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,String> paramBody) throws Exception {
		return doPost(httpsClient,url,paramHeader,paramBody,DEFAULT_CHARSET);
	}
	public static String doPost(HTTPSClient httpsClient,String> paramBody,String charset) throws Exception {
		String result = null;
		HttpPost httpPost = new HttpPost(url);
		setHeader(httpPost,paramHeader);
		setBody(httpPost,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> paramBody) throws Exception {
		return doGet(httpsClient,DEFAULT_CHARSET);
	}
	public static String doGet(HTTPSClient httpsClient,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,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,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,paramBody);
		//String result = HTTPSClientUtil.doGet(httpsClient,null,null); 
		System.out.println(result);
	}
}

（编辑：安卓应用网）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!