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JDK 源码 阅读 - 2 - 设计模式 - 创建型模式

2015-07-15 22:19 786 查看
A.创建型模式

抽象工厂(Abstract Factory)
javax.xml.parsers.DocumentBuilderFactory






DocumentBuilderFactory通过FactoryFinder实例化具体的Factory.

使用例子:
DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
Document doc = docBuilder.parse (new File("xxx.xml"));


javax.xml.transform.TransformerFactory




使用例子:
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 two.
XPathFactory xpathFactory = XPathFactory.newInstance();
XPath xpath = xpathFactory.newXPath();
XPathExpression expr = xpath.compile(XPATH_EXPRESSION_STRING);
Object result = expr.evaluate(Object item, QName returnType);


2.生成器模式(Builder)
java.lang.Appendable

java.lang.StringBuilder#append()

java.lang.StringBuffer#append()




这里我们看到状态的转换操作都会返回原来的类型的对象,这样就可以构建生成链。

java.nio.ByteBuffer#put()
(
CharBuffer
,
ShortBuffer
,
IntBuffer
,
LongBuffer
,
FloatBuffer
还有
DoubleBuffer
)
参见上例。

3.工厂方法(Factory method)
java.util.Calendar#getInstance()




工厂方法的构造方法就在所要生成的类型上。 这个抽象工厂有很大不同。
其它的可参见:
java.util.ResourceBundle#getBundle()

java.text.NumberFormat#getInstance()

java.nio.charset.Charset#forName()

java.net.URLStreamHandlerFactory#createURLStreamHandler(String)

4.原型模式(Prototye)

java.lang.Object#clone()




5.单例模式(Singleton)
java.lang.Runtime#getRuntime()

java.awt.Desktop#getDesktop()


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