简单的Spring JPA实现例子
1. 使用maven创建一个jpa的测试工程
<textarea cols="50" rows="15" name="code" class="java">mvn archetype:create -DgroupId=myjpa -DartifactId=myjpa</textarea>
2. 添加jpa所依赖的包，这里使用的hibernate的jpa实现，并且使用hsql数据库作为测试数据库
<textarea cols="50" rows="15" name="code" class="xhtml"> <build> <plugins> <plugin> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.5</source> <target>1.5</target> </configuration> </plugin> </plugins> </build> <dependencies> <dependency> <groupId>commons-lang</groupId> <artifactId>commons-lang</artifactId> <version>2.4</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.5.8</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-jdk14</artifactId> <version>1.5.8</version> </dependency> <dependency> <groupId>hsqldb</groupId> <artifactId>hsqldb</artifactId> <version>1.8.0.7</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring</artifactId> <version>2.5</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>3.3.1.GA</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-annotations</artifactId> <version>3.3.1.GA</version> </dependency> <dependency> <groupId>hibernate</groupId> <artifactId>hibernate-entitymanager</artifactId> <version>3.4.0.GA</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.3.1</version> <scope>test</scope> </dependency> <dependencies></textarea>
3. 创建两个model类
Customer.java
<textarea cols="50" rows="15" name="code" class="c-sharp">package myjpa.model; import java.io.Serializable; import java.util.ArrayList; import java.util.Date; import java.util.List; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.OneToMany; import javax.persistence.Temporal; import javax.persistence.TemporalType; @Entity public class Customer implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; private String email; @Temporal(TemporalType.DATE) private Date birthday; @OneToMany(mappedBy = "customer") private final List<Address> addresses = new ArrayList<Address>(); public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } public List<Address> getAddresses() { return addresses; } public void addAddress(Address address) { this.addresses.add(address); address.setCustomer(this); } @Override public String toString() { return org.apache.commons.lang.builder.ToStringBuilder.reflectionToString(this); } }</textarea>
Address.java
<textarea cols="50" rows="15" name="code" class="java">package myjpa.model; import java.io.Serializable; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.ManyToOne; @Entity public class Address implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; private String description; private String zipcode; @ManyToOne private Customer customer; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } public String getZipcode() { return zipcode; } public void setZipcode(String zipcode) { this.zipcode = zipcode; } public Customer getCustomer() { return customer; } public void setCustomer(Customer customer) { this.customer = customer; } @Override public String toString() { return org.apache.commons.lang.builder.ToStringBuilder.reflectionToString(this); } } </textarea>
4. 创建DAO接口和实现类，这里为了简单，省去了异常处理的代码
CustomerDAO接口如下
<textarea cols="50" rows="15" name="code" class="java">package myjpa.dao; import java.util.List; import myjpa.model.Customer; public interface CustomerDAO { Customer findById(int id); Customer add(Customer customer); List<Customer> list(); }</textarea>
CustomerDAOJPAImpl实现类如下：
<textarea cols="50" rows="15" name="code" class="java">package myjpa.dao; import java.util.List; import org.springframework.orm.jpa.support.JpaDaoSupport; import myjpa.model.Customer; public class CustomerDAOJPAImpl extends JpaDaoSupport implements CustomerDAO { public Customer findById(int id) { return getJpaTemplate().find(Customer.class, id); } public Customer add(Customer customer) { getJpaTemplate().persist(customer); return getJpaTemplate().find(Customer.class, customer.getId()); } @SuppressWarnings("unchecked") public List<Customer> list() { List<Customer> customers = getJpaTemplate().find("select c from Customer c"); return customers; } }</textarea>
5. 配置persistence.xml文件
在工程的src/main/resources目录下创建META-INF目录，并在META-INF下创建persistence.xml文件，内容如下：
<textarea cols="50" rows="15" name="code" class="xhtml"> <?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" 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_1_0.xsd"> <persistence-unit name="spring" transaction-type="RESOURCE_LOCAL"> <class>myjpa.model.Customer</class> <class>myjpa.model.Address</class> </persistence-unit> </persistence></textarea>
注意：这里只有实体类的配置，所有关于数据库的配置都放到了spring的配置文件里统一处理。
6. 配置spring文件
