转:轻松把玩HttpClient之封装HttpClient工具类(一)（现有网上分享中的最强大的工具类）

    搜了一下网络上别人封装的HttpClient，大部分特别简单，有一些看起来比较高级，但是用起来都不怎么好用。调用关系不清楚，结构有点混乱。所以也就萌生了自己封装HttpClient工具类的想法。要做就做最好的，本工具类支持插件式配置Header、插件式配置httpclient对象，这样就可以方便地自定义header信息、配置ssl、配置proxy等。

 　　相关jar包下载:http://search.maven.org/#search%7Cga%7C1%7Chttpasyncclient

       是不是觉得说的有点悬乎了，那就先看看调用吧：

 　public static void testSimple() throws HttpProcessException{
        String url = "http://www.oschina.net";
        //简单调用
        String resp = HttpClientUtil.send(url);
        System.out.println("请求结果内容长度："+ resp.length());
    }

    public static void testOne() throws HttpProcessException{
        String url = "https://sso.tgb.com:8443/cas/login";

        //自定义HttpClient，设置超时、代理、ssl
        //HttpClient client= HCB.custom().timeout(10000).proxy("127.0.0.1", 8087).ssl().build();//采用默认方式（绕过证书验证）
        HttpClient client= HCB.custom().timeout(10000).ssl("D:\keys\wsriakey","tomcat").build();

        //设置header信息
        Header[] headers=HttpHeader.custom().keepAlive("false").connection("close").contentType(Headers.APP_FORM_URLENCODED).build();

        //执行请求
        String resp=HttpClientUtil.send(client, url, headers);
        System.out.println("请求结果如下：");
        System.out.println(resp);
    }

       轻松配置了代理、自定义证书的ssl、以及各种header头信息，是不是觉得还凑合呢，那就继续看吧。

       写这个工具类时，抽象了一下所有的demo，最后封装了一个最基本的方法（拆分成了2个方法了），其所有参数列表有：HttpClient对象、url(必须有)、请求方式、请求参数parasMap、header数组、编码格式encoding。

       由于封装的是工具类，所以最好是无状态的，可以支持多线程的方式调用的，所以方法都是static类型的。这也是为什么要把HttpClient对象也是作为了一个参数传入而非成员变量了，而且这样也为扩展HttpClient的配置提供了便利。

       因为HTTP1.1规范中定义了6种HTTP方法：GET, HEAD, POST, PUT, DELETE, TRACE 和 OPTIONS，其实还有一个PATCH，这几个方法在HttpClient中都有一个对应的类：HttpGet，HttpHead，HttpPost，HttpPut，HttpDelete，HttpTrace、HttpOptions以及HttpPatch。所有的这些类均继承了HttpRequestBase超类，故可以作为参数使用（用枚举类作为参数，用另一个方法来创建具体的请求方法对象）。

       Header头信息也是作为一个重要的参数，在请求特定网站的时候需要设置不同的Header，而header又是比较繁杂的，所以这里也是作为了一个参数传入的，也是方便扩展。

       使用map来作为post方式传入参数是习惯使然，不做过多的解释。

       编码这个参数主要是为了为待提交的数据和反馈结果进行转码处理。

       简单说一下流程：

1. 创建请求对象request；
2. 为request设置header信息；
3. 判断当前请求对象是否是HttpEntityEnclosingRequestBase的子类，如果是，则支持setEntity方法，来设置参数。
4. 执行请求，并拿到结果（同步阻塞）；
5. 获取并解码请求结果实体；
6. 关闭链接

       就是这么简单，具体来看看代码吧：

  /**
     * 请求资源或服务，自定义client对象，传入请求参数，设置内容类型，并指定参数和返回数据的编码
     *
     * @param client        client对象
     * @param url           资源地址
     * @param httpMethod    请求方法
     * @param parasMap      请求参数
     * @param headers       请求头信息
     * @param encoding      编码
     * @return              返回处理结果
     * @throws HttpProcessException
     */
    public static String send(HttpClient client, String url, HttpMethods httpMethod, Map<String,String>parasMap,
                Header[] headers, String encoding) throws HttpProcessException {
        String body = "";
        try {
            //创建请求对象
            HttpRequestBase request = getRequest(url, httpMethod);

