输出生成器的例子

file : ioutputgenerator.java – 输出生成器接口

package com.h3.output;

public interface ioutputgenerator
{
	public void generateoutput();
}

file : csvoutputgenerator.java – 一个csv输出生成器用来实现ioutputgenerator接口。

package com.h3.output.impl;

import com.h3.output.ioutputgenerator;

public class csvoutputgenerator implements ioutputgenerator
{
	public void generateoutput(){
		system.out.println("csv output generator");
	}
}

file : jsonoutputgenerator.java – 一个json输出生成器用来实现ioutputgenerator接口。

package com.h3.output.impl;

import com.h3.output.ioutputgenerator;

public class jsonoutputgenerator implements ioutputgenerator
{
	public void generateoutput(){
		system.out.println("json output generator");
	}
}

1. 方法1 – 直接调用

package com.h3.common;

import com.h3.output.ioutputgenerator;
import com.h3.output.impl.csvoutputgenerator;

public class app 
{
    public static void main( string[] args )
    {
    	ioutputgenerator output = new csvoutputgenerator();
    	output.generateoutput();
    }
}

存在问题

方法2 – 用辅助类调用它

package com.h3.output;

import com.h3.output.ioutputgenerator;
import com.h3.output.impl.csvoutputgenerator;

public class outputhelper
{
	ioutputgenerator outputgenerator;
	
	public outputhelper(){
		outputgenerator = new csvoutputgenerator();
	}
	
	public void generateoutput(){
		outputgenerator.generateoutput();
	}
	
}

package com.h3.common;

import com.h3.output.outputhelper;

public class app 
{
    public static void main( string[] args )
    {
    	outputhelper output = new outputhelper();
    	output.generateoutput(); 
    }
}

存在问题

方法3 – spring

package com.h3.output;

import com.h3.output.ioutputgenerator;

public class outputhelper
{
	ioutputgenerator outputgenerator;
	
	public void generateoutput(){
		outputgenerator.generateoutput();
	}
	
	public void setoutputgenerator(ioutputgenerator outputgenerator){
		this.outputgenerator = outputgenerator;
	}
}

<!-- spring-common.xml -->
<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-2.5.xsd">

	<bean id="outputhelper" class="com.h3.output.outputhelper">
		<property name="outputgenerator" ref="csvoutputgenerator" />
	</bean>
	
	<bean id="csvoutputgenerator" class="com.h3.output.impl.csvoutputgenerator" />
	<bean id="jsonoutputgenerator" class="com.h3.output.impl.jsonoutputgenerator" />
		
</beans>

通过spring来调用它

package com.h3.common;

import org.springframework.context.applicationcontext;
import org.springframework.context.support.classpathxmlapplicationcontext;

import com.h3.output.outputhelper;

public class app 
{
    public static void main( string[] args )
    {
    	applicationcontext context = 
    	   new classpathxmlapplicationcontext(new string[] {"spring-common.xml"});

    	outputhelper output = (outputhelper)context.getbean("outputhelper");
    	output.generateoutput();
    	  
    }
}

结论