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<String, String> paramMap) throws ClientProtocolException, IOException {        HttpClient httpClient = new DefaultHttpClient();        HttpGet httpGet = new HttpGet();        List<NameValuePair> 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<NameValuePair> setHttpParams(Map<String, String> paramMap) {        List<NameValuePair> formparams = new ArrayList<NameValuePair>();        Set<Map.Entry<String, String>> set = paramMap.entrySet();        for (Map.Entry<String, String> 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 "";    }

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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<String, String> 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<NameValuePair> 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;    }