附件下载

package com.fr.web.fun;

import com.fr.base.Utils;
import com.fr.cache.Attachment;
import com.fr.stable.fun.AttachmentDownloader;
import com.fr.cache.AttachmentSource;
import com.fr.general.ComparatorUtils;
import com.fr.stable.fun.impl.AbstractAttachmentDownloader;
import com.fr.web.Browser;
import org.apache.tools.zip.ZipEntry;
import org.apache.tools.zip.ZipOutputStream;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.OutputStream;

/**
 * @author : richie
 * @since : 8.0
 * 默认的下载处理，反射加载
 */
public class DefaultAttachmentDownloader extends AbstractAttachmentDownloader {
    public static DefaultAttachmentDownloader instance = null;

    public synchronized static DefaultAttachmentDownloader  getInstance() {
        if (instance == null) {
            instance = new DefaultAttachmentDownloader();
        }
        return instance;
    }

    private DefaultAttachmentDownloader() {

    }

    /**
     * 生成下载附件的JavaScript脚本
     * @param downloadURL 附件的下载地址
     * @return 下载附件的JavaScript脚本
     */
    public String createDownloadScript(String downloadURL) {
        return "window.open('" + downloadURL + "')";
    }

    /**
     * 下载附件，根据不同的下载方式可以有不同的实现
     * @param req HTTP请求
     * @param res HTTP响应
     * @param id 附件id
     * @param idArr 附件id组成的数组
     * @throws Exception 如果下载附件异常则抛出此异常
     */
    public void download(HttpServletRequest req, HttpServletResponse res, String id, String[] idArr) throws Exception {
        if(idArr.length == 1) {
            downloadFile(req, res, id);
        } else if (idArr.length > 1) {
            downloadFileArr(req, res, idArr);
        }
    }

    private void downloadFile(HttpServletRequest req, HttpServletResponse res, String id) throws Exception{
        Attachment attach = AttachmentSource.getAttachment(id);
        if (attach != null) {
            byte[] bytes = attach.getBytes();

            res.setHeader("Pragma", "No-cache");
            res.setHeader("Cache-Control", "max-age=180");

            String reportName = attach.getFilename();
            reportName = reportName.trim();

            res.setHeader("Content-disposition", "attachment; filename=" + Browser.resolve(req).getEncodedFileName4Download(reportName));

            reportName = reportName.toLowerCase();
            if (reportName.endsWith(".pdf")) {
                res.setContentType("application/pdf");
                res.setHeader("extension", "pdf");
            } else if (reportName.endsWith(".xls")) {
                res.setContentType("application/x-excel");
                res.setHeader("extension", "xls");
            } else if (reportName.endsWith(".doc")) {
                res.setContentType("application/msword");
                res.setHeader("extension", "doc");
            } else if (reportName.endsWith(".svg")) {
                res.setContentType("image/svg+xml");
                res.setHeader("extension", "svg");
            } else if (reportName.endsWith(".csv")) {
                res.setContentType("application/octet-stream");
                res.setHeader("extension", "csv");
            } else if (reportName.endsWith(".txt")){
                res.setContentType("application/octet-stream");
                res.setHeader("extension", "txt");
            } else {
                res.setContentType("application/x-msdownload");
            }

            OutputStream out = res.getOutputStream();
            out.write(bytes);
            out.flush();
            out.close();
        }
    }

    private void downloadFileArr(HttpServletRequest req, HttpServletResponse res, String[] id_array) throws Exception{
        res.setHeader("Pragma", "No-cache");
        res.setHeader("Cache-Control", "max-age=180");
        res.setHeader("Content-disposition", "attachment; filename=" + "total.zip");
        res.setContentType("application/x-msdownload");
        OutputStream res_out = res.getOutputStream();
        ZipOutputStream out = new ZipOutputStream(res_out);
        out.setEncoding("GBK");
        for(int i = 0; i < id_array.length; i ++) {
            String id = id_array[i];
            Attachment attach = AttachmentSource.getAttachment(id);
            // shoc:处理文件重名问题，否则会导致zip文件打不开
            String newFileName = attach.getFilename();
            int duplicateNum = 0;
            boolean plusNameType = false;
            String dupPreAttName = "";
            for(int j = 0; j < i; j++){
                Attachment attachPre = AttachmentSource.getAttachment(id_array[j]);
                String preAttName = attachPre.getFilename();
                if(ComparatorUtils.equals(newFileName, preAttName)){
                    duplicateNum ++;
                    dupPreAttName = preAttName;
                    plusNameType = preAttName.indexOf('(') != -1 && preAttName.indexOf(')') != -1
                            && preAttName.lastIndexOf('(') < preAttName.lastIndexOf(')')
                            && Utils.isNumeric(preAttName.substring(preAttName.lastIndexOf('('), preAttName.lastIndexOf(')')));
                }
            }
            if(duplicateNum > 0){
                if(plusNameType){
                    newFileName = dupPreAttName.substring(0,dupPreAttName.lastIndexOf('(') + 1) +
                            (Integer.parseInt(dupPreAttName.substring(dupPreAttName.lastIndexOf('(') + 1, dupPreAttName.lastIndexOf(')')),10) + duplicateNum) +
                            dupPreAttName.substring(dupPreAttName.lastIndexOf(')'),dupPreAttName.length());
                }
                else{
                    newFileName = dupPreAttName.substring(0,dupPreAttName.lastIndexOf('.')) + "("+duplicateNum+")" +
                            dupPreAttName.substring(dupPreAttName.lastIndexOf('.'), dupPreAttName.length());
                }
            }
            attach.setFilename(newFileName);

            if (attach != null) {
                byte[] bytes = attach.getBytes();
                out.putNextEntry(new ZipEntry(attach.getFilename()));
                out.write(bytes);
            }
        }
        out.flush();
        out.close();
    }
}