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目录一、ioc如何获取对象1.1 spring是如何获取对象的?1.2 改造案例由xml选择创建对象二、ioC是通过什么方式来创建对象的?2.1 通过无参构造函数来创建对象2.2 通
①新建一个Maven项目后导入WEBmvc的依赖:因为webmvc包含了很多其他依赖,为了省事,干脆导入一个总的,方便省事!版本嘛!个人比较喜欢用最新版。
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.3.5</version>
</dependency>
②新建实体测试类:
public class Person {
private String name;
private int age;
private String like;
private String high;
//get、set、tostring方法为了篇幅省略,可以自己加或者使用lombok
}
③在resources目录下新建ContextAplication.xml
文件
<?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="Person" class="entity.Person">
<property name="age" value="23"></property>
<property name="name" value="丁大大"></property>
<property name="like" value="钓鱼"></property>
<property name="high" value="173"></property>
</bean>
</beans>
④以上前提之后,你会发现你的测试Person类种发生了变化:点击可以跳转到指定的xml位置哦~
⑤测试:
Context.getBean() 不指定类时,需要强制转换,所以建议使用第二种方式来获取对象
public class Test {
public static void main(String[] args) {
ApplicationContext Context = new ClassPathXmlApplicationContext("ContextAplication.xml");
// Person person = (Person) Context.getBean("Person");//这里不指定的话需要强转,建议用下面的方式来拿对象
Person person = Context.getBean("Person",Person.class);
System.out.println(person);
}
}
⑥执行结果如下:成功拿到值!
⑦总结:
①xml:
<bean id="StudentMapperImpl" class="mapper.impl.StudentMapperImpl"/>
<bean id="TeacherMapperImpl" class="mapper.impl.TeacherMapperImpl"/>
<bean id="PersonServiceImpl" class="service.impl.PersonServiceImpl">
<property name="studentMapper" ref="StudentMapperImpl"/>
</bean>
②测试:
ApplicationContext Context1 = new ClassPathXmlApplicationContext("ContextAplication.xml");
PersonServiceImpl personServiceImpl = Context1.getBean("PersonServiceImpl", PersonServiceImpl.class);
personServiceImpl.getPersonInfo();
③执行结果:
⑤总结:
对象由Spring 来创建 , 管理 , 装配 !这就是 IOC!
①以Person类为例子,但是加上一个无参构造函数!
public class Person {
private String name;
private int age;
private String like;
private String high;
public Person() {
//输出一句话证明自己被调用了!
System.out.println("我是Person类的无参构造函数!我被调用了!!!!");
}
//set、get、tostring方法因为篇幅原因省略,请手动加上!
}
②xml中配置:
<?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="Person" class="entity.Person">
<property name="age" value="23"></property>
<property name="name" value="丁大大"></property>
<property name="like" value="钓鱼"></property>
<property name="high" value="173"></property>
</bean>
</beans>
③测试类:
public class Test {
public static void main(String[] args) {
ApplicationContext Context = new ClassPathXmlApplicationContext("ContextAplication.xml");
Person person = Context.getBean("Person", Person.class);
System.out.println(person);
}
}
④执行结果:
⑤去除无参构造,增加有参构造:
xml配置程序直接报错:
⑥总结:
Spring创建对象默认是通过无参构造函数创建的!能通过有参构造函数来创建对象嘛?能!看下面!
①前提于 2.1 一致,新增有参构造函数:(因为类中,默认的也就是不写构造参数就是无参构造,写了有参构造才能真正意义上去除无参构造,这个不用解释太多吧,Java基础的内容了~!)
public Person(String name, int age, String like, String high) {
this.name = name;
this.age = age;
this.like = like;
this.high = high;
}
②xml配置文件中要发生一定的改变:
<?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="Person" class="entity.Person">
<!-- <property name="name" value="丁大大"></property>-->
<!-- <property name="age" value="23"></property>-->
<!-- <property name="like" value="钓鱼"></property>-->
<!-- <property name="high" value="173"></property>-->
<constructor-arg index="0" value="丁大大"/>
<constructor-arg name="age" value="23"/>
<constructor-arg type="java.lang.String" value="钓鱼"/>
<constructor-arg type="java.lang.String" value="173"/>
</bean>
</beans>
③执行结果:
⑤总结:
①xml:
<?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">
<alias name="Person" alias="personAlias1"/>
<alias name="Person" alias="personAlias2"/>
<alias name="Person" alias="personAlias3"/>
<bean id="Person" class="entity.Person">
<constructor-arg index="0" value="丁大大"/>
<constructor-arg name="age" value="23"/>
<constructor-arg type="java.lang.String" value="钓鱼"/>
<constructor-arg type="java.lang.String" value="173"/>
</bean>
</beans>
②测试类:
public class Test {
public static void main(String[] args) {
ApplicationContext Context = new ClassPathXmlApplicationContext("ContextAplication.xml");
Person person = Context.getBean("personAlias1", Person.class);
System.out.println(person);
}
}
③执行结果:
④总结:讲实话,这玩意用处不大,因为还有更好的方式来设置别名!
①xml:
<?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">
<alias name="Person" alias="personAlias1"/>
<alias name="Person" alias="personAlias2"/>
<alias name="Person" alias="personAlias3"/>
<bean id="Person" name="person1,person2 person3;person4" class="entity.Person">
<constructor-arg index="0" value="丁大大"/>
<constructor-arg name="age" value="23"/>
<constructor-arg type="java.lang.String" value="钓鱼"/>
<constructor-arg type="java.lang.String" value="173"/>
</bean>
</beans>
②测试类:
public class Test {
public static void main(String[] args) {
ApplicationContext Context = new ClassPathXmlApplicationContext("ContextAplication.xml");
Person person = Context.getBean("person4", Person.class);
System.out.println(person);
}
}
③执行结果:
④总结:
①在实际工作的开发过程中,一个项目可能由多个程序员来进行开发,所以为了解决共性问题,比如:同一文件提交时都进行了修改可能引起冲突,所以我们使用import来解耦!
②新建多个xml配置文件:
ContextAplication.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">
<import resource="dyj1.xml"/>
<import resource="dyj3.xml"/>
<import resource="dyj2.xml"/>
</beans>
dyj1.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 name="person1,person2 person3;person4" class="entity.Person">
<constructor-arg index="0" value="丁大大1"/>
<constructor-arg name="age" value="23"/>
<constructor-arg type="java.lang.String" value="钓鱼1"/>
<constructor-arg type="java.lang.String" value="173"/>
</bean>
</beans>
dyj2.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 name="person1,person2 person3;person4" class="entity.Person">
<constructor-arg index="0" value="丁大大2"/>
<constructor-arg name="age" value="23"/>
<constructor-arg type="java.lang.String" value="钓鱼2"/>
<constructor-arg type="java.lang.String" value="173"/>
</bean>
</beans>
dyj3.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 name="person1,person2 person3;person4" class="entity.Person">
<constructor-arg index="0" value="丁大大3"/>
<constructor-arg name="age" value="23"/>
<constructor-arg type="java.lang.String" value="钓鱼3"/>
<constructor-arg type="java.lang.String" value="173"/>
</bean>
</beans>
③执行:
④总结:
本篇文章就到这里了,希望能帮助到你,也希望您能够多多关注编程网的更多内容!
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本文标题: Spring(二):Spring通过IOC来创建对象
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