java - org.apache.derby.client.am.CloseFilterInputStream

Question

Sr，我是 derby 新手，当我尝试测试在数据库中显示 Blob 字段时，显示“org.apache.derby.client.am.CloseFilterInputStream”。

        response.setContentType("image/jpeg");
    ServletOutputStream out = response.getOutputStream();
    for (Images o : IM.getAllImages()) {
        InputStream is = o.getImg();
        byte[] imageBytes = getBytes(is);
        out.write(imageBytes);
        response.setContentLength(imageBytes.length);
        response.getOutputStream().write(imageBytes);
        out.close();
    }

此外，当我尝试此代码时，出现此错误“java.io.IOException:对象已关闭。”。我错过了什么吗？ error

这是将InputStream转换为字节数组的方法

    public static byte[] getBytes(InputStream is) throws IOException {

    int len;
    int size = 1024;
    byte[] buf;

    if (is instanceof ByteArrayInputStream) {
        size = is.available();
        buf = new byte[size];
        len = is.read(buf, 0, size);
    } else {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        buf = new byte[size];
        while ((len = is.read(buf, 0, size)) != -1) {
            bos.write(buf, 0, len);
        }
        buf = bos.toByteArray();
    }
    return buf;
}

我的doGet DisplayImagesController.java

    @Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    ServletOutputStream out = response.getOutputStream();
    response.setContentType("image/jpeg");
    for (Images o : IM.getAllImages()) {
        InputStream is = o.getImg();
        byte[] imageBytes = getBytes(is);
        out.write(imageBytes);
        response.setContentLength(imageBytes.length);
        response.getOutputStream().write(imageBytes);

    }
    out.close();
}

和显示

        <table width="70%" border="1">
        <tr>
            <th>id</th>
            <th>IMG</th>
            <th>IMG Name</th>
            <th>UserID</th>

            <th colspan="2">Action</th>
        </tr>
        <c:forEach items="${imgs}" var="img">
            <tr>
                <td><c:out value="${img.id}"/></td>
                <td><c:out value="${img.imgName}"/></td>
                <td><img src="DisplayImagesController" width="200" height="100"/></td>
                <td><c:out value="${img.userID}"/></td>

            </tr>
        </c:forEach>

    </table>

但是图像不显示

Answer 1

    response.setContentType("image/jpeg");
        ServletOutputStream out = response.getOutputStream();
        for (Images o : IM.getAllImages()) {
            InputStream is = o.getImg();
            byte[] imageBytes = getBytes(is);
            out.write(imageBytes);
            response.setContentLength(imageBytes.length);
            response.getOutputStream().write(imageBytes);

        }
out.close();

我认为 out.close(); 应该位于 for-each 循环之外，因为如果您有多个图像，那么它可能不会创建另一个 out 对象。