文件上传SpringBoot后端MultipartFile参数报空问题的解决办法
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2022-07-06 15:53:35
最近写了一个文件上传的小demo，就是简单的前端html页面，后端controller接收，但是后端一直报错文件为null，看了很多文章，有说spring-boot自带的org.springframe...
最近写了一个文件上传的小demo，就是简单的前端html页面，后端controller接收，但是后端一直报错文件为null，看了很多文章，有说spring-boot自带的org.springframework.web.multipart.multipartfile和multipart冲突了，要在启动类中加入@enableautoconfiguration(exclue={multipartautoconfiguration.class})，有说要在multipartfile参数前加上@requestparam(“file”)以表明该参数类型是文件类型，还有说是前端表单没有设置enctype=“multipart/form-data”，参照上面方法我还是没有解决问题，后来更换了spring-boot版本就好了，代码如下：
1、pom.xml(注意我这里用的是2.0.4版本)
<?xml version="1.0" encoding="utf-8"?>
<project xmlns="http://maven.apache.org/pom/4.0.0"
xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
xsi:schemalocation="http://maven.apache.org/pom/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelversion>4.0.0</modelversion>
<parent>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-parent</artifactid>
<version>2.0.4.release</version>
</parent>
<groupid>org.sang</groupid>
<artifactid>chapter01</artifactid>
<version>1.0-snapshot</version>
<dependencies>
<dependency>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-web</artifactid>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-maven-plugin</artifactid>
</plugin>
</plugins>
</build>
</project>
2、upload.html页面
<!doctype html> <html lang="en"> <head> <meta charset="utf-8"> <title>title</title> </head> <body> <form action="/upload" method="post" enctype="multipart/form-data"> <input type="file" name="uploadfile" value="请选择文件"> <input type="submit" value="上传"> </form> </body> </html>
3、后端controller
import org.springframework.web.bind.annotation.postmapping;
import org.springframework.web.bind.annotation.restcontroller;
import org.springframework.web.multipart.multipartfile;
import javax.servlet.http.httpservletrequest;
import java.io.file;
import java.io.ioexception;
import java.text.simpledateformat;
import java.util.date;
import java.util.uuid;
@restcontroller
public class fileuploadcontroller {
simpledateformat sdf = new simpledateformat("yyyy/mm/dd");
@postmapping("upload")
public string upload(multipartfile uploadfile, httpservletrequest req){
string realpath = req.getsession().getservletcontext().getrealpath("/uploadfile");
string format = sdf.format(new date());
file folder = new file(realpath+format);
if(!folder.isdirectory()){
folder.mkdirs();
}
string oldname = uploadfile.getoriginalfilename();
string newname = uuid.randomuuid().tostring()+oldname.substring(oldname.lastindexof("."),oldname.length());
try{
uploadfile.transferto(new file(folder,newname));
string path = req.getscheme()+"://"+req.getservername()+":"+req.getserverport()+"/uploadfile/"+format+newname;
return path;
}catch (ioexception e){
e.printstacktrace();
}
return "上传失败";
}
}
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