IOC:控制反转，对象控制权由代码交给容器
DI：依赖注入，为控制反转提供实现方法。
1.DI方式
- 构造器注入
- 属性注入
- 接口注入
1.1 构造器注入
在被注入的类声明一个构造方法（有参或无参），Spring通过反射调用构造方法，进而创建对象
1.2 属性注入
在被注入类声明set方法，通过参数注入
- Student
public class Student {
public Student(String msg) {
this.msg = msg;
}
public Student(){
}
private String msg;
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
@Override
public String toString() {
return "Student{" +
"msg='" + msg + '\'' +
'}';
}
}
- spring.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
https://www.springframework.org/schema/beans/spring-beans.xsd"
xmlns:p="http://www.springframework.org/schema/p">
<bean id="student" class="entity.Student">
<!-- 1.构造器注入属性值
通过构造器-->
<constructor-arg name="msg" value="MSG"></constructor-arg>
<!-- 2.属性注入
通过set方法-->
<property name="msg">
<value>LWX</value>
</property>
<!-- 3.接口注入-->
</bean>
</beans>
- Test类
@Test
public void fun(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("config/spring.xml");
Student student = applicationContext.getBean("student",Student.class);
System.out.println(student.getMsg());
}
2.DI方式
2.1 注入集合
- Mix实体
public class Mix {
private List<String> list;
private Map<String, String> map;
private String[] arr;
public List<String> getList() {
return list;
}
public void setList(List<String> list) {
this.list = list;
}
public Map<String, String> getMap() {
return map;
}
public void setMap(Map<String, String> map) {
this.map = map;
}
public String[] getArr() {
return arr;
}
public void setArr(String[] arr) {
this.arr = arr;
}
@Override
public String toString() {
return "Mix{" +
"list=" + list +
", map=" + map +
", arr=" + Arrays.toString(arr) +
'}';
}
}
- spring.xml
<bean id="mix" class="entity.Mix">
<property name="list">
<list>
<value>list1</value>
<value>list2</value>
</list>
</property>
<property name="map">
<map>
<entry key="key1" value="map1"></entry>
<entry key="key2" value="map2"></entry>
</map>
</property>
<property name="arr">
<array>
<value>arr1</value>
<value>arr2</value>
</array>
</property>
</bean>
2.2 注入对象属性
利用ref元素
- Clazz实体
public class Clazz {
private List<Student> students;
public List<Student> getStudents() {
return students;
}
public void setStudents(List<Student> students) {
this.students = students;
}
@Override
public String toString() {
return "Clazz{" +
"students=" + students +
'}';
}
}
- spring.xml
<bean id="clazz" class="entity.Clazz">
<!-- 第一种-->
<property name="students">
<list>
<ref bean="student"></ref>
</list>
</property>
<!-- 第二种-->
<property name="students" ref="student"></property>
</bean>
2.3 P命名空间注入
上述实体
- spring.xml
beans加入xmlns:p="http://www.springframework.org/schema/p
<!-- p命名空间-->
<bean id="clazz" class="entity.Clazz" p:students-ref="student"></bean>
2.3 SpEL注入
Spring Expression Language 表达式语言 为Bean属性进行动态赋值 通过bean的id引用bean 调用对象方法或属性
- Person实体
public class Person {
private String msg;
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
@Override
public String toString() {
return "Person{" +
"msg='" + msg + '\'' +
'}';
}
}
- spring.xml
<!-- SpEL注入-->
<bean id="person" class="entity.Person">
<property name="msg" value="#{student.msg}"></property>
</bean>
3.Bean
3.1 配置
3.2 作用域
容器创建bean实例时可以指定其作用域，默认singleton
3.3 生命周期
bean创建，初始化，销毁的过程。
- 初始化之前：init-method属性或实现initializingBean接口
- 销毁之前：destroy-method属性或实现DisposableBean接口
- Bean01实体
public class Bean01 implements DisposableBean {
public Bean01(){
}
private String value;
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
public void init(){
System.out.println("INIT");
}
public void close(){
System.out.println("CLOSE");
}
@Override
public void destroy() throws Exception {
}
}
- spring.xml
<bean id="bean01" class="entity.Bean01" init-method="init" destroy-method="close">
<property name="value" value="MyValue"></property>
</bean>
4.注解
- spring.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:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
">
<context:component-scan base-package="entity"></context:component-scan>
</beans>
- stu实体类
@Component("stu")
public class Stu {
public Stu(String msg) {
this.msg = msg;
}
public Stu(){
}
@Value("MSG")
private String msg;
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
@Override
public String toString() {
return "Student{" +
"msg='" + msg + '\'' +
'}';
}
}
- Sch实体类
@Component("sch")
@Scope(scopeName = "singleton")
public class Sch {
@Autowired
@Qualifier("stu")//注入该实例
private Stu stu;
@PostConstruct
public void init(){
System.out.println("INIT");
}
@PreDestroy
public void close(){
System.out.println("CLOSE");
}
}