浅谈java调用Restful API接口的方式

摘要：最近有一个需求，为客户提供一些RestfulAPI接口，QA使用postman进行测试，但是postman的测试接口与java调用的相似但并不相同，于是想自己写一个程序去测试RestfulAPI接口，由于使用的是HTTPS，所以还要考虑到对于HTTPS的处理。由于我也是首次使用Java调用restful接口，所以还要研究一番，自然也是查阅了一些资料。

分析：这个问题与模块之间的调用不同，比如我有两个模块frontend和backend，frontend提供前台展示，backend提供数据支持。之前使用过Hession去把backend提供的服务注册成远程服务，在frontend端可以通过这种远程服务直接调到backend的接口。但这对于一个公司自己的一个项目耦合性比较高的情况下使用，没有问题。但是如果给客户注册这种远程服务，似乎不太好，耦合性太高。所以就考虑用一下方式进行处理。

基本介绍

Restful接口的调用，前端一般使用ajax调用，后端可以使用的方法比较多，

本次介绍三种：

1.HttpURLConnection实现

2.HttpClient实现

3.Spring的RestTemplate

一、HttpClient

HttpClient大家也许比较熟悉但又比较陌生，熟悉是知道他可以远程调用比如请求一个URL，然后在response里获取到返回状态和返回信息，但是今天讲的稍微复杂一点，因为今天的主题是HTTPS，这个牵涉到证书或用户认证的问题。

确定使用HttpClient之后，查询相关资料，发现HttpClient的新版本与老版本不同，随然兼容老版本，但已经不提倡老版本是使用方式，很多都已经标记为过时的方法或类。今天就分别使用老版本4.2和最新版本4.5.3来写代码。

老版本4.2

需要认证

在准备证书阶段选择的是使用证书认证

package com.darren.test.https.v42;
import java.io.File;
import java.io.FileInputStream;
import java.security.KeyStore;
import org.apache.http.conn.ssl.SSLSocketFactory;
public class HTTPSCertifiedClient extends HTTPSClient {
	public HTTPSCertifiedClient() {
	}
	@Override
	  public void prepareCertificate() throws Exception {
		// 获得密匙库
		KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType());
		FileInputStream instream = new FileInputStream(
		        new File("C:/Users/zhda6001/Downloads/software/xxx.keystore"));
		// FileInputStream instream = new FileInputStream(new File("C:/Users/zhda6001/Downloads/xxx.keystore"));
		// 密匙库的密码
		trustStore.load(instream, "password".toCharArray());
		// 注册密匙库
		this.socketFactory = new SSLSocketFactory(trustStore);
		// 不校验域名
		socketFactory.setHostnameVerifier(SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
	}
}

跳过认证

在准备证书阶段选择的是跳过认证

package com.darren.test.https.v42;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import org.apache.http.conn.ssl.SSLSocketFactory;
public class HTTPSTrustClient extends HTTPSClient {
	public HTTPSTrustClient() {
	}
	@Override
	  public void prepareCertificate() throws Exception {
		// 跳过证书验证
		SSLContext ctx = SSLContext.getInstance("TLS");
		X509TrustManager tm = new X509TrustManager() {
			@Override
			      public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
			}
			@Override
			      public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
			}
			@Override
			      public X509Certificate[] getAcceptedIssuers() {
				return null;
			}
		}
		;
		// 设置成已信任的证书
		ctx.init(null, new TrustManager[] {
			tm
		}
		, null);
		// 穿件SSL socket 工厂，并且设置不检查host名称
		this.socketFactory = new SSLSocketFactory(ctx, SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
	}
}

总结

现在发现这两个类都继承了同一个类HTTPSClient，并且HTTPSClient继承了DefaultHttpClient类，可以发现，这里使用了模板方法模式。

package com.darren.test.https.v42;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.conn.ssl.SSLSocketFactory;
import org.apache.http.impl.client.DefaultHttpClient;
public abstract class HTTPSClient extends DefaultHttpClient {
	protected SSLSocketFactory socketFactory;
	/**
   * 初始化HTTPSClient
   *
   * @return 返回当前实例
   * @throws Exception
   */
	public HTTPSClient init() throws Exception {
		this.prepareCertificate();
		this.regist();
		return this;
	}
	/**
   * 准备证书验证
   *
   * @throws Exception
   */
	public abstract void prepareCertificate() throws Exception;
	/**
   * 注册协议和端口, 此方法也可以被子类重写
   */
	protected void regist() {
		ClientConnectionManager ccm = this.getConnectionManager();
		SchemeRegistry sr = ccm.getSchemeRegistry();
		sr.register(new Scheme("https", 443, socketFactory));
	}
}

