此处发请求的是用httpclient4,请自己下载所需要的jar包。
发post请求，并得到数据。
String url = "http://localhost:8080/lee";url = url+ "/query/action/export.action";String exportFilePath = "lee"+".csv.";final HttpClient httpClient = new DefaultHttpClient();final HttpPost post = new HttpPost(url);List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("leeSmart", leeSmart));//发post请求的参数post.setEntity(new UrlEncodedFormEntity(params,HTTP.UTF_8));final HttpResponse response = httpClient.execute(post);//得到返回的responsefinal int code = response.getStatusLine().getStatusCode();final HttpEntity entity = response.getEntity();//得到entityif (entity != null && code < 400) {InputStream inputStream = entity.getContent();//得到从服务器端返回的数据流long length = entity.getContentLength();if(length<=0) return;int len = (int)length;byte[] b = new byte[len];int readCount = 0;//建议用以下方式读inputStream为b赋值while (readCount < len) { readCount += inputStream.read(b, readCount, len - readCount); } //在客户端生成文件。更高效的做法是，在服务器端传过来一个压缩后的btye[]，然后在客户端解压，减少传输数据。try {FileOutputStream fo1 = null;fo1 = new FileOutputStream(exportFilePath);fo1.write(b);}fo1.close();} catch (Exception e2) {e2.printStackTrace();}}
在action中接请求的方法export()，并返回数据流
try {request.setCharacterEncoding("UTF-8");} catch (UnsupportedEncodingException e1) {e1.printStackTrace();}response.setCharacterEncoding("UTF-8");String leeSmart = request.getParameter("leeSmart");//前台传过来的post参数byte[] b = null;try{List ret = serivce.query("select * from dual");//得到查询结果集//将ret放到sb中StringBuilder sb = new StringBuilder();//.......对结果集进行处理，并转成字节数组 b = sb.toString().getByte();}catch(Exception e){e.printStackTrace();}//如果方便，可以把b字节数组压缩一下，这样传的数据会比较小一些。//将字节数组放到response中，并返回到客户端。try {response.reset();// 设置response的Headerresponse.addHeader("Content-Disposition", "attachment;filename=" + new String("random".getBytes("UTF-8"),"ISO-8859-1"));response.addHeader("Content-Length", "" + b.length);OutputStream toClient = new BufferedOutputStream(response.getOutputStream());response.setContentType("application/octet-stream");toClient.write(b);toClient.flush();toClient.close();} catch (Exception e) {e.printStackTrace();}finally{}
