Spring IOC控制反转

其他 2018-08-21 04:13:55 阅读次数: 0

IOC 控制反转又称为依赖注入，解决了程序的耦合问题。

一般通过new类来执行实例里的方法

人完全和代码耦合在一起了，如果换一个人，则要改动所有的代码。破坏了代码的完整性

public class JavaWork {

	public void doTest(){
		ZhangSan zhangsan=new ZhangSan();
		zhangsan.test();
	}
}
public class ZhangSan implements Tester{

	public void test(){
		System.out.println("张三-测试程序");
	}
}

public class Test {

	/**
	 * 主管执行命令
	 * @param args
	 */
	public static void main(String[] args) {
	    JavaWork javaWork=new JavaWork();
	    javaWork.setTester(new ZhangSan());
	}
}

IOC控制反转，把控制权转交出来

定义一个借口

public interface Tester {

	public void test();
}

多态，zhangsan继承Tester

public class ZhangSan implements Tester{

	public void test(){
		System.out.println("张三-测试程序");
	}
}

public class Lisi implements Tester{

	public void test(){
		System.out.println("李四-测试程序");
	}
}

具体谁执行，在test中设置

public class JavaWork {
	
	private Tester tester;
	
	public void setTester(Tester tester) {
		this.tester = tester;
	}

	public void doTest(){
		tester.test();
	}
}

设置某个人做测试，控制权不是由业务代码来管理了

public class Test {

	/**
	 * 主管执行命令
	 * @param args
	 */
	public static void main(String[] args) {
		JavaWork javaWork=new JavaWork();
		// javaWork.setTester(new ZhangSan());
		javaWork.setTester(new Lisi());
		javaWork.doTest();
	}
}

使用spring管理IOC容器

bean里面包含属性的name必须和类中的属性完全对应，在spring配置文件设置值

<?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="zhangsan" class="com.java.service.ZhangSan"></bean>
	
	<bean id="lisi" class="com.java.service.Lisi"></bean>
	
	<bean id="javaWork" class="com.java.service.JavaWork">
		<property name="tester" ref="lisi"></property>
	</bean>
  
</beans>
public class Test2 {

	public static void main(String[] args) {
		ApplicationContext ac=new ClassPathXmlApplicationContext("beans.xml");
		JavaWork javaWork=(JavaWork)ac.getBean("javaWork");
		javaWork.doTest();
	}
}

依赖注入的方式

1.属性注入

专门管理bean的

id为bean的唯一表示，通过id获取bean

public class People {

	private int id;
	private String name;
	private int age;
	}

<?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="people" class="com.java.entity.People"></bean>
</beans>

set方法注入属性

	<bean id="people2" class="com.java.entity.People">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
		<property name="age" value="11"></property>
	</bean>

2.属性的构造方法属性的注入，通过类型和索引

public People(int id, String name, int age) {
		super();
		this.id = id;
		this.name = name;
		this.age = age;
	}

	<bean id="people3" class="com.java.entity.People">
		<constructor-arg type="int" value="2"></constructor-arg>
		<constructor-arg type="String" value="李四"></constructor-arg>
		<constructor-arg type="int" value="22"></constructor-arg>
	</bean>
	
	<bean id="people4" class="com.java.entity.People">
		<constructor-arg index="0" value="3"></constructor-arg>
		<constructor-arg index="1" value="王五"></constructor-arg>
		<constructor-arg index="2" value="55"></constructor-arg>
	</bean>
	
	<bean id="people5" class="com.java.entity.People">
		<constructor-arg index="0" type="int" value="4"></constructor-arg>
		<constructor-arg index="1" type="String" value="招六"></constructor-arg>
		<constructor-arg index="2" type="int" value="66"></constructor-arg>
	</bean>

3.工厂方法注入(非静态工厂，静态工作)

