利用thumbnailator對圖片進行壓縮

使用thumbnailator首先要在mavan裡新增依賴：

    <!-- 圖片縮圖 -->
    <dependency>
      <groupId>net.coobird</groupId>
      <artifactId>thumbnailator</artifactId>
      <version>0.4.8</version>
    </dependency>

按指定比例對圖片進行縮放

//按指定比例對圖片進行縮放
        Thumbnails.of(stream).scale(0.5f,2f).toOutputStream(fileOutputStream);//按比例縮小.
 

public Thumbnails.Builder<T> scale(double var1) {
            return this.scale(var1, var1);
        }

        public Thumbnails.Builder<T> scale(double var1, double var3) {
            this.updateStatus(Thumbnails.Builder.Properties.SCALE, Thumbnails.Builder.Status.ALREADY_SET);
            this.updateStatus(Thumbnails.Builder.Properties.SIZE, Thumbnails.Builder.Status.CANNOT_SET);
            this.updateStatus(Thumbnails.Builder.Properties.KEEP_ASPECT_RATIO, Thumbnails.Builder.Status.CANNOT_SET);
            if (var1 > 0.0D && var3 > 0.0D) {
                if (!Double.isNaN(var1) && !Double.isNaN(var3)) {
                    if (!Double.isInfinite(var1) && !Double.isInfinite(var3)) {
                        this.scaleWidth = var1;
                        this.scaleHeight = var3;
                        return this;
                    } else {
                        throw new IllegalArgumentException("The scaling factor cannot be infinity.");
                    }
                } else {
                    throw new IllegalArgumentException("The scaling factor is not a number.");
                }
            } else {
                throw new IllegalArgumentException("The scaling factor is equal to or less than 0.");
            }
        }