            //设置header信息
            request.setHeaders(headers);

            //判断是否支持设置entity(仅HttpPost、HttpPut、HttpPatch支持)
            if(HttpEntityEnclosingRequestBase.class.isAssignableFrom(request.getClass())){
                List<NameValuePair> nvps = new ArrayList<NameValuePair>();

                //检测url中是否存在参数
                url = Utils.checkHasParas(url, nvps);

                //装填参数
                Utils.map2List(nvps, parasMap);

                //设置参数到请求对象中
                ((HttpEntityEnclosingRequestBase)request).setEntity(new UrlEncodedFormEntity(nvps, encoding));

                logger.debug("请求地址："+url);
                if(nvps.size()>0){
                    logger.debug("请求参数："+nvps.toString());
                }
            }else{
                int idx = url.indexOf("?");
                logger.debug("请求地址："+url.substring(0, (idx>0 ? idx-1:url.length()-1)));
                if(idx>0){
                    logger.debug("请求参数："+url.substring(idx+1));
                }
            }

            //调用发送请求
            body = execute(client, request, url, encoding);

        } catch (UnsupportedEncodingException e) {
            throw new HttpProcessException(e);
        }
        return body;
    }


    /**
     * 请求资源或服务
     *
     * @param client        client对象
     * @param request       请求对象
     * @param url           资源地址
     * @param parasMap      请求参数
     * @param encoding      编码
     * @return              返回处理结果
     * @throws HttpProcessException
     */
    private static String execute(HttpClient client, HttpRequestBase request,String url, String encoding) throws HttpProcessException {
        String body = "";
        HttpResponse response =null;
        try {

            //执行请求操作，并拿到结果（同步阻塞）
            response = client.execute(request);

            //获取结果实体
            HttpEntity entity = response.getEntity();

            if (entity != null) {
                //按指定编码转换结果实体为String类型
                body = EntityUtils.toString(entity, encoding);
                logger.debug(body);
            }
            EntityUtils.consume(entity);
        } catch (ParseException | IOException e) {
            throw new HttpProcessException(e);
        } finally {
            close(response);
        }

        return body;
    }

       第一个方法中，我们看到有HttpMethods类型的参数，在创建request对象时，用到了它。它是什么呢？其实只是一个枚举类：

     /**
     * 枚举HttpMethods方法
     *
     * @author arron
     * @date 2015年11月17日 下午4:45:59
     * @version 1.0
     */
    public enum HttpMethods{

        /**
         * 求获取Request-URI所标识的资源
         */
        GET(0, "GET"),

        /**
         * 向指定资源提交数据进行处理请求（例如提交表单或者上传文件）。数据被包含在请求体中。
         * POST请求可能会导致新的资源的建立和/或已有资源的修改
         */
        POST(1, "POST"),

        /**
         * 向服务器索要与GET请求相一致的响应，只不过响应体将不会被返回。
         * 这一方法可以在不必传输整个响应内容的情况下，就可以获取包含在响应消息头中的元信息
         * 只获取响应信息报头
         */
        HEAD(2, "HEAD"),

        /**
         * 向指定资源位置上传其最新内容（全部更新，操作幂等）
         */
        PUT (3, "PUT"),

        /**
         * 请求服务器删除Request-URI所标识的资源
         */
        DELETE  (4, "DELETE"),

        /**
         * 请求服务器回送收到的请求信息，主要用于测试或诊断
         */
        TRACE(5, "TRACE"),

        /**
         * 向指定资源位置上传其最新内容（部分更新，非幂等）
         */
        PATCH   (6, "PATCH"),

        /**
         * 返回服务器针对特定资源所支持的HTTP请求方法。
         * 也可以利用向Web服务器发送'*'的请求来测试服务器的功能性
         */
        OPTIONS (7, "OPTIONS"),

//      /**
//       * HTTP/1.1协议中预留给能够将连接改为管道方式的代理服务器
//       */
//      CONNECT(99, "CONNECT"),
        ;

        private int code;
        private String name;

        private HttpMethods(int code, String name){
            this.code = code;
            this.name = name;
        }
        public String getName() {
            return name;
        }
        public int getCode() {
            return code;
        }
    }

