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spring依赖注入DI

1、创建一个maven项目

mvn archetype:generate -DarchetypeCatalog=internal

2、修改pom.xml

引入需要的依赖，首先spring-context，还是spring-test，最后还有junit。

<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>
    <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${springframework.version}</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.springframework/spring-test -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>${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> <!-- this is used for inheritance merges -->
            <phase>package</phase> <!-- bind to the packaging phase -->
            <goals>
              <goal>single</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

3、添加类Person和Body

package com.xueyou.demo;
import org.springframework.stereotype.Component;
@Component
public class Person {
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  private String name;
}

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、在配置类App中，添加ComponentScan

需要注意的是，这里需要指定扫描的包

package com.xueyou.demo;
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!");
  }
}

5、新建一个测试类

package com.xueyou.demo;
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.xueyou.demo.Body;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = App.class)
public class Springtest {
  @Autowired
  private Body body;
  @Autowired
  private Person person;
  @Test
  public void testBodyIsNull(){
    Assert.assertNotNull(body);
  }
  @Test
  public void testPersonIsNull(){
    Assert.assertNotNull(person);
  }
}

6、运行测试类

结果如下：

7、从运行结果中我们能看到

Person类和Student类已经被依赖注入到spring中，spring能够使用这两个类了。

spring-test依赖无法使用问题

<dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>4.3.7.RELEASE</version>
      <scope>test</scope>
</dependency>

去掉

<scope>test</scope>

好了，解决！以上为个人经验，希望能给大家一个参考，也希望大家多多支持源码搜藏网。