研磨设计模式--生成器模式

最新推荐文章于 2025-05-27 20:12:36 发布

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最新推荐文章于 2025-05-27 20:12:36 发布

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分类专栏：研磨设计模式文章标签： java 开发语言后端

本文链接：https://blog.youkuaiyun.com/qq_39164603/article/details/122993050

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本文通过抽象工厂模式实例，展示了如何使用生成器模式创建不同表示的输出文件，如TXT和XML，实现松耦合和复用。理解了生成器模式如何分步骤构建复杂产品并灵活切换生成器以适应不同输出格式。

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抽象工厂模式的定义：

生成器模式的定义：将一个复杂对象的构建与它的表示分离，使得同样的构建过程可以创建不同的表示。
demo：下面使用抽象工厂模式写一个简单的打印小程序
ExportHeaderModel：描述输出到文件头到内容的对象
ExportDataModel：描述输出数据的对象
ExportFooterModel：描述输出到文件尾到内容的对象
Builder：生成器接口
Director：指导者，知道使用生成器的接口来构建输出的文件的对象
TxtBuilder：txt生成器对象
XmlBuilder：xml生成器对象
Client：客户端

/**
 * 描述输出到文件头到内容的对象
 */
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class ExportHeaderModel{
    /**
     * 分公司或门市编号
     */
    private String depId;

    /**
     * 导出数据的日期
     */
    private String exportDate;


}

/**
 * 描述输出数据的对象
 */
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class ExportDataModel {
    /**
     * 产品id
     */
    private String productId;

    /**
     * 销售价格
     */
    private Integer price;

    /**
     * 销售数量
     */
    private Integer amount;
}

/**
 * 描述输出到文件尾到内容的对象
 */
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class ExportFooterModel {
    /**
     * 输出人
     */
    private String exportUser;
}

/**
 * 生成器接口
 */
public interface Builder {
    void buildHeader(ExportHeaderModel exportHeaderModel);

    void buildData(Map<String, List<ExportDataModel>> map);

    void buildFooter(ExportFooterModel exportFooterModel);
}

/**
 * 指导者，知道使用生成器的接口来构建输出的文件的对象
 */
public class Director {
    private Builder builder;

    public Director(Builder builder) {
        this.builder = builder;
    }
    public void construct(ExportHeaderModel exportHeaderModel, Map<String, List<ExportDataModel>> mapDate, ExportFooterModel exportFooterModel){
        builder.buildHeader(exportHeaderModel);
        builder.buildData(mapDate);
        builder.buildFooter(exportFooterModel);
    }
}

/**
 * txt生成器对象
 */
public class TxtBuilder implements Builder{
    private StringBuffer sb = new StringBuffer();
    @Override
    public void buildHeader(ExportHeaderModel exportHeaderModel) {
        sb.append(exportHeaderModel.getDepId()).append(",").append(exportHeaderModel.getExportDate()).append("\n");
    }

    @Override
    public void buildData(Map<String, List<ExportDataModel>> map) {
        for (String string : map.keySet()){
            sb.append(string).append("\n");
            for (ExportDataModel exportDataModel : map.get(string)){
                sb.append(exportDataModel.getProductId()).append(",").append(exportDataModel.getPrice()).append(",")
                        .append(exportDataModel.getAmount()).append("\n");
            }
        }
    }

    @Override
    public void buildFooter(ExportFooterModel exportFooterModel) {
        sb.append(exportFooterModel.getExportUser());
    }

    public StringBuffer getResult(){
        return sb;
    }
}

/**
 * xml生成器对象
 */
public class XmlBuilder implements Builder {
    private StringBuffer sb = new StringBuffer();
    @Override
    public void buildHeader(ExportHeaderModel exportHeaderModel) {
        sb.append("<?xml version='1.0' encoding='gb2313'?>\n");
        sb.append("<Report>\n");
        sb.append("<Header>\n");
        sb.append("<DepId>").append(exportHeaderModel.getDepId()).append("</DepId>\n");
        sb.append("ExportDate>").append(exportHeaderModel.getExportDate()).append("</ExportDate>\n");
        sb.append("</Header>\n");
    }

    @Override
    public void buildData(Map<String, List<ExportDataModel>> map) {
        sb.append("<Body>\n");
        for (String string : map.keySet()) {
            sb.append("<Datas TableName=\"").append(string).append("\">\n");
            for (ExportDataModel exportDataModel : map.get(string)) {
                sb.append("<Data>\n");
                sb.append("<ProductId>").append(exportDataModel.getProductId()).append("</ProductId>");
                sb.append("<Price>").append(exportDataModel.getPrice()).append("</Price>");
                sb.append("<Amount>").append(exportDataModel.getAmount()).append("</Amount>");
                sb.append("</Data>\n");
            }
        }
        sb.append("</Body>\n");
    }

    @Override
    public void buildFooter(ExportFooterModel exportFooterModel) {
        sb.append("<Footer>\n");
        sb.append("<ExportUser>").append(exportFooterModel.getExportUser()).append("</ExportUser>\n");
        sb.append("</Footer>\n");
        sb.append("</Report>\n");
    }

    public StringBuffer getResult(){
        return sb;
    }
}

public class Client {

    public static void main(String[] args) {
        List<ExportDataModel> exportDataModelList = new ArrayList<>();
        exportDataModelList.add(ExportDataModel.builder()
                .productId("1")
                .price(1)
                .amount(1)
                .build());
        exportDataModelList.add(ExportDataModel.builder()
                .productId("2")
                .price(2)
                .amount(2)
                .build());
        ExportFooterModel exportFooterModel = ExportFooterModel.builder()
                .exportUser("lisi")
                .build();
        ExportHeaderModel exportHeaderModel = ExportHeaderModel.builder()
                .depId("1")
                .exportDate("2022-02-17")
                .build();
        Map<String, List<ExportDataModel>> map = new HashMap<>();
        map.put("销售记录", exportDataModelList);
        TxtBuilder txtBuilder = new TxtBuilder();
        Director director = new Director(txtBuilder);
        director.construct(exportHeaderModel, map, exportFooterModel);
        System.out.println("txt:" + txtBuilder.getResult().toString());
        XmlBuilder xmlBuilder = new XmlBuilder();
        Director director1 = new Director(xmlBuilder);
        director1.construct(exportHeaderModel, map, exportFooterModel);
        System.out.println("xml:" + xmlBuilder.getResult().toString());
    }
}