通过getRequest方法，来实例化对应方法的请求对象。

     /**
     * 根据请求方法名，获取request对象
     *
     * @param url                   资源地址
     * @param method            请求方式
     * @return
     */
    private static HttpRequestBase getRequest(String url, HttpMethods method) {
        HttpRequestBase request = null;
        switch (method.getCode()) {
            case 0:// HttpGet
                request = new HttpGet(url);
                break;
            case 1:// HttpPost
                request = new HttpPost(url);
                break;
            case 2:// HttpHead
                request = new HttpHead(url);
                break;
            case 3:// HttpPut
                request = new HttpPut(url);
                break;
            case 4:// HttpDelete
                request = new HttpDelete(url);
                break;
            case 5:// HttpTrace
                request = new HttpTrace(url);
                break;
            case 6:// HttpPatch
                request = new HttpPatch(url);
                break;
            case 7:// HttpOptions
                request = new HttpOptions(url);
                break;
            default:
                request = new HttpPost(url);
                break;
        }
        return request;
    }

当然最后的关闭链接也是一个小方法：

  /**
     * 尝试关闭response
     *
     * @param resp              HttpResponse对象
     */
    private static void close(HttpResponse resp) {
        try {
            if(resp == null) return;
            //如果CloseableHttpResponse 是resp的父类，则支持关闭
            if(CloseableHttpResponse.class.isAssignableFrom(resp.getClass())){
                ((CloseableHttpResponse)resp).close();
            }
        } catch (IOException e) {
            logger.error(e);
        }
    }

       当然各种参数的组合方法也简单提供一下（为了节约空间，已去掉注释）：

 public static String send(String url) throws HttpProcessException {
        return send(url, Charset.defaultCharset().name());
    }
    public static String send(String url, String encoding) throws HttpProcessException {
        return send(url, new Header[]{},encoding);
    }
    public static String send(String url, Header[] headers) throws HttpProcessException {
        return send(url, headers, Charset.defaultCharset().name());
    }
    public static String send(String url, Header[] headers, String encoding) throws HttpProcessException {
        return send(url, new HashMap<String,String>(), headers, encoding);
    }
    public static String send(String url, Map<String,String>parasMap) throws HttpProcessException {
        return send(url, parasMap, Charset.defaultCharset().name());
    }
    public static String send(String url, Map<String,String>parasMap, String encoding) throws HttpProcessException {
        return send(url, parasMap, new Header[]{}, encoding);
    }
    public static String send(String url, Map<String,String>parasMap, Header[] headers) throws HttpProcessException {
        return send(url, parasMap, headers, Charset.defaultCharset().name());
    }
    public static String send(String url, Map<String,String>parasMap, Header[] headers, String encoding) throws HttpProcessException {
        return send(url, HttpMethods.POST, parasMap, headers, encoding);
    }
    public static String send(String url, HttpMethods httpMethod) throws HttpProcessException {
        return send(url, httpMethod, Charset.defaultCharset().name());
    }
    public static String send(String url, HttpMethods httpMethod, String encoding) throws HttpProcessException {
        return send(url, httpMethod, new Header[]{},encoding);
    }
    public static String send(String url, HttpMethods httpMethod, Header[] headers) throws HttpProcessException {
        return send(url, httpMethod, headers, Charset.defaultCharset().name());
    }
    public static String send(String url, HttpMethods httpMethod, Header[] headers, String encoding) throws HttpProcessException {
        return send(url, httpMethod, new HashMap<String, String>(), headers, encoding);
    }
    public static String send(String url, HttpMethods httpMethod, Map<String,String>parasMap) throws HttpProcessException {
        return send(url, httpMethod, parasMap, Charset.defaultCharset().name());
    }
    public static String send(String url, HttpMethods httpMethod, Map<String,String>parasMap, String encoding) throws HttpProcessException {
        return send(url, httpMethod, parasMap, new Header[]{}, encoding);
    }
    public static String send(String url, HttpMethods httpMethod, Map<String,String>parasMap, Header[] headers) throws HttpProcessException {
        return send(url, httpMethod, parasMap, headers, Charset.defaultCharset().name());
    }
    public static String send(String url, HttpMethods httpMethod, Map<String,String>parasMap, Header[] headers, String encoding) throws HttpProcessException {
        return send(create(url), url, httpMethod, parasMap, headers, encoding);
    }

