java如何写接口给别人调用的示例代码

2019-11-26 08:37:25

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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：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>ws</groupId> <artifactId>restful</artifactId> <packaging>war</packaging> <version>0.0.1-SNAPSHOT</version> <name>restful-server</name> <url>http://maven.apache.org</url> <properties>    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>    <jersey.version>2.6</jersey.version>    <jersey-spring.version>2.23.1</jersey-spring.version>    <spring.version>4.2.7.RELEASE</spring.version>    <servlet-api-version>3.1.0</servlet-api-version>    <logback.version>1.1.1</logback.version>    <jcloverslf4j.version>1.7.6</jcloverslf4j.version>  </properties> <dependencies>  <dependency>   <groupId>junit</groupId>   <artifactId>junit</artifactId>   <version>3.8.1</version>   <scope>test</scope>  </dependency>    <dependency>      <groupId>org.glassfish.jersey.ext</groupId>      <artifactId>jersey-spring3</artifactId>      <version>${jersey-spring.version}</version>      <exclusions>        <exclusion>          <groupId>org.springframework</groupId>          <artifactId>spring-core</artifactId>        </exclusion>        <exclusion>          <groupId>org.springframework</groupId>          <artifactId>spring-web</artifactId>        </exclusion>        <exclusion>          <groupId>org.springframework</groupId>          <artifactId>spring-beans</artifactId>        </exclusion>      </exclusions>    </dependency>     <dependency>      <groupId>org.glassfish.jersey.containers</groupId>      <artifactId>jersey-container-servlet</artifactId>      <version>${jersey-spring.version}</version>    </dependency>    <dependency>      <groupId>org.glassfish.jersey.containers</groupId>      <artifactId>jersey-container-servlet-core</artifactId>      <version>${jersey-spring.version}</version>    </dependency>      <dependency>      <groupId>org.glassfish.jersey.media</groupId>      <artifactId>jersey-media-json-jackson</artifactId>      <version>${jersey.version}</version>    </dependency>    <dependency>      <groupId>org.glassfish.jersey.media</groupId>      <artifactId>jersey-media-multipart</artifactId>      <version>${jersey.version}</version>    </dependency>    <dependency>      <groupId>org.glassfish.jersey.ext</groupId>      <artifactId>jersey-entity-filtering</artifactId>      <version>${jersey.version}</version>    </dependency>     <!-- Spring4.2 dependencies -->    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-core</artifactId>      <version>${spring.version}</version>    </dependency>     <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-context</artifactId>      <version>${spring.version}</version>    </dependency>     <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-web</artifactId>      <version>${spring.version}</version>    </dependency>     <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-jdbc</artifactId>      <version>${spring.version}</version>    </dependency>     <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-tx</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-test</artifactId>      <version>${spring.version}</version>      <scope>test</scope>    </dependency>     <dependency>      <groupId>javax.servlet</groupId>      <artifactId>javax.servlet-api</artifactId>      <version>${servlet-api-version}</version>      <scope>provided</scope>    </dependency>     <!-- Logback dependencies -->    <dependency>      <groupId>ch.qos.logback</groupId>      <artifactId>logback-classic</artifactId>      <version>${logback.version}</version>    </dependency>    <dependency>      <groupId>org.slf4j</groupId>      <artifactId>jcl-over-slf4j</artifactId>      <version>${jcloverslf4j.version}</version>    </dependency>   </dependencies> <build>  <finalName>restful</finalName> </build></project>

4 applicationContext.xml内容如下：

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

<?xml version="1.0" encoding="UTF-8"?><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"> <display-name></display-name> <context-param>  <param-name>contextConfigLocation</param-name>  <param-value>classpath:applicationContext.xml</param-value> </context-param> <listener>  <listener-class>      org.springframework.web.context.ContextLoaderListener    </listener-class> </listener> <servlet>  <servlet-name>jersey-serlvet</servlet-name>  <servlet-class>      org.glassfish.jersey.servlet.ServletContainer    </servlet-class>  <init-param>   <param-name>javax.ws.rs.Application</param-name>   <param-value>com.kendy.filter.RestJaxRsApplication</param-value>  </init-param>  <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping>  <servlet-name>jersey-serlvet</servlet-name>  <url-pattern>/*</url-pattern> </servlet-mapping></web-app>

