使用pdf.js实现前端页面预览pdf文档，解决了跨域请求

pdf.js主要包含两个库文件，一个pdf.js和一个pdf.worker.js，，一个负责API解析，一个负责核心解析

官网地址：http://mozilla.github.io/pdf.js/

下载pdf.js插件

解压后有 web 和 build 两个文件夹如图

运行示例 将解压后的文件直接仍到项目路径下

　　访问 ip:port/文件夹名称/web/viewer.html
　　显示的是 web 文件夹下的compressed.tracemonkey-pldi-09.pdf

修改默认打开PDF

我们只用修改viewer.js文件中的pdf路径参数即可：
var DEFAULT_URL = ‘09.pdf’;
如果pdf文件与viewer.html不在一层目录中，改成相对路径即可：
var DEFAULT_URL = ’ ../doc/ 09.pdf’;

viewer.html可以通过页面参数传值的方式加载pdf文件，比如我们想打开09.pdf文件的话，只需要这样：
先把viewer.js中的参数修改为空：
var DEFAULT_URL = ”;
然后把url改写为参数传值：
http://127.0.0.1:8080/pdfjs/web/viewer.html?file=09.pdf
如果pdf文件与viewer.html不在一层目录中，改成相对路径即可：
http://127.0.0.1:8080/pdfjs/web/viewer.html?file=../doc/09.pdf
参考地址https://github.com/mozilla/pdf.js/wiki/Frequently-Asked-Questions#file

获取服务器上的PDF文件

通过页面参数传值的方式加载pdf文件
file的值需要URLEncode编码指向服务器端
例如：
http://xxxxx.com:89/demo/fileupdownfud=1&rid=4&isweb=1&iswebshow=1&dbid=01&filepath=fj_ob_item/Y201809/11.pdf
URLEncode编码：为
http%3A%2F%2Fxxxx.com%3A89%2Fdemo%2Ffileupdown%3Ffud%3D1%26rid%3D4%26isweb%3D1%26iswebshow%3D1%26dbid%3D01%26filepath%3Dfj_ob_item%2FY201809%2F11.pdf
访问地址为：
http://127.0.0.1:8080/pdfjs/web/viewer.html?file=http%3A%2F%2Fxxxx.com%3A89%2Fdemo%2Ffileupdown%3Ffud%3D1%26rid%3D4%26isweb%3D1%26iswebshow%3D1%26dbid%3D01%26filepath%3Dfj_ob_item%2FY201809%2F11.pdf
————————————————
版权声明：本文为CSDN博主「三年二班Pit」的原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/l_ai_yi/article/details/82388497

PDF.js默认好像是不能跨域请求

将viewer.js 中的错误提示注释掉即可

try {
var viewerOrigin = new URL(window.location.href).origin || 'null';
if (HOSTED_VIEWER_ORIGINS.indexOf(viewerOrigin) >= 0) {
return;
}
var fileOrigin = new URL(file, window.location.href).origin;
//跨域请求错误提示
//if (fileOrigin !== viewerOrigin) {
//throw new Error('file origin does not match viewer\'s');
//}
} catch (ex) {
var message = ex && ex.message;
PDFViewerApplication.l10n.get('loading_error', null, 'An error occurred while loading the PDF.').then(function (loadingErrorMessage) {
PDFViewerApplication.error(loadingErrorMessage, { message: message });
});
throw ex;
}

服务端代码

//跨域请求
String s0 = "C:11.pdf"
response.setHeader("Access-Control-Allow-Origin", "*"); 
File file = new File(s0);
response.setContentLength((int) file.length());
response.setHeader( "Content-Disposition", "attachment;filename=" + URLEncoder.encode(file.getName(), "UTF-8"));// 设置在下载框默认显示的文件名
response.setContentType("application/octet-stream");// 指明response的返回对象是文件流
// 读出文件到response
// 这里是先需要把要把文件内容先读到缓冲区
// 再把缓冲区的内容写到response的输出流供用户下载
FileInputStream fileInputStream = new FileInputStream(file);
BufferedInputStream bufferedInputStream = new BufferedInputStream(fileInputStream);
OutputStream outputStream = response.getOutputStream();
byte buffer[] = new byte[1024];
int len = 0; 
while ((len = bufferedInputStream.read(buffer)) > 0) {
    outputStream.write(buffer, 0, len);
}
// 人走带门
bufferedInputStream.close();
outputStream.flush();
outputStream.close();

