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策略模式：是指某个指定对象有某个行为，但是在不同的场景中，该行为有不同的实现方式。通过将不同的实现方式独立实现，并使他们之间可互相替换，从而使的不同方式独立出来，供使用者去选择。
UML如图：
下面使用策略模式实现一个简单的算术运算：
package strategy; /** * 运算符的抽象描述 * @author wxh * @vertion 1.0 */ public interface Operator { int execute(int num1, int num2); }
package strategy; /** * 加法运算 * @author wxh * @vertion 1.0 */ public class Plus implements Operator{ @Override public int execute(int num1, int num2) { return num1 + num2; } }
package strategy; /** * 减法运算 * @author wxh * @vertion 1.0 */ public class Minus implements Operator { @Override public int execute(int num1, int num2) { return num1 - num2; } }
package strategy; /** * 计算器 * @author wxh * @vertion 1.0 */ public class Calculator { //数字1 private int number1; //数字2 private int number2; //运算符 private Operator operator; //返回操作结果 public int getResult() { return operator.execute( number1, number2 ); } public int getNumber1() { return number1; } public void setNumber1(int number1) { this.number1 = number1; } public int getNumber2() { return number2; } public void setNumber2(int number2) { this.number2 = number2; } public Operator getOperator() { return operator; } public void setOperator(Operator operator) { this.operator = operator; } }
package strategy; public class Test { public static void main(String[] args) { Calculator cal = new Calculator(); cal.setNumber1( 20 ); cal.setNumber2( 30 ); //设置运算符 cal.setOperator( new Plus() ); System.out.println( cal.getResult() ); } }
执行结果：50
/** * 计算器 * @author wxh * @vertion 1.0 */ public class Calculator { private int number1; private int number2; public int getNumber1() { return number1; } public void setNumber1(int number1) { this.number1 = number1; } public int getNumber2() { return number2; } public void setNumber2(int number2) { this.number2 = number2; } }
/** * 模板方法 * @author wxh * @vertion 1.0 */ public abstract class Operator { private Calculator cal; public Operator( Calculator cal ) { this.cal = cal; } protected abstract int execute( int num1, int num2 ); public int doExecute() { return execute( cal.getNumber1( ), cal.getNumber2( ) ); } }
/** * 加法运算 * @author wxh * @vertion 1.0 */ public class Plus extends Operator{ public Plus(Calculator cal) { super(cal); } @Override protected int execute(int num1, int num2) { return num1 + num2; } }
public class Test01 { public static void main(String[] args) { Calculator cal = new Calculator(); cal.setNumber1(30); cal.setNumber2(20); Plus p = new Plus(cal); //加法 //Minus m = new Minus(cal); //减法 System.out.println( p.doExecute() ); } }
执行结果：50
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原文地址：http://www.cnblogs.com/dahao1020/p/5537492.html
