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使用Response下载文件,servlet中的文件下载是通过流来实现的
我在webRoot文件夹下新建了一个文件夹from,里边放了一张图片,这里就以下载这张图片为例:download.jsp很简单,只有一个a标签.
DownloadAction如下:
package com.wang.action;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts2.ServletActionContext;import com.opensymphony.xwork2.Action;public class DownloadAction { public String execute() throws IOException{ //获取response和request HttpServletRequest request=ServletActionContext.getRequest(); HttpServletResponse response=ServletActionContext.getResponse(); //获取要下载的文件夹路径 String path=request.getRealPath("/from"); File file=new File(path,"IMG_0968.jpg"); response.setContentLength((int)file.length()); response.setCharacterEncoding("utf-8"); //此contenttype意思是不知道文件类型,使用二进制流的方式传输 response.setContentType("application/octet-stream"); //注意,filename=后面的内容不加引号,我第一次加了引号,结果出错 response.setHeader("Content-Disposition", "attachment;filename=IMG_0968.jpg"); InputStream is=new FileInputStream(file); //通过response获得输出流 OutputStream os=response.getOutputStream(); byte[] b=new byte[1024]; int len=0; while((len=is.read(b))!=-1){ os.write(b, 0, len); } is.close(); os.close(); System.out.println("success download"); //注意:这里返回的是null return null; }} 这是使用servlet的reqsponse下载文件的方式,注意在action中,返回值是null,配置文件中不需要result标签,download.jsp和struts.xml省略.
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使用Struts2的StreamResult进行文件下载.
webRoot文件夹下新建了一个文件夹from,里边放了两张图片分别是IMG_0968.jpg和IMG_0975.jpg.以下载这两张图片为例:
downLoad.jsp页面:
StreamDownloadAction页面:
package com.wang.action;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import javax.servlet.http.HttpServletRequest;import org.apache.struts2.ServletActionContext;import com.opensymphony.xwork2.ActionSupport;public class StreamDownload extends ActionSupport{ private String fileName; @Override public String execute() throws Exception { return SUCCESS; } public InputStream getInputStream() throws IOException{ HttpServletRequest request = ServletActionContext.getRequest(); String path=request.getRealPath("/from"); InputStream is=new FileInputStream(new File(path,fileName)); return is; } public String getFileName() { return fileName; } public void setFileName(String fileName) { this.fileName = fileName; } } struts.xml页面:
InputStream attachment;fileName=${fileName}