java11下载网络文件

    /**
     * 把网络文件转换为ByteArrayInputStream
     */
    public static ByteArrayInputStream networkFileToInputStream(String imageUrl) {

        InputStream inputStream = null;
        ByteArrayOutputStream byteArrayOutputStream = null;
        ByteArrayInputStream byteArrayInputStream = null;
        try {
            //1. 将在线图片地址转换为URL对象
            URL url = new URL(imageUrl);
            // 打开URL连接
            URLConnection connection = url.openConnection();
            // 转换为HttpURLConnection对象
            HttpURLConnection httpUrlConnection = (HttpURLConnection) connection;
            // 获取输入流
            inputStream = httpUrlConnection.getInputStream();
            //2. 读取输入流中的数据，并保存到字节数组中
            byteArrayOutputStream = new ByteArrayOutputStream();
            byte[] buffer = new byte[10240];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                byteArrayOutputStream.write(buffer, 0, bytesRead);
            }
            inputStream.close();
            byteArrayOutputStream.close();
            //3. ByteArrayInputStream对象，将字节数组传递给它
            byte[] bytes = byteArrayOutputStream.toByteArray();
            byteArrayInputStream = new ByteArrayInputStream(bytes);

            return byteArrayInputStream;
        } catch (IOException ex) {
            throw new ServiceException("网络文件转换失效");
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    log.error("网络文件转换失效");
                }
            }
            if (byteArrayOutputStream != null) {
                try {
                    byteArrayOutputStream.close();
                } catch (IOException e) {
                    log.error("网络文件转换失效");
                }
            }
            if (byteArrayInputStream != null) {
                try {
                    byteArrayInputStream.close();
                } catch (IOException e) {
                    log.error("网络文件转换失效");
                }
            }
        }
    }

    /**
     * 网络文件转换为ByteArrayInputStream
     * 来自AI豆包
     */
    public static ByteArrayInputStream networkFileToInputStreamAi(String imageUrl) {
        try (ReadableByteChannel channel = openChannel(imageUrl)) {
            ByteBuffer byteBuffer = ByteBuffer.allocate(10240);
            while (channel.read(byteBuffer)!= -1) {
                // 如果缓冲区已满，进行翻转以准备读取或写入操作
                if (byteBuffer.position() == byteBuffer.limit()) {
                    byteBuffer.flip();
                    // 扩展缓冲区以容纳更多数据
                    ByteBuffer newByteBuffer = ByteBuffer.allocate(byteBuffer.capacity() * 2);
                    byteBuffer.flip();
                    newByteBuffer.put(byteBuffer);
                    byteBuffer = newByteBuffer;
                }
            }
            // 切换到读模式
            byteBuffer.flip();

            return new ByteArrayInputStream(byteBuffer.array());
        } catch (IOException ex) {
            throw new RuntimeException("网络文件转换失效");
        }
    }

    /**
     * 打开网络连接并获取可读的字节通道
     */
    private static ReadableByteChannel openChannel(String imageUrl) throws IOException {
        URL url = new URL(imageUrl);
        URLConnection connection = url.openConnection();
        InputStream inputStream = connection.getInputStream();
        return Channels.newChannel(inputStream);
    }