Constructor Argument And Local Reference : Constructor Injection « Spring « Java Tutorial

1. Java Tutorial
2. Spring
3. Constructor Injection

File: context.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
    "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>

  <bean id="RangeService" class="RangeServiceImpl">
    <constructor-arg>
      <ref local="RangeDao"/>
    </constructor-arg>
  </bean>

  <bean id="RangeDao" class="StaticDataRangeDaoImpl">
  </bean>

</beans>

File: Main.java

import java.util.Date;
import java.util.GregorianCalendar;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

class Main {
  public static void main(String args[]) throws Exception {
    ApplicationContext ctx = new ClassPathXmlApplicationContext("context.xml");
    RangeService ws = (RangeService) ctx.getBean("RangeService");

    Double high = ws.getHistoricalHigh(new GregorianCalendar(2004, 0, 1).getTime());
    System.out.println("High was: " + high);
  }
}

interface RangeService {
  Double getHistoricalHigh(Date date);
}
class RangeServiceImpl implements RangeService {
  RangeDao RangeDao;

  public RangeServiceImpl(RangeDao RangeDao) {
    this.RangeDao = RangeDao;
  }

  public Double getHistoricalHigh(Date date) {
    RangeData wd = RangeDao.find(date);
    if (wd != null)
      return new Double(wd.getHigh());
    return null;
  }
}

class RangeData {

  Date date;

  double low;

  double high;

  public Date getDate() {
    return date;
  }

  public void setDate(Date date) {
    this.date = date;
  }
  public double getLow() {
    return low;
  }

  public void setLow(double low) {
    this.low = low;
  }
  public double getHigh() {
    return high;
  }

  public void setHigh(double high) {
    this.high = high;
  }
}

interface RangeDao {
  RangeData find(Date date);

  RangeData save(Date date);

  RangeData update(Date date);
}

class StaticDataRangeDaoImpl implements RangeDao {

  public RangeData find(Date date) {

    RangeData wd = new RangeData();
    wd.setDate((Date) date.clone());
    wd.setLow(5);
    wd.setHigh(15);
    return wd;
  }

  public RangeData save(Date date) {
   return null;
  }

  public RangeData update(Date date) {
    return null;
  }
}

28.9.Constructor Injection
	28.9.1.	XML Based Bean Configuration: Constructor Injection
	28.9.2.	Constructor Confusion Demo
	28.9.3.	Constructor Caller In Context Config
	28.9.4.	Constructor Argument And Local Reference