依赖导入

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.13</version>
</dependency>

工具类封装

/**
 * @description HttpClient工具类
 * @author LoungeXi
 */
public class HttpClientUtil {

    static final int TIMEOUT_MSEC = 5 * 1000;

    /**
     * @return {@link String}
     * @description Get请求
     * @author LoungeXi
     */
    public static String doGet(String url,Map<String,String> paramMap){
        // 创建Httpclient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String result = "";
        CloseableHttpResponse response = null;
        try{
            URIBuilder builder = new URIBuilder(url);
            if(paramMap != null){
                for (String key : paramMap.keySet()) {
                    builder.addParameter(key,paramMap.get(key));
                }
            }
            URI uri = builder.build();
            //创建GET请求
            HttpGet httpGet = new HttpGet(uri);
            //发送请求
            response = httpClient.execute(httpGet);
            //判断响应状态
            if(response.getStatusLine().getStatusCode() == 200){
                result = EntityUtils.toString(response.getEntity(),"UTF-8");
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            try {
                response.close();
                httpClient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return result;
    }

    /**
     * @return {@link String}
     * @description Post请求 
     * @author LoungeXi
     */
    public static String doPost(String url, Map<String, String> paramMap) throws IOException {
        // 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 (paramMap != null) {
                List<NameValuePair> paramList = new ArrayList();
                for (Map.Entry<String, String> param : paramMap.entrySet()) {
                    paramList.add(new BasicNameValuePair(param.getKey(), param.getValue()));
                }
                // 模拟表单
                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
                httpPost.setEntity(entity);
            }
            httpPost.setConfig(builderRequestConfig());
            // 执行http请求
            response = httpClient.execute(httpPost);
            resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
        } catch (Exception e) {
            throw e;
        } finally {
            try {
                response.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return resultString;
    }

    /**
     * @return {@link String}
     * @description 发送POST方式请求 
     * @author LoungeXi
     */
    public static String doPost4Json(String url, Map<String, String> paramMap) throws IOException {
        // 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);
            if (paramMap != null) {
                //构造json格式数据
                JSONObject jsonObject = new JSONObject();
                for (Map.Entry<String, String> param : paramMap.entrySet()) {
                    jsonObject.put(param.getKey(),param.getValue());
                }
                StringEntity entity = new StringEntity(jsonObject.toString(),"utf-8");
                //设置请求编码
                entity.setContentEncoding("utf-8");
                //设置数据类型
                entity.setContentType("application/json");
                httpPost.setEntity(entity);
            }
            httpPost.setConfig(builderRequestConfig());
            // 执行http请求
            response = httpClient.execute(httpPost);
            resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
        } catch (Exception e) {
            throw e;
        } finally {
            try {
                response.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return resultString;
    }

    /**
     * @return {@link RequestConfig}
     * @description 请求配置 
     * @author LoungeXi    
     * @params * @param 
     */
    private static RequestConfig builderRequestConfig() {
        return RequestConfig.custom()
                .setConnectTimeout(TIMEOUT_MSEC)
                .setConnectionRequestTimeout(TIMEOUT_MSEC)
                .setSocketTimeout(TIMEOUT_MSEC).build();
    }
}

简易介绍

doGet(String url,Map<String,String> paramMap)和doPost(String url, Map<String, String> paramMap)中的参数说明：

• url：发送请求的路径，String类型。
• paramMap:请求所需要携带的参数，参数命和参数值以key和value的形式放入一个Map中。

使用案例

场景

微信小程序实现简单的微信登录调用微信官方提供的接口来获取每一个微信用户的openid作为用户的唯一标识，接口路径为https://api.weixin.qq.com/sns/jscode2session，需要携带的参数为appid、secret、js_code、grant_type。

代码实现

/**
     * @return {@link String}
     * @description 调用微信接口服务，获取微信用户的openId
     * @author LoungeXi
     */
    private String getOpenId(String code){
        Map<String, String> map = new HashMap<>();
        map.put("appid", weChatProperties.getAppid());
        map.put("secret", weChatProperties.getSecret());
        map.put("js_code", code);
        map.put("grant_type", "authorization_code");
        String json = HttpClientUtil.doGet(WX_LOGIN, map);
        JSONObject jsonObject = JSON.parseObject(json);
        return jsonObject.getString("openid");
    }