org.apache.commons.collections : 集合对象查询

son30

http://www.java2s.com/Code/Java/Apache-Common/PredicateChainChainingoftwoormorepredicates.htm
Bean元素对象:
package com.pandy.search4mList;
import org.apache.commons.lang.builder.ToStringBuilder;
/**
* Copyright 2009 @ jPractices v 1.0
* @SVN URL : http://jpractices.googlecode.com
* @author Ganesh Gowtham
* @Homepage : http://ganesh.gowtham.googlepages.com
*/
public class Person {
private String firstName;
private String lastName;
private int salary;
public Person(String firstName, String lastName, int salary) {
super();
this.firstName = firstName;
this.lastName = lastName;
this.salary = salary;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public int getSalary() {
return salary;
}
public void setSalary(int salary) {
this.salary = salary;
}
@Override
public String toString() {
return ToStringBuilder.reflectionToString(this);
}
}


查询:存在一个List<Person>的列表，查询这个列表的元素，这个元素的firstName="ganesh"和lastName="gowtham"的元素
package com.pandy.search4mList;

import org.apache.commons.beanutils.BeanPredicate;
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.Predicate;
import org.apache.commons.collections.PredicateUtils;
import org.apache.commons.collections.functors.EqualPredicate;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

/**
* Copyright 2009 @ jPractices v 1.0
*
* @author Ganesh Gowtham
* @SVN URL : http://jpractices.googlecode.com
* @Homepage : http://ganesh.gowtham.googlepages.com
*/
public class BeanPredicateChainExample {
List<Person> personList = new ArrayList<Person>();
/**
* Basic method which creates the list of person object's
*/
void setUpData() {
personList.add(new Person("ganesh", "gowtham", 35000));
personList.add(new Person("britney", "spears", 45000));
personList.add(new Person("ganesh", "gowtham", 36000));
personList.add(new Person("ganesh", "dummy", 45000));
}
/**
* Here we are adding multiple predicate
* filters the collection so that final person object will contain
* firstName as "ganesh" & lastName as "gowtham"
*/
void filterDataUsingMultipleCriteria() {
EqualPredicate firstNameEqlPredicate = new EqualPredicate("ganesh");
BeanPredicate firtsNameBeanPredicate = new BeanPredicate("firstName", firstNameEqlPredicate);
EqualPredicate lastNameEqlPredicate2 = new EqualPredicate("gowtham");
BeanPredicate lastNameBeanPredicate2 = new BeanPredicate("lastName", lastNameEqlPredicate2);
Predicate[] allPredicateArray = {firtsNameBeanPredicate, lastNameBeanPredicate2};
Predicate allPredicate = PredicateUtils.allPredicate(allPredicateArray);
Collection<Person> filteredCollection = CollectionUtils.select(personList, allPredicate);
for (Person person : filteredCollection) {
System.out.println(person);
}
}
public static void main(String[] args) {
BeanPredicateChainExample chainExample = new BeanPredicateChainExample();
chainExample.setUpData();
chainExample.filterDataUsingMultipleCriteria();
}
}

Map元素对象查询：存在一个List<Map>的列表，查询这个列表的元素，这个元素的firstName="ganesh"和lastName="gowtham"的元素
package com.pandy.search4mList;

import org.apache.commons.beanutils.BeanPredicate;
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.Predicate;
import org.apache.commons.collections.PredicateUtils;
import org.apache.commons.collections.functors.EqualPredicate;
import java.util.*;

/**
* Copyright 2009 @ jPractices v 1.0
*
* @author Ganesh Gowtham
* @SVN URL : http://jpractices.googlecode.com
* @Homepage : http://ganesh.gowtham.googlepages.com
*/
public class MapPredicateChainExample {
List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
/**
* Basic method which creates the list of person object's
*/
void setUpData() {
Map<String,Object> map = new HashMap<String,Object>();
map.put("firstName","ganesh");
map.put("lastName","gowtham");
map.put("salary",35000);
list.add(map);
map = new HashMap<String,Object>();
map.put("firstName","britney");
map.put("lastName","spears");
map.put("salary",45000);
list.add(map);
map = new HashMap<String,Object>();
map.put("firstName","ganesh");
map.put("lastName","gowtham");
map.put("salary",36000);
list.add(map);
map = new HashMap<String,Object>();
map.put("firstName","ganesh");
map.put("lastName","dummy");
map.put("salary",45000);
list.add(map);
}
/**
* Here we are adding multiple predicate
* filters the collection so that final person object will contain
* firstName as "ganesh" & lastName as "gowtham"
*/
void filterDataUsingMultipleCriteria() {
EqualPredicate firstNameEqlPredicate = new EqualPredicate("ganesh");
BeanPredicate firtsNameBeanPredicate = new BeanPredicate("firstName", firstNameEqlPredicate);
EqualPredicate lastNameEqlPredicate2 = new EqualPredicate("gowtham");
BeanPredicate lastNameBeanPredicate2 = new BeanPredicate("lastName", lastNameEqlPredicate2);
Predicate[] allPredicateArray = {firtsNameBeanPredicate, lastNameBeanPredicate2};
Predicate allPredicate = PredicateUtils.allPredicate(allPredicateArray);
Collection<Map<String,Object>> filteredCollection = CollectionUtils.select(list, allPredicate);
for (Map<String,Object> person : filteredCollection) {
System.out.println(person);
}
}
public static void main(String[] args) {
MapPredicateChainExample chainExample = new MapPredicateChainExample();
chainExample.setUpData();
chainExample.filterDataUsingMultipleCriteria();
}
}