潛水那么久，也該寫點東西跟各位朋友分享一下了:-)
小弟關注Groovy已有數月(您可以到Groovy官方網站
http://groovy.codehaus.org
下載)，發現其極具魅力，故在我參加的學校'創新試驗項目'中，就用它來實現最簡易的ORM，做的非常簡單，主要原因是沒有時間，因為小弟學業繁重，所以抽出一個下午的時間來實現一個簡易版的ORM，數據庫用的是MySQL。現在簡單說明一下所示代碼，將User類的一個實例通過save方法保存到數據庫中，然后再根據給定條件通過findBy方法從數據庫中取出實例，最后刪除一個特定實例。由于深知通過XML文件進行配置的痛苦，所以在設計時沒有用到任何XML文件。此程序讓程序員只需關注自己要處理的對象，而不用關心數據庫方面的東西，簡化開發過程。最后我想說明的是，由于時間問題，所以編碼方面只注重算法的體現，沒有考慮其他方面。下面給出的代碼僅供演示及參考(源碼已經上傳，點擊下載)：
??1
?
?package??edu.ecust.orm
??2
??3??import??groovy.sql.Sql
??4??import??groovy.text.Template
??5??import??groovy.text.SimpleTemplateEngine
??6
??7
???public?class?User???
{
??8
??????private???int??id
??9??????private???String?name
?10??????private???int??age
?11
?12
???????public??User()???{}
?13
?14???????public??User(?int??id)???{
?15??????????this?.id??=??id
?16
?????}
?17
?18???????public??User(?int??id,?String?name,??int??age)???{
?19??????????this.id??=??id
?20??????????this.name??=??name
?21??????????this.age??=??age
?22?????}
?23
?24???????public???int??getId()???{
?25??????????return??id
?26?????}
?27
?28???????public???void??setId(?int??id)???{
?29??????????this.id??=??id
?30?????}
?31
?32???????public??String?getName()???{
?33??????????return??name
?34?????}
?35
?36???????public???void??setName(String?name)???{
?37??????????this.name??=??name
?38?????}
?39
?40???????public???int??getAge()???{
?41??????????return??age
?42?????}
?43
?44???????public???void??setAge(?int??age)???{
?45??????????this.age??=??age
?46?????}
?47
?48
?49
?50???????public??String?toString()???{
?51??????????return??name??+??"(#"???+?id?+?",?"??+?age?+?")"
?52?????}
?53
?}
?54
?55?typemap??=??[?"int"?:?"INTEGER"?,??"java.lang.Integer"?:?"INTEGER"?,??"long"?:?"BIGINT"?,??"java.lang.Long"?:?"BIGINT"?,??"short"?:?"SMALLINT"?,??"java.lang.Short"?:?"SMALLINT"?,??"byte"?:?"TINYINT"?,??"java.lang.Byte"?:?"TINYINT"?,??"float"?:?"FLOAT"?,??"java.lang.Float"?:?"FLOAT"?,??"double"?:?"DOUBLE"?,??"java.lang.Double"?:?"DOUBLE"?,??"java.math.BigDecimal"?:?"NUMERIC"?,??"char"?:?"CHAR(1)"?,??"java.lang.Character"?:?"CHAR(1)"?,??"java.lang.String"?:?"VARCHAR(50)"?,??"boolean"?:?"BIT"?,??"java.lang.Boolean"?:?"BIT"?]
?56
?57??def?capitalize(str)???{
?58?????def?c??=??str.charAt(?0?)
?59??????int??asci??=??(?int?)c
?60???????if??(asci??>???96???&&??asci??<???123?)???{
?61??????????return??((?char?)(asci??-???32?)).toString()??+??str.substring(?1?)
?62?????}
?63?}
?64
?65?def?user??=???new??User(?1?,??"Daniel"?,??21?)
?66
?67??def?connect()???{
?68??????return??Sql.newInstance(
?69??????????"jdbc:mysql://localhost:3306/orm"?,??"root"?,
?70??????"1106"?,??"com.mysql.jdbc.Driver"?)
?71?}
?72
?73??def?pointToLine(str)???{
?74??????return??str.replaceAll(?"\\p{Punct}"?,??"_"?)
?75?}
?76
?77??def?getFields(u)???{
?78?????def?clazz??=??u.getClass()
?79?????def?fields??=??clazz.getDeclaredFields()
?80?????def?fieldunit??=??[:]
?81???????for??(f?in?fields)???{
?82?????????def?fstr??=??f.toString()
?83???????????if??(fstr.startsWith(?"private"?))???{
?84?????????????def?fieldname??=??fstr.substring(fstr.lastIndexOf(?"."?)??+???1?)
