概述
本文给大家讲解一个不常用到的知识点，但是又不容忽略的点，相信大家在使用的FlexReport.Designer的时候选择数据源的时候都会发现链接到外部程序集中的对象，这是一种什么数据源呢，想必大家都翘首以盼了，那我们就开始揭秘吧。
外部程序集简单的说就是dll文件，再简单的说就是外部对象就是我们常说的Entity的对象，但是又有点不同它有自己实现的API,实现接口有两个IC1FlexReportRecordset、IC1FlexReportExternalRecordset，这样实现后，FlexReport.Designer就可以读到这个外部程序集的对象。
现在我们主要教大家实现这两个接口
IC1FlexReportRecordset：
1: public class MyRecordset : IC1FlexReportRecordset
2: {
3: private int _recNo;
4: private int _recCount;
6: public MyRecordset()
7: {
8: _recCount = 60;
9: }
11: public int RecCount
12: {
13: get { return _recCount; }
14: set { _recCount = value; }
15: }
17: #region IC1FlexReportRecordset implementation
18: public string[] GetFieldNames()
19: {
20: return new string[] { "ID", "Caption" };
21: }
22:
23: public Type[] GetFieldTypes()
24: {
25: return new Type[] { typeof(int), typeof(string) };
26: }
28: public object GetFieldValue(int fieldIndex)
29: {
30: switch (fieldIndex)
31: {
32: case 0:
33: return _recNo + 1;
34: case 1:
35: return string.Format("Caption {0}", _recNo + 1);
36: default:
37: return null;
38: }
39: }
41: public bool BOF()
42: {
43: return _recNo < 0;
44: }
46: public bool EOF()
47: {
48: return _recNo >= _recCount;
49: }
51: public void MoveFirst()
52: {
53: _recNo = 0;
54: }
56: public void MoveLast()
57: {
58: _recNo = _recCount - 1;
59: }
61: public void MovePrevious()
62: {
63: --_recNo;
64: }
66: public void MoveNext()
67: {
68: ++_recNo;
69: }
71: public int GetBookmark()
72: {
73: return _recNo;
74: }
76: public void SetBookmark(int bkmk)
77: {
78: _recNo = bkmk;
79: }
81: public int Count
82: {
83: get { return RecCount; }
84: }
85: #endregion
86: }
IC1FlexReportExternalRecordset：
1: public class MyExtRecordset : IC1FlexReportExternalRecordset
2: {
3: private MyRecordset _recordset;
4:
5: public MyExtRecordset()
6: {
7: _recordset = new MyRecordset();
8: }
9:
10: public int RecCount
11: {
12: get { return _recordset.RecCount; }
13: set { _recordset.RecCount = value; }
14: }
15:
16: #region IC1ReportExternalRecordset Members
17: public void EditParams()
18: {
19: using (MyExtRecordsetForm f = new MyExtRecordsetForm())
20: f.Edit(this);
21: }
22:
23: public IC1FlexReportRecordset GetRecordset()
24: {
25: return _recordset;
26: }
27:
28: public string Caption
29: {
30: get { return "External Recordset Sample"; }
31: }
32:
33: public string Params
34: {
35: get
36: {
37: return _recordset.RecCount.ToString();
38: }
39: set
40: {
41: int count;
42: if (int.TryParse(value, out count))
43: _recordset.RecCount = count;
44: }
45: }
46: #endregion
47: }
这样我们编译后就会生成一个dll文件。我们看看效果
这样我们就完成了外部数据源的定义。
如果你有疑问，可以到GCDN获得技术支持：
http://gcdn.grapecity.com.cn/showforum-68.html
GCDN：http://gcdn.grapecity.com.cn/
官方网站：/developer
