java实现通过url实现浏览器下载pdf文件

// 下载pdf文件工具类
public static void toDownload(HttpServletRequest request, HttpServletResponse response, Map<String, Object> map)  {
    
        ServletOutputStream out = null;
        InputStream inputStream = null;

        try {
    
            //文件名
            String pdfName = map.get("pdfName").toString();
            //路径
            String path = map.get("PdfUrl").toString();
            // 获取外部文件流
            logger.info("下载中------invPdfUrl=" +path);
            URL url = new URL(path);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setConnectTimeout(3 * 1000);
            //防止屏蔽程序抓取而返回403错误
            conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
            inputStream = conn.getInputStream();
            /**
             * 输出文件到浏览器
             */
            int len = 0;
            // 输出 下载的响应头，如果下载的文件是中文名，文件名需要经过url编码
            response.setContentType("text/html;charset=utf-8");
            response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(pdfName, "UTF-8"));
            response.setHeader("Cache-Control", "no-cache");
            out = response.getOutputStream();
            byte[] buffer = new byte[1024];
            while ((len = inputStream.read(buffer)) > 0) {
    
                out.write(buffer, 0, len);
            }
            out.flush();
            logger.info("pdf文件下载完成.....");
        } catch (Exception e) {
    

            logger.error("pdf文件下载异常,e = {}", e);
            e.printStackTrace();
        } finally {
    
            if (inputStream != null) {
    
                try {
    
                    inputStream.close();
                } catch (Exception e) {
    
                }
            }
            if (out != null) {
    
                try {
    
                    out.close();
                } catch (Exception e) {
    
                }
            }
        }
    }

jsp页面

 //
    function toDownload(invPdfUrl){
    
        window.location.href = "/toDownload?invPdfUrl="+invPdfUrl;

    }

本地下载

package com.cellstrain.icell.util;

import java.io.*;
import java.net.*;

public class DownloadPdf {
    

    /**
     * 从网络Url中下载文件
     * @param urlStr
     * @param fileName
     * @param savePath
     * @throws IOException
     */
    public static void  downLoadByUrl(String urlStr,String fileName,String savePath) throws IOException{
    
        URL url = new URL(urlStr);
        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        //设置超时间为3秒
        conn.setConnectTimeout(5*1000);
        //防止屏蔽程序抓取而返回403错误
        conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
        //得到输入流
        InputStream inputStream = conn.getInputStream();
        //获取自己数组
        byte[] getData = readInputStream(inputStream);
        //文件保存位置
        File saveDir = new File(savePath);
        if(!saveDir.exists()){
    
            saveDir.mkdir();
        }
        File file = new File(saveDir+File.separator+fileName);
        FileOutputStream fos = new FileOutputStream(file);
        fos.write(getData);
        if(fos!=null){
    
            fos.close();
        }
        if(inputStream!=null){
    
            inputStream.close();
        }
        System.out.println("info:"+url+" download success");

    }


    /**
     * 从输入流中获取字节数组
     * @param inputStream
     * @return
     * @throws IOException
     */
    public static  byte[] readInputStream(InputStream inputStream) throws IOException {
    
        byte[] buffer = new byte[1024];
        int len = 0;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        while((len = inputStream.read(buffer)) != -1) {
    
            bos.write(buffer, 0, len);
        }
        bos.close();
        return bos.toByteArray();
    }

    public static void main(String[] args) {
    
        try{
    
            downLoadByUrl("http://218.2.192.22:9000/aisino_cms/testpdf//1503002010206301/2020/06/11/1/INV202006111124446001_159184920735.pdf","发票.pdf","E:/upload/protocol");
        }catch (Exception e) {
    
            // TODO: handle exception
        }
    }
}