45 lines
1.3 KiB
Java
45 lines
1.3 KiB
Java
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// patterns/trash/DynaFactory.java
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// (c)2021 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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// Dynamic discovery of Trash types.
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package patterns.trash;
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import java.util.*;
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import java.util.function.*;
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import java.lang.reflect.*;
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public class DynaFactory {
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private Map<String, Constructor> constructors =
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new HashMap<>();
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private String packageName;
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public DynaFactory(String packageName) {
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this.packageName = packageName;
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}
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@SuppressWarnings("unchecked")
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public
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<T extends Trash> T create(TrashInfo info) {
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try {
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String typename =
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"patterns." + packageName + "." + info.type;
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return (T)constructors.computeIfAbsent(
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typename, this::findConstructor
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).newInstance(info.data);
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} catch(Exception e) {
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throw new RuntimeException(
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"Cannot create() Trash: " + info, e);
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}
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}
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private
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Constructor findConstructor(String typename) {
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try {
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System.out.println("Loading " + typename);
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return Class.forName(typename)
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.getConstructor(double.class);
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} catch(Exception e) {
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throw new RuntimeException(
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"Trash(double) Constructor Not Found: " +
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typename, e);
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}
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}
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}
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