五、别名
于数据库和mybatis差不多;
<alias name="UserServiceImpl" alias="service"/>
前面是名字,后面是别名;但是的话,还有一种的方法是在bean下直接可以写别名:
<bean id="UserServiceImpl" class="com.saxon.Service.UserServiceImpl" name="service2">
<property name="userDao" ref="OralceUserImpl"/>
<constructor-arg type="com.saxon.Dao.UserDao" ref="OralceUserImpl"/>
</bean>
并且可以通过分隔符来进行一个分割,实现取出多个的别名的目的;
六、import
把多个配置文件合成一个,如果文件内容有完全一样的部分就会合并;
多个文件合并后,使用一个总文件就可以访问;
七、依赖注入(DI)
直接上代码:
pojo.student:
public class Student {
private String name;
private Address address;
private Map<String,String> card;
private String[] books;
private List<String> teacher;
private Set<String> games;
private Properties info;
private String wife;
@Override
public String toString () {
return "Student{" +
"name='" + name + '\'' +
", address=" + address +
", card=" + card +
", books=" + Arrays.toString (books) +
", teacher=" + teacher +
", games=" + games +
", info=" + info +
", wife='" + wife + '\'' +
'}';
}
}
//setter getter 略,但是必须要写
applicationContext:
<bean id="student" class="com.saxon.pojo.Student">
<!-- 第一种 直接注入-->
<property name="name" value="saxon"/>
<!-- 第二种 对象注入-->
<property name="address" ref="address"/>
<!-- 第三种 数组-->
<property name="books">
<array>
<value>关于我是如何变帅的那些事 1</value>
<value>关于我是如何变帅的那些事 2</value>
<value>关于我是如何变帅的那些事 3</value>
</array>
</property>
<!-- map集合-->
<property name="card">
<map>
<entry key="author" value="saxon"/>
<entry key="author" value="saxon 2"/>
</map>
</property>
<!-- list 集合-->
<property name="teacher">
<list>
<value>李老师</value>
<value>马老师</value>
</list>
</property>
<!-- set 集合-->
<property name="games">
<set>
<value>LOL</value>
<value>The Honor OF KING</value>
</set>
</property>
<!-- properties-->
<property name="info">
<props>
<prop key="Lover">null</prop>
</props>
</property>
<!-- 关于空值的设置 null和""-->
<property name="wife">
<null/>
</property>
</bean>
<bean id="address" class="com.saxon.pojo.Address">
<property name="country" value="CHINA"/>
<property name="province" value="YUNNAN"/>
</bean>
显示出来的内容:
Student{name='saxon', address=Address{country='CHINA', province='YUNNAN'}, card={author=saxon 2}, books=[关于我是如何变帅的那些事 1, 关于我是如何变帅的那些事 2, 关于我是如何变帅的那些事 3], teacher=[李老师, 马老师], games=[LOL, The Honor OF KING], info={Lover=null}, wife='null'}
c命名空间和p命名空间:
这两个需要引入我们的配置;
p命名空间,使用setter注入:
xmlns:p="http://www.springframework.org/schema/p"
<bean id="student" class="com.saxon.pojo.Student" p:name="saxon">
c命名空间,使用构造器注入:
xmlns:c="http://www.springframework.org/schema/c"
<bean id="student" class="com.saxon.pojo.Student" c:name="saxon">
七、bean的作用域
一共有6种,但是后面的四种是基于web应用的;
Scope | Description |
---|---|
singleton | (Default) Scopes a single bean definition to a single object instance for each Spring IoC container. |
prototype | Scopes a single bean definition to any number of object instances. |
request | Scopes a single bean definition to the lifecycle of a single HTTP request. That is, each HTTP request has its own instance of a bean created off the back of a single bean definition. Only valid in the context of a web-aware Spring ApplicationContext . |
session | Scopes a single bean definition to the lifecycle of an HTTP Session . Only valid in the context of a web-aware Spring ApplicationContext . |
application | Scopes a single bean definition to the lifecycle of a ServletContext . Only valid in the context of a web-aware Spring ApplicationContext . |
websocket | Scopes a single bean definition to the lifecycle of a WebSocket . Only valid in the context of a web-aware Spring ApplicationContext . |
测试代码:
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext ("applicationContext.xml");
Student student1 = (Student)context.getBean ("student");
Student student2 = (Student)context.getBean ("student");
System.out.println (student1==student2);
1.sigleton:无论创建几个都始终只有一个并且是默认的作用域
<bean id="student" class="com.saxon.pojo.Student" c:name="saxon" scope="singleton">
结果:true
2.prototype:每次创建都会新建一个对象,就是浪费资源
<bean id="student" class="com.saxon.pojo.Student" c:name="saxon" scope="prototype">
结果:false;
八、自动装配
1.显示自动装配 xml 装配
applicationContext.xml
2.Java文件自动装配
3.隐式自动装配
autowrite:
1.autowire="byName"
它会自动寻找我们属性中还没有注入的属性,选取ID 为setXXX的XXX 自动装配
比如:
public void setAddress (Address address) {
this.address = address;
}
<bean id="address" class="com.saxon.pojo.Address">
<property name="country" value="CHINA"/>
<property name="province" value="YUNNAN"/>
</bean>
这个的set后缀就是address,那么就去找ID为address的bean;如果ID不一致就不会自动装配;区分大小写,id唯一;
2.autowire="byType"
会自动寻找我们属性中还没有注入的属性,选取类的类型为setXXX的XXX 自动装配
public void setAddress (Address address) {
this.address = address;
}
//类就是address
<bean id="address" class="com.saxon.pojo.Address">
<property name="country" value="CHINA"/>
<property name="province" value="YUNNAN"/>
</bean>
com.saxon.pojo.Address类型唯一自动装配,于id无关;id可以不写;
还有一种使用resource,Java原生的注入方式,那个默认使用的是ByName,在byName找不到的时候就去byType按照id找,他的方式与spring的自动装配的默认方式相反
自学总结
学习地址:狂神说Java