• 使用HttpClient发送请求、接收响应


    使用HttpClient发送请求、接收响应很简单,一般需要如下几步即可:

    1. 创建HttpClient对象。

    2. 创建请求方法的实例,并指定请求URL。如果需要发送GET请求,创建HttpGet对象;如果需要发送POST请求,创建HttpPost对象。

    3. 如果需要发送请求参数,可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法来添加请求参数;对于HttpPost对象而言,也可调用setEntity(HttpEntity entity)方法来设置请求参数。

    4. 调用HttpClient对象的execute(HttpUriRequest request)发送请求,该方法返回一个HttpResponse。

    5. 调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取服务器的响应头;调用HttpResponse的getEntity()方法可获取HttpEntity对象,该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。

    6. 释放连接。无论执行方法是否成功,都必须释放连接

    后台代码:

    import java.io.IOException;
    import java.net.URI;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;
    
    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;
    
    
      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;
        }
    用Httpclient对象对接学习记录,此文参考和转载自https://www.cnblogs.com/guxiong/p/6661272.html;

    http协议POST请求application/json格式:
    package com.xxx.util;
    
    import org.apache.http.HttpResponse;
    import org.apache.http.HttpStatus;
    import org.apache.http.client.HttpClient;
    import org.apache.http.client.methods.HttpPost;
    import org.apache.http.entity.StringEntity;
    import org.apache.http.impl.client.HttpClientBuilder;
    import org.apache.http.protocol.HTTP;
    import org.apache.http.util.EntityUtils;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    import java.io.IOException;
    
    public class HttpUtil {
    
        private static Logger logger = LoggerFactory.getLogger(HttpUtil.class.getName());
    
        private static HttpClient httpClient = HttpClientBuilder.create().build();
        private final static String CHARSET = "UTF-8";
    
        public static String post(String url, String json) {
            HttpPost post = new HttpPost(url);
            post.addHeader(HTTP.CONTENT_TYPE, "application/json");
            StringEntity entity = new StringEntity(json, CHARSET);
            post.setEntity(entity);
            try {
                HttpResponse response = httpClient.execute(post);
                if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                    if (response.getEntity() != null) {
                        return EntityUtils.toString(response.getEntity(), CHARSET);
                    }
                }
                throw new IOException("请求出错");
            } catch (IOException e) {
                e.printStackTrace();
                logger.error(e.getMessage());
            }
            return null;
        }
    
    }
  • 相关阅读:
    一款全屏图片滑动js 插件 超快捷
    19个非常有用的 jQuery 图片滑动插件和教程
    sqlite 下载的 ZIP 包的区别
    get utc+8 当时时间
    http://www.dayandeng.com/ 诈骗网站
    This implementation is not part of the Windows Platform FIPS validated cryptographic algorithms
    c# string 数组转 list
    sql在添加新列时同时指定default约束名称
    windows证书地址
    Value Dispose() cannot be called while doing CreateHandle().
  • 原文地址:https://www.cnblogs.com/wmqiang/p/10500832.html
Copyright © 2020-2023  润新知