1 案例分析
1 文件上传原理分析
2 代码实现
1 form.html
vf<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="/WEB32/fileuploadServlet2" method="post" enctype="multipart/form-data">
<input type="text" name="username"><br>
<input type="file" name="filename"><br>
<input type="submit" value="上传文件">
</form>
</body>
</html>
2 FileuploadServlet代码
public class FileuploadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
//接受上传文件
//1、创建磁盘文件项工厂
DiskFileItemFactory factory = new DiskFileItemFactory();
//2、创建文件上传的核心类
ServletFileUpload upload = new ServletFileUpload(factory);
//3、解析request---获得文件项集合
List<FileItem> parseRequest = upload.parseRequest(request);
//4、遍历文件项集合
for(FileItem item : parseRequest){
//5、判断普通表单项/文件上传项
boolean formField = item.isFormField();//是否是一个普通表单项
if(formField){
//普通表单项
String fieldName = item.getFieldName();
String fieldValue = item.getString();
System.out.println(fieldName+":"+fieldValue);
}else{
//文件上传项
//获得上传文件的名称
String fileName = item.getName();
//获得上传文件的内容
InputStream in = item.getInputStream();
//将in中的数据拷贝服务器上
String path = this.getServletContext().getRealPath("upload");
OutputStream out = new FileOutputStream(path+"/"+fileName);
int len = 0;
byte[] buffer = new byte[1024];
while((len=in.read(buffer))>0){
out.write(buffer, 0, len);
}
in.close();
out.close();
}
}
} catch (FileUploadException e) {
e.printStackTrace();
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
3 FileuploadServlet2代码
public class FileuploadServlet2 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
//1、创建磁盘文件项工厂
//作用：设置缓存文件的大小 设置临时文件存储的位置
String path_temp = this.getServletContext().getRealPath("temp");
//DiskFileItemFactory factory = new DiskFileItemFactory(1024*1024, new File(path_temp));
DiskFileItemFactory factory = new DiskFileItemFactory();
factory.setSizeThreshold(1024*1024);
factory.setRepository(new File(path_temp));
//2、创建文件上传的核心类
ServletFileUpload upload = new ServletFileUpload(factory);
//设置上传文件的名称的编码
upload.setHeaderEncoding("UTF-8");
//ServletFileUpload的API
boolean multipartContent = upload.isMultipartContent(request);//判断表单是否是文件上传的表单
if(multipartContent){
//是文件上传的表单
//***解析request获得文件项集合
List<FileItem> parseRequest = upload.parseRequest(request);
if(parseRequest!=null){
for(FileItem item : parseRequest){
//判断是不是一个普通表单项
boolean formField = item.isFormField();
if(formField){
//username=zhangsan
String fieldName = item.getFieldName();
String fieldValue = item.getString("UTF-8");//对普通表单项的内容进行编码
System.out.println(fieldName+"----"+fieldValue);
//当表单是enctype="multipart/form-data"时 request.getParameter相关的方法
//String parameter = request.getParameter("username");
}else{
//文件上传项
//文件的名
String fileName = item.getName();
//获得上传文件的内容
InputStream in = item.getInputStream();
String path_store = this.getServletContext().getRealPath("upload");
OutputStream out = new FileOutputStream(path_store+"/"+fileName);
IOUtils.copy(in, out);
in.close();
out.close();
//删除临时文件
item.delete();
}
}
}
}else{
//不是文件上传表单
//使用原始的表单数据的获得方式 request.getParameter();
}
} catch (FileUploadException e) {
e.printStackTrace();
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
3 文件上传知识点
原文地址：https://www.cnblogs.com/jepson6669/p/8449541.html
时间： 2024-08-01 03:02:50