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基础框架 Spring框架bean注入的几种方式

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基础框架 Spring框架bean注入的几种方式

一、概念

spring bean的注入大致分为两类：XML配置 与 注解方式
XML配置：set注入、构造函数注入，P标签，静态工厂方法与实例工厂方法；
注解方式： @Autowired,@Resource,@Qualifier。
注解需要注意：
@Autowired：是自动装配，默认采用类型ByType，依赖对象必须存在，否则抛出异常，如果要允许null 值，可以设置它的required属性为false，如：@Autowired(required=false) 。
@Qualifier("cusInfoService")：根据名称装配，一般与Autowired结合使用。
@Resource(name="cusInfoService")：默认根据名称，可以指定名称或类型，也可以同时指定。
@Resource装配顺序
1. 如果同时指定了name和type，则从Spring上下文中找到唯一匹配的bean进行装配，找不到则抛出异常
2. 如果指定了name，则从上下文中查找名称（id）匹配的bean进行装配，找不到则抛出异常
3. 如果指定了type，则从上下文中找到类型匹配的唯一bean进行装配，找不到或者找到多个，都会抛出异常
4. 如果既没有指定name，又没有指定type，则自动按照byName方式进行装配；如果没有匹配，则回退为一个原始类型进行匹配，如果匹配则自动装配；
注解方式注意：
@Configuration：标识配置类，相当于spring配置文件
@ComponentScan("com.hello.bean")：扫描包路径。
@Component：用来标识一个bean，用于spring的IOC容器就是通过扫描加注解的方式将对象放入容器管理。
@Component细分@Controller，@Service，@Repository，只是为了分类，作用相同！
@Controller("Bean的名称")：定义控制层Bean,如Action
@Service("Bean的名称")：定义业务层Bean
@Repository("Bean的名称")：定义DAO层Bean
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二、案例

  1. xml配置

    /**

    • 书
    • @author zrj
    • @date 2020/12/16
    • @since V1.0

    **/
    public class Book {
    private String bookName;
    private String bookAuthor;

    public Book() {
}
public Book(String bookName, String bookAuthor) {
this.bookName = bookName;
this.bookAuthor = bookAuthor;
}
public String getBookName() {
return bookName;
}
public void setBookName(String bookName) {
this.bookName = bookName;
}
public String getBookAuthor() {
return bookAuthor;
}
public void setBookAuthor(String bookAuthor) {
this.bookAuthor = bookAuthor;
}
@Override
public String toString() {
return "Book{" +
"bookName='" + bookName + '\'' +
", bookAuthor='" + bookAuthor + '\'' +
'}';
}
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    }
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    /**

    • 订单类
    • @author zrj
    • @date 2020/12/17
    • @since V1.0

    **/
    public class Orders {
    private String orderName;
    private double orderPrice;

    public Orders() {
}
public Orders(String orderName, double orderPrice) {
this.orderName = orderName;
this.orderPrice = orderPrice;
}
public String getOrderName() {
return orderName;
}
public void setOrderName(String orderName) {
this.orderName = orderName;
}
public double getOrderPrice() {
return orderPrice;
}
public void setOrderPrice(double orderPrice) {
this.orderPrice = orderPrice;
}
@Override
public String toString() {
return "Orders{" +
"orderName='" + orderName + '\'' +
", orderPrice=" + orderPrice +
'}';
}
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    }
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    /**

    • 汽车
    • @author zrj
    • @date 2020/12/16
    • @since V1.0

    **/
    public class Car {
    private String carName;
    private String carAuthor;

    public Car() {
}
public Car(String carName, String carAuthor) {
this.carName = carName;
this.carAuthor = carAuthor;
}
public String getCarName() {
return carName;
}
public void setCarName(String carName) {
this.carName = carName;
}
public String getCarAuthor() {
return carAuthor;
}
public void setCarAuthor(String carAuthor) {
this.carAuthor = carAuthor;
}
@Override
public String toString() {
return "Car{" +
"carName='" + carName + '\'' +
", carAuthor='" + carAuthor + '\'' +
'}';
}
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    }

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    /**

    • 工厂注入
    • @author zrj
    • @date 2020/12/17
    • @since V1.0

    **/
    public class CarFactory {

    /**
* 静态工厂，返回一个Car的实例对象
*/
public static Car getCar() {
return new Car( "奔驰", "梅赛德斯你" );
}
/**
* 实例工厂，返回一个Car的实例对象
*/
public Car getNewCar() {
return new Car( "帕梅拉", "保时捷" );
}
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    }
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    <!--1 set方法注入属性-->
<bean id="book">
<!--使用property完成属性注入，name：类里面属性名称,value：向属性注入的值 -->
<property name="bookName" value="平凡世界"></property>
<property name="bookAuthor" value="路遥"></property>
</bean>
<!--2 有参数构造注入属性-->
<bean id="orders">
<constructor-arg name="orderName" value="电脑"></constructor-arg>
<constructor-arg name="orderPrice" value="12"></constructor-arg>
</bean>
<!--3 p标签注入-->
<bean id="car" p:carName="幻影" p:carAuthor="劳斯莱斯"/>
<!--4 静态工厂注入-->
<bean id="car2" factory-method="getCar"/>
<!--5 实例工厂注入-->
<bean id="carFactory"/>
<bean id="cars" factory-bean="carFactory" factory-method="getNewCar"/>
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    package com.spring5.test;

    import com.spring5.bean.Book;
    import com.spring5.bean.Car;
    import com.spring5.bean.Orders;
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;

