Java HttpServletResponse 多文件下载

在response.getOutputStream()实现文件下载，如果是多个文件可以把压缩为一个zip文件

package com.xu.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.xu.utils.DownloadFile;

/**
 * Servlet implementation class FileDownloadServlet
 */
@WebServlet(name="download",urlPatterns = {"/FileDownloadServlet", "/download"})
public class FileDownloadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public FileDownloadServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doPost(request, response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		if (request.getParameter("op").equalsIgnoreCase("download")) {
			DownloadFile file=new DownloadFile();
			String[] files= {"E:/1.txt","E:/3.txt","E:/2.txt"};
			try {
				file.multFileDownload(response, files, "a.zip");
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}

}

package com.xu.utils;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

@SuppressWarnings(value="all")
public class DownloadFile {
	/**
	 * 1 多文件下载
	 * @param response HttpServletResponse
	 * @param files[] 待下载文件
	 * @param downloadfile 下载文件文件名+文件类型(a.zip)
	 * @throws Exception
	 * @date 2019年3月29日11:31:35
	 */
	public void multFileDownload(HttpServletResponse response,String[] files,String downloadfile) throws Exception {
		response.setContentType("multipart/form-data");//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型   
		response.setHeader("Content-Disposition", "attachment;fileName="+downloadfile);   
		ServletOutputStream out;
		FileInputStream instream = null;
		try {   
			ZipOutputStream zipstream=new ZipOutputStream(response.getOutputStream());			
			for (String file:files) {
				if (!new File(file).exists()) {
					continue;
				}				
				instream=new FileInputStream(file);
				ZipEntry entry = new ZipEntry(file);				
				zipstream.putNextEntry(entry);
				byte[] buffer = new byte[1024];  
				int len = 0;    
				while (len != -1){   
					len = instream.read(buffer);
					zipstream.write(buffer,0,buffer.length);   
				}
				instream.close();
				zipstream.closeEntry();
				zipstream.flush();
			}
			zipstream.finish();
			zipstream.close();
		} catch (IOException e) {   
			new RuntimeException(e.getMessage());   
		}  
	}

	/**
	 * 2 多文件下载
	 * @param response HttpServletResponse
	 * @param files[] 待下载文件
	 * @param downloadfile 下载文件
	 * @param path 待下载文件路径
	 * @param tempfile 待下载临时文件
	 * @throws Exception 
	 * @date 2019年3月29日11:31:35
	 */
	public void multFileDownload(HttpServletResponse response,String[] files,String path,String downloadfile) throws Exception {
		response.setContentType("multipart/form-data");//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型   
		response.setHeader("Content-Disposition", "attachment;fileName="+downloadfile);   
		ServletOutputStream out;
		FileInputStream instream = null;
		try {
			ZipOutputStream zipstream=new ZipOutputStream(response.getOutputStream());
			for (String file:files) {
				if (!new File(path+file).exists()) {
					continue;
				}
				instream=new FileInputStream(path+file);
				ZipEntry entry = new ZipEntry(path+file);
				zipstream.putNextEntry(entry);
				byte[] buffer = new byte[1024];  
				int len = 0;    
				while (len != -1){   
					len = instream.read(buffer);
					zipstream.write(buffer,0,buffer.length);   
				}
				instream.close();
				zipstream.closeEntry();
				zipstream.flush();
			}
			zipstream.finish();
			zipstream.close();
		} catch (IOException e) {   
			new RuntimeException(e.getMessage());   
		}  
	}

	/**
	 * 1 单文件下载
	 * @param response HttpServletResponse
	 * @param filepath 待下载文件路径
	 * @param downloadfile 下载文件
	 * @date 2019年3月29日11:31:35
	 */
	public void singleFileDownload(HttpServletResponse response,String filepath,String downloadfile) {
		response.setContentType("multipart/form-data");//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型   
		response.setHeader("Content-Disposition", "attachment;fileName="+downloadfile);   
		ServletOutputStream out;
		File file = new File(filepath);
		if (!file.exists()) {
			new RuntimeException("文件不存在");
		}
		try {   
			FileInputStream inputStream = new FileInputStream(file);   
			out = response.getOutputStream();   
			byte[] buffer = new byte[1024];  
			int b = 0;    
			while (b != -1){   
				b = inputStream.read(buffer);   
				out.write(buffer,0,b);   
			}
			inputStream.close();   
			out.flush();
			out.close();
		} catch (IOException e) {   
			new RuntimeException(e.getMessage());   
		}  
	}

	/**
	 * 2 单文件下载
	 * @param response HttpServletResponse
	 * @param filepath 待下载文件路径
	 * @param filename 下载文件名称
	 * @param filetype 下载文件类型
	 * @date 2019年3月29日11:31:35
	 */
	public void singleFileDownload(HttpServletResponse response,String filepath,String filename,String filetype) {
		response.setContentType("multipart/form-data");//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型   
		response.setHeader("Content-Disposition", "attachment;fileName="+filename+filetype);   
		ServletOutputStream out;
		File file = new File(filepath);
		if (!file.exists()) {
			new RuntimeException("文件不存在");
		}
		try {   
			FileInputStream inputStream = new FileInputStream(file);   
			out = response.getOutputStream();   
			byte[] buffer = new byte[1024];  
			int b = 0;    
			while (b != -1){   
				b = inputStream.read(buffer);   
				out.write(buffer,0,b);   
			}
			inputStream.close();   
			out.flush();
			out.close();
		} catch (IOException e) {   
			new RuntimeException(e.getMessage());   
		}  
	}

	/**
	 * 1 多文件 压缩成 ZIP
	 * @param files 文件名字
	 * @param path  文件路径
	 * @param loaclfilepath  临时文件全路径
	 * @date 2019年3月29日11:31:35
	 */
	public void toZip(String[] files,String path,String loaclfilepath) throws Exception {
		FileInputStream instream = null;
		ZipOutputStream zipstream=new ZipOutputStream(new FileOutputStream(new File(loaclfilepath)));
		for (String file:files) {
			if (!new File(path+file).exists()) {
				continue;
			}
			instream=new FileInputStream(path+file);
			ZipEntry entry = new ZipEntry(path+file);
			zipstream.putNextEntry(entry);
			byte[] buffer = new byte[1024];  
			int len = 0;    
			while (len != -1){   
				len = instream.read(buffer);
				zipstream.write(buffer,0,buffer.length);   
			}
			zipstream.closeEntry();
			zipstream.flush();
		}
		zipstream.finish();		
		zipstream.close();
	}

	/**
	 * 2 多文件 压缩成 ZIP
	 * @param files 文件名字
	 * @param path  文件路径
	 * @param loaclfilepath  压缩文件全路径
	 * @date 2019年3月29日11:31:35
	 */
	public void toZip(List<String> files,String path,String loaclfilepath) throws Exception {
		FileInputStream instream = null;
		ZipOutputStream zipstream=new ZipOutputStream(new FileOutputStream(new File(loaclfilepath)));
		for (String file:files) {
			if (!new File(path+file).exists()) {
				continue;
			}
			instream=new FileInputStream(path+file);
			ZipEntry entry = new ZipEntry(path+file);
			zipstream.putNextEntry(entry);
			byte[] buffer = new byte[1024];  
			int len = 0;    
			while (len != -1){   
				len = instream.read(buffer);
				zipstream.write(buffer,0,buffer.length);   
			}
			zipstream.closeEntry();
			zipstream.flush();
		}
		zipstream.finish();
		zipstream.close();
	}

}