CXF开发RESTFUL的实例练习

   根据上篇博客，我们知道WebService有两种实现规范，实现了JAX-RS这种规范的技术有CXF、RESTLET、JERSEY。这篇博客简单地介绍以CXF来实现WebService的实例。

   JAX-RS规范定义了创建RESTful服务的语法。JAX-RS使用annotations注解实现RESTful的服务，使用annotations注解POJO将它暴露为RESTful资源。

0.创建一个Web项目，引入jar包：

包结构如图：

1.使用@XmlRootElement注解POJO类

package entity;import java.util.Set;import javax.xml.bind.annotation.XmlRootElement;@XmlRootElement(name="Categorys")public class Category {private String categoryId;private String categoryName;public String getCategoryId() {return categoryId;}public void setCategoryId(String categoryId) {this.categoryId = categoryId;}public String getCategoryName() {return categoryName;}public void setCategoryName(String categoryName) {this.categoryName = categoryName;}}

在POJO类Category中，注解@XmlRootElement指定Category为XML的根元素。Category类的属性默认指定映射为@XmlElement。@XmlElement用来定义XML中的子元素。@XmlRootElement和@XmlElement允许自定义命名空间和XML中元素的名称。如果没有定义的话，JAXB在运行的时候默认的使用同样的属性名和类名来定义XML元素。

该POJO类可以对应XML文件为：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>   <Category>      <categoryId>005</categoryId>      <categoryName>Fiction Series</categoryName>  </Category>

2、dao代码，未使用数据库存储数据，采用map容器存储数据。下面代码中有对Category增删改查四个方法。

package dao;import java.util.HashMap;import java.util.HashSet;import java.util.Map;import java.util.Set;import entity.Category;public class CategoryDao {private static Map<String,Category> categoryMap = new HashMap<String,Category>();static{Category c1  = new Category();c1.setCategoryId("001");c1.setCategoryName("java");categoryMap.put(c1.getCategoryId(), c1);}public void addCategory(Category category){categoryMap.put(category.getCategoryId(), category);}public Category getCategory(String id){Category cat = null;if(categoryMap.get(id) != null){cat = new Category();cat.setCategoryId(categoryMap.get(id).getCategoryId());cat.setCategoryName(categoryMap.get(id).getCategoryName());}return cat;}public void deleteCategory(String id) {          categoryMap.remove(id);          // Remove association of books          bookMap.remove(id);      }      public void updateCategory(Category category) {          categoryMap.put(category.getCategoryId(), category);      }}

3.Service层

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package service;import javax.websocket.server.PathParam;import javax.ws.rs.Consumes;import javax.ws.rs.DELETE;import javax.ws.rs.GET;import javax.ws.rs.POST;import javax.ws.rs.PUT;import javax.ws.rs.Path;import javax.ws.rs.Produces;import javax.ws.rs.QueryParam;import javax.ws.rs.WebApplicationException;import javax.ws.rs.core.MediaType;import javax.ws.rs.core.Response;import javax.ws.rs.core.Response.ResponseBuilder;import javax.ws.rs.core.Response.Status;import dao.CategoryDao;import entity.Category;@Path("/categoryservice")@Produces({"application/json","application/xml"})public class CategoryService {private CategoryDao categorydao = new CategoryDao();public CategoryDao getCategorydao() {return categorydao;}public void setCategorydao(CategoryDao categorydao) {this.categorydao = categorydao;}@GET@Path("/category")@Produces(MediaType.APPLICATION_XML)public Category getCategory(@QueryParam("id") String id){System.out.println("获取的ID为"+id);Category category = categorydao.getCategory(id);if(category == null){ResponseBuilder builder = Response.status(Status.BAD_REQUEST);              builder.type("application/xml");              builder.entity("<error>Category Not Found</error>");              throw new WebApplicationException(builder.build());}else{return category;}}/*@GET@Path("/category/{idno}")@Produces({"application/json","application/xml"})public Category getCategory(@PathParam("idno") String id){System.out.println("获取的ID为"+id);Category category = categorydao.getCategory(id);if(category == null){ResponseBuilder builder = Response.status(Status.BAD_REQUEST);              builder.type("application/xml");              builder.entity("<error>Category Not Found</error>");              throw new WebApplicationException(builder.build());}else{return category;}}*/@POST@Path("/category")@Consumes({"application/json","application/xml"})public Response addCategory(Category category){ Category cat = (Category) categorydao.getCategory(                  category.getCategoryId());            if (cat != null) {              return Response.status(Status.BAD_REQUEST).build();          } else {          categorydao.addCategory(category);              return Response.ok(category).build();          } }         @DELETE      @Path("/category/{id}")      @Consumes({"application/json","application/xml"})      public Response deleteCategory(@PathParam("id") String id) {            System.out.println("deleteCategory with category id : " + id);            Category cat = (Category) categorydao.getCategory(id);          if (cat == null) {              return Response.status(Status.BAD_REQUEST).build();          } else {              categorydao.deleteCategory(id);              return Response.ok().build();          }      }        @PUT      @Path("/category")      @Consumes({"application/json","application/xml"})      public Response updateCategory(Category category) {            System.out.println("updateCategory with category id : "                  + category.getCategoryId());            Category cat = (Category) categorydao.getCategory(                  category.getCategoryId());          if (cat == null) {              return Response.status(Status.BAD_REQUEST).build();          } else {              categorydao.updateCategory(category);              return Response.ok(category).build();          }      }    }

服务类注解：CategoryService的类声明上定义了@Path 和@Produces注解。@Path定义了URI路径，客户端可以通过这个路径访问到CategoryService对象。如@Path("/categoryservice")，那么URI请求，就可以是http://localhost:9000/categoryservice/。@Produces定义了服务类和方法生产内容的类型。如@Produces("application/xml")，那么CategoryService只会生产application/xml。方法注解：每个方法都和@Produces相关，它决定了这个方法生产什么样的响应。每个方法都有和HTTP方法映射的的注解，例如@GET 和@POST。方法中的@Path注解指定了该方法的URI。例如getCategory()方法上的@Path("/category/{id}")，可以使用http://localhost:9000/categoryservice/category/001，访问到category id 为001的分类。{id}就好比参数。接着，让我们看看@PathParam注解。@PathParam注解是用来给URI 路径一个模板变量，方法的输入参数。@PathParam("id") 就是URI中的 @Path ("/category/{id}")。

4.启动RESTFUL服务

package client;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import org.apache.cxf.jaxrs.JAXRSServerFactoryBean;import entity.Category;import service.CategoryService;public class CategoryServerStart {public static void main(String[] args) {// Service instanceCategoryService categoryService = new CategoryService();JAXRSServerFactoryBean restServer = new JAXRSServerFactoryBean();restServer.setResourceClasses(Category.class);restServer.setServiceBean(categoryService);restServer.setAddress("http://localhost:9000/");restServer.create();BufferedReader br = new BufferedReader(new InputStreamReader(System.in));try {br.readLine();} catch (IOException e) {}System.out.println("Server Stopped");System.exit(0);}}

5.现在我们可以简单地测试一个查询方法。直接在浏览器中地址栏输入地址。采用@PathParam使用如下地址：http://localhost:9000/categoryservice/category/001，采用@QueryParam使用如下地址http://localhost:9000/categoryservice/category?id=001

看到的效果如下：