HttpClient工具类

1. 什么是HttpClient

HTTP 协议可能是现在 Internet 上使用得最多、最重要的协议了，越来越多的 Java 应用程序需要直接通过 HTTP 协议来访问网络资源。虽然在 JDK 的 java net包中已经提供了访问 HTTP 协议的基本功能，但是对于大部分应用程序来说，JDK 库本身提供的功能还不够丰富和灵活。HttpClient 是Apache HttpComponents 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。

2. 功能介绍

实现了所有 HTTP 的方法（GET,POST,PUT,DELETE 等）
支持自动转向
支持 HTTPS 协议
支持代理服务器等

3. 版本比较

主要是基于 HttpClient4.5.5 版本的来讲解的，也是现在最新的版本，之所以要提供版本说明的是因为 HttpClient 3 版本和 HttpClient 4 版本差别还是很多大的，基本HttpClient里面的接口都变了，你把 HttpClient 3 版本的代码拿到 HttpClient 4 上面都运行不起来，会报错的。所以一定要注意 HtppClient 的版本问题。

4. HttpClient不能做的事情

HttpClient 不是浏览器，它是一个客户端 HTTP 协议传输类库。HttpClient 被用来发送和接受 HTTP 消息。HttpClient 不会处理 HTTP 消息的内容，不会进行 javascript 解析，不会关心 content type，如果没有明确设置，HttpClient 也不会对请求进行格式化、重定向 url，或者其他任何和 HTTP 消息传输相关的功能。

5. HttpClient使用流程

使用HttpClient发送请求、接收响应很简单，一般需要如下几步即可。

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HttpGetsetParams方法来添加请求参数；对于HttpPost对象而言，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对象。
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

<properties>
        <httpclient.version>4.5.5</httpclient.version>

        <java.version>1.8</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    </properties>

    <dependencies>
        <!-- springboot的web和test启动库 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>

        <!-- apache httpclient组件 -->
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
        </dependency>

    </dependencies>

    <build>
        <finalName>${project.artifactId}</finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <!-- 跳过单元测试 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <configuration>
                    <skipTests>true</skipTests>
                </configuration>
            </plugin>
        </plugins>
    </build>

6.2 编写spring-boot启动类

/**
 * Description: springboot启动类
 * 
 * @author JourWon
 * @date Created on 2018年4月19日
 */
@SpringBootApplication
public class Application {

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}

}

6.3 编写get和post请求测试controller

/**
 * Description: get和post请求测试controller
 * 
 * @author JourWon
 * @date Created on 2018年4月19日
 */
@RestController
@RequestMapping("/hello")
public class HelloWorldController {

	@GetMapping("/get")
	public String get() throws InterruptedException {
		return "get无参请求成功";
	}

	@GetMapping("/getWithParam")
	public String getWithParam(@RequestParam String message) {
		return "get带参请求成功,参数message: " + message;
	}

	@PostMapping("/post")
	public String post(@RequestHeader("User-Agent") String userAgent,
            @RequestHeader("Accept") String accept,
            @RequestHeader("Accept-Language") String acceptLanguage,
            @RequestHeader("Accept-Encoding") String acceptEncoding,
            @RequestHeader("Cookie") String cookie,
            @RequestHeader("Connection") String conn) {
		// 打印请求头信息
		System.out.println("Cookie = " + cookie);
		System.out.println("Connection = " + conn);
		System.out.println("Accept = " + accept);
		System.out.println("Accept-Language = " + acceptLanguage);
		System.out.println("Accept-Encoding = " + acceptEncoding);
		System.out.println("User-Agent = " + userAgent);
		
		return "post无参请求成功";
	}

	@PostMapping("/postWithParam")
	public String postWithParam(@RequestParam String code, @RequestParam String message) {
		return "post带参请求成功,参数code: " + code + ",参数message: " + message;
	}

}

6.4 创建httpClient响应结果对象

/**
 * Description: 封装httpClient响应结果
 * 
 * @author JourWon
 * @date Created on 2018年4月19日
 */
public class HttpClientResult implements Serializable {

	/**
	 * 响应状态码
	 */
	private int code;

	/**
	 * 响应数据
	 */
	private String content;

}

6.5 重点，编写httpclient工具类

/**
 * Description: httpClient工具类
 * 
 * @author JourWon
 * @date Created on 2018年4月19日
 */
public class HttpClientUtils {

	// 编码格式。发送编码格式统一用UTF-8
	private static final String ENCODING = "UTF-8";
	
	// 设置连接超时时间，单位毫秒。
	private static final int CONNECT_TIMEOUT = 6000;
	
	// 请求获取数据的超时时间(即响应时间)，单位毫秒。
	private static final int SOCKET_TIMEOUT = 6000;

