java批量下载生成zip压缩包的思路详解

//一、本地先生成zip文件
//要批量下载的文件id数组
String[] ids = new String[] {"1","2"}
byte[] buffer = new byte[1024];
//创建zip
String localZipFile = "D:/temp/test.zip" ;
if(!new File(localZipFile).exists()){
 new File(localZipFile).mkdirs();
}
ZipOutputStream out = new ZipOutputStream(new FileOutputStream(localZipFile));
//依次获取批量下载的文件
for(int i =0; i<ids.length;i++){
    //设置压缩包内的文件的字符编码，不然文件名可能变成乱码(用户为windows系统)
	out.setEncoding("GBK");
    //从数据库中获取文件的路径和文件名,并放入zip文件中
    String fileId = ids[i];
    Map<String,Object> map =exportManagerService.getFjInfo(fileId);
    FileInputStream inStream = new FileInputStream(new File(map.get("path").toString()));
    out.putNextEntry(new ZipEntry(map.get("name").toString()));
    int len;
    //读入需要下载的文件的内容，打包到zip文件  
	while ((len = inStream.read(buffer)) > 0) {  
			out.write(buffer, 0, len);  
	}  
	out.closeEntry();  
	inStream.close();  					
}
out.close();
this.downFile(response,"D:/temp","test.zip");
//二、将本地zip返回给前端
private void downFile(HttpServletResponse response,String FilePath, String str) {
		Map m = new HashMap();
		try {
			String path = FilePath +"/"+ str;
			File file = new File(path);
			if (file.exists()) {
				InputStream ins = new FileInputStream(path);
				BufferedInputStream bins = new BufferedInputStream(ins);// 放到缓冲流里面
				OutputStream outs = response.getOutputStream();// 获取文件输出IO流
				BufferedOutputStream bouts = new BufferedOutputStream(outs);
				response.addHeader("content-disposition", "attachment;filename="
						+ java.net.URLEncoder.encode(str, "UTF-8"));
				int bytesRead = 0;
				byte[] buffer = new byte[8192];
				// 开始向网络传输文件流
				while ((bytesRead = bins.read(buffer, 0, 8192)) != -1) {
					bouts.write(buffer, 0, bytesRead);
				}
				bouts.flush();// 这里一定要调用flush()方法
				ins.close();
				bins.close();
				outs.close();
				bouts.close();
			}
		} catch (IOException e) {
			m.put("code", "-1");
			m.put("text", "附件下载出错：" + e.getMessage());
			e.printStackTrace();
		}
	}

import lombok.Data;
import java.io.InputStream;
@Data
public class DownLoadUrlStream {
    //文件地址 比如/123/234/1.txt
    private String url;
    //文件流
    private InputStream stream;
}

import com.valid.util.view.DownLoadUrlStream;
import com.valid.util.view.DownLoadUrlString;
import org.springframework.stereotype.Component;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
@Component
public class DownloadUtils {
	/**
     * 
     * @param downLoadUrlStreams 文件信息 地址 流
     * @param zipName 压缩包名称
     * @param response
     * @throws IOException
     */
    public void downloadFolder(List<DownLoadUrlStream> downLoadUrlStreams,String zipName, HttpServletResponse response) throws IOException {
        response.setContentType("application/octet-stream");
        response.setHeader("Content-Disposition", "attachment; filename=\"" + URLEncoder.encode(zipName,"UTF-8")  + "\"");
        Set<String> paths = new HashSet<>(); // 用于记录已经添加到压缩文件中的目录
        try {
            ZipOutputStream zipOut = new ZipOutputStream(response.getOutputStream());
            for (DownLoadUrlStream file : downLoadUrlStreams) {
                String virtualPath = file.getUrl().substring(1);
                String[] pathArray = virtualPath.split("/");
                //构建文件的目录结构
                StringBuilder sb = new StringBuilder();
                for (int i = 0; i < pathArray.length - 1; i++) {
                    sb.append(pathArray[i]).append("/");
                    String folderPath = sb.toString();
                    if (!paths.contains(folderPath)) { // 如果该目录还未被添加到压缩文件中，则添加目录
                        ZipEntry folderEntry = new ZipEntry(folderPath);
                        zipOut.putNextEntry(folderEntry);
                        zipOut.closeEntry();
                        paths.add(folderPath); // 将新添加的目录记录到集合中
                    }
                }
                ZipEntry entry = new ZipEntry(virtualPath);
                zipOut.putNextEntry(entry);
                //将文件流写入文件中
                InputStream inputStream =  file.getStream();
                byte[] buffer = new byte[1024];
                int len;
                while ((len = inputStream.read(buffer)) > 0) {
                    zipOut.write(buffer, 0, len);
                }
                inputStream.close();
                zipOut.closeEntry();
            }
            zipOut.flush();
            zipOut.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
  }