HttpClient詳解

時間  2019-11-18
標籤 httpclient 詳解 欄目 系統網絡 简体版
原文   原文鏈接
 

Http協議的重要性相信不用我多說了，HttpClient相比傳統JDK自帶的URLConnection，增長了易用性和靈活性（具體區別，往後咱們再討論），它不只是客戶端發送Http請求變得容易，並且也方便了開發人員測試接口（基於Http協議的），即提升了開發的效率，也方便提升代碼的健壯性。所以熟練掌握HttpClient是很重要的必修內容，掌握HttpClient後，相信對於Http協議的瞭解會更加深刻。java

1、簡介

HttpClient是Apache Jakarta Common下的子項目，用來提供高效的、最新的、功能豐富的支持HTTP協議的客戶端編程工具包，而且它支持HTTP協議最新的版本和建議。HttpClient已經應用在不少的項目中，好比Apache Jakarta上很著名的另外兩個開源項目Cactus和HTMLUnit都使用了HttpClient。apache

下載地址: http://hc.apache.org/downloads.cgi編程

2、特性

1. 基於標準、純淨的Java語言。實現了Http1.0和Http1.1服務器

2. 以可擴展的面向對象的結構實現了Http所有的方法（GET, POST, PUT, DELETE, HEAD, OPTIONS, and TRACE）。多線程

3. 支持HTTPS協議。app

4. 經過Http代理創建透明的鏈接。socket

5. 利用CONNECT方法經過Http代理創建隧道的https鏈接。ide

6. Basic, Digest, NTLMv1, NTLMv2, NTLM2 Session, SNPNEGO/Kerberos認證方案。工具

7. 插件式的自定義認證方案。post

8. 便攜可靠的套接字工廠使它更容易的使用第三方解決方案。

9. 鏈接管理器支持多線程應用。支持設置最大鏈接數，同時支持設置每一個主機的最大鏈接數，發現並關閉過時的鏈接。

10. 自動處理Set-Cookie中的Cookie。

11. 插件式的自定義Cookie策略。

12. Request的輸出流能夠避免流中內容直接緩衝到socket服務器。

13. Response的輸入流能夠有效的從socket服務器直接讀取相應內容。

14. 在http1.0和http1.1中利用KeepAlive保持持久鏈接。

15. 直接獲取服務器發送的response code和 headers。

16. 設置鏈接超時的能力。

17. 實驗性的支持http1.1 response caching。

18. 源代碼基於Apache License 可免費獲取。

3、使用方法

使用HttpClient發送請求、接收響應很簡單，通常須要以下幾步便可。

1. 建立HttpClient對象。

2. 建立請求方法的實例，並指定請求URL。若是須要發送GET請求，建立HttpGet對象；若是須要發送POST請求，建立HttpPost對象。

3. 若是須要發送請求參數，可調用HttpGet、HttpPost共同的setParams(HetpParams params)方法來添加請求參數；對於HttpPost對象而言，也可調用setEntity(HttpEntity entity)方法來設置請求參數。

4. 調用HttpClient對象的execute(HttpUriRequest request)發送請求，該方法返回一個HttpResponse。

5. 調用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可獲取服務器的響應頭；調用HttpResponse的getEntity()方法可獲取HttpEntity對象，該對象包裝了服務器的響應內容。程序可經過該對象獲取服務器的響應內容。

6. 釋放鏈接。不管執行方法是否成功，都必須釋放鏈接

所需JAR

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpcore</artifactId>
<version>4.4.6</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.3</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpmime</artifactId>
<version>4.5.2</version>
</dependency>

package cn.com.demo;

import java.io.File;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

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.conn.ssl.DefaultHostnameVerifier;
import org.apache.http.conn.util.PublicSuffixMatcher;
import org.apache.http.conn.util.PublicSuffixMatcherLoader;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.entity.mime.content.FileBody;
import org.apache.http.entity.mime.content.StringBody;
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 class HttpClientUtil {
    private RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(15000).setConnectTimeout(15000)
            .setConnectionRequestTimeout(15000).build();
    // 單例模式
    private static HttpClientUtil instance = null;

    private HttpClientUtil() {
    }

    public static HttpClientUtil getInstance() {
        if (instance == null) {
            instance = new HttpClientUtil();
        }
        return instance;
    }

    /**
     * 發送 post請求
     * 
     * @param httpUrl
     *            地址
     */
    public String sendHttpPost(String httpUrl) {
        HttpPost httpPost = new HttpPost(httpUrl);// 建立httpPost
        return sendHttpPost(httpPost);
    }

    /**
     * 發送 post請求
     * 
     * @param httpUrl
     *            地址
     * @param params
     *            參數(格式:key1=value1&key2=value2)
     */
    public String sendHttpPost(String httpUrl, String params) {
        HttpPost httpPost = new HttpPost(httpUrl);
        try {
            StringEntity stringEntity = new StringEntity(params, "UTF-9=8");
            stringEntity.setContentType("application/x-www-form-urlencoded");
            httpPost.setEntity(stringEntity);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return sendHttpPost(httpPost);
    }

    /**
     * 發送 post請求
     * 
     * @param httpUrl
     *            地址
     * @param maps
     *            參數
     */
    public String sendHttpPost(String httpUrl, Map<String, String> maps) {
        HttpPost httpPost = new HttpPost(httpUrl);
        // 建立參數隊列
        List<NameValuePair> nameValuePairs = new ArrayList<>();
        for (String key : maps.keySet()) {
            nameValuePairs.add(new BasicNameValuePair(key, maps.get(key)));
        }
        try {
            httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs, "UTF-8"));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return sendHttpPost(httpPost);
    }

