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java如何写接口给别人调用_java 对外提供接口

作者：小蓝xlanll | 2024-05-22 11:15:57

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java 对外提供接口

计算机语言分类有很多，如C、C++、C#、Java、Php、Python等等，她们有各自的特性及擅长的领域，但她们各自又不是全能的。在一个稍微大型一点的项目都会用到多种语言共同完成，那么这些编程语言如何进行通信呢。什么意思呢，就是比如说我Java写的一个方法，其他编程语言要怎么去调用呢？这就是本文要探讨的问题了。

一般来说，方法层面的编程语言通信用的是网络接口形式，只暴露出形参和结果供别人调用。接口一般分为接口定义者和接口调用者，定义者可以规定接收参数的类型及返回形式，而接口定义者则只能完全按照接口定义者规定的参数进行访问。就叫是我们所说的webService(网络服务)。

以前的做法是利用XML作接口格式定义，然后通过Http做通讯和请求，如大名鼎鼎的SOAP，其实现在也是的，只不过现在流行RestFul风格的Rest接口形式，但用的还是XML+HTTP，那这两者有啥区别呢？最大的区别就是SOAP返回的主要是XML格式，有时还需要附带一些辅助文件，而Rest则还可以返回JSON类型的字符串，减少了很多繁乱的XML标签。本文就以Java为例，用她写一个接口，并让其他人去调用，以此来简单展示接口调用是怎么样一个过程。

步骤：

1、本机装有Java JDK运行环境及编程IDE（如Myeclipse)

2、建立一个maven项目，用以下载jar包，项目结构如下：



3 pom.xml文件内容如下：

  1. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  2.   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  3.   <modelVersion>4.0.0</modelVersion>
  4.   <groupId>ws</groupId>
  5.   <artifactId>restful</artifactId>
  6.   <packaging>war</packaging>
  7.   <version>0.0.1-SNAPSHOT</version>
  8.   <name>restful-server</name>
  9.   <url>http://maven.apache.org</url>
  10.   <properties>
  11.         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  12.         <jersey.version>2.6</jersey.version>
  13.         <jersey-spring.version>2.23.1</jersey-spring.version>
  14.         <spring.version>4.2.7.RELEASE</spring.version>
  15.         <servlet-api-version>3.1.0</servlet-api-version>
  16.         <logback.version>1.1.1</logback.version>
  17.         <jcloverslf4j.version>1.7.6</jcloverslf4j.version>
  18.     </properties>
  19.   <dependencies>
  20.     <dependency>
  21.       <groupId>junit</groupId>
  22.       <artifactId>junit</artifactId>
  23.       <version>3.8.1</version>
  24.       <scope>test</scope>
  25.     </dependency>
  26.     
  27.     <dependency>
  28.             <groupId>org.glassfish.jersey.ext</groupId>
  29.             <artifactId>jersey-spring3</artifactId>
  30.             <version>${jersey-spring.version}</version>
  31.             <exclusions>
  32.                 <exclusion>
  33.                     <groupId>org.springframework</groupId>
  34.                     <artifactId>spring-core</artifactId>
  35.                 </exclusion>
  36.                 <exclusion>
  37.                     <groupId>org.springframework</groupId>
  38.                     <artifactId>spring-web</artifactId>
  39.                 </exclusion>
  40.                 <exclusion>
  41.                     <groupId>org.springframework</groupId>
  42.                     <artifactId>spring-beans</artifactId>
  43.                 </exclusion>
  44.             </exclusions>
  45.         </dependency>
  46.  
  47.         <dependency>
  48.             <groupId>org.glassfish.jersey.containers</groupId>
  49.             <artifactId>jersey-container-servlet</artifactId>
  50.             <version>${jersey-spring.version}</version>
  51.         </dependency>
  52.         <dependency>
  53.             <groupId>org.glassfish.jersey.containers</groupId>
  54.             <artifactId>jersey-container-servlet-core</artifactId>
  55.             <version>${jersey-spring.version}</version>
  56.         </dependency>
  57.  
  58.          <dependency>
  59.             <groupId>org.glassfish.jersey.media</groupId>
  60.             <artifactId>jersey-media-json-jackson</artifactId>
  61.             <version>${jersey.version}</version>
  62.         </dependency>
  63.         <dependency>
  64.             <groupId>org.glassfish.jersey.media</groupId>
  65.             <artifactId>jersey-media-multipart</artifactId>
  66.             <version>${jersey.version}</version>
  67.         </dependency>
  68.         <dependency>
  69.             <groupId>org.glassfish.jersey.ext</groupId>
  70.             <artifactId>jersey-entity-filtering</artifactId>
  71.             <version>${jersey.version}</version>
  72.         </dependency>
  73.  
  74.         <!-- Spring4.2 dependencies -->
  75.         <dependency>
  76.             <groupId>org.springframework</groupId>
  77.             <artifactId>spring-core</artifactId>
  78.             <version>${spring.version}</version>
  79.         </dependency>
  80.  
  81.         <dependency>
  82.             <groupId>org.springframework</groupId>
  83.             <artifactId>spring-context</artifactId>
  84.             <version>${spring.version}</version>
  85.         </dependency>
  86.  
  87.         <dependency>
  88.             <groupId>org.springframework</groupId>
  89.             <artifactId>spring-web</artifactId>
  90.             <version>${spring.version}</version>
  91.         </dependency>
  92.  
  93.         <dependency>
  94.             <groupId>org.springframework</groupId>
  95.             <artifactId>spring-jdbc</artifactId>
  96.             <version>${spring.version}</version>
  97.         </dependency>
  98.  
  99.         <dependency>
  100.             <groupId>org.springframework</groupId>
  101.             <artifactId>spring-tx</artifactId>
  102.             <version>${spring.version}</version>
  103.         </dependency>
  104.         <dependency>
  105.             <groupId>org.springframework</groupId>
  106.             <artifactId>spring-test</artifactId>
  107.             <version>${spring.version}</version>
  108.             <scope>test</scope>
  109.         </dependency>
  110.  
  111.         <dependency>
  112.             <groupId>javax.servlet</groupId>
  113.             <artifactId>javax.servlet-api</artifactId>
  114.             <version>${servlet-api-version}</version>
  115.             <scope>provided</scope>
  116.         </dependency>
  117.  
  118.         <!-- Logback dependencies -->
  119.         <dependency>
  120.             <groupId>ch.qos.logback</groupId>
  121.             <artifactId>logback-classic</artifactId>
  122.             <version>${logback.version}</version>
  123.         </dependency>
  124.         <dependency>
  125.             <groupId>org.slf4j</groupId>
  126.             <artifactId>jcl-over-slf4j</artifactId>
  127.             <version>${jcloverslf4j.version}</version>
  128.         </dependency>
  129.     
  130.   </dependencies>
  131.   <build>
  132.     <finalName>restful</finalName>
  133.   </build>
  134. </project>