下边是工具类

package com.darren.test.https.v42;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
public class HTTPSClientUtil {
	private static final String DEFAULT_CHARSET = "UTF-8";
	public static String doPost(HTTPSClient httpsClient, String url, Map<String, String> paramHeader,
	      Map<String, String> paramBody) throws Exception {
		return doPost(httpsClient, url, paramHeader, paramBody, DEFAULT_CHARSET);
	}
	public static String doPost(HTTPSClient httpsClient, String url, Map<String, String> paramHeader,
	      Map<String, String> paramBody, String charset) throws Exception {
		String result = null;
		HttpPost httpPost = new HttpPost(url);
		setHeader(httpPost, paramHeader);
		setBody(httpPost, paramBody, charset);
		HttpResponse response = httpsClient.execute(httpPost);
		if (response != null) {
			HttpEntity resEntity = response.getEntity();
			if (resEntity != null) {
				result = EntityUtils.toString(resEntity, charset);
			}
		}
		return result;
	}
	public static String doGet(HTTPSClient httpsClient, String url, Map<String, String> paramHeader,
	      Map<String, String> paramBody) throws Exception {
		return doGet(httpsClient, url, paramHeader, paramBody, DEFAULT_CHARSET);
	}
	public static String doGet(HTTPSClient httpsClient, String url, Map<String, String> paramHeader,
	      Map<String, String> paramBody, String charset) throws Exception {
		String result = null;
		HttpGet httpGet = new HttpGet(url);
		setHeader(httpGet, paramHeader);
		HttpResponse response = httpsClient.execute(httpGet);
		if (response != null) {
			HttpEntity resEntity = response.getEntity();
			if (resEntity != null) {
				result = EntityUtils.toString(resEntity, charset);
			}
		}
		return result;
	}
	private static void setHeader(HttpRequestBase request, Map<String, String> paramHeader) {
		// 设置Header
		if (paramHeader != null) {
			Set<String> keySet = paramHeader.keySet();
			for (String key : keySet) {
				request.addHeader(key, paramHeader.get(key));
			}
		}
	}
	private static void setBody(HttpPost httpPost, Map<String, String> paramBody, String charset) throws Exception {
		// 设置参数
		if (paramBody != null) {
			List<NameValuePair> list = new ArrayList<NameValuePair>();
			Set<String> keySet = paramBody.keySet();
			for (String key : keySet) {
				list.add(new BasicNameValuePair(key, paramBody.get(key)));
			}
			if (list.size() > 0) {
				UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, charset);
				httpPost.setEntity(entity);
			}
		}
	}
}

然后是测试类：

package com.darren.test.https.v42;
import java.util.HashMap;
import java.util.Map;
public class HTTPSClientTest {
	public static void main(String[] args) throws Exception {
		HTTPSClient httpsClient = null;
		httpsClient = new HTTPSTrustClient().init();
		//httpsClient = new HTTPSCertifiedClient().init();
		String url = "https://1.2.6.2:8011/xxx/api/getToken";
		//String url = "https://1.2.6.2:8011/xxx/api/getHealth";
		Map<String, String> paramHeader = new HashMap<>();
		//paramHeader.put("Content-Type", "application/json");
		paramHeader.put("Accept", "application/xml");
		Map<String, String> paramBody = new HashMap<>();
		paramBody.put("client_id", "ankur.tandon.ap@xxx.com");
		paramBody.put("client_secret", "P@ssword_1");
		String result = HTTPSClientUtil.doPost(httpsClient, url, paramHeader, paramBody);
		//String result = HTTPSClientUtil.doGet(httpsClient, url, null, null);
		System.out.println(result);
	}
}

