发送HTTP_GET请求 表头application/json

/**
     * 发送HTTP_GET请求
     * 该方法会自动关闭连接,释放资源
     * @param reqURL    请求地址(含参数)
     * @param decodeCharset 解码字符集,解析响应数据时用之,其为null时默认采用UTF-8解码
     * @return 远程主机响应正文
     */
    public static String sendGetRequest(String reqURL,Map<String, String> paramMap, String decodeCharset){
        long responseLength = 0;       //响应长度
        String responseContent = null; //响应内容
        HttpClient httpClient = new DefaultHttpClient(); //创建默认的httpClient实例
        if (!paramMap.isEmpty()) {
            for (String key : paramMap.keySet()) {
                if (reqURL.indexOf('?') == -1) {
                    reqURL += "?" + key+"="+paramMap.get(key);
                } else {
                    reqURL += "&" + key+"="+paramMap.get(key);
                }
            }

        }
        HttpGet httpGet = new HttpGet(reqURL);           //创建org.apache.http.client.methods.HttpGet
        try{
            HttpResponse response = httpClient.execute(httpGet); //执行GET请求
            response.setHeader("Content-Type","application/json");
            HttpEntity entity = response.getEntity();            //获取响应实体
            if(null != entity){
                responseLength = entity.getContentLength();
                responseContent = EntityUtils.toString(entity, decodeCharset==null ? "UTF-8" : decodeCharset);
                EntityUtils.consume(entity); //Consume response content
            }
            System.out.println("请求地址: " + httpGet.getURI());
            System.out.println("响应状态: " + response.getStatusLine());
            System.out.println("响应长度: " + responseLength);
            System.out.println("响应内容: " + responseContent);
        }catch(ClientProtocolException e){
            logger.debug("该异常通常是协议错误导致,比如构造HttpGet对象时传入的协议不对(将'http'写成'htp')或者服务器端返回的内容不符合HTTP协议要求等,堆栈信息如下", e);
        }catch(ParseException e){
            logger.debug(e.getMessage(), e);
        }catch(IOException e){
            logger.debug("该异常通常是网络原因引起的,如HTTP服务器未启动等,堆栈信息如下", e);
        }finally{
            httpClient.getConnectionManager().shutdown(); //关闭连接,释放资源
        }
        return responseContent;
    }