62 lines
1.4 KiB
Java
62 lines
1.4 KiB
Java
// patterns/ShapeFactory2.java
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// (c)2017 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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import java.util.*;
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import java.lang.reflect.*;
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import java.util.stream.*;
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import patterns.shapes.*;
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class DynamicFactory {
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static Map<String, Constructor> factories =
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new HashMap<>();
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static Constructor load(String id) {
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System.out.println("loading " + id);
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try {
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return Class.forName("patterns.shapes." + id)
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.getConstructor();
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} catch(Exception e) {
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throw new BadShapeCreation(id);
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}
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}
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static Shape create(String id) {
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try {
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return (Shape)factories
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.computeIfAbsent(id, DynamicFactory::load)
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.newInstance();
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} catch(Exception e) {
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throw new BadShapeCreation(id);
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}
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}
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}
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public class ShapeFactory2 {
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public static void main(String[] args) {
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Stream.of("Circle", "Square", "Triangle",
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"Square", "Circle", "Circle", "Triangle")
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.map(DynamicFactory::create)
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.peek(Shape::draw)
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.peek(Shape::erase)
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.count();
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}
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}
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/* Output:
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loading Circle
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Circle[0] draw
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Circle[0] erase
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loading Square
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Square[1] draw
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Square[1] erase
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loading Triangle
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Triangle[2] draw
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Triangle[2] erase
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Square[3] draw
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Square[3] erase
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Circle[4] draw
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Circle[4] erase
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Circle[5] draw
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Circle[5] erase
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Triangle[6] draw
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Triangle[6] erase
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*/
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