	/**
	 * 发送get请求；不带请求头和请求参数
	 * 
	 * @param url 请求地址
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult doGet(String url) throws Exception {
		return doGet(url, null, null);
	}
	
	/**
	 * 发送get请求；带请求参数
	 * 
	 * @param url 请求地址
	 * @param params 请求参数集合
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult doGet(String url, Map<String, String> params) throws Exception {
		return doGet(url, null, params);
	}

	/**
	 * 发送get请求；带请求头和请求参数
	 * 
	 * @param url 请求地址
	 * @param headers 请求头集合
	 * @param params 请求参数集合
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult doGet(String url, Map<String, String> headers, Map<String, String> params) throws Exception {
		// 创建httpClient对象
		CloseableHttpClient httpClient = HttpClients.createDefault();

		// 创建访问的地址
		URIBuilder uriBuilder = new URIBuilder(url);
		if (params != null) {
			Set<Entry<String, String>> entrySet = params.entrySet();
			for (Entry<String, String> entry : entrySet) {
				uriBuilder.setParameter(entry.getKey(), entry.getValue());
			}
		}

		// 创建http对象
		HttpGet httpGet = new HttpGet(uriBuilder.build());
		/**
		 * setConnectTimeout：设置连接超时时间，单位毫秒。
		 * setConnectionRequestTimeout：设置从connect Manager(连接池)获取Connection
		 * 超时时间，单位毫秒。这个属性是新加的属性，因为目前版本是可以共享连接池的。
		 * setSocketTimeout：请求获取数据的超时时间(即响应时间)，单位毫秒。 如果访问一个接口，多少时间内无法返回数据，就直接放弃此次调用。
		 */
		RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(CONNECT_TIMEOUT).setSocketTimeout(SOCKET_TIMEOUT).build();
		httpGet.setConfig(requestConfig);
		
		// 设置请求头
		packageHeader(headers, httpGet);

		// 创建httpResponse对象
		CloseableHttpResponse httpResponse = null;

		try {
			// 执行请求并获得响应结果
			return getHttpClientResult(httpResponse, httpClient, httpGet);
		} finally {
			// 释放资源
			release(httpResponse, httpClient);
		}
	}

	/**
	 * 发送post请求；不带请求头和请求参数
	 * 
	 * @param url 请求地址
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult doPost(String url) throws Exception {
		return doPost(url, null, null);
	}
	
	/**
	 * 发送post请求；带请求参数
	 * 
	 * @param url 请求地址
	 * @param params 参数集合
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult doPost(String url, Map<String, String> params) throws Exception {
		return doPost(url, null, params);
	}

	/**
	 * 发送post请求；带请求头和请求参数
	 * 
	 * @param url 请求地址
	 * @param headers 请求头集合
	 * @param params 请求参数集合
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult doPost(String url, Map<String, String> headers, Map<String, String> params) throws Exception {
		// 创建httpClient对象
		CloseableHttpClient httpClient = HttpClients.createDefault();

		// 创建http对象
		HttpPost httpPost = new HttpPost(url);
		/**
		 * setConnectTimeout：设置连接超时时间，单位毫秒。
		 * setConnectionRequestTimeout：设置从connect Manager(连接池)获取Connection
		 * 超时时间，单位毫秒。这个属性是新加的属性，因为目前版本是可以共享连接池的。
		 * setSocketTimeout：请求获取数据的超时时间(即响应时间)，单位毫秒。 如果访问一个接口，多少时间内无法返回数据，就直接放弃此次调用。
		 */
		RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(CONNECT_TIMEOUT).setSocketTimeout(SOCKET_TIMEOUT).build();
		httpPost.setConfig(requestConfig);
		// 设置请求头
		/*httpPost.setHeader("Cookie", "");
		httpPost.setHeader("Connection", "keep-alive");
		httpPost.setHeader("Accept", "application/json");
		httpPost.setHeader("Accept-Language", "zh-CN,zh;q=0.9");
		httpPost.setHeader("Accept-Encoding", "gzip, deflate, br");
		httpPost.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36");*/
		packageHeader(headers, httpPost);
		
		// 封装请求参数
		packageParam(params, httpPost);

		// 创建httpResponse对象
		CloseableHttpResponse httpResponse = null;

		try {
			// 执行请求并获得响应结果
			return getHttpClientResult(httpResponse, httpClient, httpPost);
		} finally {
			// 释放资源
			release(httpResponse, httpClient);
		}
	}

	/**
	 * 发送put请求；不带请求参数
	 * 
	 * @param url 请求地址
	 * @param params 参数集合
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult doPut(String url) throws Exception {
		return doPut(url);
	}

