Spring使用Setter依赖注入

一个简单的Spring例子来展示如何通过setter方法注入依赖项，最常用DI方法注入bean。

1. IOutputGenerator

　　接口和实现类  

 package faj.test.javademo.set;

 /**
  * Created by JiaGao on 2016/7/30.
  */
 public interface IOutputGenerator {
     void generateOutput();
 }

 package faj.test.javademo.set;

 /**
  * Created by JiaGao on 2016/7/30.
  */
 public class CsvOutputGenerator implements IOutputGenerator {
     @Override
     public void generateOutput() {
         System.out.println("This is Csv Output Generator");
     }
 }

2. Helper类

一个辅助类，之后使用Spring 来注入 IOutputGenerator。  

 package faj.test.javademo.set;

 public class OutputHelper {
     private IOutputGenerator outputGenerator;
     public void generateOutput() {
         outputGenerator.generateOutput();
     }
     //DI via setter method
     public void setOutputGenerator(IOutputGenerator outputGenerator) {
         this.outputGenerator = outputGenerator;
     }
 }

3. Spring配置

配置Bean在Spring配置文件，并引用Bean “CsvOutputGenerator” 到 “OutputHelper”，通过property 和 ref 标签。

在这种情况下，Spring将通过setter方法注入Bean “CsvOutputGenerator” 到“OutputHelper”类，

“setOutputGenerator(IOutputGenerator outputGenerator)”.

 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:context="http://www.springframework.org/schema/context"
     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-2.5.xsd
            http://www.springframework.org/schema/context
                http://www.springframework.org/schema/context/spring-context-2.5.xsd">
     <bean id="CsvOutputGenerator" class="faj.test.javademo.set.CsvOutputGenerator" />

     <bean id="OutputHelper" class="faj.test.javademo.set.OutputHelper">
         <property name="outputGenerator" ref="CsvOutputGenerator" />
     </bean>
 </beans>

4. 执行结果

载入一切东西，并运行它。  

 package faj.test.javademo.set;

 import org.springframework.context.ApplicationContext;
 import org.springframework.context.support.ClassPathXmlApplicationContext;

 /**
  * Created by JiaGao on 2016/7/30.
  */
 public class App1 {
     public static void main(String[] args) {
         ApplicationContext context = new ClassPathXmlApplicationContext("faj/test/javademo/set/applicationContext.xml");
         OutputHelper output = (OutputHelper)context.getBean("OutputHelper");
         output.generateOutput();
     }
 }

输出结果

This is Csv Output Generator