Struts 文件的上传与下载

系统管理员 2022-05-09 06:44 160阅读 0赞

**一、struts框架提供了文件的上传和下载功能，简化了很多的代码**

**二、文件的上传**

1.前端用struts框架中的ognl标签

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <%@  taglib uri="/struts-tags" prefix="s" %>
    
    <h5>文件的上传</h5>
    <s:form namespace="/" action="upload" method="post" enctype="multipart/form-data" theme="xhtml" >
    	<s:textfield name="username" label="用户名" />
    	<s:file  name="image"  label="文件" ></s:file>
    	<s:submit  value="提交"  ></s:submit>
    </s:form>

2.后端action

public class UploadAction  extends ActionSupport{
    	
    	@Setter
    	private String username;
    	@Setter
    	private File image; // 上传的文件对象 image和前端name一致
    	@Setter
    	private String imageFileName; // 上传的文件名字
    	@Setter
    	private String imageContentType; // 上传文件的MIME类型
    	
    	@Override
    	public String execute() throws Exception {
    		// 构建文件上传的目录
    		String dir = ServletActionContext.getServletContext().getRealPath("/image") ;
    		// 构建文件上传的目录和名称
    		File destFile = new File(dir  ,imageFileName);
    		// 拷贝文件
    		FileUtils.copyFile(image, destFile);
    		
    		System.out.println("----------------");
    		System.out.println(image );
    		System.out.println(imageFileName);
    		System.out.println(imageContentType);
    		 
    		return NONE;
    		
    	}
    }

3.配置文件xml

<constant name="struts.custom.i18n.resources" value="uploadmessages"></constant>
    	<package name="p5" extends="struts-default" namespace="/upload"   >
    		
    		<interceptors>
    			
    			<interceptor-stack name="myStack">
    			
    				<interceptor-ref name="fileUpload">
    					
    					<param name="allowedExtensions">jpeg,png,jpg,excel</param>
    					
    					<param name="maximumSize">1048076</param>
    				</interceptor-ref>
    				 
    				<interceptor-ref name="defaultStack"/>
    			</interceptor-stack>
    		</interceptors>
    		
    		<default-interceptor-ref name="myStack"></default-interceptor-ref>
    		
    		<action name="upload" class="com.struts.web.upload.UploadAction" > 
    			<result name="input" >/upload/upload.jsp </result> 
    		 </action>
    	
    	</package>

4.利用框架的上传文件大小，错误类型的提示Properties文件

#struts-messages.properties 文件中
    struts.messages.error.uploading=文件上传错误: {0}
    struts.messages.error.file.too.large=文件 {0} 太大了. 限制最大为 {4} bytes!
    struts.messages.error.content.type.not.allowed=文件MIME类型限定为: {0} "{1}" "{2}" {3}
    struts.messages.error.file.extension.not.allowed=文件拓展名不被允许: {0} "{1}" "{2}" {3}

**三、文件的下载**

1.前端代码

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <%@  taglib uri="/struts-tags" prefix="s" %>
    
    <h5>文件下载</h5>
    <a href="/down/download?fileName=a.rar" >三国演义</a><br/>
    <a href="/down/download?fileName=西游记.rar" >西游记</a><br/>

2.后端action

public class DownLoadAction extends ActionSupport {
    
    	private String fileName;
    	//防止文件乱码
    	public void setFileName(String fileName) throws Exception {
    		this.fileName = new String((fileName.getBytes("ISO-8859-1")),"UTF-8");
    	}
    	// xml文件中获得文件的名字
    	public String getFileName() {
    		return fileName;
    	}
    	// 返回下载文件的输入流，把下载文件读取到程序中来
    	public InputStream getInputStream() throws Exception{
    		String dir = ServletActionContext.getServletContext().getRealPath("/image");
    		System.out.println(dir);
    		File file = new File(dir,fileName);
    		return new FileInputStream(file);
    	}
    	
    	@Override
    	public String execute() throws Exception {
    		
    		
    		System.out.println("下载文件==" + fileName);
    	
    		return SUCCESS;
    	}
    }

3.配置文件xml

<package name="p6" extends="struts-default" namespace="/down"   >
    		
    		<action name="download" class="com.struts.web.download.DownLoadAction" > 
    			<result name="success" type="stream"  >
    				
    				<param name="contentDisposition">attachment;fileName="${fileName}"</param>
    				
    				<param name="inputName">inputStream</param>
    			</result>  
    		 </action>
    	
    	</package>