	/**
	 * 发送put请求；带请求参数
	 * 
	 * @param url 请求地址
	 * @param params 参数集合
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult doPut(String url, Map<String, String> params) throws Exception {
		CloseableHttpClient httpClient = HttpClients.createDefault();
		HttpPut httpPut = new HttpPut(url);
		RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(CONNECT_TIMEOUT).setSocketTimeout(SOCKET_TIMEOUT).build();
		httpPut.setConfig(requestConfig);
		
		packageParam(params, httpPut);

		CloseableHttpResponse httpResponse = null;

		try {
			return getHttpClientResult(httpResponse, httpClient, httpPut);
		} finally {
			release(httpResponse, httpClient);
		}
	}

	/**
	 * 发送delete请求；不带请求参数
	 * 
	 * @param url 请求地址
	 * @param params 参数集合
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult doDelete(String url) throws Exception {
		CloseableHttpClient httpClient = HttpClients.createDefault();
		HttpDelete httpDelete = new HttpDelete(url);
		RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(CONNECT_TIMEOUT).setSocketTimeout(SOCKET_TIMEOUT).build();
		httpDelete.setConfig(requestConfig);

		CloseableHttpResponse httpResponse = null;
		try {
			return getHttpClientResult(httpResponse, httpClient, httpDelete);
		} finally {
			release(httpResponse, httpClient);
		}
	}

	/**
	 * 发送delete请求；带请求参数
	 * 
	 * @param url 请求地址
	 * @param params 参数集合
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult doDelete(String url, Map<String, String> params) throws Exception {
		if (params == null) {
			params = new HashMap<String, String>();
		}

		params.put("_method", "delete");
		return doPost(url, params);
	}
	
	/**
	 * Description: 封装请求头
	 * @param params
	 * @param httpMethod
	 */
	public static void packageHeader(Map<String, String> params, HttpRequestBase httpMethod) {
		// 封装请求头
		if (params != null) {
			Set<Entry<String, String>> entrySet = params.entrySet();
			for (Entry<String, String> entry : entrySet) {
				// 设置到请求头到HttpRequestBase对象中
				httpMethod.setHeader(entry.getKey(), entry.getValue());
			}
		}
	}

	/**
	 * Description: 封装请求参数
	 * 
	 * @param params
	 * @param httpMethod
	 * @throws UnsupportedEncodingException
	 */
	public static void packageParam(Map<String, String> params, HttpEntityEnclosingRequestBase httpMethod)
			throws UnsupportedEncodingException {
		// 封装请求参数
		if (params != null) {
			List<NameValuePair> nvps = new ArrayList<NameValuePair>();
			Set<Entry<String, String>> entrySet = params.entrySet();
			for (Entry<String, String> entry : entrySet) {
				nvps.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));
			}

			// 设置到请求的http对象中
			httpMethod.setEntity(new UrlEncodedFormEntity(nvps, ENCODING));
		}
	}

	/**
	 * Description: 获得响应结果
	 * 
	 * @param httpResponse
	 * @param httpClient
	 * @param httpMethod
	 * @return
	 * @throws Exception
	 */
	public static HttpClientResult getHttpClientResult(CloseableHttpResponse httpResponse,
			CloseableHttpClient httpClient, HttpRequestBase httpMethod) throws Exception {
		// 执行请求
		httpResponse = httpClient.execute(httpMethod);

		// 获取返回结果
		if (httpResponse != null && httpResponse.getStatusLine() != null) {
			String content = "";
			if (httpResponse.getEntity() != null) {
				content = EntityUtils.toString(httpResponse.getEntity(), ENCODING);
			}
			return new HttpClientResult(httpResponse.getStatusLine().getStatusCode(), content);
		}
		return new HttpClientResult(HttpStatus.SC_INTERNAL_SERVER_ERROR);
	}

	/**
	 * Description: 释放资源
	 * 
	 * @param httpResponse
	 * @param httpClient
	 * @throws IOException
	 */
	public static void release(CloseableHttpResponse httpResponse, CloseableHttpClient httpClient) throws IOException {
		// 释放资源
		if (httpResponse != null) {
			httpResponse.close();
		}
		if (httpClient != null) {
			httpClient.close();
		}
	}

}

6.6 启动spring-boot，测试get、post请求

/**
 * Description: HttpClientUtils工具类测试
 * 
 * @author JourWon
 * @date Created on 2018年4月19日
 */
public class HttpClientUtilsTest {

	/**
	 * Description: 测试get无参请求
	 * 
	 * @throws Exception
	 */
	@Test
	public void testGet() throws Exception {
		HttpClientResult result = HttpClientUtils.doGet("http://127.0.0.1:8080/hello/get");
		System.out.println(result);
	}

