java实现文件打包压缩输出到浏览器下载

下面是Java实现文件打包压缩输出到浏览器下载的详细攻略。

一、引入相关依赖

我们需要使用Java自带的ZipOutputStream类和ServletOutputStream类来实现文件压缩和下载功能。

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

二、实现文件压缩

我们需要将要下载的文件打包并压缩，在下载时再进行解压缩。

示例代码：

public String createZipFile(List<String> fileList, String zipFilePath) {

    byte[] buffer = new byte[1024];
    try {
        FileOutputStream fos = new FileOutputStream(zipFilePath);
        ZipOutputStream zos = new ZipOutputStream(fos);

        for (String file : fileList) {
            ZipEntry ze = new ZipEntry(new File(file).getName());
            zos.putNextEntry(ze);

            FileInputStream in = new FileInputStream(file);

            int len;
            while ((len = in.read(buffer)) > 0) {
                zos.write(buffer, 0, len);
            }

            in.close();
        }

        zos.closeEntry();
        zos.close();
        fos.close();
        return "success";
    } catch (IOException ex) {
        ex.printStackTrace();
    }
    return "fail";
}

三、实现文件下载

在Servlet的doGet或doPost方法中，读取压缩文件并输出到浏览器中供用户下载。

示例代码：

public class DownloadServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {

        //设置文件路径，此处以/Users/john/Downloads/zipFile.zip为例
        String filePath = "/Users/john/Downloads/zipFile.zip";
        File downloadFile = new File(filePath);
        FileInputStream inStream = new FileInputStream(downloadFile);

        //设置下载的文件类型为zip
        response.setContentType("application/zip");
        //设置文件名，此处以zipFile.zip为例
        response.setHeader("Content-Disposition", "attachment; filename=zipFile.zip");
        //获取输出流
        ServletOutputStream outputStream = response.getOutputStream();
        //创建缓冲区
        byte[] buffer = new byte[1024];
        int bytesRead = -1;
        //将文件写入输出流
        while ((bytesRead = inStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }
        inStream.close();
        outputStream.flush();
        outputStream.close();      
    }
}

以上就是Java实现文件打包压缩输出到浏览器下载的完整攻略。