    /**
     * 發送 post請求（帶文件）
     * 
     * @param httpUrl
     *            地址
     * @param maps
     *            參數
     * @param fileLists
     *            附件
     */
    public String sendHttpPost(String httpUrl, Map<String, String> maps, List<File> fileLists) {
        HttpPost httpPost = new HttpPost(httpUrl);
        MultipartEntityBuilder meBuilder = MultipartEntityBuilder.create();
        for (String key : maps.keySet()) {
            meBuilder.addPart(key, new StringBody(maps.get(key), ContentType.TEXT_PLAIN));
        }
        for (File file : fileLists) {
            FileBody fileBody = new FileBody(file);
            meBuilder.addPart("files", fileBody);
        }
        HttpEntity reqEntity = meBuilder.build();
        httpPost.setEntity(reqEntity);
        return sendHttpPost(httpPost);
    }

    /**
     * 發送Post請求
     * 
     * @param httpPost
     * @return
     */
    private String sendHttpPost(HttpPost httpPost) {
        CloseableHttpClient httpClient = null;
        CloseableHttpResponse response = null;
        HttpEntity entity = null;
        String responseContent = null;
        try {
            // 建立默認的httpClient實例
            httpClient = HttpClients.createDefault();
            httpPost.setConfig(requestConfig);
            // 執行請求
            response = httpClient.execute(httpPost);
            entity = response.getEntity();
            responseContent = EntityUtils.toString(entity, "UTF-8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (response != null) {
                    response.close();
                }
                if (httpClient != null) {
                    httpClient.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return responseContent;
    }

    /**
     * 發送 get請求
     * 
     * @param httpUrl
     */
    public String sendHttpGet(String httpUrl) {
        HttpGet httpGet = new HttpGet(httpUrl);
        return sendHttpGet(httpGet);
    }

    /**
     * 發送 get請求Https
     * 
     * @param httpUrl
     */
    public String sendHttpsGet(String httpUrl) {
        HttpGet httpGet = new HttpGet(httpUrl);
        return sendHttpGet(httpGet);
    }

    /**
     * 發送Get請求
     * 
     * @param httpPost
     * @return
     */
    public String sendHttpGet(HttpGet httpGet) {
        CloseableHttpClient httpClient = null;
        CloseableHttpResponse response = null;
        HttpEntity entity = null;
        String responseContent = null;
        try {
            // 建立默認的httpClient實例
            httpClient = HttpClients.createDefault();
            httpGet.setConfig(requestConfig);
            // 執行請求
            response = httpClient.execute(httpGet);
            entity = response.getEntity();
            responseContent = EntityUtils.toString(entity, "UTF-8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (response != null) {
                    response.close();
                }
                if (httpClient != null) {
                    httpClient.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return responseContent;
    }

    /**
     * 發送Get請求Https
     * 
     * @param httpPost
     * @return
     */
    private String sendHttpsGet(HttpGet httpGet) {
        CloseableHttpClient httpClient = null;
        CloseableHttpResponse response = null;
        HttpEntity entity = null;
        String responseContent = null;
        try {
            // 建立默認的httpClient實例
            PublicSuffixMatcher publicSuffixMatcher = PublicSuffixMatcherLoader
                    .load(new URL(httpGet.getURI().toString()));
            DefaultHostnameVerifier hostnameVerifier = new DefaultHostnameVerifier(publicSuffixMatcher);
            httpClient = HttpClients.custom().setSSLHostnameVerifier(hostnameVerifier).build();
            httpGet.setConfig(requestConfig);
            // 執行請求
            response = httpClient.execute(httpGet);
            entity = response.getEntity();
            responseContent = EntityUtils.toString(entity, "UTF-8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (response != null) {
                    response.close();
                }
                if (httpClient != null) {
                    httpClient.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return responseContent;
    }
}
工具類 
package cn.com.demo;

import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.junit.Test;

public class HttpClientUtilTest {
    @Test
    public void testSendHttpPost1() {
        String responseContent = HttpClientUtil.getInstance()
                .sendHttpPost("http://192.168.1.83:9090/manage!login?phone=1&password=1");
        System.out.println("response Content" + responseContent);
    }

    @Test
    public void testSendHttpPost2() {
        String responseContent = HttpClientUtil.getInstance().sendHttpPost("http://localhost:8089/test/send",
                "username=test01&password=123456");
        System.out.println("reponse content:" + responseContent);
    }

    @Test
    public void testSendHttpPost3() {
        Map<String, String> maps = new HashMap<String, String>();
        maps.put("username", "test01");
        maps.put("password", "123456");
        String responseContent = HttpClientUtil.getInstance().sendHttpPost("http://localhost:8089/test/send", maps);
        System.out.println("reponse content:" + responseContent);
    }

    @Test
    public void testSendHttpPost4() {
        Map<String, String> maps = new HashMap<String, String>();
        maps.put("username", "test01");
        maps.put("password", "123456");
        List<File> fileLists = new ArrayList<File>();
        fileLists.add(new File("D://test//httpclient//1.png"));
        fileLists.add(new File("D://test//httpclient//1.txt"));
        String responseContent = HttpClientUtil.getInstance().sendHttpPost("http://localhost:8089/test/sendpost/file",
                maps, fileLists);
        System.out.println("reponse content:" + responseContent);
    }

    @Test
    public void testSendHttpGet() {
        String responseContent = HttpClientUtil.getInstance()
                .sendHttpGet("http://localhost:8089/test/send?username=test01&password=123456");
        System.out.println("reponse content:" + responseContent);
    }

    @Test
    public void testSendHttpsGet() {
        String responseContent = HttpClientUtil.getInstance().sendHttpsGet("https://www.baidu.com");
        System.out.println("reponse content:" + responseContent);
    }
}
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