JDK Source Reading-2-design mode-Create pattern

A. Create pattern

1. Abstraction Factory (abstract Factory)

   javax.xml.parsers.DocumentBuilderFactory

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Documentbuilderfactory instantiate specific factory through Factoryfinder.

Example of use: documentbuilderfactory docbuilderfactory = documentbuilderfactory.newinstance ();D Ocumentbuilder DocBuilder = Docbuilderfactory.newdocumentbuilder ();D ocument doc = docbuilder.parse (new File ("Xxx.xml"));

  javax.xml.transform.TransformerFactory

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Example of use: streamsource Source = new Streamsource (...); Streamsource Stylesource = new Streamsource (...); Transformerfactory factory = Transformerfactory.newinstance (); Transformer Transformer = Factory.newtransformer (Stylesource); Streamresult result = new Streamresult (System.out); Transformer.transform (source, result)

  javax.xml.xpath.XPathFactory

The structure is almost the same as the previous.

Xpathfactory xpathfactory = Xpathfactory.newinstance (); XPath XPath = Xpathfactory.newxpath (); XPathExpression expr = Xpath.compile (xpath_expression_string); object result = Expr.evaluate (object item, QName ReturnType);

2. Generator Mode (builder)

java.lang.Appendable

 java.lang.StringBuilder#append()

 java.lang.StringBuffer#append()

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Here we see that the transformation of the State will return objects of the original type, so that the build chain can be built.

 java.nio.ByteBuffer#put()(CharBuffer, ShortBuffer, IntBuffer, LongBuffer , and more ) FloatBuffer DoubleBuffer

See the example above.

3. Factory methods (Factory method)

 java.util.Calendar#getInstance()

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The method of constructing the factory method is on the type to be generated. This abstract factory is very different.

Others can be found in:

 java.util.ResourceBundle#getBundle()

 java.text.NumberFormat#getInstance()

 java.nio.charset.Charset#forName()

 java.net.URLStreamHandlerFactory#createURLStreamHandler(String)

4. Prototype mode (Prototye)

• java.lang.Object#clone()

5. Single case mode (Singleton)

 java.lang.Runtime#getRuntime()

 java.awt.Desktop#getDesktop()

JDK Source Reading-2-design mode-Create pattern