javaweb开发（十）：文件上传、下载
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构建1个web项目，配置tomcat，导入依赖
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编写上传页面
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>文件上传</title>
</head>
<body>
<form action="<%=request.getContextPath()%>/fileUpload" method="post" enctype="multipart/form-data">
用户名:<input type="text" name="username"/>
头像:<input type="file" name="img">
<input type="submit" value="提交">
</form>
</body>
</html>
- 编写上传的servlet
@WebServlet("/fileUpload")
@MultipartConfig
public class FileUploadServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 获取文件名称
String username = request.getParameter("username");
// 获取文件
Part part = request.getPart("img");
//获取真实文件名称
String header = part.getHeader("content-disposition");
String realFileName = header.substring(header.indexOf("filename=")+10,header.length()-1);
//获取真实的文件内容
InputStream is = part.getInputStream();
//web-inf目录外界不能直接访问，如果文件机密性强则放这里
//String dir = this.getServletContext().getRealPath("/WEB-INF/file");
// 应用上下文路径
String dir = this.getServletContext().getRealPath("/file");
File dirFile = new File(dir);
//如果目录不存在，则创建
if(!dirFile.exists()){
dirFile.mkdirs();
}
// 创建名称
String uniqueName = UUID.randomUUID()+realFileName;
//文件流拷贝
File file = new File(dir,uniqueName);
FileOutputStream out = new FileOutputStream(file);
byte[] buf = new byte[1024];
int len;
while ((len = is.read(buf))!=-1 ){
out.write(buf,0,len);
}
// 关闭流
out.close();
is.close();
// 图片访问，转发到图片
request.getRequestDispatcher("/file/"+uniqueName).forward(request,response);
}
}
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测试
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编写下载servlet
@WebServlet("/download")
public class FileDownloadServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//客户端传递需要下载的文件名
String file = request.getParameter("file");
//获取文件在我们项目中的路径,发布到tomcat的实际路径
String path = request.getServletContext().getRealPath("/file/");
String filePath = path+file;
FileInputStream fis = new FileInputStream(filePath);
response.setCharacterEncoding("UTF-8");
//指明响应的配置信息，包含附件
response.setHeader("Content-Disposition","attachment; filename="+file);
//如果文件包含中文名称，需要进行编码转换
//response.setHeader("Content-Disposition","attachment; filename="+new String(file.getBytes("gb2312"),"ISO-8859-1"));
ServletOutputStream out = response.getOutputStream();
byte[] buf = new byte[1024];
int len;
while ((len= fis.read(buf))!=-1){
out.write(buf,0,len);
}
out.close();
}
}
- 测试
http://localhost:8081/download?file=f8acc99d-0d72-4963-a310-ee5c7f0af2d8test1.png
