HttpClient的用法

1.1.  功能介绍

以下列出的是 HttpClient 提供的主要的功能，要知道更多详细的功能可以参见 HttpClient 的主页。

（1）实现了所有 HTTP 的方法（GET,POST,PUT,HEAD 等）

（2）支持自动转向

（3）支持 HTTPS 协议

（4）支持代理服务器等

1.1.  项目依赖

<dependency>      <groupId>org.apache.httpcomponents</groupId>       <artifactId>httpclient</artifactid>       <version>4.3.5</version></dependency>

1.2 封装成工具类

public class HttpClientUtil {public static String doGet(String url, Map<String, String> param) {// 创建Httpclient对象CloseableHttpClient httpclient = HttpClients.createDefault();String resultString = "";CloseableHttpResponse response = null;try {// 创建uriURIBuilder builder = new URIBuilder(url);if (param != null) {for (String key : param.keySet()) {builder.addParameter(key, param.get(key));}}URI uri = builder.build();// 创建http GET请求HttpGet httpGet = new HttpGet(uri);// 执行请求response = httpclient.execute(httpGet);// 判断返回状态是否为200if (response.getStatusLine().getStatusCode() == 200) {resultString = EntityUtils.toString(response.getEntity(), "UTF-8");}} catch (Exception e) {e.printStackTrace();} finally {try {if (response != null) {response.close();}httpclient.close();} catch (IOException e) {e.printStackTrace();}}return resultString;}public static String doGet(String url) {return doGet(url, null);}public static String doPost(String url, Map<String, String> param) {// 创建Httpclient对象CloseableHttpClient httpClient = HttpClients.createDefault();CloseableHttpResponse response = null;String resultString = "";try {// 创建Http Post请求HttpPost httpPost = new HttpPost(url);// 创建参数列表if (param != null) {List<NameValuePair> paramList = new ArrayList<>();for (String key : param.keySet()) {paramList.add(new BasicNameValuePair(key, param.get(key)));}// 模拟表单UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);httpPost.setEntity(entity);}// 执行http请求response = httpClient.execute(httpPost);resultString = EntityUtils.toString(response.getEntity(), "utf-8");} catch (Exception e) {e.printStackTrace();} finally {try {response.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}return resultString;}public static String doPost(String url) {return doPost(url, null);}}