HttpClient的HttpGet和HttpPost工具类

目前大大小小的项目中，都不可避免两个系统之间的通讯交互，此处简单整理一下关于HttpClient常用的HttpGet和HttpPost这两个类的编码方式。

HttpClient常用的HttpGet和HttpPost这两个类分别对应Get方式和Post方式。

无论是使用HttpGet，还是使用HttpPost，都必须通过如下3步来访问HTTP资源。

1.创建HttpGet或HttpPost对象，将要请求的URL通过构造方法传入HttpGet或HttpPost对象。

2.使用DefaultHttpClient类的execute方法发送HTTP GET或HTTP POST请求，并返回HttpResponse对象。

3.通过HttpResponse接口的getEntity方法返回响应信息，并进行相应的处理。

如果使用HttpPost方法提交HTTP POST请求，则需要使用HttpPost类的setEntity方法设置请求参数。参数则必须用NameValuePair[]数组存储。

首先介绍HttpGet方式请求：

无参数的Get请求

    /**
     * 封装HTTP GET方法
     * 无参数的Get请求
     * @param
     * @return
     * @throws ClientProtocolException
     * @throws java.io.IOException
     */
    public static String get(String url) throws ClientProtocolException, IOException {
        //首先需要先创建一个DefaultHttpClient的实例
        HttpClient httpClient = new DefaultHttpClient();
        //先创建一个HttpGet对象,传入目标的网络地址,然后调用HttpClient的execute()方法即可:
        HttpGet httpGet = new HttpGet();
        httpGet.setURI(URI.create(url));
        HttpResponse response = httpClient.execute(httpGet);
        String httpEntityContent = getHttpEntityContent(response);
        httpGet.abort();
        return httpEntityContent;
    }

有参数的Get请求

 /**
     * 封装HTTP GET方法
     * 有参数的Get请求
     * @param
     * @param
     * @return
     * @throws ClientProtocolException
     * @throws java.io.IOException
     */
    public static String get(String url, Map paramMap) throws ClientProtocolException, IOException {
        HttpClient httpClient = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet();
        List formparams = setHttpParams(paramMap);
        String param = URLEncodedUtils.format(formparams, "UTF-8");
        httpGet.setURI(URI.create(url + "?" + param));
        HttpResponse response = httpClient.execute(httpGet);
        String httpEntityContent = getHttpEntityContent(response);
        httpGet.abort();
        return httpEntityContent;
    }

构造请求参数的公共方法（setHttpParams）

    /**
     * 设置请求参数
     * @param
     * @return
     */
    private static List setHttpParams(Map paramMap) {
        List formparams = new ArrayList();
        Set> set = paramMap.entrySet();
        for (Map.Entry entry : set) {
            formparams.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));
        }
        return formparams;
    }

获得响应HTTP实体内容（getHttpEntityContent）

/**
     * 获得响应HTTP实体内容
     * @param response
     * @return
     * @throws java.io.IOException
     * @throws java.io.UnsupportedEncodingException
     */
    private static String getHttpEntityContent(HttpResponse response) throws IOException, UnsupportedEncodingException {
       //通过HttpResponse 的getEntity()方法获取返回信息
        HttpEntity entity = response.getEntity();
        if (entity != null) {
            InputStream is = entity.getContent();
            BufferedReader br = new BufferedReader(new InputStreamReader(is, "UTF-8"));
            String line = br.readLine();
            StringBuilder sb = new StringBuilder();
            while (line != null) {
                sb.append(line + "\n");
                line = br.readLine();
            }
            br.close();
            is.close();
            return sb.toString();
        }
        return "";
    }

---

POST 请求

/**
     * 封装支付HTTP POST方法
     * @param
     * @param
     * @return
     * @throws ClientProtocolException
     * @throws java.io.IOException
     */
    public static String postPayMsg(String url, Map paramMap) throws ClientProtocolException, IOException {
        HttpClient httpClient = new DefaultHttpClient();
        httpClient.getParams().setIntParameter(CoreConnectionPNames.SO_TIMEOUT, 5000);  
        httpClient.getParams().setIntParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 3000);
        HttpPost httpPost = new HttpPost(url);
        List formparams = setHttpParams(paramMap);
        UrlEncodedFormEntity param = new UrlEncodedFormEntity(formparams, "UTF-8");
        //通过setEntity()设置参数给post
        httpPost.setEntity(param);
        //利用httpClient的execute()方法发送请求并且获取返回参数
        HttpResponse response = httpClient.execute(httpPost);
        String httpEntityContent = getHttpEntityContent(response);
        httpPost.abort();
        return httpEntityContent;
    }