6 拦截器如下：

import java.io.IOException;import java.io.InputStream;import java.util.List;import java.util.Map.Entry; import javax.ws.rs.WebApplicationException;import javax.ws.rs.container.ContainerRequestContext;import javax.ws.rs.container.ContainerRequestFilter;import javax.ws.rs.core.MultivaluedMap;import javax.ws.rs.core.Response.Status;import javax.ws.rs.ext.Provider; /** * 拦截请求 */@Providerpublic class MyFilter implements ContainerRequestFilter {  @Override public void filter(ContainerRequestContext context) throws IOException {    //打印出所有请求头  MultivaluedMap<String, String> map = context.getHeaders();  for(Entry<String, List<String>> entry : map.entrySet()){  	String key = entry.getKey();  	List<String> valueList = entry.getValue();  	String values = valueList.toString();  	System.out.println(key + ":"+values.substring(1,values.length()-1));  }

7 注册Jersey容器所要管理的类

import org.codehaus.jackson.jaxrs.JacksonJsonProvider;import org.glassfish.jersey.server.ResourceConfig; import com.kendy.restful.AccountManager;import com.kendy.restful.AuthorityManager;import com.kendy.restful.CardManager;import com.kendy.restful.DeviceManager;import com.kendy.restful.UserResource; /** * ${DESCRIPTION} */public class RestJaxRsApplication extends ResourceConfig {   /**   * Register JAX-RS application components.   */  public RestJaxRsApplication() {     //服务类所在的包路径    packages("com.kendy.*");        // register application resources    this.register(YouClass.class);       // register filters    this.register(MyFilter.class);    //this.register(RequestContextFilter.class);        register(JacksonJsonProvider.class);    //register(MultiPartFeature.class);  }}

8 接口定义（Restful风格）

package com.kendy.restful; import java.text.SimpleDateFormat;import java.util.ArrayList;import java.util.Date;import java.util.HashMap;import java.util.List;import java.util.Map; import javax.ws.rs.Consumes;import javax.ws.rs.POST;import javax.ws.rs.Path;import javax.ws.rs.Produces;import javax.ws.rs.core.MediaType; import org.springframework.stereotype.Component; @Component@Path("/CardManager")public class CardManager {	  private SimpleDateFormat sdf =new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");   @POST  @Path("size")  @Consumes(MediaType.APPLICATION_JSON)  @Produces(MediaType.APPLICATION_JSON)  public Map<String,Object> size(){  	Map<String,Object> map = new HashMap<>();  	//do something here  	map.put("Size", 1024);  	return map;  }    @POST  @Path("getDetail")  @Consumes(MediaType.APPLICATION_JSON)  @Produces(MediaType.APPLICATION_JSON)  public Map<String,List<Map<String,Object>>> getDetail(){  	Map<String,List<Map<String,Object>>> map = new HashMap<>();  	//do something here  	List<Map<String,Object>> list = new ArrayList<>();  	Map<String,Object> subMap = new HashMap<>();  	subMap.put("UUID", 10086);  	subMap.put("CardID", 10081);  	subMap.put("StartTime", sdf.format(new Date()));  	subMap.put("EndTime", sdf.format(new Date()));  	list.add(subMap);  	map.put("Card", list);  	  	return map;  }}

