spring——依赖注入DI(main函数方式)

叁歲伎倆 2022-06-16 00:54 314阅读 0赞

# spring——依赖注入DI(main函数方式) #

虽然题目上说的是main函数方式，但是更精确的说，应该是从java配置中加载spring的ApplicationContext。上一篇文章介绍了如何通过spring-test的方式进行spring的测试（http://blog.csdn.net/wild46cat/article/details/71055262），本篇文章主要介绍通过main函数作为配置入口使用spring。

好，下面上货。

1、首先创建maven仓库。

mvn archetype:generate -DarchetypeCatalog=internal

2、添加pom.xml依赖。

<properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <springframework.version>4.3.7.RELEASE</springframework.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.12</version>
                <scope>test</scope>
            </dependency>
            
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>${springframework.version}</version>
            </dependency>
            
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-test</artifactId>
                <version>${springframework.version}</version>
            </dependency>
    
        </dependencies>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <source>1.8</source>
                        <target>1.8</target>
                        <encoding>utf-8</encoding>
                    </configuration>
                </plugin>
                <plugin>
                    <artifactId>maven-assembly-plugin</artifactId>
                    <version>3.0.0</version>
                    <configuration>
                        <archive>
                            <manifest>
                                <mainClass>com.xueyoucto.xueyou.App</mainClass>
                            </manifest>
                        </archive>
                        <descriptorRefs>
                            <descriptorRef>jar-with-dependencies</descriptorRef>
                        </descriptorRefs>
                    </configuration>
                    <executions>
                        <execution>
                            <id>make-assembly</id> 
                            <phase>package</phase> 
                            <goals>
                                <goal>single</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
            </plugins>
        </build>

3、添加Person类和Body类

package com.xueyou.demo;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Component;
    import org.xueyou.demo.Body;
    
    @Component
    public class Person {
    
        @Autowired
        private Body body;
    
        public void showMyBody(){
            body.setId(100);
            System.out.println(body.getId());
        }
    
    }

package org.xueyou.demo;
    
    import org.springframework.stereotype.Component;
    
    @Component
    public class Body {
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        private int id;
    
    }

4、在main函数所在的类中配置spring扫描的包。

package com.xueyou.demo;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    
    /**
     * Hello world!
     */
    @Configuration
    @ComponentScan(basePackages = {"org.xueyou.demo","com.xueyou.demo"})
    public class App {
    
        public static void main(String[] args) {
            System.out.println("Hello World!");
            ApplicationContext applicationContext = new AnnotationConfigApplicationContext(com.xueyou.demo.App.class);
            Person p = applicationContext.getBean(Person.class);
            p.showMyBody();
    
    
        }
    }

5、看一下类所在的包的关系。

![Center][]

6、运行结果：

![Center 1][]

[Center]: /images/20220616/e81a60f8f0ef4df596cb925d558d295c.png
[Center 1]: /images/20220616/8f6392e6a6434893807c16d44a831b0c.png