文章目录

---

一、构造方法实例化Bean(无参构造)

1.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...");
    }
}

1
2
3
4
5
6
7
8
9
10
11
12

2.配置：

 <bean id="bookDao"  class="com.study.dao.impl.BookDaoImpl" ></bean>
1

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

二、使用静态工厂实例化Bean

1.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();
    }
}

1
2
3
4
5
6
7
8
9

2.配置

 <bean id="bookDao" name="dao" class="com.study.factory.BookDaoFactory" factory-method="getBookDao"></bean>
1

三、使用实例化工厂实例Bean

1.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();
    }
}

}

1
2
3
4
5
6
7
8
9
10
11

2.配置

 <bean id="bookDao" name="dao" class="com.study.factory.BookDaoFactory"></bean>
    <bean id="book" factory-method="getBookDao" factory-bean="bookDao"></bean>
1
2

四、使用FactoryBean实例化Bean

1.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;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13

2.配置

 <bean id="bookDao" class="com.study.factory.BookDaoFactoryBean"></bean>
1