    public static String send(HttpClient client, String url) throws HttpProcessException {
        return send(client, url, Charset.defaultCharset().name());
    }
    public static String send(HttpClient client, String url, String encoding) throws HttpProcessException {
        return send(client, url, new Header[]{}, encoding);
    }
    public static String send(HttpClient client, String url, Header[] headers) throws HttpProcessException {
        return send(client, url, headers, Charset.defaultCharset().name());
    }
    public static String send(HttpClient client, String url, Header[] headers, String encoding) throws HttpProcessException {
        return send(client, url, new HashMap<String, String>(), headers, encoding);
    }
    public static String send(HttpClient client, String url, Map<String,String>parasMap) throws HttpProcessException {
        return send(client, url, parasMap, Charset.defaultCharset().name());
    }
    public static String send(HttpClient client, String url, Map<String,String>parasMap, String encoding) throws HttpProcessException {
        return send(client, url, parasMap, new Header[]{}, encoding);
    }
    public static String send(HttpClient client, String url, Map<String,String>parasMap, Header[] headers) throws HttpProcessException {
        return send(client, url, parasMap, headers, Charset.defaultCharset().name());
    }
    public static String send(HttpClient client, String url, Map<String,String>parasMap,Header[] headers,String encoding) throws HttpProcessException {
        return send(client, url, HttpMethods.POST, parasMap, headers, encoding);
    }
    public static String send(HttpClient client, String url, HttpMethods httpMethod) throws HttpProcessException {
        return send(client, url, httpMethod, Charset.defaultCharset().name());
    }
    public static String send(HttpClient client, String url, HttpMethods httpMethod, String encoding) throws HttpProcessException {
        return send(client, url, httpMethod, new Header[]{}, encoding);
    }
    public static String send(HttpClient client, String url, HttpMethods httpMethod, Header[] headers) throws HttpProcessException {
        return send(client, url, httpMethod, headers, Charset.defaultCharset().name());
    }
    public static String send(HttpClient client, String url, HttpMethods httpMethod, Header[] headers, String encoding) throws HttpProcessException {
        return send(client, url, httpMethod, new HashMap<String, String>(), headers, encoding);
    }
    public static String send(HttpClient client, String url, HttpMethods httpMethod, Map<String,String>parasMap) throws HttpProcessException {
        return send(client, url, httpMethod, parasMap, Charset.defaultCharset().name());
    }
    public static String send(HttpClient client, String url, HttpMethods httpMethod, Map<String,String>parasMap, String encoding) throws HttpProcessException {
        return send(client, url, httpMethod, parasMap, new Header[]{}, encoding);
    }
    public static String send(HttpClient client, String url, HttpMethods httpMethod, Map<String,String>parasMap, Header[] headers) throws HttpProcessException {
        return send(client, url, httpMethod, parasMap, headers, Charset.defaultCharset().name());
    }

       可以看到上面这一堆方法，其实主要分成2类，一类是传入client对象的，一组是没有传入的。也就是说该工具类提供了一种默认的client对象。这个将会在下一篇文章会有补充。

       当然，为了方便操作，还是提供了get、post、put、patch、delete、head、options、trace等方法，由于推荐使用send方法，所以这几个方法只是做了一个简单的调用：

    public static String get(String url, Header[] headers,String encoding) throws HttpProcessException {
        return get(create(url), url, headers, encoding);
    }
    public static String get(HttpClient client, String url, Header[] headers,String encoding) throws HttpProcessException {
        return send(client, url, HttpMethods.GET, headers, encoding);
    }

    public static String post(String url, Map<String,String>parasMap,Header[] headers,String encoding) throws HttpProcessException {
        return post(create(url), url, parasMap, headers, encoding);
    }
    public static String post(HttpClient client, String url, Map<String,String>parasMap,Header[] headers,String encoding) throws HttpProcessException {
        return send(client, url, HttpMethods.POST, parasMap, headers, encoding);
    }

