限制读取字节数的Java InputStream包装器

import java.io.IOException;
import java.io.InputStream;

public class LimitedInputStream extends InputStream {
    private final InputStream inputStream;
    private final long limit;
    private long bytesRead;

    public LimitedInputStream(InputStream inputStream, long limit) {
        this.inputStream = inputStream;
        this.limit = limit;
        this.bytesRead = 0;
    }

    @Override
    public int read() throws IOException {
        if (bytesRead >= limit) {
            return -1; // 已达到限制字节数，返回-1表示结束
        }
        int data = inputStream.read();
        if (data != -1) {
            bytesRead++;
        }
        return data;
    }

    @Override
    public int read(byte[] b, int off, int len) throws IOException {
        if (bytesRead >= limit) {
            return -1; // 已达到限制字节数，返回-1表示结束
        }
        int bytesToRead = (int) Math.min(len, limit - bytesRead);
        int bytesRead = inputStream.read(b, off, bytesToRead);
        if (bytesRead != -1) {
            this.bytesRead += bytesRead;
        }
        return bytesRead;
    }

    @Override
    public void close() throws IOException {
        inputStream.close();
    }
}