spring注解方式 2022/08/22

spring注解方式

代码整体布局：
代码如下：
- pom.xml:
- spring-1.xml:
- Student:
- Test:
- Test2:
- spring-2.xml:
- Car:
- Driver:
- Test:
- spring-3.xml:
- IA:
- ClsA1:
- ClsA2:
- MyCls:
- MyCls2:
- Dog:
- Test:
- Test2:
讲解参考：

代码整体布局：

代码如下：

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>mybatis_0822_KTLX</artifactId><version>1.0-SNAPSHOT</version><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target></properties><dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.3.18</version></dependency></dependencies>
</project>

spring-1.xml:

<?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 https://www.springframework.org/schema/context/spring-context.xsd"><bean id="stu" class="com.test.Student" ><property name="name" value="张三"/><property name="sex" value="男"/><property name="age" value="20"/></bean>
</beans>

Student:

package com.test;import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;//@Component:用于告诉spring，当前类的对象需要spring来管理。
//          里面的名字就相当于bean标签的id，作为对象的唯一标识
@Component("stu")
public class Student {private String name;private String sex;private Integer age;public Student() {System.out.println("=====Student 无参构造=====");}public Student(String name, String sex, Integer age) {this.name = name;this.sex = sex;this.age = age;}public String getName() {return name;}public void setName(String name) {System.out.println("========setName========:"+name);this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}@Overridepublic String toString() {return "Student{" +"name='" + name + '\'' +", sex='" + sex + '\'' +", age=" + age +'}';}
}

Test:

package com.test;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;import javax.annotation.Resource;public class Test {@Resourceprivate Student stu;public static void main(String[] args) {//创建spring容器ApplicationContext ctx=new ClassPathXmlApplicationContext("spring-1.xml"); //运行结果：=====Student 无参构造===== ========setName========:张三}}

Test2:

package com.test;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test2 {public static void main(String[] args) {//通过注解从spring容器中获取对象//1.在spring配置文件中，配置包扫描//2.在需要被spring管理的类上加特定注解ApplicationContext ctx=new ClassPathXmlApplicationContext("spring-1.xml");Student stu=ctx.getBean(Student.class);System.out.println(stu); //运行结果：=====Student 无参构造===== ========setName========:张三  Student{name='张三', sex='男', age=20}Student stu1=(Student)ctx.getBean("stu");System.out.println(stu1); //运行结果： Student{name='张三', sex='男', age=20}}
}

spring-2.xml:

<?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 https://www.springframework.org/schema/context/spring-context.xsd"><context:component-scan base-package="com.test2"/>
</beans>

Car:

package com.test2;import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;@Component("mycar") //通过注释，可以用在任意对象上
//@Service  //本质就是@Component这个注释的别名，用于Service层的对象
//@Repository //本质就是@Component这个注释的别名，用于数据访问层的对象
public class Car {//品牌@Value("宝马")private String brand;//价格@Value("2000")private int price;//时速@Value("120")private int space;public Car() {}public Car(String brand, int price, int space) {this.brand = brand;this.price = price;this.space = space;}public void run(){System.out.println(this.brand+"在跑");}public String getBrand() {return brand;}public void setBrand(String brand) {this.brand = brand;}public int getPrice() {return price;}public void setPrice(int price) {this.price = price;}public int getSpace() {return space;}public void setSpace(int space) {this.space = space;}@Overridepublic String toString() {return "Car{" +"brand='" + brand + '\'' +", price=" + price +", space=" + space +'}';}
}

Driver:

package com.test2;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;import javax.annotation.Resource;@Component  //当注释没有指定id名字的时候，spring自动用类名小驼峰做对象的id名
public class Driver {//@Value只用于注入普通值@Value("张三")private String name;@Value("20")private Integer age;//@Autowired 用于注入对象类型的值（按照类型注入对象，前提是spring容器中有该类型的对象）//           该注释属于spring框架下的注释。特征是按照类型注入对象//@Autowired@Resourceprivate Car car;public Driver() {}public Driver(String name, Integer age, Car car) {this.name = name;this.age = age;this.car = car;}//开车public void drive(){System.out.println(this.name+"开车");this.car.run();}public String getName() {return name;}public void setName(String name) {//注解方式没有调用setter方法System.out.println("==========setName==============:"+name);this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public Car getCar() {return car;}public void setCar(Car car) {this.car = car;}@Overridepublic String toString() {return "Driver{" +"name='" + name + '\'' +", age=" + age +", car=" + car +'}';}
}