    public static String put(String url, Map<String,String>parasMap,Header[] headers,String encoding) throws HttpProcessException {
        return put(create(url), url, parasMap, headers, encoding);
    }
    public static String put(HttpClient client, String url, Map<String,String>parasMap,Header[] headers,String encoding) throws HttpProcessException {
        return send(client, url, HttpMethods.PUT, parasMap, headers, encoding);
    }

    public static String delete(String url, Header[] headers,String encoding) throws HttpProcessException {
        return delete(create(url), url, headers, encoding);
    }
    public static String delete(HttpClient client, String url, Header[] headers,String encoding) throws HttpProcessException {
        return send(client, url, HttpMethods.DELETE, headers, encoding);
    }

    public static String patch(String url, Map<String,String>parasMap,Header[] headers,String encoding) throws HttpProcessException {
        return patch(create(url), url, parasMap, headers, encoding);
    }
    public static String patch(HttpClient client, String url, Map<String,String>parasMap, Header[] headers,String encoding) throws HttpProcessException {
        return send(client, url, HttpMethods.PATCH, parasMap, headers, encoding);
    }

    public static String head(String url, Header[] headers,String encoding) throws HttpProcessException {
        return head(create(url), url, headers, encoding);
    }
    public static String head(HttpClient client, String url, Header[] headers,String encoding) throws HttpProcessException {
        return send(client, url, HttpMethods.HEAD, headers, encoding);
    }

    public static String options(String url, Header[] headers,String encoding) throws HttpProcessException {
        return options(create(url), url, headers, encoding);
    }
    public static String options(HttpClient client, String url, Header[] headers,String encoding) throws HttpProcessException {
        return send(client, url, HttpMethods.OPTIONS, headers, encoding);
    }

    public static String trace(String url, Header[] headers,String encoding) throws HttpProcessException {
        return trace(create(url), url, headers, encoding);
    }
    public static String trace(HttpClient client, String url, Header[] headers,String encoding) throws HttpProcessException {
        return send(client, url, HttpMethods.TRACE, headers, encoding);
    }

       差点忘记了，最后还有一个简单的通用工具类

/**
 *
 * @author arron
 * @date 2015年11月10日 下午12:49:26
 * @version 1.0
 */
public class Utils {

    /**
     * 检测url是否含有参数，如果有，则把参数加到参数列表中
     *
     * @param url                   资源地址
     * @param nvps              参数列表
     * @return  返回去掉参数的url
     */
    public static String checkHasParas(String url, List<NameValuePair> nvps) {
        // 检测url中是否存在参数
        if (url.contains("?") && url.indexOf("?") < url.indexOf("=")) {
            Map<String, String> map = buildParas(url.substring(url
                    .indexOf("?") + 1));
            map2List(nvps, map);
            url = url.substring(0, url.indexOf("?"));
        }
        return url;
    }

    /**
     * 参数转换，将map中的参数，转到参数列表中
     *
     * @param nvps              参数列表
     * @param map               参数列表（map）
     */
    public static void map2List(List<NameValuePair> nvps, Map<String, String> map) {
        if(map==null) return;
        // 拼接参数
        for (Entry<String, String> entry : map.entrySet()) {
            nvps.add(new BasicNameValuePair(entry.getKey(), entry
                    .getValue()));
        }
    }


    /**
     * 生成参数
     * 参数格式“k1=v1&k2=v2”
     *
     * @param paras             参数列表
     * @return                      返回参数列表（map）
     */
    public static Map<String,String> buildParas(String paras){
        String[] p = paras.split("&");
        String[][] ps = new String[p.length][2];
        int pos = 0;
        for (int i = 0; i < p.length; i++) {
            pos = p[i].indexOf("=");
            ps[i][0]=p[i].substring(0,pos);
            ps[i][1]=p[i].substring(pos+1);
            pos = 0;
        }
        return buildParas(ps);
    }

    /**
     * 生成参数
     * 参数类型：{{"k1","v1"},{"k2","v2"}}
     *
     * @param paras                 参数列表
     * @return                      返回参数列表（map）
     */
    public static Map<String,String> buildParas(String[][] paras){
        // 创建参数队列
        Map<String,String> map = new HashMap<String, String>();
        for (String[] para: paras) {
            map.put(para[0], para[1]);
        }
        return map;
    }

}

       简单的封装就是这样了。