Unit02: 参数值注入 、 基于注解的组件扫描    

(4)IOC (Inversion Of Controll 控制反转)

什么是IOC?

对象之间的依赖关系由容器来建立。

什么是DI? (Dependency Injection 依赖注入)

容器通过调用set方法或者构造器来建立对象之间的依赖关系。
注: IOC是目标,而DI是手段。

依赖注入的两种方式

方式一 set方法注入。

step1. 添加set方法。

step2. 配置set方法注入。

方式二 构造器注入。

step1. 添加构造器。

step2. 配置构造器注入。

自动装配 (了解)

什么是自动装配?

容器依据某些规则,自动建立对象之间的依赖关系。
注:默认情况下,容器禁止自动装配。

注入基本类型的值

使用value属性来注入。

注入集合类型的值

List,Set,Map,Properties

引用的方式注入集合类型的值

读取properties文件的内容

使用Spring表达式

案例:

auto

package auto;

public class Restaurant {
private Waiter wt; public void setWt(Waiter wt) {
System.out.println("setWt()");
this.wt = wt;
} public Restaurant() {
System.out.println("Restaurant");
} @Override
public String toString() {
return "Restaurant [wt=" + wt + "]";
} }

Restaurant.java

package auto;

public class Waiter {

    public Waiter() {
System.out.println("Waiter()");
}
}

Waiter.java

ioc

package ioc;

public class A {
private B b; public A() {
System.out.println("A()");
} public A(B b) {
System.out.println("A(B)");
this.b = b;
} public void service(){
System.out.println("A's service()");
b.f1();
} }

A.java

package ioc;

public class B {

    public B() {
System.out.println("B()");
} public void f1(){
System.out.println("B's f1()");
} }

B.java

value

package value;

public class SpelBean {
private String name;
private String interest;
private double score;
private int pageSize; public void setPageSize(int pageSize) {
this.pageSize = pageSize;
} public SpelBean() {
System.out.println("SpelBean");
} public void setScore(double score) {
this.score = score;
} public void setInterest(String interest) {
this.interest = interest;
} public void setName(String name) {
this.name = name;
} @Override
public String toString() {
return "SpelBean [name=" + name + ", interest=" + interest + ", score=" + score + ", pageSize=" + pageSize
+ "]";
} }

SpelBean.java

package value;

import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set; public class ValueBean {
private String name;
private int age;
private List<String> interest;
private Set<String> city;
private Map<String,Double> score;
private Properties db; public String getName() {
return name;
}
public int getAge() {
return age;
}
public List<String> getInterest() {
return interest;
}
public Set<String> getCity() {
return city;
}
public Map<String, Double> getScore() {
return score;
}
public Properties getDb() {
return db;
}
public void setInterest(List<String> interest) {
this.interest = interest;
}
public void setDb(Properties db) {
this.db = db;
}
public void setCity(Set<String> city) {
this.city = city;
}
public void setScore(Map<String, Double> score) {
this.score = score;
}
public ValueBean() {
System.out.println("ValueBean()");
}
public void setName(String name) {
this.name = name;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "ValueBean [name=" + name + ", age=" + age + ", interest=" + interest + ", city=" + city + ", score="
+ score + ", db=" + db + "]";
} }

ValueBean.java

src/main/resource

<?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:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc"
xmlns:jee="http://www.springframework.org/schema/jee"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">
<bean id="wt2" class="auto.Waiter"/>
<!--
autowire指定自动装配的规则,有这样三个值:
byName: 容器依据属性名查找对应的bean(即
bean的id等于属性名),找到之后,调用对应的
set方法来完成注入。
注:如果找不到,会注入null值。
byType:容器依据属性类型查找对应的bean(即
bean的类型与属性类型一致),找到之后,调用对
应的set方法来完成注入。
注:如果找不到,会注入null值。
如果找到多个,会出错。
constructor:类似byType,只不过会调用构造器
来完成注入。
-->
<bean id="rest" class="auto.Restaurant"
autowire="byType"/>
</beans>

auto.xml

pagesize=10

config.properties

<?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:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc"
xmlns:jee="http://www.springframework.org/schema/jee"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">
<bean id="b1" class="ioc.B"/>
<!--
构造器方式注入。
index属性:指定参数的下标(从0开始)
-->
<bean id="a1" class="ioc.A">
<constructor-arg index="0" ref="b1"/>
</bean> </beans>

