Java如何发送get请求和post请求

Java如何发送get请求，
常见场景，直接上代码

先构建HttpClientUtil工具类

package com.address.http;

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;

public class HttpClientUtil {
    /**
     * 发送get请求
     *
     * @param url   请求URL
     * @param param 请求参数 key:value url携带参数 或者无参可不填
     * @return
     */
    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;
    }

    /**
     * 无参数get请求
     * @param url
     * @return
     */
    public static String doGet(String url) {
        return doGet(url, null);
    }

    /**
     * 发送post请求
     *
     * @param url   请求URL
     * @param param 请求参数 key:value
     * @return
     */
    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 {
                if (response != null) {
                    response.close();
                }
                httpClient.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        return resultString;
    }


    /**
     * 发送post 请求
     *
     * @param url  请求地址
     * @param json 请求参数
     * @return
     */
    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 {
                if (response != null) {
                    response.close();
                }
                httpClient.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return resultString;
    }
}

再来个测试示例

public class getTest {
    public static void main(String[] args) throws IOException {
        Map<String,String> mp = new HashMap<>();
        mp.put("com/address","江苏省南京市江宁区秣陵街道胜太社区双龙大道1539号21世纪国际公寓西区");
//        String res = HttpClientUtil.doGet("http://localhost:8000/standard",mp);
        String res = HttpClientUtil.doGet("http://localhost:8090/test2",mp);
        System.out.println(res);

        mp.put("id","123");
        mp.put("name","张三");

        SimpleDateFormat formatter= new SimpleDateFormat("yyyy-MM-dd 'at' HH:mm:ss z");
        Date date = new Date(System.currentTimeMillis());
        System.out.println("开始时间" + formatter.format(date));
        for(int i=0;i<50000;i++){
            res = HttpClientUtil.doGet("http://localhost:8090/test1?name=张三丰",mp);
        }
        date = new Date(System.currentTimeMillis());
        System.out.println("结束时间" + formatter.format(date));
    }
}

就这么简单，大功告成！