注解的使用之Autowired注解的使用

时间：2021-07-15 09:50:36 阅读：13 评论：0 收藏：0 [点我收藏+]

引用类型的注入可以使用@Autowired
@Autowired：spring框架提供的注解，实现引用类型的赋值。
spring中通过注解给引用类型赋值，使用的是自动注入原理，支持byName，byType
@Autowired：默认使用的是byType自动注入

位置：1）在属性定义的上面，无需set方法，推荐使用
       2）在set方法的上面

@Autowired第一种使用方式---byType
1.在Student中先声明引用类型school，在声明school类的语句上面加入@Autowired

package com.example.ba03;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("myStudent")
public class Student {

    @Value(value = "张飞")
    private String name;
    @Value(value = "27")
    private Integer age;

    /*引用类型
    * @Autowired：spring框架提供的注解，实现引用类型的赋值。
    * spring中通过注解给引用类型赋值，使用的是自动注入原理，支持byName，byType
    * @Autowired：默认使用的是byType自动注入
    *
    * 位置：1）在属性定义的上面，无需set方法，推荐使用
    *       2）在set方法的上面
    * */
    @Autowired
    private School school;

    public void setName(String name) {
        this.name = name;
    }

    public void setAge(Integer age) {
        this.age = age;
    }


    @Override
    public String toString() {
        return "Student{" +
                "name=‘" + name + ‘\‘‘ +
                ", age=" + age +
                ", school=" + school +
                ‘}‘;
    }
}

2.声明School对象，通过注解在School类上面加入@Component以及给属性的对象赋值；另外也可以通过配置文件来赋值

package com.example.ba03;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "北京大学")
    private String name;
    @Value(value = "北京海淀区")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}

<?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.example.ba03"/>
    <bean id="myXueXiao" class="com.example.ba03.School">
        <property name="name" value="清华大学"/>
        <property name="address" value="北京"/>
    </bean>
</beans>

@Autowired第二种使用方式---byName

 如果要使用byName方式，需要做的是：
 1.在属性上面加入@Autowired
 2.在属性上面加入@@Qualifier(value="bean的id")：表示使用指定名称的bean完成赋值

package com.example.ba04;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("myStudent")
public class Student {

    @Value(value = "张飞")
    private String name;
    @Value(value = "27")
    private Integer age;

    /*引用类型
    * @Autowired：spring框架提供的注解，实现引用类型的赋值。
    * spring中通过注解给引用类型赋值，使用的是自动注入原理，支持byName，byType
    * @Autowired：默认使用的是byType自动注入
    *
    * 位置：1）在属性定义的上面，无需set方法，推荐使用
    *       2）在set方法的上面
    *
    * */
    @Autowired
    @Qualifier("mySchool")
    private School school;

    public void setName(String name) {
        this.name = name;
    }

    public void setAge(Integer age) {
        this.age = age;
    }


    @Override
    public String toString() {
        return "Student{" +
                "name=‘" + name + ‘\‘‘ +
                ", age=" + age +
                ", school=" + school +
                ‘}‘;
    }
}

声明School对象，通过注解在School类上面加入@Component以及给属性的对象赋值

package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}package com.example.ba04;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {
    @Value(value = "中山大学")
    private String name;
    @Value(value = "广州")
    private String address;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name=‘" + name + ‘\‘‘ +
                ", address=‘" + address + ‘\‘‘ +
                ‘}‘;
    }
}

注解的使用之Autowired注解的使用

原文：https://www.cnblogs.com/hlchacker/p/15013623.html

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