JDK代码写法总结3Java
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# 总结3
# 上下文及监听
不是对数据的增删改查，就是对Java对象的增删改查
@SuppressWarnings("rawtypes")
public interface BeanContext extends BeanContextChild, Collection, DesignMode, Visibility {
/**
* Instantiate the javaBean named as a
* child of this <code>BeanContext</code>.
* The implementation of the JavaBean is
* derived from the value of the beanName parameter,
* and is defined by the
* <code>java.beans.Beans.instantiate()</code> method.
*
* @return a javaBean named as a child of this
* <code>BeanContext</code>
* @param beanName The name of the JavaBean to instantiate
* as a child of this <code>BeanContext</code>
* @throws IOException if an IO problem occurs
* @throws ClassNotFoundException if the class identified
* by the beanName parameter is not found
*/
Object instantiateChild(String beanName) throws IOException, ClassNotFoundException;
/**
* Analagous to <code>java.lang.ClassLoader.getResourceAsStream()</code>,
* this method allows a <code>BeanContext</code> implementation
* to interpose behavior between the child <code>Component</code>
* and underlying <code>ClassLoader</code>.
*
* @param name the resource name
* @param bcc the specified child
* @return an <code>InputStream</code> for reading the resource,
* or <code>null</code> if the resource could not
* be found.
* @throws IllegalArgumentException if
* the resource is not valid
*/
InputStream getResourceAsStream(String name, BeanContextChild bcc) throws IllegalArgumentException;
/**
* Analagous to <code>java.lang.ClassLoader.getResource()</code>, this
* method allows a <code>BeanContext</code> implementation to interpose
* behavior between the child <code>Component</code>
* and underlying <code>ClassLoader</code>.
*
* @param name the resource name
* @param bcc the specified child
* @return a <code>URL</code> for the named
* resource for the specified child
* @throws IllegalArgumentException
* if the resource is not valid
*/
URL getResource(String name, BeanContextChild bcc) throws IllegalArgumentException;
/**
* Adds the specified <code>BeanContextMembershipListener</code>
* to receive <code>BeanContextMembershipEvents</code> from
* this <code>BeanContext</code> whenever it adds
* or removes a child <code>Component</code>(s).
*
* @param bcml the BeanContextMembershipListener to be added
*/
void addBeanContextMembershipListener(BeanContextMembershipListener bcml);
/**
* Removes the specified <code>BeanContextMembershipListener</code>
* so that it no longer receives <code>BeanContextMembershipEvent</code>s
* when the child <code>Component</code>(s) are added or removed.
*
* @param bcml the <code>BeanContextMembershipListener</code>
* to be removed
*/
void removeBeanContextMembershipListener(BeanContextMembershipListener bcml);
/**
* This global lock is used by both <code>BeanContext</code>
* and <code>BeanContextServices</code> implementors
* to serialize changes in a <code>BeanContext</code>
* hierarchy and any service requests etc.
*/
public static final Object globalHierarchyLock = new Object();
}
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# HashTable中key和value为对象的情况
加锁
class BeansAppletContext implements AppletContext {
Applet target;
Hashtable<URL,Object> imageCache = new Hashtable<>();
BeansAppletContext(Applet target) {
this.target = target;
}
public AudioClip getAudioClip(URL url) {
// We don't currently support audio clips in the Beans.instantiate
// applet context, unless by some luck there exists a URL content
// class that can generate an AudioClip from the audio URL.
try {
return (AudioClip) url.getContent();
} catch (Exception ex) {
return null;
}
}
public synchronized Image getImage(URL url) {
Object o = imageCache.get(url);
if (o != null) {
return (Image)o;
}
try {
o = url.getContent();
if (o == null) {
return null;
}
if (o instanceof Image) {
imageCache.put(url, o);
return (Image) o;
}
// Otherwise it must be an ImageProducer.
Image img = target.createImage((java.awt.image.ImageProducer)o);
imageCache.put(url, img);
return img;
} catch (Exception ex) {
return null;
}
}
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# 反射包中大部分调的是Native方法
public final
class Array {
/**
* Constructor. Class Array is not instantiable.
*/
private Array() {}
/**
* Creates a new array with the specified component type and
* length.
* Invoking this method is equivalent to creating an array
* as follows:
* <blockquote>
* <pre>
* int[] x = {length};
* Array.newInstance(componentType, x);
* </pre>
* </blockquote>
*
* <p>The number of dimensions of the new array must not
* exceed 255.
