html页面展示
html页面的代码
<body>
<form action="FileServlet" method="post"
enctype="multipart/form-data">
<input type="file" name="newFile"/>
<br><br>
<input type="text" name="name" value="lrc">
<br><br>
<input type="submit" name="上传" value="上传文件"/>
</form>
</body>
页面效果
servlet请求处理
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("\nparameter方式获取参数---------------------------");
Enumeration<String> enums= req.getParameterNames();
while(enums.hasMoreElements()) {
String paraName = enums.nextElement();
String paraValue = req.getParameter(paraName);
System.out.println(paraName + ": " + paraValue);
}
System.out.println("\npart方式获取参数---------------------------");
Collection<Part> parts = req.getParts();
for(Part part : parts) {
String partName = part.getName();
String partValue = req.getParameter(partName);
System.out.println(partName + ": " + partValue);
}
System.out.println("\ntext类型标头part-------------------------------------");
Part part2 = req.getPart("name");
System.out.println(part2.getName());
System.out.println(part2.getContentType());
Collection<String> headerNames2 = part2.getHeaderNames();
for(String headName : headerNames2) {
Collection<String> headValues = part2.getHeaders(headName);
System.out.println(headName + ": " + headValues);
}
System.out.println("\nfile文件类型标头part---------------------------------");
Part part = req.getPart("newFile");
System.out.println(part.getName());
System.out.println(part.getContentType());
Collection<String> headerNames = part.getHeaderNames();
for(String headName : headerNames) {
Collection<String> headValues = part.getHeaders(headName);
System.out.println(headName + ": " + headValues);
}
}
当文件上传时，控制台的打印情况
结论
- Part能获取所有的请求参数的参数名，而Parameter只能获取非文件类型的参数名
- Part不能获得普通参数的参数值，只能从 getParameter(String) 获取参数值
- 想要上传文件到服务器，必须使用Part获得二进制的输入流
- Part能获得上传文件的文件大小、文件类型