ioc.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:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc"
xmlns:jee="http://www.springframework.org/schema/jee"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">
<!--
使用Spring表达式读取其它bean的属性值。
-->
<bean id="sb1" class="value.SpelBean">
<property name="name"
value="#{vb1.name}"/>
<property name="interest"
value="#{vb1.interest[0]}"/>
<property name="score"
value="#{vb1.score['英语']}"/>
<property name="pageSize"
value="#{config.pagesize}"/>
</bean> <bean id="vb1" class="value.ValueBean">
<property name="name" value="小月"/>
<property name="age" value="22"/>
<property name="interest">
<list>
<value>钓鱼</value>
<value>旅游</value>
<value>看电视</value>
<value>看电视</value>
</list>
</property>
<property name="city">
<set>
<value>北京</value>
<value>长沙</value>
<value>南京</value>
</set>
</property>
<property name="score">
<map>
<entry key="英语" value="60"/>
<entry key="math" value="80"/>
</map>
</property>
<property name="db">
<props>
<prop key="username">King</prop>
<prop key="password">1234</prop>
</props>
</property>
</bean> <!-- 引用的方式注入集合类型的值 -->
<util:list id="interestBean">
<value>钓鱼</value>
<value>旅游</value>
<value>上网</value>
</util:list>
<util:set id="cityBean">
<value>北京</value>
<value>上海</value>
<value>武汉</value>
</util:set>
<util:map id="scoreBean">
<entry key="english" value="80"/>
<entry key="math" value="90"/>
</util:map>
<util:properties id="dbBean">
<prop key="username">King</prop>
<prop key="password">1234</prop>
</util:properties>
<bean id="vb2" class="value.ValueBean">
<property name="interest"
ref="interestBean"/>
<property name="city"
ref="cityBean"/>
<property name="score"
ref="scoreBean"/>
<property name="db"
ref="dbBean"/>
</bean> <!-- 读取properties文件的内容 -->
<!--
location属性:指定要 读取的文件的位置,
其中,classpath:表示依据类路径去查找。
-->
<util:properties id="config"
location="classpath:config.properties"/> </beans>

value.xml

src/test/java

test

package test;

import java.util.Properties;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; import auto.Restaurant;
import ioc.A;
import value.SpelBean;
import value.ValueBean; public class TestCase {
@Test
// 测试 构造器方式的注入
public void test1() {
// 启动Spring容器
String config = "ioc.xml";
ApplicationContext ac = new ClassPathXmlApplicationContext(config);
// 获得对象
A a1 = ac.getBean("a1", A.class);
a1.service();
} @Test
// 测试 自动装配
public void test2() {
// 启动Spring容器
String config = "auto.xml";
ApplicationContext ac = new ClassPathXmlApplicationContext(config);
// 获得对象
Restaurant rest = ac.getBean("rest", Restaurant.class);
System.out.println(rest);
} @Test
// 测试 注入基本类型的值
public void test3() {
// 启动Spring容器
String config = "value.xml";
ApplicationContext ac = new ClassPathXmlApplicationContext(config);
ValueBean vb1 = ac.getBean("vb2", ValueBean.class);
System.out.println(vb1);
} @Test
// 读取properties文件
public void test4() {
// 启动Spring容器
String config = "value.xml";
ApplicationContext ac = new ClassPathXmlApplicationContext(config);
Properties props = ac.getBean("config", Properties.class);
System.out.println(props);
} @Test
// 测试 Spring表达式
public void test5() {
// 启动Spring容器
String config = "value.xml";
ApplicationContext ac =
new ClassPathXmlApplicationContext(
config);
SpelBean sb1 =
ac.getBean("sb1",SpelBean.class);
System.out.println(sb1);
}
}

TestCase.java

    使用注解简化配置    

(1)什么是组件扫描?

Spring容器会扫描base-package指定的包及其子包下面的所有的类, 如果这些类前面有一些特殊的注解(比如@Component),则Spring 容器会将这些类纳入容器进行管理(相当于在配置文件当中有对应的bean)。

(2)如何进行组件扫描?

step1. 在类前面添加特定的注解。比如 @Component。

step2. 在配置文件当中,配置组件扫描。

(3)作用域和延迟加载相关注解

(4)依赖注入相关的注解

(5)value注解

案例:

annotation

package annotation;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component; @Component("eb")
public class ExampleBean {
@Value("小月")
private String name; @Value("#{config.pagesize}")
private int pageSize; public void setPageSize(int pageSize) {
this.pageSize = pageSize;
} public ExampleBean() {
System.out.println("ExampleBean()");
} public void setName(String name) {
this.name = name;
} @Override
public String toString() {
return "ExampleBean [name=" + name + ", pageSize=" + pageSize + "]";
} }

