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Spring Framework 笔记（一）：IoC
一：Spring中重要的概念
1. 容器( container ) : spring容器( ApplicationContext )的工作原则是创建容器中的组件( instance )，处理组件之间的依赖关系，并将这些组件装配到一起。
2. 控制反转( Inversion of Controll ) : 组件的依赖项由容器在运行时注入( injection )，而非组件自己实例化( new )，对依赖项的控制由组件转移到了容器。
二：依赖注入( dependency injection)
1. Bean的定义：应用程序中由Spring容器进行管理的对象称为Bean
2. IoC容器负责application中对象的实例化、初始化、装配和生命周期的管理。
三：IoC-demo
1. 新建Java项目，添加工程Jar包
1) spring核心包：org.springframework.beans、org.springframework.core、org.springframework.context
2) Java日志包：commons.logging、org.apcha.log4j 和 Log4j.properties 配置文件
2. demo代码
1) 领域对象
1 package com.znker.spring.IoC; 2 3 public class Account { 4 5 private long id; 6 private String owerName; 7 private double balance; 8 9 public long getId() {10 return id;11 }12 public void setId(long id) {13 this.id = id;14 }15 public String getOwerName() {16 return owerName;17 }18 public void setOwerName(String owerName) {19 this.owerName = owerName;20 }21 public double getBalance() {22 return balance;23 }24 public void setBalance(double balance) {25 this.balance = balance;26 }27 }
2) AccoutDao接口与实现类
package com.znker.spring.IoC;import java.util.List;public interface AccountDao { public void insert(Account account); public void update(Account account); /** update方法的重载 */ public void update(List<Account> accounts); public void delete(long accountId); public Account find(long accountId); public List<Account> find(List<Long> accountIds);}
package com.znker.spring.IoC;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.springframework.stereotype.Repository;@Repository("accountDao")public class AccountDaoInMemoryImpl implements AccountDao { /** HashMap 模拟数据库 */ private Map<Long, Account> accountsMap = new HashMap<>(); { Account account1 = new Account(); account1.setId(1L); account1.setOwerName("John"); account1.setBalance(10.0); Account account2 = new Account(); account2.setId(2L); account2.setOwerName("Mary"); account2.setBalance(20.0); accountsMap.put(account1.getId(), account1); accountsMap.put(account2.getId(), account2); } @Override public void insert(Account account) { accountsMap.put(account.getId(), account); } @Override public void update(Account account) { accountsMap.put(account.getId(), account); } @Override public void update(List<Account> accounts) { for (Account account : accounts) { accountsMap.put(account.getId(), account); } } @Override public void delete(long accountId) { accountsMap.remove(accountId); } @Override public Account find(long accountId) { return accountsMap.get(accountId); } @Override public List<Account> find(List<Long> accountIds) { List<Account> accounts = new ArrayList<Account>(); for (Long id : accountIds) { accounts.add(accountsMap.get(id)); } return accounts; }}
3) AccountService接口与实现类
package com.znker.spring.IoC;public interface AccountService { /** 客户之间转账 */ public void transferMoney(long sourceAccountId, long targetAccountId, double amount); /** 客户存款 */ public void depositMoney(long accountId, double amount); public Account getAccount(long accountId);}
package com.znker.spring.IoC;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;@Service("accountService")public class AccountServiceImpl implements AccountService { @Autowired private AccountDao accountDao; public void setAccountDao(AccountDao accountDao) { this.accountDao = accountDao; } @Override public void transferMoney(long sourceAccountId, long targetAccountId, double amount) { Account sourceAccount = accountDao.find(sourceAccountId); Account targetAccount = accountDao.find(targetAccountId); sourceAccount.setBalance(sourceAccount.getBalance() - amount); targetAccount.setBalance(targetAccount.getBalance() + amount); /** 更新数据库记录 */ accountDao.update(sourceAccount); accountDao.update(targetAccount); } @Override public void depositMoney(long accountId, double amount) { Account account = accountDao.find(accountId); account.setBalance(account.getBalance() + amount); accountDao.update(account); } @Override public Account getAccount(long accountId) { return accountDao.find(accountId); }}
4) 为spring 容器提供Bean实例化和装配所需的配置元数据（congfiguration metadata），配置元数据可以用XML文件或Java注解提供。
XML文件版：xml-beans.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" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd"> <bean id="accountService" class="com.znker.spring.IoC.AccountServiceImpl"> <!-- 依赖注入 accountDao --> <property name="accountDao" ref="accountDao" /> </bean> <bean id="accountDao" class="com.znker.spring.IoC.AccountDaoInMemoryImpl" /></beans>
Java注解版：annotation-beans.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:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd"> <!-- 扫描类路径中存在的类，通过相关联的注解创建Bean并注入其依赖项中 --> <context:component-scan base-package="com.znker.spring.IoC" /> </beans>
5) 测试类代码
package com.znker.spring.IoC;import org.springframework.context.ApplicationContext;import org.springframework.context.annotation.AnnotationConfigApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class TestMain { public static void main(String[] args) { /** 基于注解的spring容器对象实例化 */ AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(BeanConfiguration.class); /** 基于XML文件的spring容器对象实例化 */ ApplicationContext ctx = new ClassPathXmlApplicationContext("com/znker/spring/IoC/beans.xml"); // 获取 AccountService Bean AccountService accountService = ctx.getBean("accountService", AccountService.class); System.out.println("Before money transfer:"); System.out.println("Account 1 balance : " + accountService.getAccount(1).getBalance()); System.out.println("Account 2 balance : " + accountService.getAccount(2).getBalance()); // 转账 accountService.transferMoney(1, 2, 5.0); System.out.println("After money transfer:"); System.out.println("Account 1 balance : " + accountService.getAccount(1).getBalance()); System.out.println("Account 2 balance : " + accountService.getAccount(2).getBalance()); }}
Spring Framework 笔记（一）：IoC
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