Java文件下载

来源：互联网发布：什么绘画软件好编辑：程序博客网时间：2024/05/16 23:57

前台：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head>     <base href="<%=basePath%>">     <title>My JSP 'index.jsp' starting page</title>     <script type="text/javascript">        function download(filename){          var url = encodeURI("down2.jsp?filename="+filename);          window.location.href= url;        }     </script> </head> <body>普通测试：<a href="javascript:void(0)" onclick="download('a.txt');">Down a.txt</a>   中文文件名测试：<a href="javascript:void(0)" onclick="download('中文.txt');">Down 中文.txt</a>   普通转向：<a href="a.txt">down.txt</a>    </body> </html>

后台：

 request.setCharacterEncoding("utf-8"); String filename = request.getParameter("filename"); filename = new String(filename.getBytes("ISO-8859-1"),"UTF-8");  System.out.println(filename); OutputStream o=response.getOutputStream(); byte b[]=new byte[1024]; /** * 得到文件的当前路径 * @param args */  String   serverpath=request.getRealPath("\\");  File fileLoad=new File(serverpath+filename); response.setContentType("application/octet-stream"); response.setHeader("content-disposition","attachment; filename="+filename); long fileLength=fileLoad.length(); String length1=String.valueOf(fileLength); response.setHeader("Content_Length",length1); FileInputStream in=new FileInputStream(fileLoad); int n; while((n=in.read(b))!=-1){    o.write(b,0,n); } in.close(); out.clear(); out = pageContext.pushBody();

另附下载excel文件：

    OutputStream o=response.getOutputStream();    byte b[]=new byte[1024];    File fileLoad=new File("e:/text.xls");    response.reset();       response.setContentType("application/vnd.ms-excel");    response.setHeader("content-disposition","attachment; filename=text.xls");    long fileLength=fileLoad.length();    String length1=String.valueOf(fileLength);    response.setHeader("Content_Length",length1);    FileInputStream in=new FileInputStream(fileLoad);    int n;    while((n=in.read(b))!=-1){     o.write(b,0,n);    }       in.close();    out.clear();    out = pageContext.pushBody();

区别仅仅是是内容类型的不同。

注意，如果在jsp页面中直接使用上述下载代码。 out.clear(); out = pageContext.pushBody(); 这两句不可少，为什么不加入了就报异常: java.lang.IllegalStateException: getOutputStream() has already been called for this response。因为pushBody()的作用是保存当前的out对象，并更新PageContext中Page范围内Out对象。至于为什么要加上这句话，是因为JSP容器在处理完成请求后会调用releasePageConter方法释放所有的PageContestObject，并且同时调用getWriter方法。由于getWriter方法与在JSP页面中使用流相关的getOutputStream方法冲突，所以会造成这种异常，解决方法就是楼上给的一样，只需要在JSP页面的最后加上这两条语句。

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