ListView使用SimpleAdapter加载非drawable资源图片

ListView是一种常见的布局，通过SimpleAdapter加载数据既省力又美观，常用做法如下：

 

Java代码  

[java] view plaincopy

1. <a xmlns="http://www.w3.org/1999/xhtml">SimpleAdapter mySimpleAdapter = new SimpleAdapter (  
2.                                                Context context,  
3.                                                List<? extends Map<String, ?>> data,  
4.                                                int resource,  
5.                                                String[] from,  
6.                                                int[] to)  
7. myListview.setAdapter(mySimpleAdapter)</a>  

[java] view plaincopy

1. SimpleAdapter mySimpleAdapter = new SimpleAdapter (  
2.                                                Context context,  
3.                                                List<? extends Map<String, ?>> data,  
4.                                                int resource,  
5.                                                String[] from,  
6.                                                int[] to)  
7. myListview.setAdapter(mySimpleAdapter)  

 其中Context为ListView的activity

data:          为加载的数据
resource:   为ListView中加载的布局文件
from:         为data中的map的key值，与to中一一对应
to:             表示resource中对应的布局文件中空间的id，通常为R.id.xxxx
这样的做法在实际运行中有一个问题，如果map中包含有图片，而这个图片不是在drawable中存在的，比如网络图片，simpleAdapter本身是不支持的，网上搜索了很多做法，有的是自己做一个Adapter然后继承SimpleAdapter ，自定义，我查阅文档发现了一个ViewBinder，该类可以帮助SimpleAdapter加载图片。

 

Java代码  

[java] view plaincopy

1. <a xmlns="http://www.w3.org/1999/xhtml">SimpleAdapter mySimpleAdapter = new SimpleAdapter (  
2.                                                Context context,  
3.                                                 List<? extends Map<String, ?>> data,  
4.                                                int resource,  
5.                                                String[] from,  
6.                                                int[] to);  
7.   
8. myListview.setAdapter(mySimpleAdapter)  
9.   
10. mySimpleAdapter.setViewBinder(new ViewBinder() {    
11.                              public boolean setViewValue(  
12.                                                  View view,   
13.                                                  Object data,    
14.                                               String textRepresentation) {    
15.                                  //判断是否为我们要处理的对象    
16.                                  if(view instanceof ImageView  && data instanceof Bitmap){    
17.                                      ImageView iv = (ImageView) view;    
18.                                      iv.setImageBitmap((Bitmap) data);    
19.                                      return true;    
20.                                  }else    
21.                                  return false;    
22.                              }    
23.                          });  </a>  

[java] view plaincopy

1. SimpleAdapter mySimpleAdapter = new SimpleAdapter (  
2.                                                Context context,  
3.                                                 List<? extends Map<String, ?>> data,  
4.                                                int resource,  
5.                                                String[] from,  
6.                                                int[] to);  
7.   
8. myListview.setAdapter(mySimpleAdapter)  
9.   
10. mySimpleAdapter.setViewBinder(new ViewBinder() {    
11.                              public boolean setViewValue(  
12.                                                  View view,   
13.                                                  Object data,    
14.                                               String textRepresentation) {    
15.                                  //判断是否为我们要处理的对象    
16.                                  if(view instanceof ImageView  && data instanceof Bitmap){    
17.                                      ImageView iv = (ImageView) view;    
18.                                      iv.setImageBitmap((Bitmap) data);    
19.                                      return true;    
20.                                  }else    
21.                                  return false;    
22.                              }    
23.                          });    

 ViewBinder是一个接口，判断传进来的Data，通常是Object类型，然后将其转换成为Bitmap，这样我觉得多此一举，为什么对于String类型的数据可以自动转换，而Bitmap就不能转换呢，而且程序在运行期其实可以判断View是什么类型的View，完全可以在SimpleAdapter中封装好该段代码，也许还有其他用法吧。