案例二：

@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>testPdf</title>
    <script src="~/Scripts/jquery-1.8.2.min.js"></script>
    <script src="~/pdfjs2/build/pdf.js"></script>
    <style type="text/css">
        .lightbox {
            position: fixed;
            top: 0px;
            left: 0px;
            height: 100%;
            width: 100%;
            z-index: 7;
            opacity: 0.3;
            display: block;
            background-color: rgb(0, 0, 0);
            display: none;
        }

        .pop, iframe {
            position: absolute;
            left: 50%;
            top: 0;
            width: 893px;
            height: 100%;
            margin-left: -446.5px;
            z-index: 9;
        }
    </style>

    <script type="text/javascript">
        function showPdf(isShow) {
            var state = "";
            if (isShow) {
                state = "block";
            } else {
                state = "none";
            }
            var pop = document.getElementById("pop");
            pop.style.display = state;
            var lightbox = document.getElementById("lightbox");
            lightbox.style.display = state;
        }
        function close() {
            showPdf(false);
        }
        function pd(dd) {
            $("#" + dd)[0].contentWindow.print();
        }
    </script>
</head>
<body>
    <ul>
        <li><a href="../pdfjs2/web/viewer.html?file=../DownFile/430000447746159F19030038催缴通知书.pdf" target="pdfContainer" onclick="showPdf(true)">0001_pdf</a></li>
        <li><a href="../pdfjs2/web/viewer.html?name=../DownFile/430000447746159F19030038事前告知书.pdf" target="pdfContainer" onclick="showPdf(true)">0002_pdf</a></li>
    </ul>
    <div class="lightbox" id="lightbox"></div>
    <div id="pop" class="pop" style="display: none;">
        <a href="javascript:close()" style="
            position: absolute;
            right: -90px;
            display: inline-block;
            width: 80px;
            height: 30px;
        " id="close">关闭</a>
        @*<a href="#" onclick="pd('pdfContainer')" style="
           position:absolute;
           right :-90px;
           display :inline-block;
           width :80px;
           height: 30px;">打印</a>*@

        <iframe src="" frameborder="0" id="pdfContainer" name="pdfContainer"></iframe>

    </div>
</body>
</html>

案例三：

直接使用iframe

赋值显示：

  param = "chId=" + $("#chId").val() + "&unitId=" + unId;
    pdfurl = "/OverrunPunishment/ApprovedBookData?" + param;
    //pdfurl为文件流，使用encodeURIComponent()函数可把字符串作为 URI 组件进行编码。
    $("#pdf_page_1").attr('src', "../pdfjs/web/viewer.html?file=" + encodeURIComponent(pdfurl) + "");

后台将pdf文档转文件流方法：

 public string ApprovedBookData(string chId, string unitId)
        {
            InstrumentInfo instr = new InstrumentInfo();
            string name = "";
            FileStream fs = null;
            if (Request.Cookies["LoginValue"] == null) Response.Redirect("../Login/LoginPage");
            try
            {
                instr = ApprovedDataUtil.ExportPdfText(chId, unitId);
                string path = instr.fileName.Replace("\\", "/");
                fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);//读取生成的pdf文件
                byte[] buffer = new byte[fs.Length];
                fs.Position = 0;
                fs.Read(buffer, 0, (int)fs.Length);
                Response.Clear();
                Response.AddHeader("Content-Length", fs.Length.ToString());
                Response.ContentType = "application/pdf";
                Response.AddHeader("Content-Disposition", "inline;FileName=抄告文书.pdf");

                Response.BinaryWrite(buffer);
                Response.OutputStream.Flush();
                Response.OutputStream.Close();
                name = fs.Name;
                fs.Close();
            }
            catch (Exception ex)
            {
                CSysCfg.WriteLog("获取文书异常：" + ex.Message);
            }
            return name;
        }

使用pdf.js实现前端页面预览pdf文档，解决了跨域请求

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