<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpcore-nio</artifactId>
</dependency>
<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpasyncclient</artifactId>
</dependency>

public class HttpUtil {
    public static final String UTF_8 = "UTF-8";
	/**
	 * get请求
	 * @return
	 */
	public static String doGet(String url) {
        String returnString = null;
        try{
            HttpClient httpclient = HttpClients.createDefault();
            HttpGet request = new HttpGet(url);
            HttpResponse response = httpclient.execute(request);
            int code = response.getStatusLine().getStatusCode();
            if (code == HttpStatus.SC_OK) {//请求成功
                /**读取服务器返回过来的json字符串数据**/
                returnString = EntityUtils.toString(response.getEntity());
            }else{
                log.error("请求返回:"+code+"("+url+")");
            }
        }catch (IOException e) {
        	e.printStackTrace();
        }
        return returnString;
	}

    /**
     * post请求
     * @return
     */
    public static String doPost(String url) {
        String returnString = null;
        try{
            HttpClient httpclient = HttpClients.createDefault();
            HttpPost request = new HttpPost(url);
            HttpResponse response = httpclient.execute(request);
            log.info("返回信息： " + response.toString());
            int code = response.getStatusLine().getStatusCode();
            if (code == HttpStatus.SC_OK) {//请求成功
                log.info("返回200");
                /**读取服务器返回过来的json字符串数据**/
                returnString = EntityUtils.toString(response.getEntity());
            }else{
                log.error("请求返回:"+code+"("+url+")");
            }
        }catch (IOException e) {
            e.printStackTrace();
        }
        return returnString;
    }
	
	/**
	 * post请求(用于map格式的参数)
	 */
	public static String doPost(String url, Map params){
	    String returnString = null;
		BufferedReader in = null;
        CloseableHttpClient httpclient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        try {  
            HttpPost request = new HttpPost(url);
            List<NameValuePair> nvps = new ArrayList<NameValuePair>();
            for (Iterator iter = params.keySet().iterator(); iter.hasNext();) {
    			String name = (String) iter.next();
    			String value = String.valueOf(params.get(name));
    			nvps.add(new BasicNameValuePair(name, value));
    		}
            request.setEntity(new UrlEncodedFormEntity(nvps, UTF_8));
            response = httpclient.execute(request);
            int code = response.getStatusLine().getStatusCode();
            if (code == HttpStatus.SC_OK) {//请求成功
            	in = new BufferedReader(new InputStreamReader(response.getEntity()
                        .getContent(),"utf-8"));
                StringBuffer sb = new StringBuffer("");  
                String line = "";  
                String NL = System.getProperty("line.separator");  
                while ((line = in.readLine()) != null) {  
                    sb.append(line + NL);  
                }
                in.close();
                returnString = sb.toString();
            } else{
                log.error("请求返回:"+code+"("+url+")");
            }
        } catch(Exception e){
        	e.printStackTrace();
        }finally {
            closeResponseAndClient(response,httpclient);
        }
        return returnString;
    }
	
	/**
	 * post请求（用于请求json格式的参数）
	 * @param url
	 * @param params
	 * @return
	 */
	public static String doPost(String url, String params) throws Exception {
        String returnString = null;
		CloseableHttpClient httpclient = HttpClients.createDefault();
		HttpPost httpPost = new HttpPost(url);// 创建httpPost
        StringEntity entity = new StringEntity(params, UTF_8);
        httpPost.setEntity(entity);
        httpPost.setHeader("Accept", "application/json");
    	httpPost.setHeader("Content-Type", "application/json");
        CloseableHttpResponse response = null;
        try {
        	response = httpclient.execute(httpPost);
            StatusLine status = response.getStatusLine();
            int code = response.getStatusLine().getStatusCode();
            if (code == HttpStatus.SC_OK) {//请求成功
            	HttpEntity responseEntity = response.getEntity();
                returnString = EntityUtils.toString(responseEntity);
            }else{
				 log.error("请求返回:"+code+"("+url+")");
			}
        }finally {
            closeResponseAndClient(response,httpclient);
        }
        return returnString;
	}

	private static void closeResponseAndClient(CloseableHttpResponse response,CloseableHttpClient httpclient){
        if (response != null) {
            try {
                response.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        try {
            httpclient.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}