Spring Data JPA API提供了JpaTemplate類(lèi),以將spring應(yīng)用程序與JPA集成。
JPA(Java持久性API)是sun規(guī)范用于在企業(yè)應(yīng)用程序中持久存儲(chǔ)對(duì)象。當(dāng)前,它被用作復(fù)雜實(shí)體bean的代替。
許多供應(yīng)商都提供JPA規(guī)范的實(shí)現(xiàn),例如:
Hibernate Toplink iBatis OpenJPA等。
您無(wú)需編寫(xiě)前后代碼即可持久,更新,刪除或搜索對(duì)象,例如創(chuàng)建Persistence實(shí)例,創(chuàng)建EntityManagerFactory實(shí)例,創(chuàng)建EntityTransaction實(shí)例,創(chuàng)建EntityManager實(shí)例,提交EntityTransaction實(shí)例并關(guān)閉EntityManager。
因此,它 節(jié)省了大量代碼。
在此示例中,我們將使用休眠模式來(lái)實(shí)現(xiàn)JPA。
讓我們看一下將Spring應(yīng)用程序與JPA集成的簡(jiǎn)單步驟:
創(chuàng)建Account.java文件 創(chuàng)建Account.xml文件 創(chuàng)建AccountDao.java文件 創(chuàng)建persistence.xml文件 創(chuàng)建applicationContext.xml文件 創(chuàng)建AccountsClient.java文件
在此示例中,我們將把休眠應(yīng)用程序與spring集成在一起。讓我們看看帶有spring的jpa示例的 目錄結(jié)構(gòu)。
這是一個(gè)簡(jiǎn)單的POJO類(lèi)。
package com.nhooo; public class Account { private int accountNumber; private String owner; private double balance; //no-arg and parameterized constructor //getters and setters }
此映射文件包含持久類(lèi)的所有信息。
<entity-mappings version="1.0" xmlns="http://java.sun.com/xml/ns/persistence/orm" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm http://java.sun.com/xml/ns/persistence/orm_1_0.xsd "> <entity class="com.nhooo.Account"> <table name="account100"></table> <attributes> <id name="accountNumber"> <column name="accountnumber"/> </id> <basic name="owner"> <column name="owner"/> </basic> <basic name="balance"> <column name="balance"/> </basic> </attributes> </entity> </entity-mappings>
3、AccountDao.java
package com.nhooo; import java.util.List; import org.springframework.orm.jpa.JpaTemplate; import org.springframework.transaction.annotation.Transactional; @Transactional public class AccountsDao{ JpaTemplate template; public void setTemplate(JpaTemplate template) { this.template = template; } public void createAccount(int accountNumber,String owner,double balance){ Account account = new Account(accountNumber,owner,balance); template.persist(account); } public void updateBalance(int accountNumber,double newBalance){ Account account = template.find(Account.class, accountNumber); if(account != null){ account.setBalance(newBalance); } template.merge(account); } public void deleteAccount(int accountNumber){ Account account = template.find(Account.class, accountNumber); if(account != null) template.remove(account); } public List<Account> getAllAccounts(){ List<Account> accounts =template.find("select acc from Account acc"); return accounts; } }
4、persistence.xml
<?xml version="1.0" encoding="UTF-8"?> <persistence 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" version="1.0"> <persistence-unit name="ForAccountsDB"> <mapping-file>com/Nhooo/Account.xml</mapping-file> <class>com.nhooo.Account</class> </persistence-unit> </persistence>
5、applicationContext.xml
<?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:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd"> <tx:annotation-driven transaction-manager="jpaTxnManagerBean" proxy-target-class="true"/> <bean id="dataSourceBean" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver"></property> <property name="url" value="jdbc:oracle:thin:@localhost:1521:xe"></property> <property name="username" value="system"></property> <property name="password" value="oracle"></property> </bean> <bean id="hbAdapterBean" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="showSql" value="true"></property> <property name="generateDdl" value="true"></property> <property name="databasePlatform" value="org.hibernate.dialect.OracleDialect"></property> </bean> <bean id="emfBean" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="dataSource" ref="dataSourceBean"></property> <property name="jpaVendorAdapter" ref="hbAdapterBean"></property> </bean> <bean id="jpaTemplateBean" class="org.springframework.orm.jpa.JpaTemplate"> <property name="entityManagerFactory" ref="emfBean"></property> </bean> <bean id="accountsDaoBean" class="com.nhooo.AccountsDao"> <property name="template" ref="jpaTemplateBean"></property> </bean> <bean id="jpaTxnManagerBean" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="emfBean"></property> </bean> </beans>
generateDdl 屬性將自動(dòng)創(chuàng)建表。
showSql 屬性將在控制臺(tái)上顯示sql查詢。
6、Accountsclient.java
package com.nhooo; import java.util.List; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.context.support.FileSystemXmlApplicationContext; public class AccountsClient{ public static void main(String[] args){ ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); AccountsDao accountsDao = context.getBean("accountsDaoBean",AccountsDao.class); accountsDao.createAccount(15, "Jai Kumar", 41000); accountsDao.createAccount(20, "Rishi ", 35000); System.out.println("Accounts created"); //accountsDao.updateBalance(20, 50000); //System.out.println("Account balance updated"); /*List<Account> accounts = accountsDao.getAllAccounts(); for (int i = 0; i < accounts.size(); i++) { Account acc = accounts.get(i); System.out.println(acc.getAccountNumber() + " : " + acc.getOwner() + " (" + acc.getBalance() + ")"); }*/ //accountsDao.deleteAccount(111); //System.out.println("Account deleted"); } }
輸出
Hibernate: insert into account100 (balance, owner, accountnumber) values (?, ?, ?) Hibernate: insert into account100 (balance, owner, accountnumber) values (?, ?, ?) Accounts created