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。

       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 clientclient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 clientclient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:// HttpGetrequest = new HttpGet(url);break;case 1:// HttpPostrequest = new HttpPost(url);break;case 2:// HttpHeadrequest = new HttpHead(url);break;case 3:// HttpPutrequest = new HttpPut(url);break;case 4:// HttpDeleterequest = new HttpDelete(url);break;case 5:// HttpTracerequest = new HttpTrace(url);break;case 6:// HttpPatchrequest = new HttpPatch(url);break;case 7:// HttpOptionsrequest = 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 respHttpResponse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。

       由于HttpClient和Header都作为参数传入，所以也可以进行扩展，比如代理、ssl等都是对HttpClient进行配置的，下面的文章就分别分享一下如何插件式配置HttpClient以及Header。敬请期待。

       代码已上传至：https://github.com/Arronlong/httpclientUtil。

       httpclientUtil （QQ交流群:548452686 ）