java - 使用 java servlet 在浏览器中显示 Pdf

Question

我的应用程序中有 pdf 文件。我需要在浏览器中显示 pdf。我正在将文件作为 fileInputStream 读取，我需要在我的应用程序中的浏览器中显示 pdf。但是我没有pdf路径，我有文件流。

请给我一些建议和例子

---

我使用 ajax 来显示 pdf，我正在使用 call_method() javascript ajax 请求方法来调用 showPdf 操作，在 showpdf 操作中只是将 pdf 文件转换为 ByteArrayOutputStream 并将结果写入输出流。但它显示了下面提到的结果。

JSP 中的结果:

%PDF-1.4 %���� 1 endstream endobj 4 0 obj <>>>/MediaBox[0 0 595 842]>> endobj 1 0 obj <> endobj 3 0 obj <> endobj 5 0 obj <> endobj 6 0 obj <> endobj xref 0 7 0000000000 65535 F 0000000389 00000 N 0000000015 00000 N 0000000477 00000 N 0000000232 00000 N 00000000000000 N 0000000540 00000 N 000000000585 00000 n N 0000000 N337255542542.14254PAR> abrim

请给点建议。

Javascript ajax:

call_method(); <br/>
function call_method(){

    Ext.Ajax.request({
            waitMsg: 'Saving changes...',
            url:'test.action?method=showPdf',
            params : { },       
            failure:function(response,options){

            },
            success:function(response,options){
                $("#pdf_content").show();               
                $("#pdf_content").html(response.responseText);
                $("#pdf_content").show('slow');
            }
    });
}

Java 方法:

public String showPdf() throws IOException {

    getResponse().setContentType("application/pdf");

    getResponse().setHeader("Content-disposition","inline; filename=automatic_start.pdf" );


    ByteArrayOutputStream baos = getByteArrayOutputStream();

    getResponse().setContentLength(baos.size());

    ServletOutputStream sos;

    sos = getResponse().getOutputStream();

    baos.writeTo(sos);

    sos.flush();

    return null;
}


private ByteArrayOutputStream getByteArrayOutputStream() throws IOException {

    String filePath = "/homefolder/";

    String folderPath=filePath+"1122/automatic_start.pdf";

    File file = new File(folderPath);

    FileInputStream fis = new FileInputStream(file);



    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    byte[] buf = new byte[256];
     try {
            for (int readNum; (readNum = fis.read(buf)) != -1;) {
                bos.write(buf, 0, readNum); //no doubt here is 0
                //Writes len bytes from the specified byte array starting at offset off to this byte array output stream.
                System.out.println("read " + readNum + " bytes,");
            }

        } catch (IOException ex) {
            ex.printStackTrace();
        }


    return bos;
}

Answer 1

您必须将您的 InputStream 写入您的响应 OutputStream，如下所示:

• 您的Content-Disposition 必须是内联。
• 您的Content-Type 必须是application/pdf。
• 您的 Content-Length 将是 InputStream 中总数据的长度(以字节为单位)。

设置后，将输入流数据写入响应的输出流。

这种效果的东西:

/* (non-Javadoc)
 * @see org.bfs.bayweb.util.renderer.ServletViewRenderer#render(javax.servlet.ServletRequest, javax.servlet.ServletResponse)
 */
public void render(ServletRequest request, ServletResponse response) throws IOException {
    // TODO Auto-generated method stub
    try {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
        int inputStreamLength = 0;
        int length = 0;
        while ((length = getInputStream().read(buffer)) > 0) {
            inputStreamLength += length;
            baos.write(buffer, 0, length);
        }

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

        if (response instanceof HttpServletResponse) {
            HttpServletResponse httpResponse = (HttpServletResponse) response;
            httpResponse.reset();
            httpResponse.setHeader("Content-Type", getContentType());
            httpResponse.setHeader("Content-Length", String.valueOf(getContentLength()));
            httpResponse.setHeader("Content-Disposition", "\"" + getContentDisposition() + "\"" + ((getFileName() != null && !getFileName().isEmpty()) ? "; filename=\"" + getFileName() + "\"": ""));
        }

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

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

        //clear
        baos = null;
    } finally {
        // TODO Auto-generated catch block
        close(response.getOutputStream());
        close(getInputStream());
    }
}

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