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