9 调用接口，有多种方式，本文用HttpClient

/**   * 发送 post请求webService接口   * @param url 访问的接口地址   * @param account 用户名   * @param code 密码   * @param param 查询参数   * @return HttpResponse 该类包含请求方法的态码及返回的数据   */   public static HttpResponse post(String url,String account,String code,Map<String,Object> param) {     //创建HttpClient实例及Post方法  	HttpClient httpclient = new DefaultHttpClient();     HttpPost httppost = new HttpPost(url);     //对用户密码MD5加密		code = getMD5(code);		//添加相关请求头，依情况而定		httppost.setHeader("Authorization","WSSE profile=/"UsernameToken/""); 		httppost.setHeader("X-WSSE","UsernameToken Username=/""+account+"/",PasswordDigest=/""+code+"/""); 		httppost.addHeader("Content-type","application/json; charset=utf-8"); 		httppost.setHeader("Accept", "application/json"); 		httppost.setHeader("Connection","keep-alive"); 		httppost.setHeader("Accept-Encoding","gzip"); 		httppost.setHeader("Accept-Language", "zh-CN,en,*"); 		httppost.setHeader("User-Agent","Mozilla/5.0"); 		//传递请求参数		String paramJsonStr = JSON.toJSONString(param);		if(param != null)			httppost.setEntity(new StringEntity(paramJsonStr, Charset.forName("UTF-8"))); 		HttpResponse response = null;		try { 			//执行post请求      response = httpclient.execute(httppost);     } catch (Exception e) {       e.printStackTrace();     }     return response;  }

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。

	/**	 * 将从接口返回的JSON数据转换为实体集合等待插入数据表	 * 实体 IgmAccessControlChannelModel --> IGM_ACCESSCONTROL_CHANNEL	 * 	  IgmStationDoorModel --> IGM_STATION_DOOR	 */	@SuppressWarnings({ "unchecked", "rawtypes" })	private Map<String,Object> getDeviceEntityList(String data){		Map<String,Object> totalMap = new HashMap<>();		//把以下三个结果放到totalMap里返回		List<IgmAccessControlChannelModel> accessControlList = new ArrayList<>();		List<IgmStationDoorModel> doorList = new ArrayList<>();		List<String> deviceIds = new ArrayList<>();				IgmAccessControlChannelModel accessControlModel = null;		IgmStationDoorModel stationDoorModel = null;				Map map = JSON.parseObject(data, Map.class);		map = (Map<String,List<Map<String,Object>>>)map;		List<Map<String,Object>> deviceList = (List<Map<String, Object>>) map.get("Device");				for(Map<String,Object> deviceMap : deviceList){			String deviceId = (String)(deviceMap.get("DeviceID")+"");			Object channels = deviceMap.get("Channels");			List<Map<String,Object>> channelList = (List<Map<String,Object>>)channels;						String id = ""; //用于设置igmaccessControlchannel表和igmstationDoor表的stationDoorid			//判断该门禁设备ID在本平台是否匹配			boolean isMatched = isDeviceIdMatched(deviceId);						if(isMatched){				for(Map<String,Object> chnnelMap : channelList){					accessControlModel = new IgmAccessControlChannelModel();					stationDoorModel = new IgmStationDoorModel();					for(Map.Entry<String, Object> entry : chnnelMap.entrySet()){						String key = entry.getKey().trim();						String value = "";						if(key.equals("Channel")){							value =(Integer)entry.getValue()+"";						}else{							value = (String)entry.getValue();						}												switch(key){						case "Channel":							accessControlModel.setCommandCode(Integer.parseInt(value));							accessControlModel.setControlChannelName("控制通道"+value);							stationDoorModel.setDoorCode(value);							break;						case "Description":							stationDoorModel.setStationDoorName(value);							break;						default: break;						}					}					id = UUID.randomUUID().toString();										accessControlModel.setAccessControlChannelId(UUID.randomUUID().toString());					accessControlModel.setDeviceId(deviceId);					accessControlModel.setStationDoorId(id);										stationDoorModel.setStationDoorId(id);					stationDoorModel.setDeviceId(deviceId);					stationDoorModel.setRemark("指纹门禁");										accessControlList.add(accessControlModel);					doorList.add(stationDoorModel);				}				deviceIds.add(deviceId);			}else{				//deviceId不匹配的跳过			}		}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。

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