1、定义ExtractorFilter接口并实现RegionTextExtractorFilter类，如下所示：

public class RegionTextExtractorFilter implements ExtractorFilter {

    /**
     * 文本提取矩形框
     */
    private final Rectangle rectangle;

    public RegionTextExtractorFilter(Rectangle rectangle) {
        this.rectangle = rectangle;
    }

    @Override
    public String getAllowText(TextObject textObject, TextCode textCode) {
        return "";
    }
}

2、ContentExtractor增加ExtractorFilter属性
3、ContentExtractor构造函数增加ExtractorFilter参数