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In questo esempio, usiamo
mappa Come answer e user delle risposte. Qui, usiamo le coppie di chiave e valore come oggetti. Le risposte hanno le loro informazioni, come answerId, risposta e postedDate, gli utenti hanno le loro informazioni, come userId, nome utente, emailId.
Come negli esempi precedenti, è un esempio di forum.
Una domanda può avere più risposte..
Question.java
Questa classe contiene tre attributi, due costruttori e il metodo displayInfo() per visualizzare le informazioni.
package com.w3codebox;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;
public class Question {
private int id;
private String name;
private Map<Answer,User> answers;
public Question() {}
public Question(int id, String name, Map<Answer, User> answers) {
super();
this.id = id;
this.name = name;
this.answers = answers;
}
public void displayInfo(){
System.out.println("question id:"+id);
System.out.println("question name:"+name);
System.out.println("Answers....");
Set<Entry<Answer, User>> set=answers.entrySet();
Iterator<Entry<Answer, User>> itr=set.iterator();
while(itr.hasNext()){
Entry<Answer, User> entry=itr.next();
Answer ans=entry.getKey();
User user=entry.getValue();
System.out.println("Answer Information:");
System.out.println(ans);
System.out.println("Posted By:");
System.out.println(user);
}
}
}
Answer.java
package com.w3codebox;
import java.util.Date;
public class Answer {
private int id;
private String answer;
private Date postedDate;
public Answer() {}
public Answer(int id, String answer, Date postedDate) {}}
super();
this.id = id;
this.answer = answer;
this.postedDate = postedDate;
}
public String toString(){
return "Id:"+id+" Risposta:"+answer+" Data Pubblicazione:"+postedDate;
}
}
User.java
package com.w3codebox;
public class User {
private int id;
private String name,email;
public User() {}
public User(int id, String name, String email) {
super();
this.id = id;
this.name = name;
this.email = email;
}
public String toString(){
return "Id:"+id+" Nome:"+name+" Email Id:"+email;
}
}
applicationContext.xml
entrata
elemento del
key-ref e
value-ref L'attributo viene utilizzato per definire riferimenti di bean nella mappa.
<?xml version="1.0" encoding="UTF-8"?>
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
<bean id="answer1" class="com.w3codebox.Answer">
<constructor-arg value="1"</constructor-arg>
<constructor-arg value="Java è un Linguaggio di Programmazione"></constructor-arg>
<constructor-arg value="12/12/2001"></constructor-arg>
</bean>
<bean id="answer2" class="com.w3codebox.Answer">
<constructor-arg value="2"</constructor-arg>
<constructor-arg value="Java è una Piattaforma"></constructor-arg>
<constructor-arg value="12/12/2003"></constructor-arg>
</bean>
<bean id="user1" class="com.w3codebox.User">
<constructor-arg value="1"></constructor-arg>
<constructor-arg value="Arun Kumar"></constructor-arg>
<constructor-arg value="[email protected]"></constructor-arg>
</bean>
<bean id="user2" class="com.w3codebox.User">
<constructor-arg value="2"></constructor-arg>
<constructor-arg value="Varun Kumar"></constructor-arg>
<constructor-arg value="[email protected]"></constructor-arg>
</bean>
<bean id="q" class="com.w3codebox.Question">
<constructor-arg value="1"></constructor-arg>
<constructor-arg value="Cosa è Java?"></constructor-arg>
<constructor-arg>
<map>
<entry key-ref="answer1" value-ref="user1"></entry>
<entry key-ref="answer2" value-ref="user2"></entry>
</map>
</constructor-arg>
</bean>
</beans>
Test.java
Questa classe recupera i Bean dal file applicationContext.xml e chiama il metodo displayInfo() per visualizzare le informazioni.
package com.w3codebox;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
public class Test {
public static void main(String[] args) {
Resource r=new ClassPathResource("applicationContext.xml");
BeanFactory factory=new XmlBeanFactory(r);
Question q=(Question)factory.getBean("q");
q.displayInfo();
}
}