+     * 测试压缩后文件大小不超过原始文件
+     */
+    static void testCompressedFileSmallerOrEqual() {
+        String testName = "testCompressedFileSmallerOrEqual";
+        File pngFile = null;
+        try {
+            // 创建一个较大的、有压缩空间的测试图片（纯色+渐变）
+            pngFile = createLargeTestPNG("test_compression_ratio", 500, 500);
+            long originalSize = pngFile.length();
+
+            File result = CompressPNG.PNG(pngFile, CompressPNG.PNGThreshold.THRESHOLD_5);
+
+            if (result != null) {
+                long compressedSize = result.length();
+                assertCondition(testName + " - 压缩后文件大小(" + compressedSize + ")应不超过原始大小(" + originalSize + ")",
+                        compressedSize <= originalSize);
+                System.out.println("  原始: " + originalSize + " bytes, THRESHOLD_5压缩后: " + compressedSize + " bytes");
+            } else {
+                assertCondition(testName + " - 压缩不应返回null", false);
+            }
+        } catch (Exception e) {
+            assertCondition(testName + " - 不应抛出异常: " + e.getMessage(), false);
+        } finally {
+            deleteTestFile(pngFile);
+        }
+    }
+
+    // ========== 辅助方法 ==========
+
+    /**
+     * 创建一个100x100的测试PNG图片
+     */
+    static File createTestPNG(String name) throws IOException {
+        File file = File.createTempFile(name, ".png");
+        BufferedImage image = new BufferedImage(100, 100, BufferedImage.TYPE_INT_ARGB);
+        Graphics2D g2d = image.createGraphics();
+        // 绘制渐变图案，使图片有一定的压缩空间
+        for (int y = 0; y < 100; y++) {
+            for (int x = 0; x < 100; x++) {
+                image.setRGB(x, y, new Color(x * 2, y * 2, (x + y)).getRGB());
+            }
+        }
+        g2d.dispose();
+        ImageIO.write(image, "png", file);
+        return file;
+    }
+
+    /**
+     * 创建一个指定尺寸的测试PNG图片（包含更多颜色变化以增加压缩效果差异）
+     */
+    static File createLargeTestPNG(String name, int width, int height) throws IOException {
+        File file = File.createTempFile(name, ".png");
+        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
+        Graphics2D g2d = image.createGraphics();
+        // 绘制大面积纯色区域（压缩率高）
+        g2d.setColor(Color.WHITE);
+        g2d.fillRect(0, 0, width, height);
+        g2d.setColor(Color.RED);
+        g2d.fillRect(0, 0, width / 2, height / 2);
+        g2d.setColor(Color.BLUE);
+        g2d.fillRect(width / 2, 0, width / 2, height / 2);
+        g2d.setColor(Color.GREEN);
+        g2d.fillRect(0, height / 2, width / 2, height / 2);
+        g2d.setColor(Color.YELLOW);
+        g2d.fillRect(width / 2, height / 2, width / 2, height / 2);
+        g2d.dispose();
+        ImageIO.write(image, "png", file);
+        return file;
+    }
+
+    /**
+     * 安全删除测试文件
+     */
+    static void deleteTestFile(File file) {
+        if (file != null && file.exists()) {
+            file.delete();
+        }
+    }
+
+    static void assertCondition(String message, boolean condition) {
+        if (condition) {
+            System.out.println("[PASS] " + message);
+            passed++;
+        } else {
+            System.out.println("[FAIL] " + message);
+            failed++;
+        }
+    }
+}