知识大全在Struts 2中实现文件上传

Posted 2022-07-18 知

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　　Struts 是通过Commons FileUpload文件上传 Commons FileUpload通过将HTTP的数据保存到临时文件夹然后Struts使用fileUpload拦截器将文件绑定到Action的实例中从而我们就能够以本地文件方式的操作浏览器上传的文件 具体实现 前段时间Apache发布了Struts GA 所以本文的实现是以该版本的Struts作为框架的以下是例子所依赖类包的列表清单依赖类包的列表

　　首先创建文件上传页面FileUpload jsp 内容如下 <% @ page language = java contentType = text/; charset=utf pageEncoding = utf %> <% @ taglib prefix = s uri = /struts tags %> <! DOCTYPE PUBLIC //W C//DTD XHTML Transitional//EN transitional dtd > < xmlns = > < head > < title > Struts File Upload </ title > </ head > < body > < s:form action = fileUpload method = POST enctype = multipart/form data > < s:file name = myFile label = Image File /> < s:textfield name = caption label = Caption /> < s:submit /> </ s:form > </ body > </ >

清单 FileUpload jsp

　　在FileUpload jsp中先将表单的提交方式设为POST 然后将enctype设为multipart/form data 这并没有什么特别之处接下来 <s:file/>标志将文件上传控件绑定到Action的myFile属性

　　其次是FileUploadAction java代码

package tutorial; import java io BufferedInputStream; import java io BufferedOutputStream; import java io File; import java io FileInputStream; import java io FileOutputStream; import java io InputStream; import java io OutputStream; import java util Date; import apache struts ServletActionContext; import opensymphony xwork ActionSupport; public class FileUploadAction extends ActionSupport private static final long serialVersionUID = l ; private static final int BUFFER_SIZE = * ; private File myFile; private String contentType; private String fileName; private String imageFileName; private String caption; public void setMyFileContentType(String contentType) ntentType = contentType; public void setMyFileFileName(String fileName) this fileName = fileName; public void setMyFile(File myFile) this myFile = myFile; public String getImageFileName() return imageFileName; public String getCaption() return caption; public void setCaption(String caption) this caption = caption; private static void copy(File src File dst) try InputStream in = null ; OutputStream out = null ; try in = new BufferedInputStream( new FileInputStream(src) BUFFER_SIZE); out = new BufferedOutputStream( new FileOutputStream(dst) BUFFER_SIZE); byte [] buffer = new byte [BUFFER_SIZE]; while (in read(buffer) > ) out write(buffer); finally if ( null != in) in close(); if ( null != out) out close(); catch (Exception e) e printStackTrace(); private static String getExtention(String fileName) int pos = fileName lastIndexOf( ); return fileName substring(pos); @Override public String execute() imageFileName = new Date() getTime() + getExtention(fileName); File imageFile = new File(ServletActionContext getServletContext() getRealPath( /UploadImages ) + / + imageFileName); copy(myFile imageFile); return SUCCESS; 清单 tutorial/FileUploadAction java

　　在FileUploadAction中我分别写了setMyFileContentType setMyFileFileName setMyFile和setCaption四个Setter方法后两者很容易明白分别对应FileUpload jsp中的<s:file/>和<s:textfield/>标志但是前两者并没有显式地与任何的页面标志绑定那么它们的值又是从何而来的呢？其实 <s:file/>标志不仅仅是绑定到myFile 还有myFileContentType（上传文件的MIME类型）和myFileFileName（上传文件的文件名该文件名不包括文件的路径）因此 <s:file name= xxx />对应Action类里面的xxx xxxContentType和xxxFileName三个属性

　　FileUploadAction作用是将浏览器上传的文件拷贝到WEB应用程序的UploadImages文件夹下新文件的名称是由系统时间与上传文件的后缀组成该名称将被赋给imageFileName属性以便上传成功的跳转页面使用

　　下面我们就来看看上传成功的页面

<% @ page language = java contentType = text/; charset=utf pageEncoding = utf %> <% @ taglib prefix = s uri = /struts tags %> <! DOCTYPE PUBLIC //W C//DTD XHTML Transitional//EN transitional dtd > < xmlns = > < head > < title > Struts File Upload </ title > </ head > < body > < div style = padding: px; border: solid px #cccccc; text align: center > < img src = UploadImages/<s:property value = imageFileName /> /> < br /> < s:property value = caption /> </ div > </ body > </ > 清单 ShowUpload jsp

