AS3 类型强转类

原文：http://blog.csdn.net/isaaq/archive/2007/08/25/1758859.aspx

还在为类型强转烦愁吗？

看看darron schall 给我们带来的这个强制转换类：

http://www.darronschall.com/weblog/archives/000247.cfm

用法：ObjectTranslator.objectToInstance(Object对象,要强转成的类型) as 要强转成的类型

嘿嘿，这回不用担心Object转VO转不成了。

源码：

package com.goufang.util
...{

import flash.net.ObjectEncoding;
import flash.net.registerClassAlias;
import flash.utils.ByteArray;
import flash.utils.describeType;
import flash.utils.getDefinitionByName;

/** *//**
* Utility class to convert vanilla objects to class instances.
*/
public final class ObjectTranslator
...{
   
    /** *//**
     * Converts a plain vanilla object to be an instance of the class
     * passed as the second variable.  This is not a recursive funtion
     * and will only work for the first level of nesting.  When you have
     * deeply nested objects, you first need to convert the nested
     * objects to class instances, and then convert the top level object.
     *
     * TODO: This method can be improved by making it recursive.  This would be
     * done by looking at the typeInfo returned from describeType and determining
     * which properties represent custom classes.  Those classes would then
     * be registerClassAlias'd using getDefinititonByName to get a reference,
     * and then objectToInstance would be called on those properties to complete
     * the recursive algorithm.
     *
     * @param object The plain object that should be converted
     * @param clazz The type to convert the object to
     */
    public static function objectToInstance( object:Object, clazz:Class ):*
    ...{
        var bytes:ByteArray = new ByteArray();
        bytes.objectEncoding = ObjectEncoding.AMF0;
       
        // Find the objects and byetArray.writeObject them, adding in the
        // class configuration variable name -- essentially, we're constructing
        // and AMF packet here that contains the class information so that
        // we can simplly byteArray.readObject the sucker for the translation
       
        // Write out the bytes of the original object
        var objBytes:ByteArray = new ByteArray();
        objBytes.objectEncoding = ObjectEncoding.AMF0;
        objBytes.writeObject( object );
               
        // Register all of the classes so they can be decoded via AMF
        var typeInfo:XML = describeType( clazz );
        var fullyQualifiedName:String = typeInfo.@name.toString().replace( /::/, "." );
        registerClassAlias( fullyQualifiedName, clazz );
       
        // Write the new object information starting with the class information
        var len:int = fullyQualifiedName.length;
        bytes.writeByte( 0x10 );  // 0x10 is AMF0 for "typed object (class instance)"
        bytes.writeUTF( fullyQualifiedName );
        // After the class name is set up, write the rest of the object
        bytes.writeBytes( objBytes, 1 );
       
        // Read in the object with the class property added and return that
        bytes.position = 0;
       
        // This generates some ReferenceErrors of the object being passed in
        // has properties that aren't in the class instance, and generates TypeErrors
        // when property values cannot be converted to correct values (such as false
        // being the value, when it needs to be a Date instead).  However, these
        // errors are not thrown at runtime (and only appear in trace ouput when
        // debugging), so a try/catch block isn't necessary.  I'm not sure if this
        // classifies as a bug or not... but I wanted to explain why if you debug
        // you might seem some TypeError or ReferenceError items appear.
        var result:* = bytes.readObject();
        return result;
    }
   
} // end class
} // end package