一、場景描述
工廠模式有一缺點,就是破壞了類的封閉性原則。例如,如果需要增加Word文件的數據采集,此時按以下步驟操作:
步驟2修改了工廠類,如果每增加一實現類都需要修改工廠類,那么這樣就不合理了。
解決辦法是使用抽象工廠類,為每一個實現類都創建其工廠類,并增加工廠接口,使各工廠類實現該接口。
使用抽象工廠后,上述步驟更改為:
修改后,由于對工廠類進行了抽象,定義了工廠接口,因此新增實現類時不再需要修改原有代碼,不破壞原有實現。
如下圖所示:
二、示例代碼
儀器數據采集接口:
package lims.designpatterndemo.abstractfactorydemo;public interface EquipmentDataCapture { public String capture(String filePath);}
PDF文件采集類:
package lims.designpatterndemo.abstractfactorydemo;public class PdfFileCapture implements EquipmentDataCapture{ @Override public String capture(String filePath) { return "PDF file content"; }}
Excel文件采集類:
package lims.designpatterndemo.abstractfactorydemo;public class ExcelFileCapture implements EquipmentDataCapture{ @Override public String capture(String filePath) { return "Excel File Content"; }}
抽象工廠,即工廠接口:
package lims.designpatterndemo.abstractfactorydemo;public interface EquipmentDataCaptureFactory { public EquipmentDataCapture getCapture(); }
PDF文件采集工廠類:
package lims.designpatterndemo.abstractfactorydemo;public class PdfFileCaptureFactory implements EquipmentDataCaptureFactory { @Override public EquipmentDataCapture getCapture() { return new PdfFileCapture(); }}
Excel文件采集工廠類:
package lims.designpatterndemo.abstractfactorydemo;public class ExcelFileCaptureFactory implements EquipmentDataCaptureFactory { @Override public EquipmentDataCapture getCapture() { return new ExcelFileCapture(); }}
調用示例:
package lims.designpatterndemo.abstractfactorydemo;public class AbstractFactoryDemo { public static void main(String[] args) { EquipmentDataCaptureFactory facotry = new PdfFileCaptureFactory(); facotry = new ExcelFileCaptureFactory(); EquipmentDataCapture capture = facotry.getCapture(); String fileContent = capture.capture(""); System.out.println(fileContent); }}
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