Builder
public class Pizza {
private int size;
private boolean cheese;
private boolean pepperoni;
private boolean bacon;
public static class Builder {
//required
private final int size;
//optional
private boolean cheese = false;
private boolean pepperoni = false;
private boolean bacon = false;
public Builder(int size) {
this.size = size;
}
public Builder setCheese(boolean value) {
cheese = value;
return this;
}
public Builder setPepperoni(boolean value) {
pepperoni = value;
return this;
}
public Builder setBacon(boolean value) {
bacon = value;
return this;
}
public Pizza build() {
return new Pizza(this);
}
}
private Pizza(Builder builder) {
size = builder.size;
cheese = builder.cheese;
pepperoni = builder.pepperoni;
bacon = builder.bacon;
}
}
- Pizza Required class member in Builder’s Constructor.
- Pizza Optional class member in Builder’s setting method (return is Builder object）
- “build” method of builder object return “Pizza” object
- Pizza class has private Constructor of Builder object. Implements:
Pizza pizza = new Pizza.Builder(12).setCheese(true).setPepperoni(true).setBacon(true).build();
Using Generic with Abstract
Interface Design
public interface Extractor<T> {
void extract(JobContext<T> jobContext);
}
Abstract Class design
public abstract class AbstractExtractor<T> implements Extractor<T>{
...
}
Concrete class design
public class DBDataExtractor<SampleJobEvent> extends AbstractExtractor<SampleJobEvent> {
@Override
public void extract(JobContext<SampleJobEvent> jobContext) {
JobConfig jobConfig = getJobConfig();
if(this.spark == null){
initSparkSession(jobConfig);
}
final Properties connectionProperties = new Properties();
connectionProperties.put("user", jobConfig.getUserName());
connectionProperties.put("password", jobConfig.getPassword());
String dbTable = jobConfig.getDbTable();
Dataset<Row> jdbcDF = spark.read().jdbc(jobConfig.getDbConnectionURL(), dbTable, connectionProperties);
jobContext.setDataSet(jdbcDF);
}
}