ExampleBean.java

package annotation;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component; @Component("mg")
public class Manager {
private Waiter wt; public Manager() {
System.out.println("Manager()");
} @Autowired
public Manager(@Qualifier("wt") Waiter wt) {
System.out.println("Manager(wt)");
this.wt = wt;
} @Override
public String toString() {
return "Manager [wt=" + wt + "]";
} }

Manager.java

package annotation;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component; @Component("rest")
public class Restaurant { @Autowired
@Qualifier("wt")
private Waiter wt; // @Autowired
// public void setWt(@Qualifier("wt") Waiter wt) {
// System.out.println("setWt()");
// this.wt = wt;
// } @Override
public String toString() {
return "Restaurant [wt=" + wt + "]";
} public Restaurant() {
System.out.println("Restaurant()");
} }

Restaurant.java

package annotation;

import javax.annotation.Resource;

import org.springframework.stereotype.Component;

@Component("school")
public class School { private Waiter wt; @Resource(name="wt")
public void setWt(Waiter wt) {
System.out.println("setWt()");
this.wt = wt;
} public School() {
System.out.println("School()");
} @Override
public String toString() {
return "School [wt=" + wt + "]";
} }

School.java

package annotation;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy; import org.springframework.context.annotation.Lazy;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component; @Component("stu1")
@Scope("singleton")
@Lazy(true)
public class Student { public Student() {
System.out.println("Student()");
} @PostConstruct
public void init(){
System.out.println("init()");
} @PreDestroy
public void destroy(){
System.out.println("destroy()");
} }

Student.java

package annotation;

import org.springframework.stereotype.Component;

@Component("wt")
public class Waiter { public Waiter() {
System.out.println("Waiter()");
} }

Waiter.java

src/main/resources

<?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:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc"
xmlns:jee="http://www.springframework.org/schema/jee"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">
<!-- 配置组件扫描 -->
<!--
Spring容器会扫描base-package指定的包及
其子包下面的所有的类,如果这些类前面有一
些特殊的注解(比如@Component),则Spring
容器会将这些类纳入容器进行管理(相当于在
配置文件当中有对应的bean)。
-->
<context:component-scan
base-package="annotation"/> <util:properties id="config"
location="classpath:config.properties"/> </beans>

annotation.xml

pagesize=10

config.properties

src/test/java

test

package test;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; import annotation.ExampleBean;
import annotation.Manager;
import annotation.Restaurant;
import annotation.School;
import annotation.Student; public class TestCase {
@Test
//测试 组件扫描
public void test1(){
String config = "annotation.xml";
ApplicationContext ac =
new ClassPathXmlApplicationContext(
config);
Student stu1 =
ac.getBean("stu1",
Student.class);
System.out.println(stu1);
} @Test
//测试 作用域
public void test2(){
String config = "annotation.xml";
ApplicationContext ac =
new ClassPathXmlApplicationContext(
config);
Student stu1 =
ac.getBean("stu1",
Student.class);
Student stu2 =
ac.getBean("stu1",
Student.class);
System.out.println(stu1 == stu2);
} @Test
// 测试 生命周期
public void test3(){
String config = "annotation.xml";
AbstractApplicationContext ac =
new ClassPathXmlApplicationContext(
config);
Student stu1 =
ac.getBean("stu1",
Student.class);
ac.close();
} @Test
// 测试 延迟加载
public void test4(){
String config = "annotation.xml";
ApplicationContext ac =
new ClassPathXmlApplicationContext(
config);
} @Test
// 测试 @Autowired和 @Qualifier
public void test5(){
String config = "annotation.xml";
ApplicationContext ac =
new ClassPathXmlApplicationContext(
config);
Restaurant rest =
ac.getBean("rest",Restaurant.class);
System.out.println(rest); Manager mg =
ac.getBean("mg",Manager.class);
System.out.println(mg);
} @Test
//测试 @Resource
public void test6(){
String config = "annotation.xml";
ApplicationContext ac =
new ClassPathXmlApplicationContext(
config);
School s =
ac.getBean("school",
School.class);
System.out.println(s);
} @Test
//测试 @Value
public void test7(){
String config = "annotation.xml";
ApplicationContext ac =
new ClassPathXmlApplicationContext(
config);
ExampleBean eb =
ac.getBean("eb",ExampleBean.class);
System.out.println(eb);
} }

TestCase.java

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