07_配置文件中决定接口的实现类

【工程截图】

【Document.java】

package com.HigginCui.document;

public interface Document {
    public void readDocument();
    public void writeDocument();
}

【ExcelDocument.java】

package com.HigginCui.document;

public class ExcelDocument implements Document{
    @Override
    public void readDocument() {
        System.out.println("Excel read...");
    }
    @Override
    public void writeDocument() {
        System.out.println("Excel write...");
    }
}

【PdfDocument.java】

package com.HigginCui.document;

public class PdfDocument implements Document{
    @Override
    public void readDocument() {
        System.out.println("Pdf read...");
    }
    @Override
    public void writeDocument() {
        System.out.println("Pdf write...");
    }
}

【WordDocument.java】

package com.HigginCui.document;

public class WordDocument implements Document{
    @Override
    public void readDocument() {
        System.out.println("Word read...");
    }
    @Override
    public void writeDocument() {
        System.out.println("Word write...");
    }
}

【DocumentManager.java】

package com.HigginCui.document;

public class DocumentManager {
    private Document document;
    
    public DocumentManager(){}
    
    //可以利用构造方法进行赋值
    public DocumentManager(Document document){
        this.document=document;
    }
    //也可以利用setter方法进行赋值
    public void setDocument(Document document) {
        this.document = document;
    }
    public Document getDocument() {
        return document;
    }
    
    public void read(){
        this.document.readDocument();
    }
    public void write(){
        this.document.writeDocument();
    }
}

【applicationContext.xml】

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:aop="http://www.springframework.org/schema/aop"
       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/aop 
           http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">
           
    <bean id="wordDocument" class="com.HigginCui.document.WordDocument"></bean>
    <bean id="excelDocument" class="com.HigginCui.document.ExcelDocument"></bean>
    <bean id="pdfDocument" class="com.HigginCui.document.PdfDocument"></bean>
    
    <!-- 
        把DocumentManager、wordDocument、excelDocument、pdfDocument都放入Spring容器
        在Spring容器中的配置文件决定了documentManager中接口的实现类是什么 
    -->
    <bean id="documentManager" class="com.HigginCui.document.DocumentManager">
        <!-- 该document接口是由下面的wordDocument类来实现 -->
        <property name="document">
            <ref bean="wordDocument"/>
        </property>
    </bean>
</beans>

【testDocument.java】

package com.HigginCui.test;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.HigginCui.document.DocumentManager;

public class testDocument {
    @Test
    public void test(){
        ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");
        DocumentManager documentManager=(DocumentManager) context.getBean("documentManager");
        documentManager.read();
        documentManager.write();
    }
}

【运行结果】

Word read...
Word write...

package com.HigginCui.document;
public interface Document {public void readDocument();public void writeDocument();}