Spring 装配bean

1、实例化方式：

三种实例化方式：默认构造，静态工厂，实例工厂

一、默认构造（前面的文章都是最基本的默认构造）

配置语法：

<bean id="" class="">

二、静态工厂

配置语法：

<bean id=""  class="工厂全限定类名"  factory-method="静态方法">

我们来举个栗子：
代码：

public class MyBeanFactory {
     // 建立实例
    public static UserService createService(){
        return new UserServiceImpl();
    }
}

配置：

<!--class 肯定静态工厂全限定类名
        factory-method 肯定静态方法名-->
    <bean id="userServiceId" class="[包名].MyBeanFactory" factory-method="createService"></bean>

三、实例工厂

public class MyBeanFactory {
    public UserService createService(){
        return new UserServiceImpl();
    }
}

<!-- 建立工厂实例 -->
    <bean id="myBeanFactoryId" class="com.itheima.c_inject.c_factory.MyBeanFactory"></bean>
    <!-- 得到userservice 
        * factory-bean 肯定工厂实例
        * factory-method 肯定普通方法
    -->
    <bean id="userServiceId" factory-bean="myBeanFactoryId" factory-method="createService"></bean>

2、做用域

配置信息：
<bean id="" class="" scope="">

<bean id="userServiceId" class="[包名].UserServiceImpl" 
        scope="prototype" ></bean>

如图所示为做用域类别与说明，Spring默认做用域为单例，经常使用的为单例（singleton）与多例（prototype）

3、生命周期

主要介绍初始化与销毁、后处理bean

一、初始化与销毁

目标方法执行前或后，将进行初始化或销毁。初始化方法经常使用于准备资源、初始化数据，销毁方法经常使用于释放资源等。
要求：1.容器必须close，销毁方法执行; 2.必须是单例的

public class UserServiceImpl implements UserService {

    @Override
    public void addUser() {
        System.out.println("e_lifecycle add user");
    }
    
    public void myInit(){
        System.out.println("初始化");
    }
    public void myDestroy(){
        System.out.println("销毁");
    }

}

<bean id="userServiceId" class="com.itheima.e_lifecycle.UserServiceImpl" 
        init-method="myInit" destroy-method="myDestroy" ></bean>

二、BeanPostProcessor 后处理Bean

spring 提供一种机制，只要实现此接口BeanPostProcessor，并将实现类提供给spring容器，spring容器将自动执行，在初始化方法前执行before()，在初始化方法后执行after() 。 配置

public class MyBeanPostProcessor implements BeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("前方法 ： " + beanName);
        return bean;
    }
    @Override
    public Object postProcessAfterInitialization(final Object bean, String beanName) throws BeansException {
        System.out.println("后方法 ： " + beanName);
        // bean 目标对象,可生成 jdk 代理
        return Proxy.newProxyInstance(
                    MyBeanPostProcessor.class.getClassLoader(), 
                    bean.getClass().getInterfaces(), 
                    new InvocationHandler(){
                        @Override
                        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                            System.out.println("------开启事务");
                            //执行目标方法
                            Object obj = method.invoke(bean, args);
                            System.out.println("------提交事务");
                            return obj;
                        }});
    }
}

配置添加：

<!-- 将后处理的实现类注册给spring -->
    <bean class="[包名].MyBeanPostProcessor"></bean>

4、属性依赖注入

依赖注入方式分为：手动装配和自动装配；

一、基于XML的手动装配：构造方法、setter方法；

1.1构造方法

目标类：

public class User {
    
    private Integer uid;
    private String username;
    private Integer age;
    
    public User(Integer uid, String username) {
        super();
        this.uid = uid;
        this.username = username;
    }
    
    public User(String username, Integer age) {
        super();
        this.username = username;
        this.age = age;
    }

<!-- 构造方法注入 
        * <constructor-arg> 用于配置构造方法一个参数argument
            name ：参数的名称
            value：设置普通数据
            ref：引用数据，通常是另外一个bean id值
            index ：参数的索引号，从0开始 。若是只有索引，匹配到了多个构造方法时，默认使用第一个。
            type ：肯定参数类型
    -->
    <bean id="userId" class="com.itheima.f_xml.a_constructor.User" >
        <constructor-arg index="0" type="java.lang.String" value="1"></constructor-arg>
        <constructor-arg index="1" type="java.lang.Integer" value="2"></constructor-arg>
    </bean>

1.2setter方法

<bean id="personId" class="com.itheima.f_xml.b_setter.Person">
        <property name="pname" value="阳志"></property>
        <property name="age">
            <value>1234</value>
        </property>
        
        <property name="homeAddr" ref="homeAddrId"></property>
        <property name="companyAddr">
            <ref bean="companyAddrId"/>
        </property>
    </bean>
    
    <bean id="homeAddrId" class="com.itheima.f_xml.b_setter.Address">
        <property name="addr" value="阜南"></property>
        <property name="tel" value="911"></property>
    </bean>
    <bean id="companyAddrId" class="com.itheima.f_xml.b_setter.Address">
        <property name="addr" value="北京八宝山"></property>
        <property name="tel" value="120"></property>
    </bean>

