java如何写接口给别人调用的示例代码

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
 */
@provider
public 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。