java中排序实现简单的策略模式
jopen
12年前
<b> <span style="font-size:18px;">策略模式（Strategy Pattern）中体现了两个非常基本的面向对象设计的原则</span></b> <div> <b><span style="font-size:18px;">–封装变化的概念</span></b> </div> <div> <b><span style="font-size:18px;">–编程中使用接口，而不是对接口的实现</span></b> </div> <div> <b><br /> </b> </div> <div> <div> <b><span style="font-size:18px;">策略模式的定义 </span></b> </div> <div> <b><span style="font-size:18px;">–定义一组算法，将每个算法都封装起来，并且使它们之间可以互换。 </span></b> </div> <div> <b><span style="font-size:18px;">–策略模式使这些算法在客户端调用它们的时候能够互不影响地变化 </span></b> </div> </div> <div> <b><br /> </b> </div> <div> <div> <b><span style="font-size:18px;">策略模式的编写步骤 </span></b> </div> <div> <b><span style="font-size:18px;">–1．对策略对象定义一个公共接口。 </span></b> </div> <div> <b><span style="font-size:18px;">–2．编写策略类，该类实现了上面的公共接口 </span></b> </div> <div> <b><span style="font-size:18px;">–3．在使用策略对象的类中保存一个对策略对 </span></b> </div> <div> <b><span style="font-size:18px;">象的引用。 </span></b> </div> <div> <b><span style="font-size:18px;">–4．在使用策略对象的类中，实现对策略对象 </span></b> </div> <div> <b><span style="font-size:18px;">的set和get方法（注入）或者使用构造方法完 </span></b> </div> <p><b><span style="font-size:18px;">成赋值</span></b></p> <p><b><span style="font-size:18px;"><br /> </span></b></p> <p><b><span style="font-size:18px;">java排序策略模式实现：</span></b></p> <p><span style="font-size:medium;"><span style="line-height:27px;"><b>有这样一个类：</b></span></span></p> <p></p> <p><b>public class Person {</b></p> <b> <p>private int id;</p> <p>private String name;</p> <p>private int age;</p> <p>}</p> <p></p> <p>要求：假如有若干个类Person对象存在一个List当中，对他们进行排序，分别按照名字、</p> <p></p> <b> <p>年龄、id 进行排序（要有正序与倒序两种排序方式）。假如年龄或者姓名重复，按照id的正序进行排序。</p> </b><b> <p></p> </b> <p></p> <p></p> <p><b>以下为实现源代码。</b></p> <p></p> <p></p> <p><b>类Person</b></p> <p></p> <p></p> </b> <p></p> <p></p> <pre class="brush:java; toolbar: true; auto-links: false;"><b>package com.jack.SortStrategy; public class Person { private int id; private String name; private int age; public Person(int id,String name,int age){ this.id=id; this.age=age; this.name=name; } /** * @return the id */ public int getId() { return id; } /** * @param id the id to set */ public void setId(int id) { this.id = id; } /** * @return the name */ public String getName() { return name; } /** * @param name the name to set */ public void setName(String name) { this.name = name; } /** * @return the age */ public int getAge() { return age; } /** * @param age the age to set */ public void setAge(int age) { this.age = age; } }</b></pre> <p></p> <p><b><span style="font-size:18px;">类IdOrder</span></b></p> <p></p> <pre class="brush:java; toolbar: true; auto-links: false;"><b>package com.jack.SortStrategy; import java.util.Comparator; public class IdOrder implements Comparator<Person> { @Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub return o1.getId()-o2.getId(); } public String getMethodName() { return "按id正序"; } }</b></pre> <p></p> <p><b><span style="font-size:18px;">类IdReverseOrder</span></b></p> <p></p> <pre class="brush:java; toolbar: true; auto-links: false;"><b>package com.jack.SortStrategy; import java.util.Comparator; public class IdReverseOrder implements Comparator<Person> { @Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub return o2.getId()-o1.getId(); } public String getMethodName() { return "按id逆序"; } }</b></pre> <p></p> <p><b><span style="font-size:18px;">类AgeOrder</span></b></p> <p></p> <pre class="brush:java; toolbar: true; auto-links: