HttpClient的使用（get、post请求）

【bak】https://www.cnblogs.com/uncleyong/p/15859872.html

        
        
            org.apache.httpcomponents
            httpclient
            4.5.6
        

package com.qzcsbj;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;


public class HttpGetRequest {
    public static void main(String[] args) {
        String url = "http://127.0.0.1:9999/download";
        String fname = "qzcsbj.txt";
        Map params = new HashMap();
        params.put("fname", fname);
        String res = getRequest(url, params);
        System.out.println("获取到的结果为：" + res);

    }
    public static String getRequest(String url, Map params){
        String res = "";
        boolean flag = true;
        Set keys = params.keySet();
        for (String key : keys) {
            if (flag){
                url += "?" + key + "=" + params.get(key);
                flag = false;
            }else {
                url += "&" + key + "=" + params.get(key);
            }
        }
        HttpGet httpGet = new HttpGet(url);
        HttpClient httpClient = HttpClients.createDefault();

        try {
            HttpResponse response = httpClient.execute(httpGet);
            res = EntityUtils.toString(response.getEntity());
        } catch (IOException e) {
            e.printStackTrace();
        }
        return res;
    }
}

package com.qzcsbj;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
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.HashMap;
import java.util.Map;
import java.util.Set;


public class HttpPostRequest {
    public static void main(String[] args) {
        String url = "http://127.0.0.1:9999/login";
        HashMap params = new HashMap();
        String username = "qzcsbj";
        String password = "123456";
        params.put("username", username);
        params.put("password", password);
        String res = postRequest(url, params);
        System.out.println("获取到的结果为：" + res);
    }

    public static String postRequest(String url, Map params){
        String res = "";
        HttpPost httpPost = new HttpPost(url);
        ArrayList basicNamevaluePairs = new ArrayList();
        Set keys = params.keySet();
        for (String key : keys) {
            basicNamevaluePairs.add(new BasicNamevaluePair(key,params.get(key)));
        }
        try {
            httpPost.setEntity(new UrlEncodedFormEntity(basicNamevaluePairs,"utf-8"));
            HttpClient httpClient = HttpClients.createDefault();
            HttpResponse httpResponse = httpClient.execute(httpPost);
            res = EntityUtils.toString(httpResponse.getEntity());
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return res;
    }
}