extjs grid checkbox 默认选中

var sm2= new Ext.grid.CheckboxSelectionModel({
                   singleSelect:true,
                    renderer:this.checkboxRenderer.createDelegate(this) //注意添加这个renderer
 });      　   
           this.grid = new Ext.grid.GridPanel({//列表
                        border:false, 
                        height:300,
                        store: ds,
                        cm: colModel,
                        sm: sm2,
            });
//定义renderer
checkboxRenderer:function(value, cellmeta, record,rowIndex, columnIndex, store){
         var row =  this.grid.getStore().getById(record.id);
         var id = row.get(this.id_key); //this.id_key 是一行的key 这样，可以根据这一行资料确定是否需要默认选择或根本就不出现选择框。
         var isSelect = false;
//选中逻辑
        if(!isSelect){
            return '<div  class="x-grid3-row-checker">&nbsp;</div>';
        }else{
            return '';
        }
               
  },

//Extjs.grid.Checkbox获值

    var sm = grid.getSelectionModel();

    var store = grid.getStore();

    var view = grid.getView();

    for(var i = 0; i < view.getRows().length; i ++){
     if(sm.isSelected(i)){
      var record = store.getAt(i);
      var name = record.get("rec_name");
      var url = record.get("rec_url");
      alert(name + "," + url);
     }
    }

Extjs checkbox Grid勾选时事件

1. var sm = new Ext.grid.CheckboxSelectionModel();    
2.         sm.handleMouseDown = Ext.emptyFn;//不响应MouseDown事件    
3.         sm.on('rowselect',function(sm_,rowIndex,record){//行选中的时候    
4.                
5.         }, this);    
6.         sm.on('rowdeselect',function(sm_,rowIndex,record){//行未选中的时候    
7.                
8.         }, this);