Spring之IOC案例分析以及注解案例

xiaoxiao2025-04-02 9

day2..........

一、spring中IOC的常用注解

1.注解创建对象

@Component

2.自动按照类型注入

如果有唯一一个匹配时，直接注入；若有多个匹配，则首先圈出匹配的对象，接着使用变量名称

作为bean的id在圈定的对象中继续查找，若圈中的对象一样则匹配成功，否则匹配失败；

3.该边作用范围和生命周期的注解

二、基于XML的IOC案例

案例分析：用基于XML的IOC实现对一个标的CURD操作

1）创建数据库，添加数据

CREATE TABLE `t_account` ( `id` int(11) NOT NULL AUTO_INCREMENT, `aname` varchar(30) DEFAULT NULL, `money` float DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8

2）创建西maven项目，导入必要的；依赖编写实体类、数据持久层、以及业务层的接口类和实现类，项目结构如图所示

pom文件如下：

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.dzg</groupId> <artifactId>spring-day2-xml-ioc</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <dependencies> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.6</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>5.1.3.RELEASE</version> </dependency> <dependency> <groupId>c3p0</groupId> <artifactId>c3p0</artifactId> <version>0.9.1.2</version> </dependency> <dependency> <groupId>commons-dbutils</groupId> <artifactId>commons-dbutils</artifactId> <version>1.6</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.10</version> <scope>test</scope> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.46</version> </dependency> </dependencies> </project>

实体类：

public class Account implements Serializable { private Integer id; private String aname; private float money; 生成对应的set和get方法 }

业务层：

/** * 账户的业务接口层 */ public interface IAccountService{ /** * 查询所有账户信息 * @return */ List<Account> findAllAccount(); /** * 根据id查询一个账户 * @param accountId * @return */ Account findAccountById(Integer accountId); /** * 增加账户信息 * @param account */ void insertAccount(Account account); /** * 修改账户信息 * @param account */ void updateAccount(Account account); /** * 根据id删除账户信息 * @param accountId */ void deleteAccount(Integer accountId); } /** * 账户的业务层实现类 */ public class AccountServiceImpl implements IAccountService { private IAccountDao accountDao; public void setAccountDao(IAccountDao accountDao) { this.accountDao = accountDao; } public List<Account> findAllAccount() { return accountDao.findAllAccount(); } public Account findAccountById(Integer accountId) { return accountDao.findAccountById(accountId); } public void insertAccount(Account account) { accountDao.insertAccount(account); } public void updateAccount(Account account) { accountDao.updateAccount(account); } public void deleteAccount(Integer accountId) { accountDao.deleteAccount(accountId); } }

持久层：持久层接口和业务层接口方法相同，只需要实现持久层实现类，实现和数据库的交互

/** * 账户持久层实现类 */ public class AccountDaoImpl implements IAccountDao { private QueryRunner qr; public void setQr(QueryRunner qr) { this.qr = qr; } public List<Account> findAllAccount() { try { return qr.query("select * from t_account",new BeanListHandler<Account>(Account.class)); } catch (SQLException e) { throw new RuntimeException(e); } } public Account findAccountById(Integer accountId) { try { return qr.query("select * from t_account where id=?",new BeanHandler<Account>(Account.class),accountId); } catch (SQLException e) { throw new RuntimeException(e); } } public void insertAccount(Account account) { try { qr.update("insert into t_account(aname,money) values(?,?)",account.getAname(),account.getMoney()); } catch (SQLException e) { throw new RuntimeException(e); } } public void updateAccount(Account account) { try { qr.update("update t_account set aname = ?,money=? where id = ?",account.getAname(),account.getMoney(),account.getId()); } catch (SQLException e) { throw new RuntimeException(e); } } public void deleteAccount(Integer accountId) { try { qr.update("delete from t_account where id = ?",accountId); } catch (SQLException e) { throw new RuntimeException(e); } } }

