首页 > 代码库 > [原创]java WEB学习笔记72：Struts2 学习之路-- 文件的上传下载，及上传下载相关问题
[原创]java WEB学习笔记72：Struts2 学习之路-- 文件的上传下载，及上传下载相关问题
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1.文件上传
1）表单需要注意三点：
① 须把 HTML 表单的 enctype 属性设置为 multipart/form-data
②须把 HTML 表单的method 属性设置为 post
③需添加 <input type=“file”> 字段.
2）Struts2 的文件上传实际使用的是Common FileUpload 组件，导入jar包。commons-fileupload / commons-io
3）Struts2 进行文件上传需要使用FileUpload拦截器
4）基本的文件操作：直接在Action 中定义如下 3个属性，并提供对应的get / set方法
private File [fileFieldName]; //文件对应的file 对象
private String [fileFieldName]ContentType; // 文件类型
private String [fileFieldName]pptFileName; // 文件名
5）使用IO 流进行文件的上传
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE struts PUBLIC 3 "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN" 4 "http://struts.apache.org/dtds/struts-2.3.dtd"> 5 6 <struts> 7 8 9 <!-- 配置国际化资源文件 -->10 <constant name="strut2.custom.i18n.resouce" value="i18n"></constant>11 12 <constant name="struts.action.extension" value="action,do,"></constant>13 <package name="default" namespace="/" extends="struts-default">14 15 <action name="testUpload" class="com.jason.upload.app.UploadAction">16 <result>/sucess.jsp</result>17 </action>18 19 </package>20 21 </struts>
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <%@ taglib prefix="s" uri="/struts-tags" %> 4 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 5 <html> 6 <head> 7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 8 <title>Insert title here</title> 9 </head>10 <body>11 12 <s:form action="testUpload" method="post" enctype="multipart/form-data">13 <s:file name="ppt" label="PPTfile"></s:file>14 <s:textfield name="pptDesc" label="PPTDesc"></s:textfield>15 16 <s:submit></s:submit>17 </s:form>18 19 20 </body>21 </html>
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 4 <html> 5 <head> 6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 7 <title>Insert title here</title> 8 </head> 9 <body>10 11 <h4> success page</h4>12 </body>13 </html>
1 package com.jason.upload.app; 2 3 import java.io.File; 4 import java.io.FileInputStream; 5 import java.io.FileOutputStream; 6 7 import javax.servlet.Servlet; 8 import javax.servlet.ServletContext; 9 10 import org.apache.struts2.ServletActionContext;11 12 import com.opensymphony.xwork2.ActionSupport;13 14 public class UploadAction extends ActionSupport {15 16 /**17 * @Fields:serialVersionUID18 */19 private static final long serialVersionUID = 1L;20 21 private File ppt;22 private String pptContentType;23 private String pptFileName;24 25 26 public File getPpt() {27 return ppt;28 }29 30 public void setPpt(File ppt) {31 this.ppt = ppt;32 }33 34 public String getPptContentType() {35 return pptContentType;36 }37 38 public void setPptContentType(String pptContentType) {39 this.pptContentType = pptContentType;40 }41 42 public String getPptFileName() {43 return pptFileName;44 }45 46 public void setPptFileName(String pptFileName) {47 this.pptFileName = pptFileName;48 }49 50 51 @Override52 public String execute() throws Exception {53 54 ServletContext servletContext = ServletActionContext.getServletContext();55 56 String dir = servletContext.getRealPath("/files/" + pptFileName);57 System.out.println(dir);58 59 FileOutputStream out = new FileOutputStream(dir);60 FileInputStream in = new FileInputStream(ppt);61 62 byte[] buffer = new byte[1024];63 int len = 0;64 while((len = in.read(buffer)) != -1){65 out.write(buffer, 0, len);66 }67 out.close();68 in.close();69 70 71 System.out.println(ppt);72 System.out.println(pptContentType);73 System.out.println(pptFileName);74 return SUCCESS;75 }76 77 }
2.相关问题
1）一次性上传过个文件？
若传递多个文件，则上述3个属性，可以改为list类型，多个文件的name 属性需要一致
1 <s:form action="testUpload" method="post" enctype="multipart/form-data"> 2 <s:file name="ppt" label="PPTfile"></s:file> 3 <s:textfield name="pptDesc[0]" label="PPTDesc"></s:textfield> 4 5 <s:file name="ppt" label="PPTfile"></s:file> 6 <s:textfield name="pptDesc[1]" label="PPTDesc"></s:textfield> 7 8 <s:file name="ppt" label="PPTfile"></s:file> 9 <s:textfield name="pptDesc[2]" label="PPTDesc"></s:textfield>10 11 <s:file name="ppt" label="PPTfile"></s:file>12 <s:textfield name="pptDesc[3]" label="PPTDesc"></s:textfield>13 14 <s:submit></s:submit>15 </s:form>
1 private List<File> ppts;2 private String pptContentType;3 private String pptFileName;
2）对上传文件的限制？例如扩展名，内容类型，上传文件的大小？如果出错， 显示错误消息？消息可以定制?
Interceptor parameters: •maximumSize (optional) - the maximum size (in bytes) that the interceptor will allow a file reference to be set on the action. Note, this is not related to the various properties found in struts.properties. Default to approximately 2MB.默认文件的最大值2M，上传的单个文件•allowedTypes (optional) - a comma separated list of content types (ie: text/html) that the interceptor will allow a file reference to be set on the action. If none is specified allow all types to be uploaded.允许上传的文件类型，多个使用 ‘,‘ 分割•allowedExtensions (optional) - a comma separated list of file extensions (ie: .html) that the interceptor will allow a file reference to be set on the action. If none is specified allow all extensions to be uploaded.
允许的上传文件的类型，多个使用 ‘ , ’分割
定制文件上传错误消息
This interceptor will add several field errors, assuming that the action implements ValidationAware. These error messages are based on several i18n values stored in struts-messages.properties, a default i18n file processed for all i18n requests. You can override the text of these messages by providing text for the following keys: •struts.messages.error.uploading - a general error that occurs when the file could not be uploaded
文件上传出错的消息•struts.messages.error.file.too.large - occurs when the uploaded file is too large文件超过最大值的消息•struts.messages.error.content.type.not.allowed - occurs when the uploaded file does not match the expected content types specified文件内容不合法的消息•struts.messages.error.file.extension.not.allowed - occurs when the uploaded file does not match the expected file extensions specified
文件扩展名不合法的消息
可以参考 org.apache.struts2. 下的 struts-message.properties ，可提供更多的定制信息
在 org.apache.struts2. 下的 default.properties 中有对文件上传总的大小的限制。可以使用常量的方式，修改限制：struts.multipart.maxSize = ?
