初始化HttpURLConnection

public HttpURLConnection initHttp(String url, String method, Map<String,String> headers)throws IOException {
    URL _url =new URL(url);
    HttpURLConnection http = (HttpURLConnection) _url.openConnection();
    http.setUseCaches(false);
    http.setConnectTimeout(5000);
    http.setReadTimeout(5000);
    http.setRequestMethod(method);
    http.setRequestProperty("Accept", "*/*");
    http.setRequestProperty("Accept-Encoding", "gzip,deflate");
    http.setRequestProperty("Cache-Control", "no-cache");
    http.setRequestProperty("Connection", "keep-alive");
    if (null != headers && !headers.isEmpty()) {
        for (Entry entry : headers.entrySet()) {
        http.setRequestProperty(entry.getKey(), entry.getValue());
        }
    }
  return http;
}

GET 请求

public String get(String url, Map<String,Object> params, Map<String,String> headers) {
    StringBuffer bufferRes =null;
    try {
        HttpURLConnection http = initHttp(initParams(url, params), "GET", headers);
        int status = http.getResponseCode();
        InputStream in =null;
        if (status >=400) {
           in = http.getErrorStream();
        }else {
           in = http.getInputStream();
        }
        BufferedReader read =new BufferedReader(new InputStreamReader(in,         DEFAULT_CHARSET));
            String valueString =null;
            bufferRes =new StringBuffer();
            while ((valueString = read.readLine()) !=null) {
                bufferRes.append(valueString);
        }
            in.close();
        if (http !=null) {
            http.disconnect();// 关闭连接
        }
      return bufferRes.toString();
    }catch (Exception e) {
        e.printStackTrace();
        return null;
       }
}


/**
 *初始化参数
 */
public String  initParams(String url, Map<String,Object> params) {
    if (null == params || params.isEmpty()) {
         return url;
    }
    StringBuilder sb =new StringBuilder(url);
     if (url !=null && url.indexOf("?") == -1) {
       sb.append("?");
    }
    sb.append(map2Url(params));
    return sb.toString();
  }
  
/**
 *map转url参数
 */

public String map2Url (Map<String,Object> paramToMap) {
    if (null == paramToMap || paramToMap.isEmpty()) {
        return null;
    }
    StringBuilder url =new StringBuilder();
    boolean isFirst =true; //标记一下是否是第一次，第一次不添加&符合
    for (Entry entry : paramToMap.entrySet()) {
        if (isFirst) {
           isFirst =false;
        }else {
           url.append("&");
        }
       url.append(entry.getKey()).append("=");
       String value =null;
       if (entry.getValue() !=null) {
          value = String.valueOf(entry.getValue());
      }
      if (null == value ||"".equals(value.trim())) {
          try {
              url.append(URLEncoder.encode(value, DEFAULT_CHARSET));
            }catch (UnsupportedEncodingException e) {
            e.printStackTrace();
          }
        }
        url.append(value);
      }
      return url.toString();
}

POST 请求

public static String post(String url, Map<String,Object> param, Map<String,String> headers) {
    StringBuffer bufferRes =null;
        try {
    HttpURLConnection http =initHttp(url, "POST", headers);
    http.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
        http.setDoInput(true);
        if (params !=null) {
          http.setDoOutput(true);
          OutputStreamWriter outs =new OutputStreamWriter(
          http.getOutputStream(), DEFAULT_CHARSET);
            // 发送请求params参数
            String params = mapToJson(param)
            outs.write(params);
            outs.flush();
            outs.close();
        }
        http.connect();
        InputStream inputStream =null;
        int status = http.getResponseCode();
        if (status >=400) {
          inputStream = http.getErrorStream();
        }else {
          inputStream = http.getInputStream();
        }
        BufferedReader read =new BufferedReader(new InputStreamReader(inputStream, DEFAULT_CHARSET));
        String valueString =null;
        bufferRes =new StringBuffer();
        while ((valueString = read.readLine()) !=null) {
            bufferRes.append(valueString);
        }
        if (inputStream !=null) {
          inputStream.close();
        }
        if (http !=null) {
          http.disconnect();// 关闭连接
        }
        return bufferRes.toString();
    }catch (Exception e) {
        e.printStackTrace();
        return null;
    }
}



public String mapToJson(Map map) {
    try {
        JSONObject object =new JSONObject(map);
        return object.toString();
    }catch (Exception e) {
      return "{}";
    }
}