【javaweb】form表单的文件上传demo

「爱情、让人受尽委屈。」 2022-05-29 11:09 275阅读 0赞

**1.基础知识**

**![70][]**

**2.demo如下**

package indi.fileupload;
    
    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.List;
    
    import javax.servlet.ServletException;
    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;
    import org.apache.commons.io.IOUtils;
    
    public class Fileuploadservlet extends HttpServlet {
    
    	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		//1.第一步新建一个磁盘文件项工厂
    		String path_temp=this.getServletContext().getRealPath("temp");
    		//第一个参数是设置缓存文件的大小(也就是要多大才缓存)，第二个参数是设置缓存的地址
    		//DiskFileItemFactory factory=new DiskFileItemFactory(1024*1024, new File(path_temp));
    		//当然也可以这样设置
    		DiskFileItemFactory factory=new DiskFileItemFactory();
    		factory.setSizeThreshold(1024*1024);//设置缓存大小为1M
    		factory.setRepository(new File(path_temp));
    		
    		//2.第二步新建一个文件上传的核心类
    		ServletFileUpload upload=new ServletFileUpload(factory);
    		//3.判断是否是一个文件上传的表单，即判断是否是enctype="multipart/form-data"
    		boolean multipartContent = ServletFileUpload.isMultipartContent(request);
    		if(multipartContent) {
    			//是文件上传类表单
    			//4.设置上传文件名的编码方式,目的是解决文件名为中文的乱码问题
    			upload.setHeaderEncoding("UTF-8");
    			//5.解析request获得表单项的集合,设置设置泛型为FileItem
    			List<FileItem> parseRequest=null;
    			try {
    				parseRequest = upload.parseRequest(request);
    			} catch (FileUploadException e) {
    				e.printStackTrace();
    			}
    			//6.遍历文件项集合
    			for(FileItem item:parseRequest) {
    				//7.判断是否是普通表单项
    				boolean formField = item.isFormField();
    				if(formField) {
    					//普通表单项
    					//获得表单的name属性值
    					String fieldName=item.getFieldName();
    					String fieldValue=item.getString("UTF-8");//参数表示对普通表单项的内容进行UTF-8编码，防止中文乱码，若非中文直接getString()
    					System.out.println(fieldName+"----"+fieldValue);
    				}else {
    					//文件上传项
    					//获得文件上传的内容
    					String fileName=item.getName();
    					//获得上传文件的输入流
    					InputStream in = item.getInputStream();
    					//将输入流的数据copy至服务器上
    					String path_store=this.getServletContext().getRealPath("upload");
    					//新建一个输出流
    					FileOutputStream out = new FileOutputStream(new File(path_store+"/"+fileName));//当然也可以直接path_store+"/"+fileName
    					int len=0;
    					byte[] buffer = new byte[1024];
    					while((len=in.read(buffer))>0) {
    						out.write(buffer, 0, len);
    					}
    					//当然上面的操作可以通过IO工具简化书写，其它步骤相同
    					//IOUtils.copy(in, out);
    					in.close();
    					out.close();
    					//8.删除临时文件
    					item.delete();
    				}
    			}
    		}else {
    			//是传统表单
    			//那么就用传统的request.getAttribute(arg0)就行
    			
    		}
    		
    		
    	}
    
    	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		doGet(request, response);
    	}
    }

[70]: /images/20220529/93af3438dd2c4c449fe97a264beab3ba.png