返回信息：

<?xml version="1.0" encoding="utf-8"?>
 <token>jkf8RL0sw+Skkflj8RbKI5hP1bEQK8PrCuTZPpBINqMYKRMxY1kWCjmCfT191Zpp88VV1aGHW8oYNWjEYS0axpLuGAX89ejCoWNbikCc1UvfyesXHLktcJqyUFiVjevhrEQxJPHncLQYWP+Xse5oD9X8vKFKk7InNTMRzQK7YBTZ/e3U7gswM/5cvAHFl6o9rEq9cWPXavZNohyvnXsohSzDo+BXAtXxa1xpEDLy/8h/UaP4n4dlZDJJ3B8t1Xh+CRRIoMOPxf7c5wKhHtOkEOeXW+xoPQKKSx5CKWwJpPuGIIFWF/PaqWg+JUOsVT7QGdPv8PMWJ9DwEwjTdxguDg==</token> 

新版本4.5.3

需要认证

package com.darren.test.https.v45;
import java.io.File;
import java.io.FileInputStream;
import java.security.KeyStore;
import javax.net.ssl.SSLContext;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.TrustSelfSignedStrategy;
import org.apache.http.ssl.SSLContexts;
public class HTTPSCertifiedClient extends HTTPSClient {
	public HTTPSCertifiedClient() {
	}
	@Override
	  public void prepareCertificate() throws Exception {
		// 获得密匙库
		KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType());
		FileInputStream instream = new FileInputStream(
		        new File("C:/Users/zhda6001/Downloads/software/xxx.keystore"));
		// FileInputStream instream = new FileInputStream(new File("C:/Users/zhda6001/Downloads/xxx.keystore"));
		try {
			// 密匙库的密码
			trustStore.load(instream, "password".toCharArray());
		}
		finally {
			instream.close();
		}
		SSLContext sslcontext = SSLContexts.custom().loadTrustMaterial(trustStore, TrustSelfSignedStrategy.INSTANCE)
		        .build();
		this.connectionSocketFactory = new SSLConnectionSocketFactory(sslcontext);
	}
}

跳过认证

package com.darren.test.https.v45;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
public class HTTPSTrustClient extends HTTPSClient {
	public HTTPSTrustClient() {
	}
	@Override
	  public void prepareCertificate() throws Exception {
		// 跳过证书验证
		SSLContext ctx = SSLContext.getInstance("TLS");
		X509TrustManager tm = new X509TrustManager() {
			@Override
			      public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
			}
			@Override
			      public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
			}
			@Override
			      public X509Certificate[] getAcceptedIssuers() {
				return null;
			}
		}
		;
		// 设置成已信任的证书
		ctx.init(null, new TrustManager[] {
			tm
		}
		, null);
		this.connectionSocketFactory = new SSLConnectionSocketFactory(ctx);
	}
}

总结

package com.darren.test.https.v45;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
public abstract class HTTPSClient extends HttpClientBuilder {
	private CloseableHttpClient client;
	protected ConnectionSocketFactory connectionSocketFactory;
	/**
   * 初始化HTTPSClient
   *
   * @return 返回当前实例
   * @throws Exception
   */
	public CloseableHttpClient init() throws Exception {
		this.prepareCertificate();
		this.regist();
		return this.client;
	}
	/**
   * 准备证书验证
   *
   * @throws Exception
   */
	public abstract void prepareCertificate() throws Exception;
	/**
   * 注册协议和端口, 此方法也可以被子类重写
   */
	protected void regist() {
		// 设置协议http和https对应的处理socket链接工厂的对象
		Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create()
		        .register("http", PlainConnectionSocketFactory.INSTANCE)
		        .register("https", this.connectionSocketFactory)
		        .build();
		PoolingHttpClientConnectionManager connManager = new PoolingHttpClientConnectionManager(socketFactoryRegistry);
		HttpClients.custom().setConnectionManager(connManager);
		// 创建自定义的httpclient对象
		this.client = HttpClients.custom().setConnectionManager(connManager).build();
		// CloseableHttpClient client = HttpClients.createDefault();
	}
}

