spring学习1之（组件注册-@Configuration&@Bean给容器中注册组件）

你的名字 2022-05-13 14:52 203阅读 0赞

一，xml配置文件版bean注入

1，新建一个maven工程，导入依赖，pom文件如下：

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   <td> <pre>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;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"&gt;
    &lt;modelVersion&gt;4.0.0&lt;/modelVersion&gt;

&lt;groupId&gt;com.dream&lt;/groupId&gt;
    &lt;artifactId&gt;spring-study001&lt;/artifactId&gt;
    &lt;version&gt;1.0-SNAPSHOT&lt;/version&gt;

&lt;dependencies&gt;
        &lt;!-- https://mvnrepository.com/artifact/org.springframework/spring-context --&gt;
        &lt;dependency&gt;
            &lt;groupId&gt;org.springframework&lt;/groupId&gt;
            &lt;artifactId&gt;spring-context&lt;/artifactId&gt;
            &lt;version&gt;4.3.13.RELEASE&lt;/version&gt;
        &lt;/dependency&gt;

&lt;/dependencies&gt;
&lt;/project&gt;</pre> </td> 
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2，新建一个Student类，代码如下：

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   <td> <pre>package com.dream.bean;

public class Student {

private String name;

private Integer age;

public Student(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

public Student() {
    }

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;
    }

@Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}
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3，配置文件版显示bean注入，配置文件为beans.xml:

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   <td> <pre>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;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"&gt;

&lt;bean id="student" class="com.dream.bean.Student"&gt;
        &lt;property name="age" value="18"&gt;&lt;/property&gt;
        &lt;property name="name" value="lisi"&gt;&lt;/property&gt;
    &lt;/bean&gt;
&lt;/beans&gt;</pre> </td> 
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4,测试配置文件注入bean

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   <td> <pre>package com.dream;

import com.dream.bean.Student;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainTest {

public static void main(String[] args) {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
        Student student=(Student)applicationContext.getBean("student");
        System.out.print(student);
    }
}
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5，测试结果

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   <td><br> 信息: Loading XML bean definitions from class path resource [beans.xml]<br><span style="color:#f33b45;">Student{name='lisi', age=18}</span><br> Process finished with exit code 0</td> 
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二，注解版bean注入

1，新建配置类

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   <td> <pre>package com.dream.config;

import com.dream.bean.Student;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
//配置类（等价原来的配置文件）
@Configuration
public class BeansConfig {

//给容器中注册一个bean；类型为返回值类型，id默认是方法名作为id
    @Bean
    public Student student(){
        return new Student("王五",28);
    }
}
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2，测试

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   <td> <pre>package com.dream;

import com.dream.bean.Student;
import com.dream.config.BeansConfig;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainTest {

public static void main(String[] args) {
        ApplicationContext applicationContext=new AnnotationConfigApplicationContext(BeansConfig.class);
        Student bean = applicationContext.getBean(Student.class);
        System.out.print("获取对象："+bean );
    }

private static void xmlBean() {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
        Student student=(Student)applicationContext.getBean("student");
        System.out.print(student);
    }
}
</pre> </td> 
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3，测试结果

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   <td>获取对象：Student{name='王五', age=28}</td> 
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