Java restful之使用Apache olingo库来将JPA操作自动转化为RESTful

     Apache Olingo 是个 Java 库，用来实现 Open Data Protocol (OData)。 Apache Olingo 包括服务客户端和 OData 服务器方面。当前支持 OData 2.0 ，未来会支持 OData 4.0。Apache Olingo 扩展部分支持 JPA 持久性或者注释 bean 类。The Open Data Protocol (OData) 是个 web 协议，为了增强各种网页应用程序之间的数据兼容性，微软公司启动了一项旨在推广网页程序数据库格式标准化的开源数据协议（OData）计划，于此同时，他们还发
布了一款适用于OData协议的开发工具，以方便网页程序开发者们使用。

    Open Data Protocol （开放数据协议，OData）是用来查询和更新数据的一种Web协议，其提供了把存在于应用程序中的数据暴露出来的方式。OData运用且构建于很多 Web技术之上，比如HTTP、Atom Publishing Protocol（AtomPub）和JSON，提供了从各种应用程序、服务和存储库中访问信息的能力。OData被用来从各种数据源中暴露和访问信息， 这些数据源包括但不限于：关系数据库、文件系统、内容管理系统和传统Web站点。

Olingo的官网：http://olingo.apache.org

下面使用Apache olingo库来将JPA操作自动转化为RESTful service。

1.使用的jar包

<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.3.1</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.8</version>
</dependency>
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>eclipselink</artifactId>
<version>2.5.2</version>
</dependency>
<dependency>
<groupId>org.apache.cxf</groupId>
<artifactId>cxf-api</artifactId>
<version>2.7.10</version>
</dependency>
<dependency>
<groupId>org.apache.cxf</groupId>
<artifactId>cxf-rt-transports-http</artifactId>
<version>2.7.10</version>
</dependency>
<dependency>
<groupId>org.apache.cxf</groupId>
<artifactId>cxf-rt-frontend-jaxws</artifactId>
<version>2.7.10</version>
</dependency>
<dependency>
<groupId>org.apache.cxf</groupId>
<artifactId>cxf-rt-frontend-jaxrs</artifactId>
<version>2.7.10</version>
</dependency>
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>javax.persistence</artifactId>
<version>2.1.0</version>
</dependency>
<dependency>
<groupId>javax.ws.rs</groupId>
<artifactId>javax.ws.rs-api</artifactId>
<version>2.0-m10</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.34</version>
</dependency>
<dependency>
<groupId>org.apache.olingo</groupId>
<artifactId>olingo-odata2-api</artifactId>
<version>2.0.2</version>
</dependency>
<dependency>
<groupId>org.apache.olingo</groupId>
<artifactId>olingo-odata2-api-annotation</artifactId>
<version>2.0.2</version>
</dependency>
<dependency>
<groupId>org.apache.olingo</groupId>
<artifactId>olingo-odata2-core</artifactId>
<version>2.0.2</version>
</dependency>
<dependency>
<groupId>org.apache.olingo</groupId>
<artifactId>olingo-odata2-jpa-processor-api</artifactId>
<version>2.0.2</version>
</dependency>
<dependency>
<groupId>org.apache.olingo</groupId>
<artifactId>olingo-odata2-jpa-processor-core</artifactId>
<version>2.0.2</version>
</dependency>

2.定义实体类，数据库

package cn.slimsmart.olingo.test;

import javax.persistence.Basic;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class User {
@Id
@GeneratedValue
private long id;
@Basic
private String name;
@Basic
private int age;
@Basic
private String sex;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public String getSex() {
return sex;
}

public void setSex(String sex) {
this.sex = sex;
}

public long getId() {
return id;
}

public void setId(long id) {
this.id = id;
}

}

数据库

CREATE TABLE `user` (
`name` varchar(40) COLLATE utf8_bin NOT NULL COMMENT '用户名称',
`age` int(3) DEFAULT NULL,
`sex` varchar(1) COLLATE utf8_bin DEFAULT NULL,
`id` int(99) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

INSERT INTO `user` VALUES ('张珊', '27', '女', '1');
INSERT INTO `user` VALUES ('李斯', '40', '男', '2');
INSERT INTO `user` VALUES ('王武', '34', '男', '3');
INSERT INTO `user` VALUES ('赵琦', '33', '女', '0');

3.定义JPA Service Factory

package cn.slimsmart.olingo.test;

import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

import org.apache.olingo.odata2.jpa.processor.api.ODataJPAContext;
import org.apache.olingo.odata2.jpa.processor.api.ODataJPAServiceFactory;
import org.apache.olingo.odata2.jpa.processor.api.exception.ODataJPARuntimeException;

public class UserServiceFactory extends ODataJPAServiceFactory {

private static final String PERSISTENCE_UNIT_NAME = "jpa";

@Override
public ODataJPAContext initializeODataJPAContext() throws ODataJPARuntimeException {
ODataJPAContext oDataJPAContext = this.getODataJPAContext();
try {
EntityManagerFactory emf = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
oDataJPAContext.setEntityManagerFactory(emf);
oDataJPAContext.setPersistenceUnitName(PERSISTENCE_UNIT_NAME);
return oDataJPAContext;
} catch (Exception e) {
throw new RuntimeException(e);
}
}

}

4.配置persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"> <persistence-unit name="jpa" transaction-type="RESOURCE_LOCAL">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<class>cn.slimsmart.olingo.test.User</class>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/slimsmart" />
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
<property name="javax.persistence.jdbc.user" value="root" />
<property name="javax.persistence.jdbc.password" value="" />
</properties>
</persistence-unit>
</persistence>

5.web.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>olingo</display-name>
<servlet>
<servlet-name>ODataServlet</servlet-name>
<servlet-class>org.apache.cxf.jaxrs.servlet.CXFNonSpringJaxrsServlet</servlet-class>
<init-param>
<param-name>javax.ws.rs.Application</param-name>
<param-value>org.apache.olingo.odata2.core.rest.app.ODataApplication</param-value>
</init-param>
<init-param>
<param-name>org.apache.olingo.odata2.service.factory</param-name>
<param-value>cn.slimsmart.olingo.test.UserServiceFactory</param-value>
</init-param>
<load-on-startup>2</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>ODataServlet</servlet-name>
<url-pattern>/User.svc/*</url-pattern>
</servlet-mapping>

<!--session超时定义,单位为分钟 -->
<session-config>
<session-timeout>10</session-timeout>
</session-config>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>

6.项目结构，代码下载



启动访问：http://localhost:8080/olingo-test/User.svc/Users



通过http://localhost:8080/olingo-test/User.svc/Users(3)访问单条数据库实体。