　　ShowUpload jsp获得imageFileName 将其UploadImages组成URL 从而将上传的图像显示出来

　　然后是Action的配置文件

<? xml version= encoding= UTF ?> <! DOCTYPE struts PUBLIC //Apache Sofare Foundation//DTD Struts Configuration //EN dtd > < struts > < package name = fileUploadDemo extends = struts default > < action name = fileUpload class = tutorial FileUploadAction > < interceptor ref name = fileUploadStack /> < result name = success > /ShowUpload jsp </ result > </ action > </ package > </ struts > 清单 struts xml

　　fileUpload Action显式地应用fileUploadStack的拦截器

　　最后是web xml配置文件

<? xml version= encoding= UTF ?> < web app id = WebApp_ version = xmlns = xmlns:xsi = instance xsi:schemaLocation = app_ _ xsd > < display name > Struts Fileupload </ display name > < filter > < filter name > struts cleanup </ filter name > < filter class > apache struts dispatcher ActionContextCleanUp </ filter class > </ filter > < filter > < filter name > struts </ filter name > < filter class > apache struts dispatcher FilterDispatcher </ filter class > </ filter > < filter mapping > < filter name > struts cleanup </ filter name > < url pattern > /* </ url pattern > </ filter mapping > < filter mapping > < filter name > struts </ filter name > < url pattern > /* </ url pattern > </ filter mapping > < wele file list > < wele file > l </ wele file > </ wele file list > </ web app > 清单 WEB INF/web xml

　　发布运行应用程序在浏览器地址栏中键入出现图示页面

　　清单 FileUpload页面

　　选择图片文件填写Caption并按下Submit按钮提交出现图示页面

　　清单上传成功页面

错误处理

　　上述例子实现的图片上传的功能所以应该阻止用户上传非图片类型的文件在Struts 中如何实现这点呢？其实这也很简单对上述例子作如下修改即可

　　首先修改FileUpload jsp 在<body>与<s:form>之间加入 <s:fielderror /> 用于在页面上输出错误信息

　　然后修改struts xml文件将Action fileUpload的定义改为如下所示

< action name = fileUpload class = tutorial FileUploadAction > < interceptor ref name = fileUpload > < param name = allowedTypes > image/bmp image/png image/gif image/jpeg </ param > </ interceptor ref > < interceptor ref name = defaultStack /> < result name = input > /FileUpload jsp </ result > < result name = success > /ShowUpload jsp </ result > </ action > 清单修改后的配置文件

　　显而易见起作用就是fileUpload拦截器的allowTypes参数另外配置还引入defaultStack它会帮我们添加验证等功能所以在出错之后会跳转到名称为 input 的结果也即是FileUpload jsp

　　发布运行应用程序出错时页面如下图所示

　　清单出错提示页面

　　上面的出错提示是Struts 默认的大多数情况下我们都需要自定义和国际化这些信息通过在全局的国际资源文件中加入 ntent type not allowed=The file you uploaded is not a image 可以实现以上提及的需求对此有疑问的朋友可以参考我之前的文章《在Struts 中国际化(i n)您的应用程序》

　　实现之后的出错页面如下图所示

　　清单自定义出错提示页面

　　同样的做法你可以使用参数 maximumSize 来限制上传文件的大小它对应的字符资源名为 ssages error file too large

　　字符资源 ssages error uploading 用提示一般的上传出错信息

多文件上传

　　与单文件上传相似 Struts 实现多文件上传也很简单你可以将多个<s:file />绑定Action的数组或列表如下例所示

< s:form action = doMultipleUploadUsingList method = POST enctype = multipart/form data > < s:file label = File ( ) name = upload /> < s:file label = File ( ) name = upload /> < s:file label = FIle ( ) name = upload /> < s:submit /> </ s:form > 清单多文件上传JSP代码片段

　　如果你希望绑定到数组 Action的代码应类似

private File[] uploads; private String[] uploadFileNames; private String[] uploadContentTypes; public File[] getUpload() return this uploads; public void setUpload(File[] upload) this uploads = upload; public String[] getUploadFileName() return this uploadFileNames; public void setUploadFileName(String[] uploadFileName) this uploadFileNames = uploadFileName; public String[] getUploadContentType() return this uploadContentTypes; public void setUploadContentType(String[] uploadContentType) this uploadContentTypes = uploadContentType; 清单多文件上传数组绑定Action代码片段

　　如果你想绑定到列表则应类似

private List < File > uploads = new ArrayList < File > (); private List < String > uploadFileNames = new ArrayList < String > (); private List < String > uploadContentTypes = new ArrayList < String > (); public List < File > getUpload() return this uploads; public void setUpload(List < File > uploads) this uploads = uploads; public List < String > getUploadFileName() return this uploadFileNames; public void setUploadFileName(List < String > uploadFileNames) this uploadFileNames = uploadFileNames; public List < String > getUploadContentType() return this uploadContentTypes; public void setUploadContentType(List < String > contentTypes) this uploadContentTypes = contentTypes; 清单多文件上传列表绑定Action代码片段

总结

cha138/Article/program/Java/ky/201311/28217

知识大全 在Struts 2中实现文件上传

更多配置

错误处理

多文件上传

总结

知识大全在Struts 2中实现文件上传