Struts中上传文件需要注意的地方

Struts文件上传实践

最新推荐文章于 2021-10-19 23:36:36 发布

最新推荐文章于 2021-10-19 23:36:36 发布 · 130 阅读

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#Struts #IE #Servlet #JSP #CSS

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本文详细介绍了使用Struts框架实现文件上传的过程，包括web.xml和struts-config.xml配置、FormBean及Action设置，并解决了上传过程中的参数类型转换错误。

今天突然想研究下Struts的上传功能，没想到搞了两个小时才搞出来，卡在一个地方，总是报错说参数类型转化异常，结果我改动了下页面，却又神出鬼没的上传成功了，赶紧记录下

首先是web.xml中的配置，我个人喜欢每次弄个字符过滤器，以免出错

 

<filter>

<filter-name>filter</filter-name>

<filter-class>com.wujintao.dao.SetCharacterEncodingFilter</filter-class>

<init-param>

<param-name>encode</param-name>

<param-value>utf-8</param-value>

</init-param>

</filter>

<filter-mapping>

<filter-name>filter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<servlet>

    <servlet-name>action</servlet-name>

    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>

    <init-param>

      <param-name>config</param-name>

      <param-value>/WEB-INF/struts-config.xml</param-value>

    </init-param>

    <init-param>

      <param-name>debug</param-name>

      <param-value>2</param-value>

    </init-param>

    <init-param>

      <param-name>detail</param-name>

      <param-value>2</param-value>

    </init-param>

    <load-on-startup>2</load-on-startup>

  </servlet>

  <!-- Standard Action Servlet Mapping -->

  <servlet-mapping>

    <servlet-name>action</servlet-name>

    <url-pattern>*.do</url-pattern>

  </servlet-mapping>

 

  <welcome-file-list>

    <welcome-file>index.jsp</welcome-file>

  </welcome-file-list>

struts-config.xml中的配置，挺奇怪的最后两行必须得配上

<struts-config>

 

<!-- ================================================ Form Bean Definitions -->

    <form-beans>

     <form-bean name="uploadForm" type="com.javacrazyer.web.formbean.UploadForm"/>

    </form-beans>

 

<!-- =========================================== Action Mapping Definitions -->

    <action-mappings>

<action path="/upload" 

name="uploadForm" 

type="com.javacrazyer.web.action.UploadAction">

<forward name="succ" path="/succ.jsp"/>

<forward name="fail" path="/failure.jsp"/>

</action>

    </action-mappings>

 

    <controller bufferSize="8192" maxFileSize="1M" />

 

    <message-resources parameter="msgs"/>

</struts-config>

其次就是业务逻辑的代码了，在这之前我必须说下，这个Struts的上传用到的关键点就是自己自带的FormFile类了，因此在FormBean里面应该配上一个FormFile类型的属性

private String description; //文件的描述

private FormFile file;  //文件具体内容对应的实例 

 

public String getDescription() {

return description;

}

public void setDescription(String description) {

this.description = description;

}

public FormFile getFile() {

return file;

}

public void setFile(FormFile file) {

this.file = file;

}

业务逻辑处理代码

//具体业务流程处理方法，由Struts框架回调

public ActionForward execute(ActionMapping mapping, ActionForm form,

HttpServletRequest request, HttpServletResponse response)

throws Exception {

 

String toURL = "succ";

//取数据

UploadForm uForm = (UploadForm)form;

 

String desc = uForm.getDescription();

System.out.println("description==" + desc);

 

FormFile ff = uForm.getFile();

 

if(ff == null){

toURL = "fail";

return mapping.findForward(toURL);

}

System.out.println("文件名：" + ff.getFileName());

System.out.println("内容类型：" + ff.getContentType());

System.out.println("文件大小：" + ff.getFileSize() + "字节");

 

BufferedInputStream bis = new BufferedInputStream(ff.getInputStream());

 

//目标路径

String destPath = this.getServlet().getServletContext().getRealPath("/files");

System.out.println(destPath+"===============================");

BufferedOutputStream bos = null;

 

try{

bos = new BufferedOutputStream(new FileOutputStream(destPath + "/" + ff.getFileName()));

 

//从源文件中取数据，写到目标文件中

byte [] buff = new byte[8192];

 

for(int len = -1; (len = bis.read(buff)) != -1;){

bos.write(buff, 0, len);

}

 

bos.flush();

 

}catch(IOException ie){

ie.printStackTrace();

toURL = "fail";

}finally{

if(bis != null){

try{

bis.close();

}catch(IOException ie){

ie.printStackTrace();

}

}

if(bos != null){

try{

bos.close();

}catch(IOException ie){

ie.printStackTrace();

}

}

}

 

return mapping.findForward(toURL);

 

}

接下来我要说的，大家都猜到了肯定是JSP页面的上传表单了，这里就是卡住我的罪魁祸首

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%@ taglib uri="http://jakarta.apache.org/struts/tags-html" prefix="html" %> 

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <title>My JSP 'index.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">

<meta http-equiv="cache-control" content="no-cache">

<meta http-equiv="expires" content="0">    

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

<meta http-equiv="description" content="This is my page">

<!--

<link rel="stylesheet" type="text/css" href="styles.css">

-->

  </head>

  <body>

 <html:form action="upload.do" enctype="multipart/form-data"> 

<html:text property="description"></html:text>

<html:file property="file"/> 

<html:submit/> 

</html:form> 

  </body>

</html>

为什么说它是罪魁祸首呢，因为一直都认为<input type="file" />是最佳的上传表单，谁知道我找了大半天，竟然出现在这里的它必须是STRUTS标签的表单元素，郁闷！！！深刻的教训啊。