    /**

    • spring测试类
    • @author zrj
    • @date 2020/12/13
    • @since V1.0

    **/
    public class SpringTest {

    /**
* 加载spring配置文件
*/
ApplicationContext context = new ClassPathXmlApplicationContext( "bean1.xml" );
/**
* set注入
*/
@Test
public void bookTest() {
Book book = context.getBean( "book", Book.class );
System.out.println( book.toString() );
}
/**
* 构造函数
*/
@Test
public void orderTest() {
Orders order = context.getBean( "orders", Orders.class );
System.out.println( order.toString() );
}
/**
* p空间注入
*/
@Test
public void curTest() {
Car car = context.getBean( "car", Car.class );
System.out.println( car.toString() );
}
/**
* 静态工厂注入
*/
@Test
public void curTest2() {
Car car = context.getBean( "car2", Car.class );
System.out.println( car.toString() );
}
/**
* 实例工厂注入
*/
@Test
public void curTest3() {
Car car = context.getBean( "cars", Car.class );
System.out.println( car.toString() );
}
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    }

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  2. 注解方式

    package com.hello.config;

    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;

    /**

    • springBean配置类
    • @author 20023262
    • @date 2020/12/18
    • @since 1.0

    */
    @Configuration
    @ComponentScan(“com.hello.bean”)
    public class SpringBeanConfiguration {
    }

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    package com.hello.bean;

    import lombok.*;
    import org.springframework.context.annotation.Scope;
    import org.springframework.stereotype.Component;

    /**

    • 汽车
    • @author 20023262
    • @date 2020/12/18
    • @since 1.0

    */
    @Data
    @Builder
    @ToString
    @Scope(value = “prototype”)
    @Component(value = “car”)
    public class Car {
    private String name;
    private String auth;
    }

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    package com.hello.bean;

    import lombok.Builder;
    import lombok.Data;
    import lombok.ToString;
    import org.springframework.context.annotation.Scope;
    import org.springframework.stereotype.Component;

    /**

    • 电脑
    • @author 20023262
    • @date 2020/12/18
    • @since 1.0

    */
    @Data
    @Builder
    @ToString
    @Scope(value = “prototype”)
    @Component(value = “computer”)
    public class Computer {
    private String brand;
    private String name;
    }

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    package com.hello.bean;

    import lombok.Builder;
    import lombok.Data;
    import lombok.ToString;
    import org.springframework.context.annotation.Scope;
    import org.springframework.stereotype.Component;

    /**

    • 手机
    • @author 20023262
    • @date 2020/12/18
    • @since 1.0

    */
    @Data
    @Builder
    @ToString
    @Scope(value = “prototype”)
    @Component(value = “mobile”)
    public class Mobile {
    private String brand;
    private String name;
    }

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    package com.hello.bean;

    import lombok.Builder;
    import lombok.Data;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Qualifier;
    import org.springframework.context.annotation.Scope;
    import org.springframework.stereotype.Component;

    import javax.annotation.Resource;

    /**

    • 用户类
    • Component(value = “user”) //相当于在配置文件中
    • Scope(value = “prototype”) //配置创建对象是否是以单列模式进行创建
    • Autowired：自动装配，默认按type注入
    • Resource(name = “book”)：默认按name注入，可以通过name和type属性进行选择性注入
    • Qualifier：按照名称装配
    • @author 20023262
    • @date 2020/12/18
    • @since 1.0

    */
    @Scope(value = “prototype”)
    @Component(value = “user”)
    public class User {
    private String name;
    private int age;

    @Autowired(required = false)
private Car car;
@Resource(name = "mobile")
private Mobile mobile;
@Qualifier("computer")
@Autowired(required = false)
private Computer computer;
public User() {
}
public User(String name, int age, Car car, Mobile mobile, Computer computer) {
this.name = name;
this.age = age;
this.car = car;
this.mobile = mobile;
this.computer = computer;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Car getCar() {
return car;
}
public void setCar(Car car) {
this.car = car;
}
public Mobile getMobile() {
return mobile;
}
public void setMobile(Mobile mobile) {
this.mobile = mobile;
}
public Computer getComputer() {
return computer;
}
public void setComputer(Computer computer) {
this.computer = computer;
}
@Override
public String toString() {
return "User{" +
"name='" + name + '\'' +
", age=" + age +
", car=" + car +
", mobile=" + mobile +
", computer=" + computer +
'}';
}
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    }

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    package com.hello.bean;

    import com.hello.config.SpringBeanConfiguration;
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;

    /**

    • springBean注解注入测试类
    • @author 20023262
    • @date 2020/12/18
    • @since 1.0

    */
    public class SpringBeanTest {

    @Test
public void springBeanTest() {
// 加载配置类
ApplicationContext applicationContext = new AnnotationConfigApplicationContext(SpringBeanConfiguration.class);
User user = applicationContext.getBean("user", User.class);
System.out.println("user：" + user);
}
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    }

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