SSM学习2：依赖注入、依赖自动装配、集合注入、加载properties文件

依赖注入

依赖注入方式
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setter注入——引用类型

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setter注入——简单类型

public class BookDaoImpl implements BookDao {public void setDatabaseName(String databaseName) {this.databaseName = databaseName;}public void setNum(int num) {this.num = num;}private String databaseName;private int num;public void save() {System.out.println("book dao save ..." + databaseName + "," + num);}
}

为databaseName和num两个属性提供可访问的set方法，然后在applicationContext.xml里进行配置

<?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="bookDao" class="com.itheima.dao.impl.BookDaoImpl"><property name="databaseName" value="mysql"/><property name="num" value="100"/></bean>
</beans>

运行时会自动把设置好的值注入进去
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构造器注入——引用类型

BookServiceImpl.java

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

applicationContext.xml

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

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构造器注入——简单类型

BookDaoImpl.java

public class BookDaoImpl implements BookDao {public BookDaoImpl(String databaseName, int num) {this.databaseName = databaseName;this.num = num;}private String databaseName;private int num;public void save() {System.out.println("book dao save ..." + databaseName + "," + num);}
}

applicationContext.xml

<?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="bookDao" class="com.itheima.dao.impl.BookDaoImpl"><constructor-arg name="databaseName" value="mysql"/><constructor-arg name="num" value="100"/></bean><bean id="bookService" class="com.itheima.service.impl.BookServiceImpl"><constructor-arg name="bookDao" ref="bookDao"/></bean>
</beans>

自动装配

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按类型

BookServiceImpl

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();}
}

applicationContext.xml

<?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 class="com.itheima.dao.impl.BookDaoImpl"/><!--autowire属性：开启自动装配，通常使用按类型装配--><bean id="bookService" class="com.itheima.service.impl.BookServiceImpl" autowire="byType"/></beans>

使用这种方式：
1、必须提供对应的set方法
2、必须有要装配类的对应的bean配置

 <bean class="com.itheima.dao.impl.BookDaoImpl"/>

3、按类型装配时，对应的bean需要是唯一的
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按名称

<?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="bookDao" class="com.itheima.dao.impl.BookDaoImpl"/><bean id="bookService" class="com.itheima.service.impl.BookServiceImpl" autowire="byName"/>
</beans>

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注意点

集合注入

BookDaoImpl

public class BookDaoImpl implements BookDao {private int[] array;private List<String> list;private Set<String> set;private Map<String,String> map;private Properties properties;public void setArray(int[] array) {this.array = array;}public void setList(List<String> list) {this.list = list;}public void setSet(Set<String> set) {this.set = set;}public void setMap(Map<String, String> 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);}
}

applicationContext.xml

<?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="bookDao" class="com.itheima.dao.impl.BookDaoImpl"><!--数组注入--><property name="array"><array><value>100</value><value>200</value><value>300</value></array></property><!--list集合注入--><property name="list"><list><value>itcast</value><value>itheima</value><value>boxuegu</value><value>chuanzhihui</value></list></property><!--set集合注入--><property name="set"><set><value>itcast</value><value>itheima</value><value>boxuegu</value><value>boxuegu</value></set></property><!--map集合注入--><property name="map"><map><entry key="country" value="china"/><entry key="province" value="henan"/><entry key="city" value="kaifeng"/></map></property><!--Properties注入--><property name="properties"><props><prop key="country">china</prop><prop key="province">henan</prop><prop key="city">kaifeng</prop></props></property></bean>
</beans>

名称要一一对应
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加载properties文件

jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/spring_db
jdbc.username=root
jdbc.password=root

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsd"><!--    1.开启context命名空间--><!--    2.使用context空间加载properties文件--><!--classpath*:*.properties  ：  设置加载当前工程类路径和当前工程所依赖的所有jar包中的所有properties文件--><context:property-placeholder location="classpath*:*.properties" system-properties-mode="NEVER"/><!--    3.使用属性占位符${}读取properties文件中的属性--><!--    说明：idea自动识别${}加载的属性值，需要手工点击才可以查阅原始书写格式--><bean class="com.alibaba.druid.pool.DruidDataSource"><property name="driverClassName" value="${jdbc.driver}"/><property name="url" value="${jdbc.url}"/><property name="username" value="${jdbc.username}"/><property name="password" value="${jdbc.password}"/></bean>
</beans>