工具类：

package com.darren.test.https.v45;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
public class HTTPSClientUtil {
	private static final String DEFAULT_CHARSET = "UTF-8";
	public static String doPost(HttpClient httpClient, String url, Map<String, String> paramHeader,
	      Map<String, String> paramBody) throws Exception {
		return doPost(httpClient, url, paramHeader, paramBody, DEFAULT_CHARSET);
	}
	public static String doPost(HttpClient httpClient, String url, Map<String, String> paramHeader,
	      Map<String, String> paramBody, String charset) throws Exception {
		String result = null;
		HttpPost httpPost = new HttpPost(url);
		setHeader(httpPost, paramHeader);
		setBody(httpPost, paramBody, charset);
		HttpResponse response = httpClient.execute(httpPost);
		if (response != null) {
			HttpEntity resEntity = response.getEntity();
			if (resEntity != null) {
				result = EntityUtils.toString(resEntity, charset);
			}
		}
		return result;
	}
	public static String doGet(HttpClient httpClient, String url, Map<String, String> paramHeader,
	      Map<String, String> paramBody) throws Exception {
		return doGet(httpClient, url, paramHeader, paramBody, DEFAULT_CHARSET);
	}
	public static String doGet(HttpClient httpClient, String url, Map<String, String> paramHeader,
	      Map<String, String> paramBody, String charset) throws Exception {
		String result = null;
		HttpGet httpGet = new HttpGet(url);
		setHeader(httpGet, paramHeader);
		HttpResponse response = httpClient.execute(httpGet);
		if (response != null) {
			HttpEntity resEntity = response.getEntity();
			if (resEntity != null) {
				result = EntityUtils.toString(resEntity, charset);
			}
		}
		return result;
	}
	private static void setHeader(HttpRequestBase request, Map<String, String> paramHeader) {
		// 设置Header
		if (paramHeader != null) {
			Set<String> keySet = paramHeader.keySet();
			for (String key : keySet) {
				request.addHeader(key, paramHeader.get(key));
			}
		}
	}
	private static void setBody(HttpPost httpPost, Map<String, String> paramBody, String charset) throws Exception {
		// 设置参数
		if (paramBody != null) {
			List<NameValuePair> list = new ArrayList<NameValuePair>();
			Set<String> keySet = paramBody.keySet();
			for (String key : keySet) {
				list.add(new BasicNameValuePair(key, paramBody.get(key)));
			}
			if (list.size() > 0) {
				UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, charset);
				httpPost.setEntity(entity);
			}
		}
	}
}

测试类：

package com.darren.test.https.v45;
import java.util.HashMap;
import java.util.Map;
import org.apache.http.client.HttpClient;
public class HTTPSClientTest {
	public static void main(String[] args) throws Exception {
		HttpClient httpClient = null;
		//httpClient = new HTTPSTrustClient().init();
		httpClient = new HTTPSCertifiedClient().init();
		String url = "https://1.2.6.2:8011/xxx/api/getToken";
		//String url = "https://1.2.6.2:8011/xxx/api/getHealth";
		Map<String, String> paramHeader = new HashMap<>();
		paramHeader.put("Accept", "application/xml");
		Map<String, String> paramBody = new HashMap<>();
		paramBody.put("client_id", "ankur.tandon.ap@xxx.com");
		paramBody.put("client_secret", "P@ssword_1");
		String result = HTTPSClientUtil.doPost(httpClient, url, paramHeader, paramBody);
		//String result = HTTPSClientUtil.doGet(httpsClient, url, null, null);
		System.out.println(result);
	}
}

结果：

<?xml version="1.0" encoding="utf-8"?> 

<token>RxitF9//7NxwXJS2cjIjYhLtvzUNvMZxxEQtGN0u07sC9ysJeIbPqte3hCjULSkoXPEUYGUVeyI9jv7/WikLrzxYKc3OSpaTSM0kCbCKphu0TB2Cn/nfzv9fMLueOWFBdyz+N0sEiI9K+0Gp7920DFEncn17wUJVmC0u2jwvM5FAjQKmilwodXZ6a0Dq+D7dQDJwVcwxBvJ2ilhyIb3pr805Vppmi9atXrVAKO0ODa006wEJFOfcgyG5p70wpJ5rrBL85vfy9WCvkd1R7j6NVjhXgH2gNimHkjEJorMjdXW2gKiUsiWsELi/XPswao7/CTWNwTnctGK8PX2ZUB0ZfA==</token> 

