httpClient

使用HttpClient发送请求、接收响应很简单，一般需要如下几步即可。

1. 创建HttpClient对象。

HttpClient httpclient = new DefaultHttpClient();

在httpClient4.3，弃用 DefaultHttpClient使用

 HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();

 CloseableHttpClient closeableHttpClient = httpClientBuilder.build(); 

2. 创建请求方法的实例，并指定请求URL。如果需要发送GET请求，创建HttpGet对象；如果需要发送POST请求，创建HttpPost对象。

HttpGet httpget = new HttpGet("http://localhost/");

3. 如果需要发送请求参数，可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法来添加请求参数；对于HttpPost对象而言，也可调用setEntity(HttpEntity entity)方法来设置请求参数。

4. 调用HttpClient对象的execute(HttpUriRequest request)发送请求，该方法返回一个HttpResponse。

HttpResponse response = httpclient.execute(httpget);

5. 调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取服务器的响应头；调用HttpResponse的getEntity()方法可获取HttpEntity对象，该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。

HttpEntity entity = response.getEntity();

6. 释放连接。无论执行方法是否成功，都必须释放连接

 httpclient.close();  

 

 

 

 

 两种传值方式对应两种接收解析的方式：

 

第一种请求：

HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost("url");
JSONObject json = new JSONObject();
String jsonStr = json.toJSONString();

StringEntity entity = new StringEntity(jsonStr, "UTF-8"); httpPost.setEntity(entity); HttpResponse res = httpClient.execute(httpPost); HttpEntity entity2 = res.getEntity(); String s = EntityUtils.toString(entity2); System.out.println("s===" + s);

 

 

接收上述http请求，并返回返回值的两个方法

 

 

private JSONObject getReq(HttpServletRequest req)throws Exception{
    StringBuilder builder = new StringBuilder();
BufferedReader reader = new BufferedReader(new InputStreamReader(req.getInputStream(), "utf-8"));
String line;
    while ((line = reader.readLine()) != null) {
        builder.append(line);
}
    JSONObject obj = JSON.parseObject(builder.toString());
    return obj;
}
private void response(JSONObject resObj,HttpServletResponse response) 
throws Exception{
 response.setContentType("application/json;charset=utf-8");
 response.setHeader("Pragma", "no-cache"); 
response.setHeader("Cache-Control", "no-cache"); 
response.setDateHeader("Expires", 0); 
response.getWriter().write(resObj.toJSONString());
 } 

第二种：         HttpPost httpPost = new HttpPost(url);

List<NameValuePair> params = new ArrayList<NameValuePair>();

JSONObject json = new JSONObject();

json.put("cardNo","6227001217450010000");

json.put("mobile","18612811333");

json.put("surename","史戈雅");

json.put("cardid", "451025197308146588");

json.put("RequestType", "OpenCG");

 

 

//params.add(new BasicNameValuePair("param", json.toJSONString()));

Set<String> keys=json.keySet();

Iterator<String> it=keys.iterator();

while(it.hasNext()){

String key=it.next();

params.add(new BasicNameValuePair(key, json.get(key).toString()));

}

 

 

httpPost.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));

HttpResponse res = httpClient.execute(httpPost);

HttpEntity entity = res.getEntity();

String s = EntityUtils.toString(entity);

System.out.println("s==="+s);

 

 

 

如何解析以上请求方式：

public static Map<String, String> getRequestMap(HttpServletRequest request) {
    Enumeration<?> enu = request.getParameterNames();
Map<String, String> rmap = new HashMap<String, String>();
    while (enu.hasMoreElements()) {
        String xsql = (String) enu.nextElement();
String value = request.getParameter(xsql);
rmap.put(xsql, value);
}
    return rmap;
}




增加一种获取http请求的一种方法

public void pushLoanInfo(@RequestBody String body, HttpServletRequest req, HttpServletResponse response) {
   JSONObject resObj = new JSONObject();
body = URLDecoder.decode(body, "UTF-8");
//Map<String, String> map = getRequestMap(req);
JSONObject objectBody = JSON.parseObject(body);

还可以直接request.getParameter("");