4 applicationContext.xml内容如下： 

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <beans xmlns="http://www.springframework.org/schema/beans"
  3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.        xmlns:context="http://www.springframework.org/schema/context"
  5.        xmlns:tx="http://www.springframework.org/schema/tx"
  6.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
  7.         http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">
  8.  
  9.     <context:component-scan base-package="com.kendy.*"></context:component-scan>
  10. </beans>

5 web.xml则主要配置采用的容器、日志管理及拦截器，拦截器可以实现到达请求郑涛之前进行身份认证，踢除没有访问资格的请求，而rest项目一般是用Jersey容器。配置如下：（kendy只是我的英文名，你们可以自己定义路径） 

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <web-app xmlns:javaee="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  3.   <display-name></display-name>
  4.   <context-param>
  5.     <param-name>contextConfigLocation</param-name>
  6.     <param-value>classpath:applicationContext.xml</param-value>
  7.   </context-param>
  8.   <listener>
  9.     <listener-class>
  10.             org.springframework.web.context.ContextLoaderListener
  11.         </listener-class>
  12.   </listener>
  13.   <servlet>
  14.     <servlet-name>jersey-serlvet</servlet-name>
  15.     <servlet-class>
  16.             org.glassfish.jersey.servlet.ServletContainer
  17.         </servlet-class>
  18.     <init-param>
  19.       <param-name>javax.ws.rs.Application</param-name>
  20.       <param-value>com.kendy.filter.RestJaxRsApplication</param-value>
  21.     </init-param>
  22.     <load-on-startup>1</load-on-startup>
  23.   </servlet>
  24.   <servlet-mapping>
  25.     <servlet-name>jersey-serlvet</servlet-name>
  26.     <url-pattern>/*</url-pattern>
  27.   </servlet-mapping>
  28. </web-app>


6 拦截器如下：

  1. import java.io.IOException;
  2. import java.io.InputStream;
  3. import java.util.List;
  4. import java.util.Map.Entry;
  5.  
  6. import javax.ws.rs.WebApplicationException;
  7. import javax.ws.rs.container.ContainerRequestContext;
  8. import javax.ws.rs.container.ContainerRequestFilter;
  9. import javax.ws.rs.core.MultivaluedMap;
  10. import javax.ws.rs.core.Response.Status;
  11. import javax.ws.rs.ext.Provider;
  12.  
  13. /**
  14.  * 拦截请求
  15.  */
  16. @Provider
  17. public class MyFilter implements ContainerRequestFilter {
  18.  
  19.   @Override
  20.   public void filter(ContainerRequestContext context) throws IOException {
  21.     
  22.     //打印出所有请求头
  23.     MultivaluedMap<String, String> map =  context.getHeaders();
  24.     for(Entry<String, List<String>> entry : map.entrySet()){
  25.     	String key = entry.getKey();
  26.     	List<String> valueList = entry.getValue();
  27.     	String values = valueList.toString();
  28.     	System.out.println(key + ":"+values.substring(1,values.length()-1));
  29.     }

