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@TOC

✨构造方法实例化Bean(无参构造)

🔥提供可访问的构造方法：

package com.study.dao.impl;
import com.study.dao.BookDao;
public class BookDaoImpl implements BookDao {
    public BookDaoImpl() {
        System.out.println("无参构造！");
    }

    public void save() {
        System.out.println("book dao save...");
    }
}

🔥配置：

 <bean id="bookDao"  class="com.study.dao.impl.BookDaoImpl" ></bean>

注意：
⭐⭐⭐：如果无参构造方法不存在则抛出BeabCreationException。

✨使用静态工厂实例化Bean

🔥静态工厂

package com.study.factory;
import com.study.dao.BookDao;
import com.study.dao.impl.BookDaoImpl;
public class BookDaoFactory {
    public static BookDao getBookDao(){
        return new BookDaoImpl();
    }
}

🔥配置

 <bean id="bookDao" name="dao" class="com.study.factory.BookDaoFactory" factory-method="getBookDao"></bean>

✨使用实例化工厂实例Bean

🔥实例化工厂

package com.study.factory;
import com.study.dao.BookDao;
import com.study.dao.impl.BookDaoImpl;
public class BookDaoFactory {
    public  BookDao getBookDao(){
        return new BookDaoImpl();
    }
}

}

🔥配置

 <bean id="bookDao" name="dao" class="com.study.factory.BookDaoFactory"></bean>
    <bean id="book" factory-method="getBookDao" factory-bean="bookDao"></bean>

✨使用FactoryBean实例化Bean

🔥FactoryBean

package com.study.factory;
import com.study.dao.BookDao;
import com.study.dao.impl.BookDaoImpl;
import org.springframework.beans.factory.FactoryBean;
public class BookDaoFactoryBean implements FactoryBean<BookDao> {
    public BookDao getObject() throws Exception {
        return new BookDaoImpl();
    }

    public Class<?> getObjectType() {
        return BookDao.class;
    }
}

🔥配置

 <bean id="bookDao" class="com.study.factory.BookDaoFactoryBean"></bean>