非静态工厂,依然要在bean.xml中定义bean。工厂的方法

public class PeopleFactory {

	public People createPeople(){
		People p=new People();
		p.setId(5);
		p.setName("小七");
		p.setAge(77);
		return p;
	}
}
	<bean id="peopleFactory" class="com.java.factory.PeopleFactory"></bean>
    <bean id="people7" factory-bean="peopleFactory" factory-method="createPeople"></bean>
		// 工厂方法注入
		People people7=(People)ac.getBean("people7");
		System.out.println(people7);

静态工厂，不需要new实例，直接类名点方法

	public static People createPeople(){
		People p=new People();
		p.setId(8);
		p.setName("小八");
		p.setAge(88);
		return p;
	}
 	<bean id="people8" class="com.java1234.factory.PeopleFactory2" factory-method="createPeople"></bean>
		
		People people8=(People)ac.getBean("people8");
		System.out.println(people8);

注入参数

注入实体bean，bean之间的嵌套

public class People {

	private int id;
	private String name;
	private int age;
	private Dog dog;
}
	<bean id="dog1" class="com.java.entity.Dog">
		<property name="name" value="Jack"></property>
	</bean>
	
	<bean id="people2" class="com.java.entity.People">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
		<property name="age" value="11"></property>
		<property name="dog" ref="dog1"></property>
	</bean>

内部bean，只能被一个引用

	<bean id="people3" class="com.java.entity.People">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
		<property name="age" value="11"></property>
		<property name="dog">
			<bean class="com.java.entity.Dog">
				<property name="name" value="Tom"></property>
			</bean>
		</property>
	</bean>

null值

	<bean id="people4" class="com.java.entity.People">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
		<property name="age" value="11"></property>
		<property name="dog">
			<null></null>
		</property>
	</bean>

级联属性

	private Dog dog = new Dog();
<bean id="people5" class="com.java.entity.People">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
		<property name="age" value="11"></property>
		<property name="dog.name" value="Jack2"></property>
	</bean>

List集合属性注入

	private List<String> hobbies=new ArrayList<String>();
	private Set<String> loves=new HashSet<String>();
	private Map<String,String> works=new HashMap<String,String>();
	private Properties addresses=new Properties();
	<bean id="people6" class="com.java1234.entity.People">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
		<property name="age" value="11"></property>
		<property name="dog" ref="dog1"></property>
		<property name="hobbies">
			<list>
				<value>唱歌</value>
				<value>跳舞</value>
			</list>
		</property>
		<property name="loves">
			<set>
				<value>唱歌2</value>
				<value>跳舞2</value>
			</set>
		</property>
		<property name="works">
			<map>
				<entry>
					<key><value>上午</value></key>
					<value>写代码</value>
				</entry>
				<entry>
					<key><value>下午</value></key>
					<value>测试代码</value>
				</entry>
			</map>
		</property>
		<property name="addresses">
			<props>
				<prop key="address1">aaaaa</prop>
				<prop key="address2">bbbbb</prop>
			</props>
		</property>
	</bean>

自动装配

byName 通过名字

byType 通过类型

constructor 构造方法

default-autowire 

byName注入的应该是和people的属性dog一样的而不是dog2

public class People {

	private int id;
	private String name;
	private int age;
	private Dog dog;
]

<?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"
        default-autowire="byName">

	
	<bean id="dog2" class="com.java.entity.Dog">
		<property name="name" value="Jack"></property>
	</bean>

    <bean id="dog" class="com.java.entity.Dog">
		<property name="name" value="Jack"></property>
	</bean>

只要有类型相同就能注入

​
<?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"
        default-autowire="byType">
	<bean id="dog2" class="com.java.entity.Dog">
		<property name="name" value="Jack"></property>
	</bean>
​</beans>

根据构造方法注入

<?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"
        default-autowire="constructor">

	
	<bean id="dog2" class="com.java.entity.Dog">
		<property name="name" value="Jack"></property>
	</bean>
	
	
	
	<bean id="people1" class="com.java.entity.People">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
		<property name="age" value="11"></property>
	