	/**
	 * Description: 测试get带参请求
	 * 
	 * @throws Exception
	 */
	@Test
	public void testGetWithParam() throws Exception {
		Map<String, String> params = new HashMap<String, String>();
		params.put("message", "helloworld");
		HttpClientResult result = HttpClientUtils.doGet("http://127.0.0.1:8080/hello/getWithParam", params);
		System.out.println(result);
	}

	/**
	 * Description: 测试post带请求头不带请求参数
	 * 
	 * @throws Exception
	 */
	@Test
	public void testPost() throws Exception {
		Map<String, String> headers = new HashMap<String, String>();
		headers.put("Cookie", "123");
		headers.put("Connection", "keep-alive");
		headers.put("Accept", "application/json");
		headers.put("Accept-Language", "zh-CN,zh;q=0.9");
		headers.put("User-Agent", "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36");
		HttpClientResult result = HttpClientUtils.doPost("http://127.0.0.1:8080/hello/post", headers, null);
		System.out.println(result);
	}

	/**
	 * Description: 测试post带参请求
	 * 
	 * @throws Exception
	 */
	@Test
	public void testPostWithParam() throws Exception {
		Map<String, String> params = new HashMap<String, String>();
		params.put("code", "0");
		params.put("message", "helloworld");
		HttpClientResult result = HttpClientUtils.doPost("http://127.0.0.1:8080/hello/postWithParam", params);
		System.out.println(result);
	}

}

HttpsUtils工具类

实现利用HttpClient发送Https请求，信任任何证书、不对主机校验

参见官方文档

public class HttpsUtils {
    private static final String HTTP = "http";
    private static final String HTTPS = "https";
    private static SSLConnectionSocketFactory sslsf = null;
    private static PoolingHttpClientConnectionManager cm = null;
    private static SSLContextBuilder builder = null;
    static {
        try {
            builder = new SSLContextBuilder();
            // 全部信任 不做身份鉴定
            builder.loadTrustMaterial(null, (org.apache.http.ssl.TrustStrategy) (x509Certificates, s) -> true);
            sslsf = new SSLConnectionSocketFactory(builder.build(), new String[]{"SSLv2Hello", "SSLv3", "TLSv1", "TLSv1.2"},
                    null, NoopHostnameVerifier.INSTANCE);
            //设置协议http和https对应的处理socket连接工厂的对象
            Registry<ConnectionSocketFactory> registry = RegistryBuilder.<ConnectionSocketFactory>create()
                    .register(HTTP, new PlainConnectionSocketFactory())
                    .register(HTTPS, sslsf)
                    .build();
            cm = new PoolingHttpClientConnectionManager(registry);
            cm.setMaxTotal(200);//max connection
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * httpClient get请求
     * @param url 请求url
     * @param
     * @param
     * @return 可能为空 需要处理
     * @throws Exception
     *
     */
    public static String get(String  url) throws Exception {
        String result = "";
        CloseableHttpClient httpClient = null;
        try {
            httpClient = getHttpClient();
            HttpGet httpGet = new HttpGet(url);
            // 设置头信息 ,必须添加，否则会报403
            httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.90 Safari/537.36");

            HttpResponse httpResponse = httpClient.execute(httpGet);
            int statusCode = httpResponse.getStatusLine().getStatusCode();
            if (statusCode == HttpStatus.SC_OK) {
                HttpEntity resEntity = httpResponse.getEntity();
                result = EntityUtils.toString(resEntity, "utf-8");
            } else {
            	readHttpResponse(httpResponse);
            }
        } catch (Exception e) {throw e;
        } finally {
            if (httpClient != null) {
                httpClient.close();
            }
        }
        return result;
    }
    public static CloseableHttpClient getHttpClient() throws Exception {
        CloseableHttpClient httpClient = HttpClients.custom()
                .setSSLSocketFactory(sslsf)
                .setConnectionManager(cm)
                .setConnectionManagerShared(true)
                .build();
        return httpClient;
    }
    public static String readHttpResponse(HttpResponse httpResponse)
            throws ParseException, IOException {
        StringBuilder builder = new StringBuilder();
        // 获取响应消息实体
        HttpEntity entity = httpResponse.getEntity();
        // 响应状态
        builder.append("status:" + httpResponse.getStatusLine());
        builder.append("headers:");
        HeaderIterator iterator = httpResponse.headerIterator();
        while (iterator.hasNext()) {
            builder.append("\t" + iterator.next());
        }
        // 判断响应实体是否为空
        if (entity != null) {
            String responseString = EntityUtils.toString(entity);
            builder.append("response length:" + responseString.length());
            builder.append("response content:" + responseString.replace("\r\n", ""));
        }
        return builder.toString();
    }
}

参考github开源工具

https://github.com/Arronlong/httpclientutil

https://github.com/JourWon/httpclientutil