import com.itheima.dao.BookDao;
import com.itheima.service.BookService;
 
public class BookServiceImpl implements BookService {
    private BookDao bookDao;
 
    public void save() {
        System.out.println("book service save ...");
        bookDao.save();
    }
    public void setBookDao(BookDao bookDao) {
        this.bookDao = bookDao;
    }
}

<!--注入引用類型-->
    <bean id="bookService" class="com.itheima.service.impl.BookServiceImpl">
        <!--property標簽：設置注入屬性-->
        <!--name屬性：設置注入的屬性名，實際是set方法對應的名稱-->
        <!--ref屬性：設置注入引用類型bean的id或name-->
        <property name="bookDao" ref="bookDao"/>
        <property name="userDao" ref="userDao"/>
    </bean>

import com.itheima.dao.BookDao;
 
public class BookDaoImpl implements BookDao {
 
    private String databaseName;
    private int connectionNum;
 
    //setter注入需要提供要注入對象的set方法
    public void setConnectionNum(int connectionNum) {
        this.connectionNum = connectionNum;
    }
 
    //setter注入需要提供要注入對象的set方法
    public void setDatabaseName(String databaseName) {
        this.databaseName = databaseName;
    }
 
    public void save() {
        System.out.println("book dao save ..." + databaseName + "," + connectionNum);
    }
}

<!--注入簡單類型-->
    <bean id="bookDao" class="com.itheima.dao.impl.BookDaoImpl">
        <!--property標簽：設置注入屬性-->
        <!--name屬性：設置注入的屬性名，實際是set方法對應的名稱-->
        <!--value屬性：設置注入簡單類型數(shù)據(jù)值-->
        <property name="connectionNum" value="100"/>
        <property name="databaseName" value="mysql"/>
    </bean>

public class BookServiceImpl implements BookService{
    private BookDao bookDao;
    private UserDao userDao;
 
    public BookServiceImpl(BookDao bookDao, UserDao userDao) {
        this.bookDao = bookDao;
        this.userDao = userDao;
    }
}

<bean id="bookDao" class="com.itheima.dao.impl.BookDaoImpl"/>
<bean id="userDao" class="com.itheima.dao.impl.UserDaoImpl"/>
 
<bean id="bookService" class="com.itheima.service.impl.BookServiceImpl">
        <constructor-arg name="userDao" ref="userDao"/>
        <constructor-arg name="bookDao" ref="bookDao"/>
    </bean>

public class BookDaoImpl implements BookDao {
    private String databaseName;
    private int connectionNum;
 
    public BookDaoImpl(String databaseName, int connectionNum) {
        this.databaseName = databaseName;
        this.connectionNum = connectionNum;
    }
}

<bean id="bookDao" class="com.itheima.dao.impl.BookDaoImpl">
        <!--根據(jù)構造方法參數(shù)名稱注入-->
        <constructor-arg name="connectionNum" value="10"/>
        <constructor-arg name="databaseName" value="mysql"/>
 </bean>

<!--解決形參名稱的問題，與形參名不耦合-->
    <bean id="bookDao" class="com.itheima.dao.impl.BookDaoImpl">
        <!--根據(jù)構造方法參數(shù)類型注入-->
        <constructor-arg type="int" value="10"/>
        <constructor-arg type="java.lang.String" value="mysql"/>
    </bean>

 <!--解決參數(shù)類型重復問題，使用位置解決參數(shù)匹配-->
    <bean id="bookDao" class="com.itheima.dao.impl.BookDaoImpl">
        <!--根據(jù)構造方法參數(shù)位置注入-->
        <constructor-arg index="0" value="mysql"/>
        <constructor-arg index="1" value="100"/>
    </bean>