1.3 P命令空间

对“setter方法注入”进行简化，替换 ，而是在

p命名空间使用前提，必须添加命名空间

public class Person {
    private String pname;
    private Integer age;
    private Address homeAddr;
    private Address componyAddr;
    public String getPname() {
        return pname;
    }
    public void setPname(String pname) {
        this.pname = pname;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public Address getHomeAddr() {
        return homeAddr;
    }
    public void setHomeAddr(Address homeAddr) {
        this.homeAddr = homeAddr;
    }
    public Address getComponyAddr() {
        return componyAddr;
    }
    public void setComponyAddr(Address componyAddr) {
        this.componyAddr = componyAddr;
    }
    @Override
    public String toString() {
        return "Person [pname=" + pname + ", age=" + age + ", homeAddr="
                + homeAddr + ", componyAddr=" + componyAddr + "]";
    }
    
    
}

public class Address {
    private String addr;
    private String tel;
    public String getAddr() {
        return addr;
    }
    public void setAddr(String addr) {
        this.addr = addr;
    }
    public String getTel() {
        return tel;
    }
    public void setTel(String tel) {
        this.tel = tel;
    }
    @Override
    public String toString() {
        return "Address [addr=" + addr + ", tel=" + tel + "]";
    }
    
}

<?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"
       xsi:schemaLocation="
            http://www.springframework.org/schema/beans 
            http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="person" class="com.jdwa.spring.f_xml.c_p.Person" p:pname="zkn" p:age="22" 
        p:componyAddr-ref="componyAddr" p:homeAddr-ref="homeAddr" />
    <bean id="homeAddr" class="com.jdwa.spring.f_xml.c_p.Address" 
        p:addr="南京" p:tel="666"/>
    <bean id="componyAddr" class="com.jdwa.spring.f_xml.c_p.Address"
        p:addr="沈阳" p:tel="888"/>
</beans>

1.4.集合注入

public class CollData {
    private String[] arrayData;
    private List<String> listData;
    private Set<String> setData;
    private Map<String,String> mapData;
    private Properties propsData;
    public String[] getArrayData() {
        return arrayData;
    }
    public void setArrayData(String[] arrayData) {
        this.arrayData = arrayData;
    }
    public List<String> getListData() {
        return listData;
    }
    public void setListData(List<String> listData) {
        this.listData = listData;
    }
    public Set<String> getSetData() {
        return setData;
    }
    public void setSetData(Set<String> setData) {
        this.setData = setData;
    }
    public Map<String, String> getMapData() {
        return mapData;
    }
    public void setMapData(Map<String, String> mapData) {
        this.mapData = mapData;
    }
    public Properties getPropsData() {
        return propsData;
    }
    public void setPropsData(Properties propsData) {
        this.propsData = propsData;
    }
    @Override
    public String toString() {
        return "CollData [\narrayData=" + Arrays.toString(arrayData)
                + ", \nlistData=" + listData + ",\n setData=" + setData
                + ", \nmapData=" + mapData + ",\n propsData=" + propsData + "\n]";
    }
    
    
    
    
    
}

<?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="collData" class="com.jdwa.spring.f_xml.e_coll.CollData">
        <property name="arrayData">
            <array>
                <value>array1</value>
                <value>array2</value>
                <value>array3</value>
            </array>
        </property>
        <property name="listData">
            <list>
                <value>list1</value>
                <value>list2</value>
                <value>list3</value>
            </list>
        </property>
        <property name="setData">
            <set>
                <value>set1</value>
                <value>set2</value>
                <value>set3</value>
            </set>
        </property>
        <property name="mapData">
            <map>
                <entry key="map-key1" value="map-val1"></entry>
                <entry key="map-key2" value="map-val2"></entry>
                <entry key="map-key3" value="map-val3"></entry>
            </map>
        </property>
        <property name="propsData">
            <props>
                <prop key="prop-key1">prop-val1</prop>
                <prop key="prop-key2">prop-val2</prop>
                <prop key="prop-key3">prop-val3</prop>
            </props>
        </property>
    </bean>
</beans>

5、装配Bean 基于注解

1. @Component取代
   @Component("id") 取代
   2.web开发，提供3个@Component注解衍生注解（功能同样）取代
   @Repository ：dao层
   @Service：service层
   @Controller：web层
   3.依赖注入 ，给私有字段设置，也能够给setter方法设置
   普通值：@Value("")
   引用值：
   方式1：按照【类型】注入
   @Autowired
   方式2：按照【名称】注入1
   @Autowired
   @Qualifier("名称")
   方式3：按照【名称】注入2
   @Resource("名称")
   4.生命周期
   初始化：@PostConstruct
   销毁：@PreDestroy
   5.做用域
   @Scope("prototype") 多例

注解使用前提，添加命名空间，让spring扫描含有注解类
xmlns:context="http://www.springframework.org/schema/context"
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
<context:component-scan base-package="【包名】"></context:component-scan>

<?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"
       xsi:schemaLocation="
            http://www.springframework.org/schema/beans 
            http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context.xsd">
        
         <context:component-scan base-package="【包名】"></context:component-scan>
</beans>

你们有兴趣也能够关注个人公众号查看文章。