如何用BlazeDS前后台数据交互

续上一篇文章如何用BlazeDS更改图片 之后，本篇文章介绍了如何在后台构建数据，并传送到前台。一般来讲有两种方式：构造XML数据，传送到前台后，通过XMLSerializer反序列化到DataBox中；后台构建Java对象，通过BlazeDS传送到前台后，映射成TWaver Flex的数据对象，然后直接添加到DataBox中。这里只介绍后面这种RemoteObject的方式，XML的方式将在后续文章中介绍。

先来看看技术点：BlazeDS的序列化机制。Flex的类只要指定[RemoteClass(alias="common.CNode")]，或者registerClassAlias(“common.CNode”, CNode)，就可以将Java类映射成Flex类。public的变量，或者有get和set方法的变量都将自动映射。但有些类型的变量映射就会出问题，比如Point：java和flex的Point类型无法自动映射。因此，自己控制哪些变量序列化，如何序列化相当关键。更多资料请参考官方文档。

Serializing between ActionScript and Java
Explicitly mapping ActionScript and Java objects

下面介绍如何自定义序列化
1. 创建Java数据类，这里将TWaver Flex的Data、Element和Node分开创建了，以便复用。其他数据类型，比如Link，Group等，大家可以类似创建，可以自己实现试试，练练手。

 

 

  
  

   
    1 
   
   public class CData implements Externalizable {

   
    2 
   
    ...

   
    3 
   
    public 
   
   void
   
    readExternal(ObjectInput 
   
   in
   
   ) throws IOException, ClassNotFoundException {

   
    4 
   
    
   
   this
   
   .setIcon((String)
   
   in
   
   .readObject());

   
    5 
   
    
   
   this
   
   .setName((String)
   
   in
   
   .readObject());

   
    6 
   
    
   
   this
   
   .setToolTip((String)
   
   in
   
   .readObject());

   
    7 
   
    }

   
    8 
   
   

   
    9 
   
    public 
   
   void
   
    writeExternal(ObjectOutput out) throws IOException {

   
   10 
   
    out.writeObject(
   
   this
   
   .getIcon());

   
   11 
   
    out.writeObject(
   
   this
   
   .getName());

   
   12 
   
    out.writeObject(
   
   this
   
   .getToolTip());

   
   13 
   
    }

   
   14 
   
   }
  
  

  
  

   
    1 
   
   public class CElememt extends CData implements Externalizable {

   
    2 
   
    ...

   
    3 
   
    public 
   
   void
   
    readExternal(ObjectInput 
   
   in
   
   ) throws IOException, ClassNotFoundException {

   
    4 
   
    super.readExternal(
   
   in
   
   );

   
    5 
   
    
   
   this
   
   .setLayerID(
   
   in
   
   .readObject());

   
    6 
   
    }

   
    7 
   
   

   
    8 
   
    public 
   
   void
   
    writeExternal(ObjectOutput out) throws IOException {

   
    9 
   
    super.writeExternal(out);

   
   10 
   
    out.writeObject(
   
   this
   
   .getLayerID());

   
   11 
   
    }

   
   12 
   
   }
  
  

  
  

   
    1 
   
   public class CNode extends CElememt implements Externalizable {

   
    2 
   
    ...

   
    3 
   
    public 
   
   void
   
    readExternal(ObjectInput 
   
   in
   
   ) throws IOException, ClassNotFoundException {

   
    4 
   
    super.readExternal(
   
   in
   
   );

   
    5 
   
   

   
    6 
   
    
   
   this
   
   .setImage((String)
   
   in
   
   .readObject());

   
    7 
   
    
   
   this
   
   .setX(
   
   in
   
   .readDouble());

   
    8 
   
    
   
   this
   
   .setY(
   
   in
   
   .readDouble());

   
    9 
   
    
   
   this
   
   .setWidth(
   
   in
   
   .readDouble());

   
   10 
   
    
   
   this
   
   .setHeight(
   
   in
   
   .readDouble());

   
   11 
   
    }

   
   12 
   
   

   
   13 
   
    public 
   
   void
   
    writeExternal(ObjectOutput out) throws IOException {

   
   14 
   
    super.writeExternal(out);

   
   15 
   
   

   
   16 
   
    out.writeObject(
   
   this
   
   .getImage());

   
   17 
   
    out.writeDouble(
   
   this
   
   .getX());

   
   18 
   
    out.writeDouble(
   
   this
   
   .getY());

   
   19 
   
    out.writeDouble(
   
   this
   
   .getWidth());

   
   20 
   
    out.writeDouble(
   
   this
   
   .getHeight());

   
   21 
   
    }

   
   22 
   
   }
  
  

2. 生成数据，很简单，一个循环模拟了一些数据

  
  

   
    1 
   
   public static CNode[] getNodes(){

   
    2 
   
    CNode[] result 
   
   =
   
    
   
   new
   
    CNode[
   
   4
   
   ];

