用apache的httpclient发请求和接受数据
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response
final int code = response.getStatusLine().getStatusCode();
final HttpEntity entity = response.getEntity();//得到entity
if (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;
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Header
response.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{
}
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