1 1 <!-- 配置国际化资源文件 --> 2 2 <constant name="strut2.custom.i18n.resouce" value="i18n"></constant> 3 3 4 4 <constant name="struts.action.extension" value="action,do,"></constant> 5 5 6 6 <package name="default" namespace="/" extends="struts-default"> 7 7 8 8 <interceptors> 9 9 <interceptor-stack name="jasonStack">10 10 <interceptor-ref name="defaultStack">11 11 <param name="fileUpload.maximumSize">2000</param>12 12 <param name="fileUpload.allowedTypes">text/html,text/xml</param>13 13 <param name="fileUpload.allowedExtensions">html,ppt,xml</param>14 14 </interceptor-ref>15 15 </interceptor-stack>16 16 </interceptors>17 17 18 18 19 19 <default-interceptor-ref name="jasonStack"></default-interceptor-ref>20 20 <action name="testUpload" class="com.jason.upload.app.UploadAction">21 21 <result>/sucess.jsp</result>22 22 </action>23 23 24 24 </package>25 25
1 struts.messages.error.uploading=\u6587\u4EF6\u4E0A\u4F20\u51FA\u9519\u7684\u6D88\u606F2 struts.messages.error.file.too.large=\u6587\u4EF6\u8D85\u8FC7\u6700\u5927\u503C\u7684\u6D88\u606F3 struts.messages.error.content.type.not.allowed=\u6587\u4EF6\u5185\u5BB9\u4E0D\u5408\u6CD5\u7684\u6D88\u606F4 struts.messages.error.file.extension.not.allowed=\u6587\u4EF6\u6269\u5C55\u540D\u4E0D\u5408\u6CD5\u7684\u6D88\u606F
2.文件的下载
1）struts2 中使用 type="stream" 的result 进行下载即可：具体细节 /struts-2.3.15.3-all/struts-2.3.15.3/docs/WW/docs/stream-result.html
2）Struts 专门为文件下载提供了一种 Stream 结果类型. 在使用一个 Stream 结果时, 不必准备一个 JSP 页面.
3）Stream 结果类型可以设置如下参数:(以下参数可以在Action中以 getter 方法的方式提供)
- contentType：被下载的文件的 MIME 类型。默认值为 text/plain
- contentLength：被下载的文件的大小，以字节为单位
- contentDisposition： 可以设置下载文件名的ContentDispositon 响应头，默认值为 inline，通常设置为如下格式： attachment;filename="document.pdf".
- inputName：Action 中提供的文件的输入流。默认值为 inputStream
- bufferSize：文件下载时缓冲区的大小。默认值为 1024
- allowCaching ：文件下载时是否允许使用缓存。默认值为 true
- contentCharSet：文件下载时的字符编码。
4）Stream 结果类型的参数可以在 Action 以属性的方式覆盖
download.jsp
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 4 <html> 5 <head> 6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 7 <title>Insert title here</title> 8 </head> 9 <body>10 <a href="testDownload">Down Load</a>11 </body>12 </html>
DownLoadAction.java
对于contentTypecontentLengthcontentDispositioninputStream
我们需要在对应的Action 中声明一个变量 且提供 getter方法 1 package com.jason.upload.app; 2 3 import java.io.FileInputStream; 4 import java.io.InputStream; 5 6 import javax.servlet.ServletContext; 7 8 import org.apache.struts2.ServletActionContext; 9 10 import com.opensymphony.xwork2.ActionSupport;11 12 public class DownLoadAction extends ActionSupport {13 14 /**15 * @Fields:serialVersionUID16 */17 private static final long serialVersionUID = 1L;18 19 private String contentType;20 private long contentLength;21 private String contentDisposition;22 private InputStream inputStream;23 24 public String getContentDisposition() {25 return contentDisposition;26 }27 28 public long getContentLength() {29 return contentLength;30 }31 32 public String getContentType() {33 return contentType;34 }35 36 public InputStream getInputStream() {37 return inputStream;38 }39 @Override40 public String execute() throws Exception {41 42 //1.确定各成员的值43 contentType = "text/html";44 contentDisposition = "attachment;filename=‘a.html‘";45 46 ServletContext servletContext = ServletActionContext.getServletContext();47 String fileName = servletContext.getRealPath("/files/a.html");48 inputStream = new FileInputStream(fileName);49 contentLength = inputStream.available();50 return super.execute();51 }52 53 }
struts.xml
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE struts PUBLIC 3 "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN" 4 "http://struts.apache.org/dtds/struts-2.3.dtd"> 5 6 <struts> 7 <action name="testDownload" class="com.jason.upload.app.DownLoadAction"> 8 <result type="stream"> 9 <param name="bufferSize">2048</param>10 </result>11 </action>12 </package>13 14 </struts>
[原创]java WEB学习笔记72：Struts2 学习之路-- 文件的上传下载，及上传下载相关问题
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