7 注册Jersey容器所要管理的类 

  1. import org.codehaus.jackson.jaxrs.JacksonJsonProvider;
  2. import org.glassfish.jersey.server.ResourceConfig;
  3.  
  4. import com.kendy.restful.AccountManager;
  5. import com.kendy.restful.AuthorityManager;
  6. import com.kendy.restful.CardManager;
  7. import com.kendy.restful.DeviceManager;
  8. import com.kendy.restful.UserResource;
  9.  
  10. /**
  11.  * ${DESCRIPTION}
  12.  */
  13. public class RestJaxRsApplication extends ResourceConfig {
  14.  
  15.     /**
  16.      * Register JAX-RS application components.
  17.      */
  18.     public RestJaxRsApplication() {
  19.  
  20.         //服务类所在的包路径
  21.         packages("com.kendy.*");
  22.         
  23.         // register application resources
  24.         this.register(YouClass.class);
  25.      
  26.         // register filters
  27.         this.register(MyFilter.class);
  28.         //this.register(RequestContextFilter.class);
  29.         
  30.         register(JacksonJsonProvider.class);
  31.         //register(MultiPartFeature.class);
  32.     }
  33. }

8 接口定义（Restful风格） 

  1. package com.kendy.restful;
  2.  
  3. import java.text.SimpleDateFormat;
  4. import java.util.ArrayList;
  5. import java.util.Date;
  6. import java.util.HashMap;
  7. import java.util.List;
  8. import java.util.Map;
  9.  
  10. import javax.ws.rs.Consumes;
  11. import javax.ws.rs.POST;
  12. import javax.ws.rs.Path;
  13. import javax.ws.rs.Produces;
  14. import javax.ws.rs.core.MediaType;
  15.  
  16. import org.springframework.stereotype.Component;
  17.  
  18. @Component
  19. @Path("/CardManager")
  20. public class CardManager {
  21. 	
  22.     private SimpleDateFormat sdf =new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
  23.  
  24.     @POST
  25.     @Path("size")
  26.     @Consumes(MediaType.APPLICATION_JSON)
  27.     @Produces(MediaType.APPLICATION_JSON)
  28.     public Map<String,Object> size(){
  29.     	Map<String,Object> map = new HashMap<>();
  30.     	//do something here
  31.     	map.put("Size", 1024);
  32.     	return map;
  33.     }
  34.     
  35.     @POST
  36.     @Path("getDetail")
  37.     @Consumes(MediaType.APPLICATION_JSON)
  38.     @Produces(MediaType.APPLICATION_JSON)
  39.     public Map<String,List<Map<String,Object>>> getDetail(){
  40.     	Map<String,List<Map<String,Object>>> map = new HashMap<>();
  41.     	//do something here
  42.     	List<Map<String,Object>> list = new ArrayList<>();
  43.     	Map<String,Object> subMap = new HashMap<>();
  44.     	subMap.put("UUID", 10086);
  45.     	subMap.put("CardID", 10081);
  46.     	subMap.put("StartTime", sdf.format(new Date()));
  47.     	subMap.put("EndTime", sdf.format(new Date()));
  48.     	list.add(subMap);
  49.     	map.put("Card", list);
  50.     	
  51.     	return map;
  52.     }
  53. }

9 调用接口，有多种方式，本文用HttpClient 

  1. /**
  2.      * 发送 post请求webService接口
  3.      * @param url 访问的接口地址
  4.      * @param account 用户名
  5.      * @param code 密码
  6.      * @param param 查询参数
  7.      * @return HttpResponse 该类包含请求方法的态码及返回的数据
  8.      */  
  9.     public static HttpResponse post(String url,String account,String code,Map<String,Object> param) {  
  10.         //创建HttpClient实例及Post方法
  11.     	HttpClient httpclient = new DefaultHttpClient();  
  12.         HttpPost httppost = new HttpPost(url); 
  13.         //对用户密码MD5加密
  14. 		code = getMD5(code);
  15. 		//添加相关请求头，依情况而定
  16. 		httppost.setHeader("Authorization","WSSE profile=\"UsernameToken\"");  
  17. 		httppost.setHeader("X-WSSE","UsernameToken Username=\""+account+"\",PasswordDigest=\""+code+"\"");  
  18. 		httppost.addHeader("Content-type","application/json; charset=utf-8");  
  19. 		httppost.setHeader("Accept", "application/json");  
  20. 		httppost.setHeader("Connection","keep-alive");  
  21. 		httppost.setHeader("Accept-Encoding","gzip");  
  22. 		httppost.setHeader("Accept-Language", "zh-CN,en,*");  
  23. 		httppost.setHeader("User-Agent","Mozilla/5.0"); 
  24. 		//传递请求参数
  25. 		String paramJsonStr = JSON.toJSONString(param);
  26. 		if(param != null)
  27. 			httppost.setEntity(new StringEntity(paramJsonStr, Charset.forName("UTF-8")));  
  28. 		HttpResponse response = null;
  29. 		try {  
  30. 			//执行post请求
  31.             response = httpclient.execute(httppost);  
  32.         } catch (Exception e) {  
  33.             e.printStackTrace();  
  34.         } 
  35.         return response;
  36.     }

