servlet文件下载
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
@WebServlet("/downloadServlet")
public class download extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String filename = req.getParameter("filename");
String filepath = req.getServletContext().getRealPath("E:/java1/servlet04/src/main/webapp/upload");
File file = new File(filename+filepath);
if (file.exists() && file.isFile()){
resp.setContentType("application/x-msdomload");
resp.setHeader("Contest-Disposition","attachment;filename="+filename);
InputStream in = new FileInputStream(file);
ServletOutputStream out =resp.getOutputStream();
int len = 0;
byte[]bytes = new byte[1024];
while ((len = in.read(bytes))!=-1){
out.write(bytes,0,len);
}
out.close();
in.close();
}else {
resp.setContentType("text/html;charset=UTF-8");
resp.getWriter().write("<h2>要下载的文件不存在!!</h2>");
resp.getWriter().close();
}
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>文件下载</title>
</head>
<body>
<a href="../../../target/servlet04-1.0-SNAPSHOT/uploadQQ图片20210315175557.jpg" download="li">图片</a>
<form action="downloadServlet">
文件名:<input type="text" name="filename">
<button>下载</button>
</form>
</body>
</html>
servlet文件上传
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import java.io.IOException;
@MultipartConfig
@WebServlet("/uploadServlet")
public class uploadServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("UTF-8");
String uname = req.getParameter("uname");
System.out.println("用户名:"+uname);
Part part = req.getPart("myfile");
String filename = part.getSubmittedFileName();
String uploadPath = req.getServletContext().getRealPath("E:/java1/servlet04/src/main/webapp/upload");
part.write(uploadPath + filename);
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>文件上传</title>
</head>
<body>
<form action="uploadServlet" enctype="multipart/form-data" method="post">
姓名:<input type="text" name="uname"><br>
头像:<input type="file" name="myfile">
<button>提交</button>
</form>
</body>
</html>