false;"><b>package com.jack.SortStrategy; import java.util.Comparator; public class AgeOrder implements Comparator<Person> { @Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub int result=o1.getAge()-(o2.getAge()); if(0==result){ //若年龄相同按id排 return o1.getId()-o2.getId(); } return result; } public String getMethodName() { return "按年龄正序"; } }</b></pre> <p></p> <p><b><span style="font-size:18px;">类AgeReverseOrder</span></b></p> <p></p> <pre class="brush:java; toolbar: true; auto-links: false;"><b>package com.jack.SortStrategy; import java.util.Comparator; public class AgeReverseOrder implements Comparator<Person> { @Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub int result=o2.getAge()-(o1.getAge()); if(0==result){ //若年龄相同按id排 return o1.getId()-o2.getId(); } return result; } public String getMethodName() { return "按年龄逆序"; } }</b></pre> <p></p> <p><b><span style="font-size:18px;">类</span></b><span style="font-size:medium;"><span style="line-height:27px;"><b>NameOrder</b></span></span></p> <p></p> <pre class="brush:java; toolbar: true; auto-links: false;"><b>package com.jack.SortStrategy; import java.util.Comparator; public class NameOrder implements Comparator<Person> { @Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub int result=o1.getName().compareTo(o2.getName()); if(0==result){ //若姓名相同按id排 return o1.getId()-o2.getId(); } return result; } public String getMethodName() { return "按姓名正序"; } }</b></pre> <p></p> <p><span style="font-size:medium;"><span style="line-height:27px;"><b>类NameReverseOrder</b></span></span></p> <p></p> <pre class="brush:java; toolbar: true; auto-links: false;"><b>package com.jack.SortStrategy; import java.util.Comparator; public class NameReverseOrder implements Comparator<Person> { @Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub int result=o2.getName().compareTo(o1.getName()); if(0==result){ //若姓名相同按id排 return o1.getId()-o2.getId(); } return result; } public String getMethodName() { return "按姓名逆序"; } }</b></pre> <p></p> <p><span style="font-size:medium;"><span style="line-height:27px;"><b>类Client</b></span></span></p> <p></p> <pre class="brush:java; toolbar: true; auto-links: false;"><b>package com.jack.SortStrategy; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.Comparator; import java.util.Iterator; public class Client { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub ArrayList<Person> personList = new ArrayList<Person>(); personList.add(new Person(1, "zhangsan", 20)); personList.add(new Person(2, "lisi", 21)); personList.add(new Person(3, "wangwu", 25)); personList.add(new Person(4, "zhaoliu", 26)); personList.add(new Person(5, "chenqi", 28)); personList.add(new Person(6, "dongba", 10)); personList.add(new Person(7, "zhansan", 15)); personList.add(new Person(8, "liujiu", 26)); /* * 可通过这里new不同的Comparator的实现从而实现不同的排序策略 * 分别有 * IdOrder：按Id正序 * IdReverseOrder：按Id逆序 * NameOrder：按姓名正序 * NameReverseOrder：按姓名逆序 * AgeOrder：按年龄正序 * AgeReverseOrder：按年龄逆序 */ Comparator<Person> comp = new IdOrder(); Collections.sort(personList, comp); System.out.println(((IdOrder)comp).getMethodName()+" 排序后的序列是:"); System.out.println("-----------------------"); for (Iterator<Person> itor=personList.iterator();itor.hasNext();) { Person p=itor.next(); System.out.println(p.getId() + " " +p.getName()+ " " + p.getAge()); } } }</b></pre> <div> <b><br /> </b> </div> <p></p> <b>执行Client可以得到排序的结果</b> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> </div>