	</bean>
	
</beans>

 自动把dog2注入到了构造方法里

	public People(Dog dog) {
		super();
		System.out.println("constructor");
		this.dog = dog;
	}

方法注入

lookup-method

通过配置scope的prototype实现多例，singleton单例(默认)

每次获取狗都获取新的狗

public abstract class People {

	private int id;
	private String name;
	private int age;
	private Dog dog;
	
	public abstract Dog getDog();
	
	public void setDog(Dog dog) {
		this.dog = dog;
	}
}

<?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="dog" class="com.java.entity.Dog" scope="prototype">
		<property name="name" value="Jack"></property>
	</bean>
	
	
	
	<bean id="people1" class="com.java.entity.People">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
		<property name="age" value="11"></property>
		<lookup-method name="getDog" bean="dog"/>
	</bean>
	
</beans>
public void test1() {
		People people=(People)ac.getBean("people1");
		People people2=(People)ac.getBean("people1");
		System.out.println(people.getDog()==people2.getDog());
		
		System.out.println(ac.getBean("dog")==ac.getBean("dog"));
	}

方法替换

两个人

第一个people

public class People {

	private int id;
	private String name;
	private int age;
	private Dog dog;

	
	public Dog getDog() {
		Dog dog=new Dog();
		dog.setName("Jack");
		return dog;
	}
}

第二个people2

import java.lang.reflect.Method;

import org.springframework.beans.factory.support.MethodReplacer;


public class People2 implements MethodReplacer {

	@Override
	public Object reimplement(Object arg0, Method arg1, Object[] arg2)
			throws Throwable {
		Dog dog=new Dog();
		dog.setName("Tom");
		return dog;
	}
}

people1使用people2的getDog(0方法

​
<?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="people1" class="com.java.entity.People">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
		<property name="age" value="11"></property>
		<replaced-method name="getDog" replacer="people2"></replaced-method>
	</bean>
	
	<bean id="people2" class="com.java.entity.People2"></bean>
</beans>

​

bean之间的关系

继承，依赖，引用

有一个通用的属性，抽出来一个通用的父类，抽象的

	<bean id="abstractPeople" class="com.java.entity.People" abstract="true">
		<property name="className" value="高三5班"></property>
		<property name="age" value="19"></property>
	</bean>
public class People {

	private int id;
	private String name;
	private int age;
	private String className;
}
	
	<bean id="zhangsan" parent="abstractPeople">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
	</bean>
	
	<bean id="lisi" parent="abstractPeople">
		<property name="id" value="2"></property>
		<property name="name" value="李四"></property>
		<property name="age" value="20"></property>
		<property name="dog" ref="dog"></property>
	</bean>
	public void test1() {
		People zhangsan=(People)ac.getBean("zhangsan");
		System.out.println(zhangsan);
		
		People lisi=(People)ac.getBean("lisi");
		System.out.println(lisi);
	}

依赖

查看zhangsan的信息必须要有权限

public class Authority {

	public Authority() {
		System.out.println("获取权限");
	}

	
}

	<bean id="zhangsan" parent="abstractPeople" depends-on="autority">
		<property name="id" value="1"></property>
		<property name="name" value="张三"></property>
	</bean>
<bean id="autority" class="com.java.service.Authority"></bean>

引用

<bean id="dog" class="com.java.entity.Dog">
		<property name="name" value="jack"></property>
	</bean>
	<bean id="lisi" parent="abstractPeople">
		<property name="id" value="2"></property>
		<property name="name" value="李四"></property>
		<property name="age" value="20"></property>
		<property name="dog" ref="dog"></property>
	</bean>

bean的作用范围

scope 默认 singleton 单例 IOC容器只有一个bean实例，

prototype 多例，每次从容器中调用bean时，返回新实例

request 每次HTTP请求都会创建一个新的bean

session 同一个HTTP Session共享一个Bean

global session 同一个全局Session共享一个bean 

application 同一个Application共享一个Bean

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