Struts文件上传实践-优快云博客

本文链接：https://blog.youkuaiyun.com/lzqwebsoft/article/details/8109602

本文介绍如何使用Struts框架简化文件上传过程。通过创建特定的ActionForm和Action类，配合Struts配置，实现文件的接收与保存。示例代码详细展示了各组件的实现方式。

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Struts通过封装，可以非常简的实现文件上传，在页面上只需要提供一个<input type="file" name="属性名">元素，则Struts自动的将其提交的属性封装成一个org.apache.struts.upload.FormFile对象注入到对应ActionForm对象中，则在Action中直接可以通过ActionForm对象的FormFile属性来操作上传的文件流，从而实现上传功能，具体的示例如下：

首先，要先创建一个上传的页面视图文件index.jsp:

<%@ page language="java" contentType="text/html; charset=utf-8"%>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html" %>
<%@ taglib uri="http://struts.apache.org/tags-bean" prefix="bean" %>
<%@ taglib uri="http://struts.apache.org/tags-logic" prefix="logic" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html:html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>文件上传</title>
</head>
<body>
   <h2>文件上传示例</h2>
   <html:form action="uploadAction" method="post" enctype="multipart/form-data">
      <p>请选择您要上传的文件后提交：</p>
      <html:file property="file" /><br /><br />
      <html:submit>上传</html:submit>
   </html:form>
   
   <logic:notEmpty name="htmlFileForm" property="fname">
       <p>刚上传的文件为：</p>
       <ul>
           <li>文件名：<bean:write name="htmlFileForm" property="fname" /></li>
           <li>大小：<bean:write name="htmlFileForm" property="size" /></li>
       </ul>
   </logic:notEmpty>
</body>
</html:html>

注意这里使用的<html:form>标签的method属性，以及enctype属性的值。

其次创建一个封装该页面对应属性的ActionForm：

package test.upload.form;

import org.apache.struts.action.ActionForm;
import org.apache.struts.upload.FormFile;

public class FileForm extends ActionForm {
	
	private static final long serialVersionUID = 1L;

	/**
	 * The file that the user has uplaod. 
	 */
	private FormFile file;
	
	/**
	 * The name of the file - only for displaying results
	 */
	private String fname;
	
	/**
	 * The size of the file - only for displaying results
	 */
	private String size;

	public FormFile getFile() {
		return file;
	}

	public void setFile(FormFile file) {
		this.file = file;
	}

	public String getFname() {
		return fname;
	}

	public void setFname(String fname) {
		this.fname = fname;
	}

	public String getSize() {
		return size;
	}

	public void setSize(String size) {
		this.size = size;
	}
}

注意这里ActionForm的属性名与index.jsp视图中的表单属性要相对应，可以看出这里的FormFile对象file，对应视图中的<html:file>标签的property属性。

接着创建处理表单上传的Action类：

package test.upload.action;

import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.upload.FormFile;

import test.upload.form.FileForm;

public class FileUploadAction extends Action {

	@Override
	public ActionForward execute(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response)
			throws Exception {
		String dir=servlet.getServletContext().getRealPath("/upload");
		
		FileForm ff = (FileForm)form;
		
		// org.apache.struts.upload.FormFile contains the uploaded file
		FormFile file =  ff.getFile();
		
		// If no file was uploaded(e.g first form load), then display View
		if(file == null) {
			return mapping.findForward("success");
		}
		
		// Get the name and file Size
		String fname = file.getFileName();
		String size = Integer.toString(file.getFileSize()) + "bytes";
		
		InputStream streamIn = file.getInputStream();
		OutputStream streamOut = new FileOutputStream(dir+"/"+fname);
		
		// Just output the real path of the uploaded file for test.
		System.out.println("============"+dir+"/"+fname+"===========");
		
		int bytesRead = 0;
		byte[] buffer = new byte[8192];
		while((bytesRead = streamIn.read(buffer, 0, 8192))!=-1) {
			streamOut.write(buffer, 0, bytesRead);
		}
		streamOut.close();
		streamIn.close();
		
		ff.setFname(fname);
		ff.setSize(size);
		
		// Clean up our toys then done playing
		file.destroy();
		
		return mapping.findForward("success");
	}

}

可以看出通过Struts的提供的FormFile对象就可以直接的操作上传的文件流，这样显得十分的方便。

注意：再运行本程序之前必须要保证WebContent目录下有一个upload目录。

最后配制相应的struts-config.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC
       "-//Apache Software Foundation//DTD Struts Configuration 1.3//EN"
       "http://struts.apache.org/dtds/struts-config_1_3.dtd">
<struts-config>
    <form-beans>
      <form-bean name="htmlFileForm" type="test.upload.form.FileForm" />
    </form-beans>
    
    <action-mappings>
       <action path="/uploadAction" name="htmlFileForm"
           type="test.upload.action.FileUploadAction">
           <forward name="success" path="/index.jsp" />
       </action>
    </action-mappings>
    
</struts-config>

最后运行截图：