创建bean的三种方式
- 使用默认构造函数创建(默认构造函数创建bean对象,如果没有构造函数,则对象无法创建)
package com.ay.service;
public interface AccountService {
public void saveAccount();
}
package com.ay.service.impl;
import com.ay.service.AccountService;
public class AccountServiceImpl implements AccountService {
@Override
public void saveAccount() {
System.out.println("方法创建成功了");
}
public AccountServiceImpl() {
System.out.println("对象开始创建了");
}
}
<?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.ay.service.impl.AccountServiceImpl"></bean>
</beans>
package com.ay.ui;
import com.ay.service.AccountService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Client {
public static void main(String[] args) {
ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
AccountService as = (AccountService)ac.getBean("accountService");
as.saveAccount();
}
}
package com.ay.service;
public interface AccountService {
public void saveAccount();
}
- 使用普通工厂中的方法创建对象(使用某个类中的方法创建对象,并存入spring容器)
<?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="InstanceFactory" class="com.ay.factory.InstanceFactory"></bean>
<bean id="accountService" factory-bean="InstanceFactory" factory-method="getAccountService"></bean>
</beans>
package com.ay.factory;
import com.ay.service.AccountService;
import com.ay.service.impl.AccountServiceImpl;
public class InstanceFactory {
public AccountService getAccountService(){
return new AccountServiceImpl();
}
}
package com.ay.service.impl;
import com.ay.service.AccountService;
public class AccountServiceImpl implements AccountService {
@Override
public void saveAccount() {
System.out.println("方法创建成功了");
}
public AccountServiceImpl() {
System.out.println("对象开始创建了");
}
}
- 使用工厂中的静态方法创建对象(使用某个类中的静态方法创建对象,并存入spring容器)
package com.ay.factory;
import com.ay.service.AccountService;
import com.ay.service.impl.AccountServiceImpl;
public class StaticFactory {
public static AccountService getAccountService(){
return new AccountServiceImpl();
}
}
<?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.ay.factory.StaticFactory" factory-method="getAccountService"></bean>
</beans>
运行截图