编辑上传文件的页面upload.html
注意事项：上传方式使用post不能使用get（get不能上传文件）
表单 enctype 属性应该设置为 multipart/form-data.（表示提交的数据是二进制文件）
upload.html
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<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>文件上传</title>
</head>
<body>
<form action="uploadphotoservlet" method="post" enctype="multipart/form-data">
人物名称:<input type="text" name="heroname"/><br>
上传头像:<input type="file" name="filepath"/><br>
<input type="submit" value="上传">
</form>
</body>
</html>
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uploadptotoservlet文件上传类--上传功能的开发
将commons-io-1.4.jar和commons-fileupload-1.2.2.jar 两个jar包放到web-inf/lib 目录下。
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import java.io.file;
import java.io.fileoutputstream;
import java.io.ioexception;
import java.io.inputstream;
import java.io.printwriter;
import java.util.iterator;
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;
/**
* servlet implementation class uploadphotoservlet
*/
@webservlet("/uploadphotoservlet")
public class uploadphotoservlet extends httpservlet {
private static final long serialversionuid = 1l;
/**
* @see httpservlet#httpservlet()
*/
public uploadphotoservlet() {
super();
// todo auto-generated constructor stub
}
/**
* @see httpservlet#doget(httpservletrequest request, httpservletresponse response)
*/
protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
// todo auto-generated method stub
// response.getwriter().append("served at: ").append(request.getcontextpath());
string filename=null;
diskfileitemfactory factory=new diskfileitemfactory(); //磁盘文件条目工厂
servletfileupload upload=new servletfileupload(factory); //负责处理上传的文件数据，并将表单中每个输入项封装成一个fileitem对象中
//设置上传文件的大小为10m
factory.setsizethreshold(2*1024*1024);
list items=null;
try {
//parse 解析
items=upload.parserequest(request); //得到一个保存了所有上传内容的list对象
} catch (fileuploadexception e) {
// todo auto-generated catch block
e.printstacktrace();
}
iterator iter=items.iterator(); //迭代上传的文件数据
while(iter.hasnext()){
fileitem item=(fileitem) iter.next();
if(!item.isformfield()){ //如果不是上传的
//根据时间戳创建头像文件
filename=system.currenttimemillis()+".jpg";
//通过getrealpath获取上传文件夹，如果项目存在将存在当前项目下 不存在的话创建项目文件夹
//图片文件夹
string photofolder=request.getservletcontext().getrealpath("uploaded");
file f=new file(photofolder,filename);
f.getparentfile().mkdirs(); //如果父文件夹不存在则自动创建
//通过item.getinputstream() 获取浏览器上传的文件
inputstream is = item.getinputstream(); //将文件读进来
//复制文件
fileoutputstream fos=new fileoutputstream(f); //往界面上显示
byte[] b=new byte[2*1024*1024];
int len=0;
while((len=is.read(b))!=-1){
fos.write(b, 0, len);
}
fos.close();
}else{
system.out.println(item.getfieldname());//heroname
string value=item.getstring();
value=new string(value.getbytes("iso-8859-1"), "utf-8");
system.out.println(value); //桑葚
}
}
string html="<img width='200' height='150' src='uploaded/%s'/>";
response.setcontenttype("text/html");
printwriter pw=response.getwriter();
pw.format(html, filename);
}
/**
* @see httpservlet#dopost(httpservletrequest request, httpservletresponse response)
*/
protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
// todo auto-generated method stub
doget(request, response);
}
}
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运行结果：
总结
以上所述是小编给大家介绍的j2ee servlet上传文件到服务器并相应显示功能的实现代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持！
原文链接：https://www.cnblogs.com/gaohuanhuan/archive/2018/07/06/9271718.html