easyui datagrid 批量编辑和提交

前台主要代码：
<script type="text/javascript">
	$(function() {
		var $dg = $("#dg");
		$dg.datagrid({
			url : "servlet/list",
			width : 700,
			height : 250,
			columns : [ [ {
				field : 'code',
				title : 'Code',
				width : 100,
				editor : "validatebox"
			}, {
				field : 'name',
				title : 'Name',
				width : 200,
				editor : "validatebox"
			}, {
				field : 'price',
				title : 'Price',
				width : 200,
				align : 'right',
				editor : "numberbox"
			} ] ],
			toolbar : [ {
				text : "添加",
				iconCls : "icon-add",
				handler : function() {
					$dg.datagrid('appendRow', {});
					var rows = $dg.datagrid('getRows');
					$dg.datagrid('beginEdit', rows.length - 1);
				}
			}, {
				text : "编辑",
				iconCls : "icon-edit",
				handler : function() {
					var row = $dg.datagrid('getSelected');
					if (row) {
						var rowIndex = $dg.datagrid('getRowIndex', row);
						$dg.datagrid('beginEdit', rowIndex);
					}
				}
			}, {
				text : "删除",
				iconCls : "icon-remove",
				handler : function() {
					var row = $dg.datagrid('getSelected');
					if (row) {
						var rowIndex = $dg.datagrid('getRowIndex', row);
						$dg.datagrid('deleteRow', rowIndex);
					}
				}
			}, {
				text : "结束编辑",
				iconCls : "icon-cancel",
				handler :endEdit
			}, {
				text : "保存",
				iconCls : "icon-save",
				handler : function() {
					endEdit();
					if ($dg.datagrid('getChanges').length) {
						var inserted = $dg.datagrid('getChanges', "inserted");
						var deleted = $dg.datagrid('getChanges', "deleted");
						var updated = $dg.datagrid('getChanges', "updated");
						
						var effectRow = new Object();
						if (inserted.length) {
							effectRow["inserted"] = JSON.stringify(inserted);
						}
						if (deleted.length) {
							effectRow["deleted"] = JSON.stringify(deleted);
						}
						if (updated.length) {
							effectRow["updated"] = JSON.stringify(updated);
						}

						$.post("servlet/commit", effectRow, function(rsp) {
							if(rsp.status){
								$.messager.alert("提示", "提交成功！");
								$dg.datagrid('acceptChanges');
							}
						}, "JSON").error(function() {
							$.messager.alert("提示", "提交错误了！");
						});
					}
				}
			} ]
		});
		
		function endEdit(){
			var rows = $dg.datagrid('getRows');
			for ( var i = 0; i < rows.length; i++) {
				$dg.datagrid('endEdit', i);
			}
		}
	});
</script>
<body>
	<table id="dg" title="批量操作"></table>
</body>
</html>
<script type="text/javascrip