目录

1.依赖注入方式

依赖注入(DI：dependence injection)：在容器中建立bean与bean之间的依赖关系的整个过程。

向一个bean中传递数据有三种方法：setter注入、构造器注入、自动装配

/src/main/java/com/itheima/dao/BookDao.java

package com.itheima.dao;public interface BookDao {public void save();
}

/src/main/java/com/itheima/dao/impl/BookDaoImpl.java

package com.itheima.dao.impl;
import com.itheima.dao.BookDao;public class BookDaoImpl implements BookDao {public void save() {System.out.println("book dao save...");}
}

/src/main/java/com/itheima/service/BookService.java

package com.itheima.service;public interface BookService {public void save();
}

/src/main/java/com/itheima/App.java

package com.itheima;
import com.itheima.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class App{public static void main(String[] args) {ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");BookService bookService = (BookService) ctx.getBean("bookService");bookService.save();}
}

①setter注入

/src/main/java/com/itheima/service/impl/BookServiceImpl.java

package com.itheima.service.impl;
import com.itheima.dao.BookDao;
import com.itheima.service.BookService;public class BookServiceImpl implements BookService {private BookDao bookDao;private int connectionNumber;// 在bean中定义引用类型属性并提供可访问的set方法public void setBookDao(BookDao bookDao) {this.bookDao = bookDao;}// 在bean中定义简单类型属性并提供可访问的set方法public void setConnectionNumber(int connectionNumber) {this.connectionNumber = connectionNumber;}public void save() {System.out.println("book service save ..." + connectionNumber);bookDao.save();}
}

/src/main/resources/applicationContext.xml

②构造器注入

/src/main/java/com/itheima/service/impl/BookServiceImpl.java

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

/src/main/resources/applicationContext.xml

测试结果：

③自动装配

依赖自动装配：IoC容器根据bean所依赖的资源在容器中自动查找并注入到bean中的过程称为自动装配。

/src/main/java/com/itheima/service/impl/BookServiceImpl.java

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

/src/main/resources/applicationContext.xml

2.集合注入

/src/main/java/com/itheima/dao/impl/BookDaoImpl.java

package com.itheima.dao.impl;
import com.itheima.dao.BookDao;
import java.util.*;public class BookDaoImpl implements BookDao {private int[] array;private List list;private Set set;private Map map;private Properties properties;public void setArray(int[] array) {this.array = array;}public void setList(List list) {this.list = list;}public void setSet(Set set) {this.set = set;}public void setMap(Map map) {this.map = map;}public void setProperties(Properties properties) {this.properties = properties;}public void save() {System.out.println("book dao save ...");System.out.println("遍历数组:" + Arrays.toString(array));System.out.println("遍历List" + list);System.out.println("遍历Set" + set);System.out.println("遍历Map" + map);System.out.println("遍历Properties" + properties);}
}

/src/main/resources/applicationContext.xml

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/src/main/java/com/itheima/App.java

package com.itheima;import com.itheima.dao.BookDao;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class App {public static void main( String[] args ) {ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");BookDao bookDao = (BookDao) ctx.getBean("bookDao");bookDao.save();}
}

测试：