10 返回接口



11 最后通过Map、List和Json工具对返回来的字面量进行各种处理。

  1. 	/**
  2. 	 * 将从接口返回的JSON数据转换为实体集合等待插入数据表
  3. 	 * 实体 IgmAccessControlChannelModel --> IGM_ACCESSCONTROL_CHANNEL
  4. 	 * 	   IgmStationDoorModel --> IGM_STATION_DOOR
  5. 	 */
  6. 	@SuppressWarnings({ "unchecked", "rawtypes" })
  7. 	private Map<String,Object> getDeviceEntityList(String data){
  8. 		Map<String,Object> totalMap = new HashMap<>();
  9. 		//把以下三个结果放到totalMap里返回
  10. 		List<IgmAccessControlChannelModel> accessControlList = new ArrayList<>();
  11. 		List<IgmStationDoorModel> doorList = new ArrayList<>();
  12. 		List<String> deviceIds = new ArrayList<>();
  13. 		
  14. 		IgmAccessControlChannelModel accessControlModel = null;
  15. 		IgmStationDoorModel stationDoorModel = null;
  16. 		
  17. 		Map map = JSON.parseObject(data, Map.class);
  18. 		map = (Map<String,List<Map<String,Object>>>)map;
  19. 		List<Map<String,Object>> deviceList = (List<Map<String, Object>>) map.get("Device");
  20. 		
  21. 		for(Map<String,Object> deviceMap : deviceList){
  22. 			String deviceId = (String)(deviceMap.get("DeviceID")+"");
  23. 			Object channels = deviceMap.get("Channels");
  24. 			List<Map<String,Object>> channelList = (List<Map<String,Object>>)channels;
  25. 			
  26. 			String id = ""; //用于设置igmaccessControlchannel表和igmstationDoor表的stationDoorid
  27. 			//判断该门禁设备ID在本平台是否匹配
  28. 			boolean isMatched = isDeviceIdMatched(deviceId);
  29. 			
  30. 			if(isMatched){
  31. 				for(Map<String,Object> chnnelMap : channelList){
  32. 					accessControlModel = new IgmAccessControlChannelModel();
  33. 					stationDoorModel = new IgmStationDoorModel();
  34. 					for(Map.Entry<String, Object> entry : chnnelMap.entrySet()){
  35. 						String key =  entry.getKey().trim();
  36. 						String value = "";
  37. 						if(key.equals("Channel")){
  38. 							value =(Integer)entry.getValue()+"";
  39. 						}else{
  40. 							value = (String)entry.getValue();
  41. 						}
  42. 						
  43. 						switch(key){
  44. 						case "Channel":
  45. 							accessControlModel.setCommandCode(Integer.parseInt(value));
  46. 							accessControlModel.setControlChannelName("控制通道"+value);
  47. 							stationDoorModel.setDoorCode(value);
  48. 							break;
  49. 						case "Description":
  50. 							stationDoorModel.setStationDoorName(value);
  51. 							break;
  52. 						default: break;
  53. 						}
  54. 					}
  55. 					id = UUID.randomUUID().toString();
  56. 					
  57. 					accessControlModel.setAccessControlChannelId(UUID.randomUUID().toString());
  58. 					accessControlModel.setDeviceId(deviceId);
  59. 					accessControlModel.setStationDoorId(id);
  60. 					
  61. 					stationDoorModel.setStationDoorId(id);
  62. 					stationDoorModel.setDeviceId(deviceId);
  63. 					stationDoorModel.setRemark("指纹门禁");
  64. 					
  65. 					accessControlList.add(accessControlModel);
  66. 					doorList.add(stationDoorModel);
  67. 				}
  68. 				deviceIds.add(deviceId);
  69. 			}else{
  70. 				//deviceId不匹配的跳过
  71. 			}
  72. 		}





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