Test:

package com.test2;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test {public static void main(String[] args) {ApplicationContext ctx=new ClassPathXmlApplicationContext("spring-2.xml");//获取容器中的司机对象Driver driver=ctx.getBean(Driver.class);//调用开车的方法driver.drive(); //运行结果：张三开车 宝马在跑Car car=ctx.getBean(Car.class);System.out.println(car);   //运行结果：Car{brand='宝马', price=2000, space=120}Car mycar=(Car)ctx.getBean("mycar");System.out.println(mycar); //运行结果：Car{brand='宝马', price=2000, space=120}}}

spring-3.xml:

<?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 https://www.springframework.org/schema/context/spring-context.xsd"><context:component-scan base-package="com.test3"/>
</beans>

IA:

package com.test3;public interface IA {void test();
}

ClsA1:

package com.test3;import org.springframework.stereotype.Component;@Component
public class ClsA1 implements IA{@Overridepublic void test() {System.out.println("这是A1测试");}
}

ClsA2:

package com.test3;import org.springframework.stereotype.Component;@Component
public class ClsA2 implements IA{@Overridepublic void test() {System.out.println("这是A2测试");}
}

MyCls:

package com.test3;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;import javax.annotation.Resource;@Component //当注释没有指定id名字的时候，spring自动用类名小驼峰做对象的id名
public class MyCls {
//    @Autowired
//    private IA a;  //运行结果：ERROR:expected single matching bean but found 2: clsA1,clsA2//    //@Autowired先按类型，再按照名字注入
//    @Autowired
//    private IA clsA1;    //指定名字注入。 ClsA1类名小写clsA1 。
//
//    public void show(){
//        this.clsA1.test();
//    }                   //运行结果：这是A1测试//@Autowired先按类型，再按照名字注入@Autowired@Qualifier("clsA1") //按名字注入对象aprivate IA a;public void show(){this.a.test();}                   //运行结果：这是A1测试}

MyCls2:

package com.test3;import org.springframework.stereotype.Component;import javax.annotation.Resource;@Component
public class MyCls2 {//    @Resource(name = "clsA1")
//    private IA a;
//
//    public void show(){
//        this.a.test();
//    }                   //运行结果：这是A1测试//    @Resource
//    private IA clsA1; //指定名字注入
//
//    public void show(){
//        this.clsA1.test();
//    }                   //运行结果：这是A1测试//    //先按名字，再按类型注入
//    @Resource
//    private IA a;
//
//    public void show(){
//        this.a.test();
//    }  //运行结果：BeanNotOfRequiredTypeException: Bean named 'a' is expected to be of type 'com.test3.IA' but was actually of type 'com.test3.Dog'//先按名字，再按类型注入@Resourceprivate IA a;public void show(){this.a.test();} //运行结果：NoUniqueBeanDefinitionException: No qualifying bean of type 'com.test3.IA' available: expected single matching bean but found 2: clsA1,clsA2
}

Dog:

package com.test3;import org.springframework.stereotype.Component;//@Component("a")
@Component("dog")
public class Dog {}

Test:

package com.test3;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test {public static void main(String[] args) {ApplicationContext ac=new ClassPathXmlApplicationContext("spring-3.xml");MyCls myCls=ac.getBean(MyCls.class);
//        ac.getBean(MyCls.class);myCls.show();}
}

Test2:

package com.test3;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test2 {public static void main(String[] args) {ApplicationContext ac=new ClassPathXmlApplicationContext("spring-3.xml");MyCls2 myCls2=ac.getBean(MyCls2.class);myCls2.show();}}

讲解参考：

// A code block
var foo = 'bar';

// A code block
var foo = 'bar';

// A code block
var foo = 'bar';

// A code block
var foo = 'bar';

// A code block
var foo = 'bar';

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spring注解方式 2022/08/22

spring注解方式

代码整体布局：

代码如下：

pom.xml:

spring-1.xml:

Student:

Test:

Test2:

spring-2.xml:

Car:

Driver:

Test:

spring-3.xml:

IA:

ClsA1:

ClsA2:

MyCls:

MyCls2:

Dog:

Test:

Test2:

讲解参考：

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