java实现文件上传(使用FromData)
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2022-04-10 18:39:26
一、使用FromData将表单对象序列化后,使用request.getInputStream()来获取数据 1、表单代码如下 2、js的代码 3、由于是序列化的表单所以java后端，不能使用request.getParameter()获取数据，需要使用request.getInputStream() ......
一、使用fromdata将表单对象序列化后,使用request.getinputstream()来获取数据
1、表单代码如下
<form id="user-info" method="post" action="upload" >
<input type="file" name="file" multiple>
<input type="text" name="username">
<input type="text" name="password">
</form>
<button id="sub">提交</button>
2、js的代码
<script>
function createxhr(){
return new xmlhttprequest();
}
var sub = document.getelementbyid("sub");
sub.onclick=function(){
var xhr = createxhr();
var form = document.getelementbyid("user-info");//获取上边的表单
xhr.open("post","upload",true);
xhr.send(new formdata(form));
}
</script>
3、由于是序列化的表单所以java后端，不能使用request.getparameter()获取数据，需要使用request.getinputstream();获取数据
首先我们看到获取的数据
inputstream in = request.getinputstream();
bufferedreader br = new bufferedreader(new inputstreamreader(in));
string str = "";
while((str=br.readline())!=null){
system.out.println(str);
}
可以看到读取到这些数据
4、接着使用apache的上传文件框架进行上传
实现效果
以下是代码
package com.wangyang.servlet;
import java.io.file;
import java.io.ioexception;
import java.util.list;
import javax.servlet.servletexception;
import javax.servlet.annotation.webservlet;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
import org.apache.commons.fileupload.fileitem;
import org.apache.commons.fileupload.fileuploadexception;
import org.apache.commons.fileupload.disk.diskfileitemfactory;
import org.apache.commons.fileupload.servlet.servletfileupload;
@webservlet("/upload")
public class upload extends httpservlet {
private static final long serialversionuid = 1l;
protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
request.setcharacterencoding("utf-8");
response.setcontenttype("text/html;charset=utf-8");
/*
inputstream in = request.getinputstream();
bufferedreader br = new bufferedreader(new inputstreamreader(in));
string str = "";
while((str=br.readline())!=null){
system.out.println(str);
}
*/
system.out.println("[-------------------------------------------------------]");
string filepath=request.getservletcontext().getrealpath("/")+"upload/";
file file = new file(filepath);
if(!file.exists()) {
file.mkdir();
}
diskfileitemfactory factory = new diskfileitemfactory();
servletfileupload upload = new servletfileupload(factory);
try {
list<fileitem> items= upload.parserequest(request);
for(fileitem item: items) {
system.out.println(filepath+item.getname());
if(!item.isformfield()) {
item.write(new file(filepath+item.getname()));
}
if(item.isformfield()){
system.out.println(item.getstring());
system.out.println(item.getfieldname());
}
}
} catch (fileuploadexception e) {
e.printstacktrace();
} catch (exception e) {
// todo auto-generated catch block
e.printstacktrace();
}
response.sendredirect("index.jsp");
}
}
<%@ page language="java" contenttype="text/html; charset=utf-8"
pageencoding="utf-8"%>
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>insert title here</title>
</head>
<body>
<form id="user-info" method="post" action="upload" >
<input type="file" name="file" multiple>
<input type="text" name="username">
<input type="text" name="password">
</form>
<button id="sub">提交</button>
<script>
function createxhr(){
return new xmlhttprequest();
}
var sub = document.getelementbyid("sub");
sub.onclick=function(){
var xhr = createxhr();
var form = document.getelementbyid("user-info");
xhr.open("post","upload",true);
xhr.send(new formdata(form));
}
</script>
</body>
</html>
这里没有进行细节上的编程，只是为了说明简单原理
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