java 读取本地文件到ByteArrayOutputStream

为了将本地文件读取到ByteArrayOutputStream中，你可以使用FileInputStream来读取文件的字节数据，并将其写入到ByteArrayOutputStream中。下面是一个示例代码：

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.IOException;

public class FileToByteArray {
    public static void main(String[] args) {
        String filePath = "path/to/file.txt";
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

        try (FileInputStream inputStream = new FileInputStream(filePath)) {
            byte[] buffer = new byte[1024];
            int length;
            while ((length = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, length);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

        byte[] data = outputStream.toByteArray();        System.out.println("读取到的字节数组长度：" + data.length);
        System.out.println("读取到的字节数组内容：" + Arrays.toString(data));
    }
}