Spring 入门 IOC 笔记

深碍√TFBOYSˉ_ 2024-02-19 17:23 73阅读 0赞

*  **概念理解** 详细的自行搜索

IOC:Inverse Of Control控制反转

DI:Dependency Injection依赖注入

*  **注入类型**

**Setter(常用)**

**UserService类（省略非关键性代码）**

![20190217215728296.png][]

Spring.xml

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0h1bW9yQ2hlbjk5_size_16_color_FFFFFF_t_70][]

测试运行

![20190217215806251.png][]

运行结果：正确

![20190217215820356.png][]

**构造方法**

**引用其他bean作为参数**

![20190217220001661.png][]

新建bean作为参数

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0h1bW9yQ2hlbjk5_size_16_color_FFFFFF_t_70 1][]

通过参数类型识别

![20190217220026267.png][]

通过下标识别

![20190217220037567.png][]

**接口注入（不建议使用）**

![20190217220110146.png][]

*  **Bean 的ID和NAME区别**  
    **Id vs name**

**name中可以加入特殊字符比如\#，实际作用不大**

**实际上id和name一样的**

*  **简单属性的注入**

**示范:**

**User类如下(省去getter/setter部分代码)**

![20190217220134401.png][]

![20190217220142577.png][]

Spring.xml中添加

![20190217220155358.png][]

测试运行

![20190217220211121.png][]

运行结果 正确输出了  
![2019021722022495.png][]

*  **Bean的Scope属性（范围）**  
    ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0h1bW9yQ2hlbjk5_size_16_color_FFFFFF_t_70 2][]  
    singleton第一个单例模式，就是你每次getBean得到的是同一个  
    ![2019021722030619.png][]  
    ![2019021722031565.png][]  
    运行结果为true![20190217220330752.png][]
    
    prototype第二个原型模式，每次getBean给你造一个新的每次造出来的==结果为false
    
    同上做法运行结果为false，截图就不贴了  
    
 *  **Bean的集合注入**
 *  Properties  
    ![20190217220423192.png][]  
    Set  
    ![20190217220435907.png][]  
    List  
    ![20190217220447873.png][]  
    Map  
    ![20190217220500269.png][]  
    
 *  **自动装配autowire属性**
 *  **单个配**  
    ![20190217220514190.png][]  
    全部配  
    ![20190217220527922.png][]  
    
    
    两个常用
    
    byName 将bean中名字和属性名相同的装载
    
    byType 将bean中class类型相同的装载，不得出现多个，会报错，可使用qualifier区分  
    
 *  **生命周期LifeCycle**
 *  lazy-init属性 当为true的时候spring容器初始化的时候不会创建这个Bean，使用情况在启动特别慢的情况下，避免加载暂时不用的bean提高速度
 *  单个添加  
    ![20190217220630728.png][]  
    全部添加  
    ![20190217220645212.png][]  
    
    
    init-method bean初始化的时候先调用此方法  
    destroy-method销毁的时候调方法（不要和scope=”prototype”一起使用,因为在此情况下spring 不持续监控对象的整个生命周期了，不要去研究）  
    ![20190217220659477.png][]  
    ![20190217220707727.png][]  
    ![2019021722071324.png][]  
    
 *  **Annotation注解**
    
    <?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-2.5.xsd">
    
    红色标出的是需要添加的
    
    beans中添加
    
    <context:annotation-config/>
    
    上面一句包含了下面四个注解的处理器
    
    ![2019021722112253.png][]
    
    就可以使用注解了
    
    使用@Component 、@Controller、@Service、@Repository标记过的类能被识别为Bean
    
    **语法**
    
    自动注入
    
    @Autowired （默认byType）  
    ![20190217221241831.png][]
 *  自动从beans中找匹配的对象注入
    
    当beans中存在多个同类型bean时使用@Qualifier(“beanname”)来指定使用哪里bean来注入（bean的name作为一个默认的qualifier使用）  
    示范如下  
    ![20190217221255727.png][]  
    定义qualifier属性  
    ![20190217221308161.png][]  
    @Autowired(required=false)意思是如果没有找到能注入的bean也没关系  
    ![20190217221320124.png][]  
    
    
    @Resource(name=”n”) 常用，(不写名字的时候默认byName，找不到尝试byType)
    
    如下例子释义：从beans中拿name为u的bean作为参数传入  
    ![20190217221331595.png][]  
    
    
    @Component 指定名字的写法 @Component(“name”) 
    
    下面意思为从com.spring.bean包下扫描组件(包括子包)
    
    <context:component-scan base-package="com.spring.bean"/>  
    ![20190217221344933.png][]![20190217221349257.png][]
 *  ![20190217221354740.png][]
    
    注解指定属性
    
    例如scope
    
    注解：@Scope(“prototype”)  
    ![20190217221411463.png][]  
    
    
    Init-method destroy-method  
    注解： @PosstConstruct @PreDestroy  
    ![20190217221424335.png][]
 *

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