Unit02： 参数值注入 、 基于注解的组件扫描

　　　　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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原文地址：https://www.cnblogs.com/tangshengwei/p/6487081.html