Spring 裝配bean

時間 2019-11-18

標籤 spring 裝配 bean 欄目 Spring 简体版

原文原文鏈接

1、實例化方式：

三種實例化方式：默認構造，靜態工廠，實例工廠java

一、默認構造（前面的文章都是最基本的默認構造）

配置語法：web

<bean id="" class="">

二、靜態工廠

配置語法：spring

<bean id=""  class="工廠全限定類名"  factory-method="靜態方法">

我們來舉個栗子：
代碼：ide

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

配置：post

<!--class 肯定靜態工廠全限定類名
        factory-method 肯定靜態方法名-->
    <bean id="userServiceId" class="[包名].MyBeanFactory" factory-method="createService"></bean>

三、實例工廠

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

<!-- 建立工廠實例 -->
    <bean id="myBeanFactoryId" class="com.itheima.c_inject.c_factory.MyBeanFactory"></bean>
    <!-- 得到userservice 
        * factory-bean 肯定工廠實例
        * 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="">ui

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

如圖所示爲做用域類別與說明，Spring默認做用域爲單例，經常使用的爲單例（singleton）與多例（prototype）
this

3、生命週期

主要介紹初始化與銷燬、後處理beanprototype

一、初始化與銷燬

目標方法執行前或後，將進行初始化或銷燬。初始化方法經常使用於準備資源、初始化數據，銷燬方法經常使用於釋放資源等。
要求：1.容器必須close，銷燬方法執行; 2.必須是單例的代理

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("銷燬");
    }

}

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

二、BeanPostProcessor 後處理Bean

spring 提供一種機制，只要實現此接口BeanPostProcessor，並將實現類提供給spring容器，spring容器將自動執行，在初始化方法前執行before()，在初始化方法後執行after() 。配置 code

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("後方法 ： " + beanName);
        // bean 目標對象,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("------開啓事務");
                            //執行目標方法
                            Object obj = method.invoke(bean, args);
                            System.out.println("------提交事務");
                            return obj;
                        }});
    }
}

配置添加：

<!-- 將後處理的實現類註冊給spring -->
    <bean class="[包名].MyBeanPostProcessor"></bean>

4、屬性依賴注入

依賴注入方式分爲：手動裝配和自動裝配；

一、基於XML的手動裝配：構造方法、setter方法；

1.1構造方法

目標類：

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;
    }

<!-- 構造方法注入 
        * <constructor-arg> 用於配置構造方法一個參數argument
            name ：參數的名稱
            value：設置普通數據
            ref：引用數據，通常是另外一個bean id值
            index ：參數的索引號，從0開始 。若是隻有索引，匹配到了多個構造方法時，默認使用第一個。
            type ：肯定參數類型
    -->
    <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="陽志"></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="北京八寶山"></property>
        <property name="tel" value="120"></property>
    </bean>

1.3 P命令空間

對「setter方法注入」進行簡化，替換，而是在

p命名空間使用前提，必須添加命名空間

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="瀋陽" 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、裝配Bean 基於註解

@Component取代
@Component("id") 取代
2.web開發，提供3個@Component註解衍生註解（功能同樣）取代
@Repository ：dao層
@Service：service層
@Controller：web層
3.依賴注入，給私有字段設置，也能夠給setter方法設置
普通值：@Value("")
引用值：
方式1：按照【類型】注入
@Autowired
方式2：按照【名稱】注入1
@Autowired
@Qualifier("名稱")
方式3：按照【名稱】注入2
@Resource("名稱")
4.生命週期
初始化：@PostConstruct
銷燬：@PreDestroy
5.做用域
@Scope("prototype") 多例

註解使用前提，添加命名空間，讓spring掃描含有註解類
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>

你們有興趣也能夠關注個人公衆號查看文章。

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