*
* @param componentType the {@code Class} object representing the
* component type of the new array
* @param length the length of the new array
* @return the new array
* @exception NullPointerException if the specified
* {@code componentType} parameter is null
* @exception IllegalArgumentException if componentType is {@link
* Void#TYPE} or if the number of dimensions of the requested array
* instance exceed 255.
* @exception NegativeArraySizeException if the specified {@code length}
* is negative
*/
public static Object newInstance(Class<?> componentType, int length)
throws NegativeArraySizeException {
return newArray(componentType, length);
}
/**
* Creates a new array
* with the specified component type and dimensions.
* If {@code componentType}
* represents a non-array class or interface, the new array
* has {@code dimensions.length} dimensions and
* {@code componentType} as its component type. If
* {@code componentType} represents an array class, the
* number of dimensions of the new array is equal to the sum
* of {@code dimensions.length} and the number of
* dimensions of {@code componentType}. In this case, the
* component type of the new array is the component type of
* {@code componentType}.
*
* <p>The number of dimensions of the new array must not
* exceed 255.
*
* @param componentType the {@code Class} object representing the component
* type of the new array
* @param dimensions an array of {@code int} representing the dimensions of
* the new array
* @return the new array
* @exception NullPointerException if the specified
* {@code componentType} argument is null
* @exception IllegalArgumentException if the specified {@code dimensions}
* argument is a zero-dimensional array, if componentType is {@link
* Void#TYPE}, or if the number of dimensions of the requested array
* instance exceed 255.
* @exception NegativeArraySizeException if any of the components in
* the specified {@code dimensions} argument is negative.
*/
public static Object newInstance(Class<?> componentType, int... dimensions)
throws IllegalArgumentException, NegativeArraySizeException {
return multiNewArray(componentType, dimensions);
}
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# 构造器类
public final class Constructor<T> extends Executable {
private Class<T> clazz;
private int slot;
private Class<?>[] parameterTypes;
private Class<?>[] exceptionTypes;
private int modifiers;
// Generics and annotations support
private transient String signature;
// generic info repository; lazily initialized
private transient ConstructorRepository genericInfo;
private byte[] annotations;
private byte[] parameterAnnotations;
// Generics infrastructure
// Accessor for factory
private GenericsFactory getFactory() {
// create scope and factory
return CoreReflectionFactory.make(this, ConstructorScope.make(this));
}
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# 类的成员变量类Field
public final class Field extends AccessibleObject implements Member {
private Class<?> clazz;
private int slot;
// This is guaranteed to be interned by the VM in the 1.4
// reflection implementation
private String name;
private Class<?> type;
private int modifiers;
// Generics and annotations support
private transient String signature;
// generic info repository; lazily initialized
private transient FieldRepository genericInfo;
private byte[] annotations;
// Cached field accessor created without override
private FieldAccessor fieldAccessor;
// Cached field accessor created with override
private FieldAccessor overrideFieldAccessor;
// For sharing of FieldAccessors. This branching structure is
// currently only two levels deep (i.e., one root Field and
// potentially many Field objects pointing to it.)
//
// If this branching structure would ever contain cycles, deadlocks can
// occur in annotation code.
private Field root;
// Generics infrastructure
private String getGenericSignature() {return signature;}
// Accessor for factory
private GenericsFactory getFactory() {
Class<?> c = getDeclaringClass();
// create scope and factory
return CoreReflectionFactory.make(c, ClassScope.make(c));
}
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# 类中的方法类
public final class Method extends Executable {
private Class<?> clazz;
private int slot;
// This is guaranteed to be interned by the VM in the 1.4
// reflection implementation
private String name;
private Class<?> returnType;
private Class<?>[] parameterTypes;
private Class<?>[] exceptionTypes;
private int modifiers;
// Generics and annotations support
private transient String signature;
// generic info repository; lazily initialized
private transient MethodRepository genericInfo;
private byte[] annotations;
private byte[] parameterAnnotations;
private byte[] annotationDefault;
private volatile MethodAccessor methodAccessor;
// For sharing of MethodAccessors. This branching structure is
// currently only two levels deep (i.e., one root Method and
// potentially many Method objects pointing to it.)
//
// If this branching structure would ever contain cycles, deadlocks can
// occur in annotation code.
private Method root;
// Generics infrastructure
private String getGenericSignature() {return signature;}
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