二、HttpURLConnection

@Controller
public class RestfulAction {
	@Autowired
	  private UserService userService;
	// 修改
	@RequestMapping(value = "put/{param}", method = RequestMethod.PUT)
	  public @ResponseBody String put(@PathVariable String param) {
		return "put:" + param;
	}
	// 新增
	@RequestMapping(value = "post/{param}", method = RequestMethod.POST)
	  public @ResponseBody String post(@PathVariable String param,String id,String name) {
		System.out.println("id:"+id);
		System.out.println("name:"+name);
		return "post:" + param;
	}
	// 删除
	@RequestMapping(value = "delete/{param}", method = RequestMethod.DELETE)
	  public @ResponseBody String delete(@PathVariable String param) {
		return "delete:" + param;
	}
	// 查找
	@RequestMapping(value = "get/{param}", method = RequestMethod.GET)
	  public @ResponseBody String get(@PathVariable String param) {
		return "get:" + param;
	}
	// HttpURLConnection 方式调用Restful接口
	// 调用接口
	@RequestMapping(value = "dealCon/{param}")
	  public @ResponseBody String dealCon(@PathVariable String param) {
		try {
			String url = "http://localhost:8080/tao-manager-web/";
			url+=(param+"/xxx");
			URL restServiceURL = new URL(url);
			HttpURLConnection httpConnection = (HttpURLConnection) restServiceURL
			          .openConnection();
			//param 输入小写，转换成 GET POST DELETE PUT
			httpConnection.setRequestMethod(param.toUpperCase());
			//      httpConnection.setRequestProperty("Accept", "application/json");
			if("post".equals(param)){
				//打开输出开关
				httpConnection.setDoOutput(true);
				//        httpConnection.setDoInput(true);
				//传递参数
				String input = "&id="+ URLEncoder.encode("abc", "UTF-8");
				input+="&name="+ URLEncoder.encode("啊啊啊", "UTF-8");
				OutputStream outputStream = httpConnection.getOutputStream();
				outputStream.write(input.getBytes());
				outputStream.flush();
			}
			if (httpConnection.getResponseCode() != 200) {
				throw new RuntimeException(
				            "HTTP GET Request Failed with Error code : "
				                + httpConnection.getResponseCode());
			}
			BufferedReader responseBuffer = new BufferedReader(
			          new InputStreamReader((httpConnection.getInputStream())));
			String output;
			System.out.println("Output from Server: \n");
			while ((output = responseBuffer.readLine()) != null) {
				System.out.println(output);
			}
			httpConnection.disconnect();
		}
		catch (MalformedURLException e) {
			e.printStackTrace();
		}
		catch (IOException e) {
			e.printStackTrace();
		}
		return "success";
	}
}

三、Spring的RestTemplate

springmvc.xml增加

<!-- 配置RestTemplate -->
  <!--Http client Factory -->
  <bean id="httpClientFactory"
    class="org.springframework.http.client.SimpleClientHttpRequestFactory">
    <property name="connectTimeout" value="10000" />
    <property name="readTimeout" value="10000" />
  </bean>

  <!--RestTemplate -->
  <bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
    <constructor-arg ref="httpClientFactory" />
  </bean>

controller

@Controller
public class RestTemplateAction {
	@Autowired
	  private RestTemplate template;
	@RequestMapping("RestTem")
	  public @ResponseBody User RestTem(String method) {
		User user = null;
		//查找
		if ("get".equals(method)) {
			user = template.getForObject(
			          "http://localhost:8080/tao-manager-web/get/{id}",
			          User.class, "呜呜呜呜");
			//getForEntity与getForObject的区别是可以获取返回值和状态、头等信息
			ResponseEntity<User> re = template.
			          getForEntity("http://localhost:8080/tao-manager-web/get/{id}",
			          User.class, "呜呜呜呜");
			System.out.println(re.getStatusCode());
			System.out.println(re.getBody().getUsername());
			//新增
		} else if ("post".equals(method)) {
			HttpHeaders headers = new HttpHeaders();
			headers.add("X-Auth-Token", UUID.randomUUID().toString());
			MultiValueMap<String, String> postParameters = new LinkedMultiValueMap<String, String>();
			postParameters.add("id", "啊啊啊");
			postParameters.add("name", "部版本");
			HttpEntity<MultiValueMap<String, String>> requestEntity = new HttpEntity<MultiValueMap<String, String>>(
			          postParameters, headers);
			user = template.postForObject(
			          "http://localhost:8080/tao-manager-web/post/aaa", requestEntity,
			          User.class);
			//删除
		} else if ("delete".equals(method)) {
			template.delete("http://localhost:8080/tao-manager-web/delete/{id}","aaa");
			//修改
		} else if ("put".equals(method)) {
			template.put("http://localhost:8080/tao-manager-web/put/{id}",null,"bbb");
		}
		return user;
	}
}

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