Java三大框架之struts的上传文件

川长思鸟来 2022-09-24 04:21 194阅读 0赞

在没有struts之前，想要用Java上传文件还得写很多复杂的代码，利用servlet3.0的新特性，或者在servlet3.0之前比如借助其他的插件，比如commons-fileupload组件，或者其他的。并且代码写得十分复杂。利用struts框架进行上传文件核心代码只需要几行。但是框架用起来感觉有点复杂的就是搭建这个环境了。

首先应该包含核心jar包。这些文件可以从网上下载。我用到的核心jar包如下：

![Center][]

第二步：struts是基于拦截器实现的。因此需要在web.xml里面配置一个拦截器，把控制权交给struts来处理。

<filter>
        <filter-name>Struts2</filter-name>
        <filter-class>
                org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
            </filter-class>
      </filter>
      <filter-mapping>
        <filter-name>Struts2</filter-name>
        <url-pattern>/*</url-pattern>
      </filter-mapping>

第三步：在struts.xml文件中写action的配置

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE struts PUBLIC
        "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
        "http://struts.apache.org/dtds/struts-2.0.dtd">
    
    <struts>
    	<package name="fileAction" extends="struts-default" namespace="/">
    		<action name="MyfileUpload" class="com.levi.action.FileUpload">
    			<result name="success">/fileUpload_Success.jsp</result>
    			<result name="error">/error.jsp</result>
    			<result name="input">/fileUpload.jsp</result>
    		</action>
    	</package>
    
    </struts>

第四步前端上传页面代码为:

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
     <%@taglib prefix="s" uri="/struts-tags" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
    <form action="MyfileUpload" method="post" enctype="multipart/form-data">
    	<input type="file" name="fileUpload"/><br>
    	<button type="submit">上传</button>
    </form>
    <br>
    错误信息如下:<s:fielderror></s:fielderror>
    </body>
    </html>

前端上传成功页面如下：

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
        <%@taglib prefix="s" uri="/struts-tags" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
    文件上传成功<br>
    文件名:<s:property value="#session.fileUploadFileName"/><br>
    文件类型为:<s:property value="#session.fileUploadContentType"/><br>
    
    </body>
    </html>

最后编写处理Action的类

package com.levi.action;
    
    import java.io.File;
    import java.util.Map;
    
    import org.apache.commons.io.FileUtils;
    
    import com.opensymphony.xwork2.ActionContext;
    import com.opensymphony.xwork2.ActionSupport;
    
    public class FileUpload extends ActionSupport
    {
    
    	/**
    	 * 
    	 */
    	private static final long serialVersionUID = 1L;
    
    	private File fileUpload;
    	private String fileUploadFileName;
    	public File getFileUpload()
    	{
    		return fileUpload;
    	}
    	public void setFileUpload(File fileUpload)
    	{
    		this.fileUpload = fileUpload;
    	}
    	public String getFileUploadFileName()
    	{
    		return fileUploadFileName;
    	}
    	public void setFileUploadFileName(String fileUploadFileName)
    	{
    		this.fileUploadFileName = fileUploadFileName;
    	}
    	public String getFileUploadContentType()
    	{
    		return fileUploadContentType;
    	}
    	public void setFileUploadContentType(String fileUploadContentType)
    	{
    		this.fileUploadContentType = fileUploadContentType;
    	}
    	private String fileUploadContentType;
    	@Override
    	public String execute() throws Exception
    	{
    		ActionContext actionContext=ActionContext.getContext();
    		Map<String, Object> session=actionContext.getSession();
    		session.put("fileUploadFileName", fileUploadFileName);
    		session.put("fileUploadContentType", fileUploadContentType);
    		System.out.println("文件名为:"+fileUploadFileName);
    		System.out.println("文件的类型为:"+fileUploadContentType);
    		String filePath="d:/upload/"+fileUploadFileName;
    		File saveFile=new File(filePath);
    		FileUtils.copyFile(fileUpload, saveFile);
    		return SUCCESS;
    	}
    }

然后就可以实现上传了。这个绝对简单很多的，只是前面配置有点麻烦。这个只实现了一个单文件的上传，后面可以增加一些配置，比如设定最大文件大小，上传类型等等，下一篇再详细实现

[Center]: /images/20220720/2f24e297038749468faf794ba9e6c535.png