上述步骤完成之后，配置spring环境：

<?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="accountService" class="com.dzg.service.impl.AccountServiceImpl">  <property name="accountDao" ref="accountDao"></property> </bean>  <bean id="accountDao" class="com.dzg.dao.impl.AccountDaoImpl">  <property name="qr" ref="runner"></property> </bean>  <bean id="runner" class="org.apache.commons.dbutils.QueryRunner" scope="prototype">  <constructor-arg name="ds" ref="dataSource"></constructor-arg> </bean>  <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">  <property name="driverClass" value="com.mysql.jdbc.Driver"></property> <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/db_spring"></property> <property name="user" value="root"></property> <property name="password" value="root"></property> </bean> </beans>

编写junit单元测试，对上述代码进行测试:

/** * 使用juint单元测试，测试配置 */ public class AccountServiceTest { @Test public void testFindAll(){ //1.获取数据信息 ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml"); //2.得到业务层对象 IAccountService as = ac.getBean("accountService",IAccountService.class); //3.执行方法 List<Account> accountList = as.findAllAccount(); for (Account account: accountList) { System.out.println(account); } } @Test public void testFindOne(){ //1.获取数据信息 ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml"); //2.得到业务层对象 IAccountService as = ac.getBean("accountService",IAccountService.class); Account account = as.findAccountById(3); System.out.println(account); } @Test public void testAdd(){ Account account = new Account(); account.setAname("ddd"); account.setMoney(1234f); //1.获取数据信息 ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml"); //2.得到业务层对象 IAccountService as = ac.getBean("accountService",IAccountService.class); as.insertAccount(account); } @Test public void testUpdate(){ Account account = new Account(); account.setId(4); account.setAname("dddupdate"); account.setMoney(4434f); //1.获取数据信息 ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml"); //2.得到业务层对象 IAccountService as = ac.getBean("accountService",IAccountService.class); //3.执行方法 as.updateAccount(account); } @Test public void testDelete(){ //1.获取数据信息 ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml"); //2.得到业务层对象 IAccountService as = ac.getBean("accountService",IAccountService.class); //3.执行方法 as.deleteAccount(4); } }

三、注解开发ioc案例

使用注解开发，更改上述案例：

对于JavaBean，持久层和业务层的实现类，使用注解的方式进行更改，则对应的beans.xml文件中删除已经注解的bean；通知spring

在创建容器时需要扫描的包；

在对相应的实现类进行注解后，则类中的成员变量不再需要相应的set方法，删除即可；同时将变量注解为Autowired

注解开发，更改之后的beans.xml文件  <context:component-scan base-package="com.dzg"></context:component-scan>  <bean id="runner" class="org.apache.commons.dbutils.QueryRunner" scope="prototype">  <constructor-arg name="ds" ref="dataSource"></constructor-arg> </bean>  <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">  <property name="driverClass" value="com.mysql.jdbc.Driver"></property> <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/db_spring"></property> <property name="user" value="root"></property> <property name="password" value="root"></property> </bean>

四、去掉beans.xml文件的注解开发

1.spring的新注解Configuation和ComponentScan

但是并不绝对！

2.spring的新注解bean

在config包下

删除xml文件

进行测试：

@Test public void testFindAll(){ //1.获取数据信息 // ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml"); ApplicationContext ac = new AnnotationConfigApplicationContext("com.dzg"); //2.得到业务层对象 IAccountService as = ac.getBean("accountService", IAccountService.class); //3.执行方法 List<Account> accountList = as.findAllAccount(); for (Account account: accountList) { System.out.println(account); }

3.AnnotationConfigApplicationContext的使用

注意，曾经的QueryRunner是一个多例的，现在是一个单例子的；

test测试下：

在createQueryRunner上添加注解 @Scope("prototype")

4.spring的新注解Import

将内容拷贝到JdbcConfig

即@Configuration注解不写

ApplicationContext ac = new AnnotationConfigApplicationContext(SpringConfiguration.class); 此时使用另一个方法来创建ApplicationContext对象，传递的参数为注解的类

5.spring的新注解PropertySource

将数据库连接信息提取出，写入一个properties文件

jdbc.driver=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/db_spring jdbc.username=root jdbc.password=root