HttpClient的使用(GET和POST请求、Json参数)

httpClient版本为4.5.3
建议通过HttpGet获取信息，HttpPost提交信息，而HttpGet获取信息时需要提交的参数一般会在url中体现，或者以？ &传参，所以就没写HttpGet带参数的。

添加依赖

        <!--http-->
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient-cache</artifactId>
            <version>4.5.3</version>
        </dependency>

        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpmime</artifactId>
            <version>4.5.3</version>
        </dependency>

        <!-- fastjson -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>

代码实现

import com.alibaba.fastjson.JSON;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.config.RequestConfig;
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.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.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class HttpClientUtils {
    private static final String CONTENT_TYPE_TEXT_JSON = "text/json";

    private static final CloseableHttpClient httpClient = HttpClients.createDefault();

    private static final RequestConfig requestConfig = RequestConfig.custom() 
                                       .setConnectTimeout(2000)
                                       .setSocketTimeout(10000).build();

    /**
     * GET请求  参数携带在url中
     *
     * @param url
     * @return
     */
    public static String executeGet(String url) {
        HttpGet httpGet = new HttpGet(url);
        httpGet.setConfig(requestConfig);
        CloseableHttpResponse response = null;
        String result = null;

        try {
            response = httpClient.execute(httpGet);

            HttpEntity entity = response.getEntity();
            if (entity != null) {
                result = EntityUtils.toString(entity, "UTF-8");
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                response.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return result;
    }

    /**
     * POST请求 带参数
     *
     * @param url 请求地址
     * @param map 参数
     * @return
     */
    public static String executePost(String url, Map<String, String> map) {
        List<NameValuePair> params = new ArrayList<>();
        for (Map.Entry<String, String> entry : map.entrySet()) {
            params.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));
        }
        UrlEncodedFormEntity entity = null;
        String result = null;
        try {
            entity = new UrlEncodedFormEntity(params, "UTF-8");
            HttpPost httpPost = new HttpPost(url);
            httpPost.setConfig(requestConfig);
            httpPost.setEntity(entity);
            CloseableHttpResponse response = httpClient.execute(httpPost);

            HttpEntity httpEntity = response.getEntity();
            result = EntityUtils.toString(httpEntity, "UTF-8");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return result;
    }


    /**
     * POST请求   不带参数
     *
     * @param url
     * @return
     */
    public static String executePost(String url) {
        HttpPost httpPost = new HttpPost(url);
        httpPost.setConfig(requestConfig);
        CloseableHttpResponse response = null;
        String result = null;
        try {
            response = httpClient.execute(httpPost);

            HttpEntity entity = response.getEntity();
            result = EntityUtils.toString(entity, "UTF-8");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }


    /**
     * POST请求   携带Json格式的参数
     *
     * @param url
     * @param param
     * @return
     * @throws IOException
     */
    public static String postJson(String url, Object param) {
        HttpPost httpPost = new HttpPost(url);
        httpPost.setHeader("Content-Type", "application/json;charset=UTF-8");

        httpPost.setConfig(requestConfig);
        String parameter = JSON.toJSONString(param);
        StringEntity se = null;
        try {
            System.out.println(parameter);
            se = new StringEntity(parameter);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        se.setContentType(CONTENT_TYPE_TEXT_JSON);
        httpPost.setEntity(se);

        CloseableHttpResponse response = null;
        String result = null;
        try {
            response = httpClient.execute(httpPost);

            HttpEntity httpEntity = response.getEntity();
            result = EntityUtils.toString(httpEntity, "UTF-8");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return result;
    }
}