Node.js对上传图片进行压缩、裁剪、格式转换与尺寸统一的处理指南

npm install sharp

const sharp = require('sharp');
const path = require('path');
const fs = require('fs');

async function compressImage(inputPath) {
  const ext = path.extname(inputPath).toLowerCase();
  const outputPath = inputPath.replace(ext, `-compressed${ext}`);

  let image = sharp(inputPath);

  if (ext === '.jpg' || ext === '.jpeg') {
    image = image.jpeg({ quality: 80 });
  } else if (ext === '.png') {
    image = image.png({ compressionLevel: 8 });
  }

  await image.toFile(outputPath);
  return outputPath;
}

app.post('/upload', upload.single('image'), async (req, res) => {
  try {
    const compressedPath = await compressImage(req.file.path);

    res.json({
      message: '上传并压缩成功',
      original: req.file.path,
      compressed: compressedPath
    });
  } catch (err) {
    res.status(500).json({ error: '图片处理失败' });
  }
});

async function resizeImage(inputPath) {
  const outputPath = inputPath.replace('.', '-resized.');

  await sharp(inputPath)
    .resize(800, 800, {
      fit: 'inside',
      withoutEnlargement: true
    })
    .toFile(outputPath);

  return outputPath;
}

async function cropImage(inputPath) {
  const outputPath = inputPath.replace('.', '-cropped.');

  await sharp(inputPath)
    .resize(300, 300, { fit: 'cover' })
    .toFile(outputPath);

  return outputPath;
}

async function convertToWebP(inputPath) {
  const outputPath = inputPath.replace(/\.\w+$/, '.webp');

  await sharp(inputPath)
    .webp({ quality: 80 })
    .toFile(outputPath);

  return outputPath;
}

async function generateThumbnails(inputPath) {
  const sizes = [200, 400, 800];
  const results = [];

  for (const size of sizes) {
    const outputPath = inputPath.replace('.', `-${size}.`);
    await sharp(inputPath)
      .resize(size, size, { fit: 'inside' })
      .toFile(outputPath);
    results.push(outputPath);
  }

  return results;
}