java 如何使用 Servlet 和 JSP 显示 PDF 文档？

How to Display a PDF document with a Servlet and JSP?

提问by Siya Sosibo

I looking to display a PDF document from a database to a browser, I wish the browser to open it but it's also ok if its prompt for it to be download. I know this question has been asked here and other forums but I'm still not winning with this task.

我希望将 PDF 文档从数据库显示到浏览器，我希望浏览器打开它，但如果它提示下载它也可以。我知道这里和其他论坛上有人问过这个问题，但我仍然没有赢得这项任务。

I have looked at these: JSP n ServletsDisplay PDF via JSP n Servlet tutorial

我看过这些： JSP n Servlets Display PDF via JSP n Servlet tutorial

My current code.

我当前的代码。

OBJ/Entity:``

对象/实体：``

 public class Attach
   {
    private String filename = null;
    private InputStream attach = null;
    private int ContentLength = 0;

    public String getFilename() {

        return filename;
    }
    public void setFilename(String filename) {

        this.filename = filename;
    }
    public InputStream getAttach() {

        return attach;
    }
    public void setAttach(InputStream attach) {

        this.attach = attach;
    }

    public int getContentLength() {

        return ContentLength;
    }
    public void setContentLength(int contentLength) {

        ContentLength = contentLength;
    }

    public Attach() {

    }

    public Attach(String filename, InputStream attach) {
        this.attach = attach;
        this.filename = filename;
    }


    }

Method to retrieve PDF from DB:

从数据库检索PDF的方法：

public Attach getPDFData(String filename) {

    try {
        pstmt = conn.prepareStatement("SELECT * FROM FUNC_AREA WHERE FILE_NME = ?");
        pstmt.setString(1, filename);
        rs = pstmt.executeQuery();
        if (rs.next()) {
            newattach.setFilename(rs.getString(3));
            newattach.setAttach(rs.getBinaryStream(5));
        }

    } catch (SQLException e) {
        e.printStackTrace();
    }
    return newattach;
}

My Servlet:

我的小服务程序：

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        showAttach(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        showAttach(request, response);
    }

    public void showAttach(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         RepoOperations repops = new RepoOperations();
        Attach newattachobj = repops.getPDFData("bond.pdf");

        try {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
            int inputStreamLength = 0;
            int length = 0;
            while ((length = newattachobj.getAttach().read(buffer)) > 0) {
                inputStreamLength += length;
                baos.write(buffer, 0, length);
            }

            if (inputStreamLength > newattachobj.getContentLength()) {
                newattachobj.setContentLength(inputStreamLength);
            }

            if (response instanceof HttpServletResponse) {
                HttpServletResponse httpResponse = (HttpServletResponse) response;
                httpResponse.reset();
                httpResponse.setHeader("Content-Type", "application/pdf");
                httpResponse.setHeader("Content-Length", String.valueOf(newattachobj.getContentLength()));
                httpResponse.setHeader("Content-Disposition", "inline; filename=\"" + newattachobj.getFilename() + "\"");
            }

            response.getOutputStream().write(baos.toByteArray(), 0, (int)newattachobj.getContentLength());

            //finally
            response.getOutputStream().flush();

            //clear
            baos = null;

            System.out.println(newattachobj.getFilename());
        } finally {
            // TODO Auto-generated catch block
            close(response.getOutputStream());
            close(newattachobj.getAttach());
        }

    }

    private void close(Closeable resource) throws IOException {
        if (resource != null) {
            resource.close();
        }
    }

JSP:

JSP：

 <form action="ShowAttach">
    <a href="ShowAttach">click here</a>
    <br/>
    <input type="submit" value="submit" id="submit">
    </form>

I'm looking to have a Hyperlink on the JSP page to open the PDF document.Thank You

我希望在 JSP 页面上有一个超链接来打开 PDF 文档。谢谢

The problem is that when I click the button on the JSP page, it gives me a 404 error.

问题是当我点击 JSP 页面上的按钮时，它给了我 404 错误。

采纳答案by Siya Sosibo

Thanks everyone. I managed to solve the issue. My anchor wasn't finding the servlet in the directory. This was the fix below

感谢大家。我设法解决了这个问题。我的锚没有在目录中找到 servlet。这是下面的修复

Before:

前：

<a href="ShowAttach">Open</a>

After:

后：

<a href="../ShowAttach">Open</a>

Thanks.

谢谢。