Spring——IOC

缺乏、安全感 2023-10-11 11:08 3阅读 0赞

**一、IOC：控制反转；（DI：依赖注入）**

1）控制反转：将创建对象、属性值的方式进行反转，从new、setXxx()反转为SpringIOC容器getBean()；

2）依赖注入：将属性值注入给了属性；将属性注入给了bean；将bean注入给了IOC容器；

**二、核心依赖：**

1）Spring AOP：开发aop；

2）Spring Beans：处理bean；//<bean>

3）Spring Context ：处理spring上下文；//<context>

4）Spring Core：spring核心,IOC；

5）Spring Expression：spring表达式；

6）Commons Logging：日志；

**三、****IOC使用示例****：**

**　　**1）导入依赖：

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<dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>1.2.12</version>
            </dependency>
    
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>4.2.8.Release</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context-support</artifactId>
                <version>4.2.8.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-core</artifactId>
                <version>4.2.8.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-beans</artifactId>
                <version>4.2.8.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-expression</artifactId>
                <version>4.2.8.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>commons-logging</groupId>
                <artifactId>commons-logging</artifactId>
                <version>1.1.2</version>
            </dependency>

依赖

2）配置spring-context.xml应用上下文：

3）测试：

public class SpringTest {
        public static void main(String[] args) {
            ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("application-context.xml");
            User user = applicationContext.getBean(User.class);
            System.out.println(user);  //User{id=1, name='zs', age=17}
        }
    }

**四、配置bean的三种方式：**

**1）构造方法：**

1、scope="singleton"：单例；默认为单例；初始化时创建对象；

scope="prototype"：多例；每次调用都创建对象；

**　　　　**2、lazy-init="true"：延迟加载，只有使用的时候加载；

3、init-method：初始化对象调用方法；

4、destroy-method：销毁对象调用放过发；

5、id：唯一标识，不可以有特殊字符；

6、name：和id一样，但可以有特殊字符，且可以用，逗号隔开设置多个；

PS：如果name和id都没有，则默认给一个类的全类名；也不可以name/id同时存在；

**　2）工厂方法：**

**　　　　1、静态工厂：**

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public class UserFactory{
        public static User getUser(){
            System.out.println("获取一个User对象");
            return new User();
        }
    }

静态工厂类

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application-context.xml

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public class SpringTest {
        public static void main(String[] args) {
            ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("application-context.xml");
            User user = (User) applicationContext.getBean("userFactory");
            System.out.println(user);
        }
    }

test

2、非静态工厂：

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public class UserFactory{
        public User getUser(){
            System.out.println("获取一个User对象");
            return new User();
        }
    }

非静态工厂类

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application-context.xml

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test

**五、bean属性注入：**

**　　1）set方法注入：**

**　　　　1、基本类型：value；**

**　　　　2、引用类型：ref；**

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<?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 name="user" class="com.qf.entity.User">
            <property name="id" value="01"></property>
            <property name="name" value="zs"></property>
            <property name="age" value="12"></property>
            <property name="userDetail" ref="userDetail"></property>
        </bean>
        <bean name="userDetail" class="com.qf.entity.UserDetail">
            <property name="uId" value="01"></property>
            <property name="balance" value="100"></property>
        </bean>
    </beans>

application-context.xml

**　　2）构造函数注入：**

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public class User {
        private Long id;
        private String name;
        private Integer age;
        private UserDetail userDetail;
    
        public User() {
        }
    
        public User(Long id, String name, Integer age, UserDetail userDetail) {
            this.id = id;
            this.name = name;
            this.age = age;
            this.userDetail = userDetail;
        }
    
        public Long getId() {
            return id;
        }
    
        public void setId(Long id) {
            this.id = id;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        public UserDetail getUserDetail() {
            return userDetail;
        }
    
        public void setUserDetail(UserDetail userDetail) {
            this.userDetail = userDetail;
        }
    
        @Override
        public String toString() {
            return "User{" +
                    "id=" + id +
                    ", name='" + name + '\'' +
                    ", age=" + age +
                    ", userDetail=" + userDetail +
                    '}';
        }
    }

User实体类，需要创建有参构造；

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<?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 name="user" class="com.qf.entity.User">
            <constructor-arg name="id" value="01"></constructor-arg>
            <constructor-arg name="name" value="zs"></constructor-arg>
            <constructor-arg name="age" value="12"></constructor-arg>
            <constructor-arg name="userDetail" ref="userDetail"></constructor-arg>
        </bean>
        <bean name="userDetail" class="com.qf.entity.UserDetail">
            <property name="uId" value="01"></property>
            <property name="balance" value="100"></property>
        </bean>
    </beans>

application-context.xml

PS：如果构造函数有多个参数属性时，可以用index标识传入的位置和用type标识参数类型；

**　　3）p：命名空间注入：**使用的是set方法；

**　　　　1、简单类型：**p:属性名="值"

**　　　　2、引用类型：**P:属性名-ref="bean名称"

使用方法：beans中引入：xmlns:p="http://www.springframework.org/schema/p"

