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：
- 创建请求对象request；
- 为request设置header信息；
- 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。
- 执行请求，并拿到结果（同步阻塞）；
- 获取并解码请求结果实体；
- 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。
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。
