What you see on paper is ultimately shallow, but you know you have to do it! Today the blogger shared about javaweb response (response) download
The following is my Demo:
I will stick to the main part of the page Code
<a href = "${pageContext.request.contextPath }/user/courseTab">模板下载</a>
Of course, everyone uses frameworks in current projects, here I use (SSM) , ok, paste the code
@Controller
@RequestMapping("/user")
public class UploadController {
@RequestMapping(value="/courseTab",method=RequestMethod.GET)
public void courseTab(HttpServletResponse response,HttpServletRequest request) throws IOException{
String path = request.getSession().getServletContext().getRealPath("/courseTab/课表上传模板.xls");
DownUtil.downMb(response, path, "课表模板"+DateFormat.formatSimple(new Date()));
}
}The DownUtil tool class I use here is written by myself, I will paste it into the article
package org.cxxy.base.cxsc.util;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import javax.servlet.http.HttpServletResponse;
/**
* @Title: DownUtil.java
* @Package org.cxxy.base.cxsc.util
* @Description:文件下载工具类
* @author ChoviWu
* @date 2017年6月18日 下午2:44:17
* @version V1.0
*/
public class DownUtil {
/**
*
* @Description:
* @param @param response
* @param @param url 文件在数据库的路径
* @param @param base 文件存放的基础路径
* @param @param folderPath 上传所在的文件夹
* @param @return
* @param @throws IOException
* @return int
* @throws
*/
@SuppressWarnings("unused")
public static int downFile(HttpServletResponse response, String url,
Integer down, String base, String folderPath) throws IOException {
// 文件的名称
String fileName = url.split("/")[1];
System.out.println(fileName);
// 文件的后缀
String last = url.substring(url.lastIndexOf(".") + 1);
System.out.println(last);
// 文件路径
String downFilePath = base + folderPath + fileName;
Long fileLength = new File(downFilePath).length();// 文件的长度
if (fileLength != 0) {
response.reset();
response.setContentType("application/octet-stream;charset=utf-8"); // 改成输出excel文件
try {
response.setHeader(
"Content-disposition",
"attachment; filename="
+ new String(fileName.getBytes("utf-8"),
"ISO8859-1"));
response.setHeader("Content-Length", String.valueOf(fileLength));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
BufferedInputStream bis = null;
BufferedOutputStream bos = null;
FileInputStream fis = null;
try {
fis = new FileInputStream(downFilePath);
bis = new BufferedInputStream(fis);
// 输出流
bos = new BufferedOutputStream(response.getOutputStream());
byte[] buff = new byte[2048];
int bytesread;
// 写文件
while (-1 != (bytesread = bis.read(buff, 0, buff.length))) {
bos.write(buff, 0, bytesread);
}
// 跳转的路径
fis.close();
bis.close();
bos.close();
} catch (FileNotFoundException e) {
System.out.println("File is Not Exsist!");
}
} else {
// 抛异常
response.getWriter()
.write("<script charset='utf-8' type='text/javascript'>alert('该资源不存在！');history.go(-1);</script>");
return down;
}
down++;
return down;
}
/**
*
* @Description: 下载的模板
* @param @param response
* @param @param path 路径名
* @param @param name 模板名称
* @param @throws IOException
* @return void
* @throws
*/
@SuppressWarnings("unused")
public static void downMb(HttpServletResponse response, String path,
String name) throws IOException {
Long fileLength = new File(path).length();// 文件的长度
System.out.println("文件的长度：" + fileLength);
if (fileLength != 0) {
response.reset();
response.setContentType("application/octet-stream;charset=utf-8"); // 改成输出excel文件
try {
response.setHeader(
"Content-disposition",
"attachment; filename="
+ new String(name.getBytes("utf-8"),
"ISO8859-1"));
response.setHeader("Content-Length", String.valueOf(fileLength));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
BufferedInputStream bis = null;
BufferedOutputStream bos = null;
FileInputStream fis = null;
try {
fis = new FileInputStream(path);
bis = new BufferedInputStream(fis);
// 输出流
bos = new BufferedOutputStream(response.getOutputStream());
byte[] buff = new byte[2048];
int bytesread;
// 写文件
while (-1 != (bytesread = bis.read(buff, 0, buff.length))) {
bos.write(buff, 0, bytesread);
}
fis.close();
bis.close();
bos.close();
} catch (FileNotFoundException e) {
System.out.println("File is Not Exsist!");
}
}
}
}Come on, let me talk about it. We all know that downMb is called to download a file on the server.
//Set the response header, controls the browser to download the file, the formal parameter adjusts the length of the file
response.setHeader("Content-Length", String.valueOf(fileLength));//Set the response type, set the output stream type
response.setContentType("application/octet-stream;charset=utf-8"); // 改成输出excel文件Here I am using the output Excel file
The next step is to read the file and write the file. I believe I have learned java. The basics will come into contact with IO. I will skip it here
BufferedInputStream bis = null; BufferedOutputStream bos = null;
The buffer stream is used here because it uses the browser to open the file for download
The next step is to write files. Writing files is also a consistent routine. First, save the file to the buff data buffer, and then output the buff data to the browser for the user to view
byte[] buff = new byte[2048];
int bytesread;
// 写文件
while (-1 != (bytesread = bis.read(buff, 0, buff.length))) {
bos.write(buff, 0, bytesread);
}
After reading and writing the file, don’t forget to close the file stream (of course, the order of closing the stream It cannot be changed)
fis.close(); bis.close(); bos.close();
The above is the detailed content of Explain the response download method of Java Web. For more information, please follow other related articles on the PHP Chinese website!
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