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application-context.xml

**　4）****spel注入：**spring Expression Language：spring表达式语言

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application-context.xml

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public class SpringTest {
        public static void main(String[] args) {
            ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("application-context.xml");
            User user2 = applicationContext.getBean("user2",User.class);
            System.out.println(user2);
        }
    }

test

**　　5）复杂类型注入：**

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public class Car {
        private String name;
        private String color;
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public String getColor() {
            return color;
        }
    
        public void setColor(String color) {
            this.color = color;
        }
    
        @Override
        public String toString() {
            return "Car{" +
                    "name='" + name + '\'' +
                    ", color='" + color + '\'' +
                    '}';
        }
    }

实体类1

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public class TestCollection {
        private Object[] arrs;
        private List list;
        private Map map;
        private Properties properties;
    
        public Object[] getArrs() {
            return arrs;
        }
    
        public void setArrs(Object[] arrs) {
            this.arrs = arrs;
        }
    
        public List getList() {
            return list;
        }
    
        public void setList(List list) {
            this.list = list;
        }
    
        public Map getMap() {
            return map;
        }
    
        public void setMap(Map map) {
            this.map = map;
        }
    
        public Properties getProperties() {
            return properties;
        }
    
        public void setProperties(Properties properties) {
            this.properties = properties;
        }
    
        @Override
        public String toString() {
            return "TestCollection{" +
                    "arrs=" + Arrays.toString(arrs) +
                    ", list=" + list +
                    ", map=" + map +
                    ", properties=" + properties +
                    '}';
        }
    }

实体类2

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<?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 name="car" class="com.qf.entity.Car">
            <property name="name" value="保时捷"/>
            <property name="color" value="红色"/>
        </bean>
    
        <bean name="testColl" class="com.qf.entity.TestCollection">
    
            
            <property name="arrs">
                <list>
                    <value>数组1</value>
                    
                    <ref bean="car"/>
                </list>
            </property>
    
            
            <property name="list">
                <list>
                    <value>集合1</value>
                    
                    <list>
                        <value>集合中的集合1</value>
                        <value>集合中的集合2</value>
                        <value>集合中的集合3</value>
                    </list>
                    <ref bean="car"/>
                </list>
            </property>
    
            
            <property name="map">
                <map>
                    <entry key="car" value-ref="car"/>
                    <entry key="name" value="保时捷"/>
                    <entry key="age" value="11"/>
                </map>
    
            </property>
    
            
            <property name="properties">
                <props>
                    <prop key="name">pro1</prop>
                    <prop key="age">111</prop>
                </props>
            </property>
        </bean>
    
    </beans>

application-context.xml

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public class SpringTest {
        public static void main(String[] args) {
            ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("application-context.xml");
            TestCollection testColl = applicationContext.getBean("testColl", TestCollection.class);
            System.out.println(testColl);
        }
    }

test

**六、构建应用上下文：**

1）FileSystemXmlApplicationContext：从硬盘绝对路径下获取；

ApplicationContext applicationContext = new FileSystemXmlApplicationContext("D:\\applicationContext-bean.xml");

**2）ClassPathXmlApplicationContext：**从类路径下获取；

普通项目：src；maven项目：resources；

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("application-context.xml");

** 七、注解配置：**

**　1）配置注解扫描器：**

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application-context.xml

**　2）类注解：**

1、@Component("")：

用表标记需要注入的bean，等效于配置xml<bean id="" class="">：

不指定name则按类型类名匹配；

@Repository("")；dao层；

@Service("")；Service层；

@Controller("")；Controller层；

2、指定是单例还是多例；

@Scope(scopeName="singleton")  
　　　　　@Scope(scopeName="prototype")

**　　2）属性/方法注解：**

1、给属性赋值：

@Value("name值")
    private String name;

2、给方法参数赋值：

@Value("name值")
    public void setName(String name)
    {
      this.name = name;
    }

3、@PostConstruct：初始化方法；@PreDestroy：销毁方法；

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@PostConstruct
     public  void init(){
       System.out.println("初始化方法");
     }
    
     @PreDestroy
     public void destroy(){
       System.out.println("销毁方法");
     }

**　　3）自动装配注解：**

1、@Autowired：默认按类型指定；

//如果装配的是接口，自动会去找实现类；但是实现类有两个，就需要@Qualifier()指定；

2、@Qualifier(“类名”)：

@Scope(scopeName = "prototype")
    @Component("User")
    public class User {
        @Value("name值")
        private String name;
        private Integer age;
        @Autowired  
        @Qualifier("userDetail02")   //指定实现类
        private UserDetail userDetail;  //自动装配

3、@Resource：等同于上面两个一起；

@Resource("name") == @Autowired + @Qualifier("name")

@Resource("userDetail02") 
    private UserDetail userDetail;  //自动装配

转载于:https://www.cnblogs.com/Tractors/p/11318413.html

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