用Httpclient通过post方式来实现http请求

Http协议的重要性这里不多介绍，基于上一篇介绍Http请求的GET和POST方式，这篇继续用Httpclient通过post方式来实现Http请求。先简单介绍一下Httpclient。Httpclient相比传统JDK自带的URL Connection增加了易用性和灵活性，它支持Http协议，提供了功能丰富的工具包，不仅让客户端发送Http请求变得容易，而且也提高了开发人员的开发效率。

下面重点介绍一下使用方法，首先，pom文件

<!-- httpClient --><dependency>      <groupId>org.apache.httpcomponents</groupId>      <artifactId>httpclient</artifactId>      <version>4.3.6</version>  </dependency><dependency>    <groupId>commons-logging</groupId>    <artifactId>commons-logging</artifactId>    <version>1.2</version></dependency><dependency>    <groupId>net.sf.json-lib</groupId>    <artifactId>json-lib</artifactId>    <version>2.4</version>    <classifier>jdk15</classifier></dependency><!-- json-lib还需要以下依赖包 -->        <dependency>        <groupId>commons-lang</groupId>        <artifactId>commons-lang</artifactId>        <version>2.5</version>    </dependency>    <dependency>        <groupId>commons-beanutils</groupId>        <artifactId>commons-beanutils</artifactId>        <version>1.9.2</version>    </dependency>    <dependency>        <groupId>commons-collections</groupId>        <artifactId>commons-collections</artifactId>        <version>3.2.1</version>    </dependency>

具体代码如下：

public class HttpclientDemo {public List<DemoTypeEntity> getDemoList(String demoName, String demoStatus){List<String> resultList = new ArrayList<String>();CloseableHttpClient httpClient = HttpClients.createDefault();CloseableHttpResponse httpResponse = null;//URLString url = "http://192.168.0.1/httpclientDemo/service/getDemoList.do";//封装请求参数List<NameValuePair> params = Lists.newArrayList();params.add(new BasicNameValuePair("demoName", demoName));params.add(new BasicNameValuePair("demoStatus", demoStatus));try{//转换键值对String str = EntityUtils.toString(new UrlEncodedFormEntity(params, Consts.UTF_8));//创建请求--getHttpGet httpGet = new HttpGet(url+"?"+str);httpResponse = httpClient.execute(httpGet);//判断状态码if(httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK){//解析结果String result = EntityUtils.toString(httpResponse.getEntity());JSONArray jsonArray = JSONArray.fromObject(result);resultList = JSONArray.toList(jsonArray, new DemoTypeEntity(), new JsonConfig());}//释放连接httpResponse.close();}catch(Exception e){e.printStackTrace();}return resultList;}}

具体的调用过程如下：

1.创建CloseableHttpClient对象
2.设置请求参数
3.创建请求方法的实例，如果需要发送GET请求则创建HttpGet对象，如果需要发送POST请求则创建HttpPost对象，我们这里创建的是HttpGet对象
4.指定URL
5.设置头信息
6.调用CloseableHttpClient对象的execute方法，返回一个CloseableHttpResponse对象
解析结果时需要注意，通过调用CloseableHttpClient对象的execute方法，返回一个CloseableHttpResponse对象，返回的对象调用getEntity方法可获取HttpEntity对象，该对象包含了服务器的响应内容