   
    3 
   
    
   
   for
   
   (
   
   int
   
    i
   
   =
   
   0
   
   ; i
   
   <
   
   result.length; i
   
   ++
   
   ){

   
    4 
   
    CNode node 
   
   =
   
    
   
   new
   
    CNode();

   
    5 
   
    node.setName(
   
   "
   
   Node
   
   "
   
   +
   
   i);

   
    6 
   
    node.setX(
   
   50
   
   *
   
   i);

   
    7 
   
    node.setY(
   
   50
   
   *
   
   i);

   
    8 
   
    node.setToolTip(
   
   "
   
   toolTip
   
   "
   
   +
   
   i);

   
    9 
   
    node.setIcon(
   
   "
   
   group_icon
   
   "
   
   );

   
   10 
   
    node.setImage(
   
   "
   
   group_image
   
   "
   
   );

   
   11 
   
    node.setLayerID(
   
   "
   
   Layer
   
   "
   
   +
   
   i);

   
   12 
   
    result[i] 
   
   =
   
    node;

   
   13 
   
    }

   
   14 
   
    
   
   return
   
    result;

   
   15 
   
   }
  
  

3. 创建Flex数据类，这里注意保持和Java序列化的顺序一致

 

  
  

   
    1 
   
   public class CNode extends twaver.Node implements IExternalizable {

   
    2 
   
    ...

   
    3 
   
    public 
   
   function
   
    readExternal(input:IDataInput):
   
   void
   
    {

   
    4 
   
    
   
   //
   
   Data
   
   

   
    5 
   
    
   
    super.icon 
   
   =
   
    input.readObject() as String;

   
    6 
   
    super.name 
   
   =
   
    input.readObject() as String;

   
    7 
   
    super.toolTip 
   
   =
   
    input.readObject() as String;

   
    8 
   
    
   
   //
   
   parent
   
   

   
    9 
   
   
   
   

   
   10 
   
    
   
   //
   
   Element
   
   

   
   11 
   
   
   
    super.layerID 
   
   =
   
    input.readObject();

   
   12 
   
   

   
   13 
   
    
   
   //
   
   Node
   
   

   
   14 
   
   
   
    super.image 
   
   =
   
    input.readObject() as String;

   
   15 
   
    super.location 
   
   =
   
    
   
   new
   
    Point(input.readDouble(), input.readDouble());

   
   16 
   
    
   
   var
   
    width:Number 
   
   =
   
    input.readDouble();

   
   17 
   
    
   
   if
   
   (width 
   
   >=
   
    
   
   0
   
   ){

   
   18 
   
    super.width 
   
   =
   
    width;

   
   19 
   
    }

   
   20 
   
    
   
   var
   
    height:Number 
   
   =
   
    input.readDouble();

   
   21 
   
    
   
   if
   
   (height 
   
   >=
   
    
   
   0
   
   ){

   
   22 
   
    super.height 
   
   =
   
    height;

   
   23 
   
    }

   
   24 
   
    }

   
   25 
   
   

   
   26 
   
    public 
   
   function
   
    writeExternal(output:IDataOutput):
   
   void
   
    {

   
   27 
   
    
   
   //
   
   Data
   
   

   
   28 
   
   
   
    output.writeObject(super.icon);

   
   29 
   
    output.writeObject(super.name);

   
   30 
   
    output.writeObject(super.toolTip);

   
   31 
   
    
   
   //
   
   parent
   
   

   
   32 
   
   
   
   

   
   33 
   
    
   
   //
   
   Element
   
   

   
   34 
   
   
   
    output.writeObject(super.layerID);

   
   35 
   
   

   
   36 
   
    
   
   //
   
   Node
   
   

   
   37 
   
   
   
    output.writeObject(super.image);

   
   38 
   
    output.writeDouble(super.x);

   
   39 
   
    output.writeDouble(super.y);

   
   40 
   
    output.writeDouble(super.width);

   
   41 
   
    output.writeDouble(super.height);

   
   42 
   
    }

   
   43 
   
   }
  
  

4. 加载数据，用上一篇文章封装好的方法一个调用就OK了，另外别忘了用registerClassAlias给Flex类指定别名

 

  
  

   
    1 
   
   registerClassAlias(
   
   "
   
   common.CNode
   
   "
   
   , CNode);

   
    2 
   
   

   
    3 
   
   private 
   
   function
   
    loadDatas(event:MouseEvent):
   
   void
   
    {

   
    4 
   
    RemoteObjectUtil.invoke(
   
   "
   
   DataUtil
   
   "
   
   , 
   
   "
   
   getNodes
   
   "
   
   , 
   
   function
   
   (result:Object):
   
   void
   
   {

   
    5 
   
    
   
   var
   
    nodes:Array 
   
   =
   
    result as Array;

   
    6 
   
    
   
   for
   
    each(
   
   var
   
    node:CNode 
   
   in
   
    nodes){

   
    7 
   
    box.add(node);

   
    8 
   
    }

   
    9 
   
    });

   
   10 
   
   }
  
  

如需源码请留言