Apache HttpClient

谁践踏了优雅 2023-10-11 11:12 27阅读 0赞

**一、Apache HttpClient：**

HttpClient 是 Apache Jakarta Common 下的子项目，用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。HttpClient 已经应用在很多的项目中，比如 Apache Jakarta 上很著名的另外两个开源项目 Cactus 和 HTMLUnit 都使用了 HttpClient。

**二、Apache HttpClient 使用流程：**

*  创建 `HttpClient` 对象。
 *  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。
 *  如果需要发送请求参数，可调用 `HttpGet`、`HttpPost` 共同的 `setParams(HttpParams 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。
 *  调用 `HttpClient` 对象的 `execute(HttpUriRequest request)` 发送请求，该方法返回一个 `HttpResponse`。
 *  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。
 *  释放连接。无论执行方法是否成功，都必须释放连接

**三、示例：**

（1）依赖：

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<dependency>
                <groupId>org.apache.httpcomponents</groupId>
                <artifactId>httpclient</artifactId>
                <version>4.5.5</version>
            </dependency>
            <dependency>
                <groupId>org.apache.httpcomponents</groupId>
                <artifactId>fluent-hc</artifactId>
                <version>4.5.5</version>
            </dependency>
            <dependency>
                <groupId>org.apache.httpcomponents</groupId>
                <artifactId>httpmime</artifactId>
                <version>4.5.5</version>
            </dependency>

pom.xml

（2）测试：

public class HttpClientTest {
        public static void main(String[] args) {
            get();
        }
        private static void get() {
            // 创建 HttpClient 客户端
            CloseableHttpClient httpClient = HttpClients.createDefault();
    
            // 创建 HttpGet 请求
            HttpGet httpGet = new HttpGet("http://www.baidu.com");
            // 设置长连接
            httpGet.setHeader("Connection", "keep-alive");
            // 设置代理（模拟浏览器版本）
            httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36");
            // 设置 Cookie
            httpGet.setHeader("Cookie", "UM_distinctid=16442706a09352-0376059833914f-3c604504-1fa400-16442706a0b345; CNZZDATA1262458286=1603637673-1530123020-%7C1530123020; JSESSIONID=805587506F1594AE02DC45845A7216A4");
    
            CloseableHttpResponse httpResponse = null;
            try {
                // 请求并获得响应结果
                httpResponse = httpClient.execute(httpGet);
                HttpEntity httpEntity = httpResponse.getEntity();
                // 输出请求结果
                System.out.println(EntityUtils.toString(httpEntity));
            } catch (IOException e) {
                e.printStackTrace();
            }
    
            // 无论如何必须关闭连接
            finally {
                if (httpResponse != null) {
                    try {
                        httpResponse.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if (httpClient != null) {
                    try {
                        httpClient.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }

**四、工具类：**

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import org.apache.http.HttpEntity;
    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.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.util.Arrays;
    
    /**
     * HttpClient工具类
     */
    public class HttpClientUtils {
        private static final String REQUEST_METHOD_GET = "GET";
        private static final String REQUEST_METHOD_POST = "POST";
        private static final String REQUEST_HEADER_CONNECTION = "keep-alive";
        private static final String REQUEST_HEADER_USER_AGENT = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36";
    
        /**
         * Get请求
         *
         * @param url 路径
         * @return 字符串
         */
        public static String doGet(String url) {
            String result = HttpClientUtils.getResult("GET", url, null);
            return result;
        }
    
        /**
         * GET请求
         *
         * @param url    API
         * @param cookie cookie
         * @return json字符串
         */
        public static String doGet(String url, String cookie) {
            String result = HttpClientUtils.getResult("GET", url, cookie);
            return result;
        }
    
        /**
         * POST请求
         *
         * @param url
         * @param params 请求参数
         * @return json字符串
         */
        public static String doPost(String url, BasicNameValuePair... params) {
            String result = HttpClientUtils.getResult("POST", url, null, params);
            return result;
        }
    
        /**
         * POST请求
         *
         * @param url
         * @param cookie
         * @param params 请求参数
         * @return json字符串
         */
        public static String doPost(String url, String cookie, BasicNameValuePair... params) {
            String result = HttpClientUtils.getResult("POST", url, cookie, params);
            return result;
        }
    
    
        /**
         * 使用HttpClient通过API请求来获得json字符串
         *
         * @param requestMethod 请求方式
         * @param url           请求路径
         * @param cookie        cookie
         * @param params        请求参数
         * @return json字符串
         */
        private static String getResult(String requestMethod, String url, String cookie, BasicNameValuePair... params) {
            CloseableHttpClient httpClient = HttpClients.createDefault();
            CloseableHttpResponse httpResponse = null;
            String result = null;
            try {
                //GET
                if (requestMethod.equals(HttpClientUtils.REQUEST_METHOD_GET)) {
                    HttpGet httpGet = new HttpGet(url);
                    httpGet.setHeader("Connection", HttpClientUtils.REQUEST_HEADER_CONNECTION);
                    httpGet.setHeader("Cookie", cookie);
                    httpGet.setHeader("User-Agent", HttpClientUtils.REQUEST_HEADER_USER_AGENT);
                    httpResponse = httpClient.execute(httpGet);
                }
    
                //POST
                else if (requestMethod.equals(HttpClientUtils.REQUEST_METHOD_POST)) {
                    HttpPost httpPost = new HttpPost(url);
                    httpPost.setHeader("Connection", HttpClientUtils.REQUEST_HEADER_CONNECTION);
                    httpPost.setHeader("Cookie", cookie);
                    httpPost.setHeader("User-Agent", HttpClientUtils.REQUEST_HEADER_USER_AGENT);
                    httpPost.setEntity(new UrlEncodedFormEntity(Arrays.asList(params)));
                    httpResponse = httpClient.execute(httpPost);
                }
                //----
    
                HttpEntity entity = httpResponse.getEntity();
                result = EntityUtils.toString(entity);
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (httpClient != null) {
                    try {
                        httpClient.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
            return result;
        }
    }

HttpClientUtils

转载于:https://www.cnblogs.com/Tractors/p/11360890.html

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