HttpClientUtil

1.首先引入maven坐标

 <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpmime</artifactId>
            <version>4.3.6</version>
        </dependency>

2.编写HttpClientUtil工具类

import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * @Author zz
 * @DATE 2020/10/25.
 */
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uri
            URIBuilder 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200
            if (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 block
                e.printStackTrace();
            }
        }

        return resultString;
    }

    public static String doPost(String url) {
    
        return doPost(url, null);
    }

    public static String doPostJson(String url, String json) {
    
        // 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);
            // 创建请求内容
            StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
            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 block
                e.printStackTrace();
            }
        }

        return resultString;
    }
}

3.该工具类接收的返回值为String 类型。可通过
JSONObject jsonObject = new JSONObject(HttpClientUtil.doGet(path));
方式把字符串转换成json。 之后通过 get方法可以获取json里的值。如下代码。

JSONObject jsonObject = new JSONObject(HttpClientUtil.doGet(path));
       String access_token = (String) jsonObject.get("access_token");