Apache的HttpClient可以被用于从客户端发送HTTP请求到服务器端,
使用Apache的HttpClient发送GET和POST请求的步骤如下:
1. 使用帮助类HttpClients创建CloseableHttpClient对象.
2. 基于要发送的HTTP请求类型创建HttpGet或者HttpPost实例.
3. 使用addHeader方法添加请求头部,诸如User-Agent, Accept-Encoding等参数.
4. 对于POST请求,创建NameValuePair列表,并添加所有的表单参数.然后把它填充进HttpPost实体.
5. 通过执行此HttpGet或者HttpPost请求获取CloseableHttpResponse实例
6. 从此CloseableHttpResponse实例中获取状态码,错误信息,以及响应页面等等.
7. 最后关闭HttpClient资源.
public String doPost(String url, String params) {
String result = "";
CloseableHttpClient httpclient = null;
CloseableHttpResponse response = null;
HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
HttpSession session = request.getSession();
if (session != null) {
httpclient = (CloseableHttpClient) session.getAttribute("httpclient");
}
if (httpclient == null) {
httpclient = HttpClients.createDefault();
}
try {
HttpPost httppost = new HttpPost(url);
httppost.setHeader("accept", "*/*");
httppost.setHeader("connection", "Keep-Alive");
httppost.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36");
if (params != null && !"".equals(params)) {
MultipartEntityBuilder reqEntity = MultipartEntityBuilder.create();
reqEntity.setCharset(Charset.forName("utf-8"));
String[] nameAndValue = params.split("&");
for (String s : nameAndValue) {
String[] keyAndvalue = s.split("=",2);
//String[] keyAndvalue = s.split("=");
StringBody value = new StringBody("", ContentType.TEXT_PLAIN);
if(keyAndvalue.length == 2) {
value = new StringBody(keyAndvalue[1], Charset.forName("utf-8"));
//value = new StringBody(keyAndvalue[1], ContentType.TEXT_PLAIN);
}
reqEntity.addPart(keyAndvalue[0], value);
}
HttpEntity httpEntity = reqEntity.build();
httppost.setEntity(httpEntity);
}
response = httpclient.execute(httppost);
HttpEntity resEntity = response.getEntity();
if(resEntity != null) {
result = EntityUtils.toString(resEntity, "utf-8");
}
EntityUtils.consume(resEntity);
//if (url.endsWith("center/login") || url.endsWith("#forgetPswd") || url.endsWith("#register")) {
session.setAttribute("httpclient", httpclient);
//}
//2017-08-24 解决由session过期导致请求返回会员未登录的问题
if(StringUtils.isNotBlank(result)){
boolean isJson = Common.isJson(result);
//有些请求不是json格式,比如医院动态
if(isJson){
JSONObject js = JSONObject.fromObject(result);
//有些result没有返回code
if(js.has("code")){
if(ErrorCode.LS_ILLEGAL_LOGIN.equals(js.getString("code"))){
log.info("【本次请求返回会员未登录】"+js.toString());
//将请求信息放入缓存
RCacheEnTity rCacheEnTity = new RCacheEnTity(url,params,new Date());
CachePool.getInstance().putCacheItem("RC", rCacheEnTity);
String openId = (String) request.getSession().getAttribute("openId");
log.info("【重新登陆的openID】"+openId);
//进行重新登陆
String cxdl = doPost(WechatContext.getInstance().getServerUrl() + "center/wechatLogin", "username=" + openId);
//将上次的请求信息取出
CacheItem cacheItem = (CacheItem) CachePool.getInstance().getCacheItem("RC");
RCacheEnTity rCacheEnTity2 = (RCacheEnTity) cacheItem.getEntity();
log.info("【重新请求的URL】"+rCacheEnTity2.getUrl());
//重新发送上次的请求
String cxqq = doPost(rCacheEnTity2.getUrl(),rCacheEnTity2.getParams());
JSONObject cx = JSONObject.fromObject(cxqq);
//请求成功之后将缓存中的上次的请求信息去除
if(ErrorCode.LS_SUCCESS.equals(cx.getString("code"))){
//如果请求成功则去除缓存
CachePool.getInstance().removeCacheItem("RC");
result=cxqq;
}else{
CachePool.getInstance().removeCacheItem("RC");
}
}
}
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (response != null) {
response.close();
}
// httpclient.close();
} catch (IOException e1) {
e1.printStackTrace();
}
}
return result;
}