在工程的src/main/resources目录下创建spring.xml文件，内容如下：
<textarea cols="50" rows="15" name="code" class="xhtml"> <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="customerDAOTarget" class="myjpa.dao.CustomerDAOJPAImpl"> <property name="entityManagerFactory" ref="entityManagerFactory" /> </bean> <bean id="customerDAO" class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean"> <property name="transactionManager" ref="transactionManager" /> <property name="target" ref="customerDAOTarget" /> <property name="transactionAttributes"> <props> <prop key="save*">PROPAGATION_REQUIRED</prop> <prop key="del*">PROPAGATION_REQUIRED</prop> <prop key="update*">PROPAGATION_REQUIRED</prop> <prop key="create*">PROPAGATION_REQUIRED</prop> <prop key="add*">PROPAGATION_REQUIRED</prop> <prop key="find*">PROPAGATION_REQUIRED,readOnly</prop> <prop key="get*">PROPAGATION_REQUIRED,readOnly</prop> <prop key="*">PROPAGATION_REQUIRED</prop> </props> </property> </bean> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="spring" /> <property name="dataSource" ref="dataSource" /> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="showSql" value="false" /> <property name="generateDdl" value="true" /> <property name="databasePlatform" value="org.hibernate.dialect.HSQLDialect" /> </bean> </property> <property name="loadTimeWeaver"> <bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver" /> </property> </bean> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="org.hsqldb.jdbcDriver" /> <property name="url" value="jdbc:hsqldb:mem:." /> <property name="username" value="sa" /> <property name="password" value="" /> </bean> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory" /> <property name="dataSource" ref="dataSource" /> </bean> </beans></textarea>
7. 编写测试类，这里简单起见就没有再引入别的数据库测试包，而是使用的CustomerDAO自己的添加和查询方法测试自己，通常情况应该是使用第三方的JDBC测试工具来做这些测试。在src/test/java目录下创建测试类CustomerDAOJPAImplTest
<textarea cols="50" rows="15" name="code" class="java">package myjpa.dao; import java.util.Calendar; import java.util.List; import junit.framework.Assert; import org.junit.After; import org.junit.AfterClass; import org.junit.Before; import org.junit.BeforeClass; import org.junit.Test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import myjpa.model.Address; import myjpa.model.Customer; public class CustomerDAOJPAImplTest { private static CustomerDAO customerDAO; @BeforeClass public static void setUpBeforeClass() throws Exception { ApplicationContext ctx = new ClassPathXmlApplicationContext("/spring.xml"); customerDAO = (CustomerDAO)ctx.getBean("customerDAO"); for (int i = 0; i < 10; i++) { Customer customer = new Customer(); customer.setName("customer_" + i); customer.setEmail("customer_" + i + "@my.com"); customer.setBirthday(Calendar.getInstance().getTime()); Address addressHome = new Address(); addressHome.setName("Home"); addressHome.setDescription("Home"); addressHome.setZipcode("123456"); Address addressOffice = new Address(); addressOffice.setName("Office"); addressOffice.setDescription("Office"); addressOffice.setZipcode("654321"); customer.addAddress(addressHome); customer.addAddress(addressOffice); customerDAO.add(customer); } } @AfterClass public static void tearDownAfterClass() throws Exception { } @Before public void setUp() throws Exception { } @After public void tearDown() throws Exception { } @Test public void testFindById() { List<Customer> customers = customerDAO.list(); for (Customer customer : customers) { Customer anotherCustomer = customerDAO.findById(customer.getId()); Assert.assertNotNull(anotherCustomer); Assert.assertEquals(customer.getId(), anotherCustomer.getId()); Assert.assertEquals(customer.getName(), anotherCustomer.getName()); } } @Test public void testAdd() { Customer customer = new Customer(); customer.setName("customer_abc"); customer.setEmail("customer_abc" + "@my.com"); customer.setBirthday(Calendar.getInstance().getTime()); Address addressHome = new Address(); addressHome.setName("Home"); addressHome.setDescription("Home"); addressHome.setZipcode("123456"); Address addressOffice = new Address(); addressOffice.setName("Office"); addressOffice.setDescription("Office"); addressOffice.setZipcode("654321"); customer.addAddress(addressHome); customer.addAddress(addressOffice); Customer persistedCustomer = customerDAO.add(customer); Assert.assertNotNull(customer); Assert.assertEquals(customer.getName(), persistedCustomer.getName()); } @Test public void testList() { List<Customer> customers = customerDAO.list(); Assert.assertEquals(true, customers.size() > 0); } }</textarea>
8. 运行测试类，JPA会自动创建所要使用的数据库和表，然后就会执行相应的添加和查询操作，并使用断言来验证测试的正确性。