?85?????????????def?methodname??=???"get"???+??capitalize(fieldname)
?86??????????????fieldunit.put(fieldname,?clazz.getMethod(methodname).invoke(u))
?87?????????}
?88?????}
?89
?90??????return??fieldunit
?91?}
?92
?93??tablename?=?"";
?94??def?save(u)???{
?95?????def?clazz??=??u.getClass()
?96?????def?classname??=??clazz.getName()
?97?????def?classunit??=??[:]
?98?????fieldunit??=??getFields(u)
?99?????classunit.put(classname,?fieldunit)
100?????def?keySet??=??classunit.keySet()
101?????def?it??=??keySet.iterator()
102?????def?fields
103???????while??(it.hasNext())???{
104?????????tablename??=??it.next()
105?????????fields??=??classunit.get(tablename)
106?????}
107?????tablename??=??pointToLine(tablename)
108?????def?fkeySet??=??fields.keySet()
109?????def?fit??=??fkeySet.iterator()
110???????def?creationstmt??=???""
111
112???????def?order??=??[:]
113???????def?num??=???0
114?????while??(fit.hasNext())???{
115???????def?fieldname??=??fit.next()
116???????def?fieldvalue??=??fields.get(fieldname)
117?????????if??(?"id"???==??fieldname)???{
118???????????creationstmt??+=???"id?INTEGER?PRIMARY?KEY?not?null,"
119????????}???else????{
120???????????creationstmt??+=??fieldname??+???"?"???+??typemap.get(fieldvalue.getClass().getName())??+???","
121???????}
122???????order.put(num++?,?fieldname)
123???}
124???creationstmt??=??creationstmt.substring(?0?,?creationstmt.length()??-???1?)
125???def?valuestr??=???"("
126???def?vkeySet??=??order.keySet()
127???def?vit??=??vkeySet.iterator()
128???params??=???"("
129?????while??(vit.hasNext())???{
130???????def?elem??=??vit.next()
131???????def?v??=??order.get(elem)
132???????valuestr??+=???"'\${"???+??v??+???"}',"
133???????params??+=???"`"???+??v??+???"`,"
134???}
135???valuestr??=??valuestr.substring(?0?,?valuestr.length()??-???1?)
136???params??=??params.substring(?0?,?params.length()??-???1?)
137???valuestr??+=???")"
138???params??+=???")"
139???def?insertstmt??=???"INSERT?INTO?`"???+??tablename??+???"`"???+??params??+???"?VALUES"
140???insertstmt??+=??valuestr
141???def?engine??=???new??SimpleTemplateEngine()
142???def?template??=??engine.createTemplate(insertstmt).make(fields)
143???insertstmt??=??template.toString()
144???def?createstmt??=???"""
145??????????CREATE?TABLE?IF?NOT?EXISTS?`"""??+?tablename?+??"""`
146?????????(
147??????????????"""??+?creationstmt?+??"""
148?????????);
149??????"""
150???????try????{
151?????????????????def?sql??=??connect()
152?????????????????sql.execute(createstmt)
153?????????????????sql.execute(insertstmt)
154
155??????????????}???catch??(Exception?e)???{
156?????????????????int?id?=?u.getId()
157?????????????????id++
158?????????????????u.setId(id)
159?????????????????save(u)
160?????????????????//println?e.getMessage()
161?????????????}
162
163??????return??u.getId()
164?}
165
166?def?delete(u)?{
167????try?{
168????????def?id?=?u.getId()
169????????def?sql??=??connect()
170????????def?result?=?sql.execute("DELETE?FROM?`"?+?tablename?+?"`?WHERE?id="?+?id);
171????????println?"delete?operation?completed!"
172????}?catch?(Exception?e)?{
173????????println?e.getMessage()
174????}
175?}
176
177??def?findBy(classname,?condition)???{
178?????def?sql??=??connect()
179?????objs??=??[]
180?????sql.eachRow(?"select?*?from?"???+??pointToLine(classname)??+???"?where?"???+??condition)???{
181?????obj??=??Class.forName(classname).newInstance()
182
183?????def?clazz??=??obj.getClass()
184?????def?fields??=??clazz.getDeclaredFields()
185?????def?methods??=??clazz.getDeclaredMethods()
186?????for??(f?in?fields)???{
187?????????????def?fstr??=??f.toString()
188???????????????if??(fstr.startsWith(?"private"?))???{
189?????????????????def?fieldname??=??fstr.substring(fstr.lastIndexOf(?"."?)??+???1?)
190?????????????????def?setmethodname??=???"set"???+??capitalize(fieldname)
191?????????????????def?setmethod
192???????????????????for??(m?in?methods)???{
193?????????????????????def?methodname??=??m.toString()
194???????????????????????if??(methodname.contains(setmethodname))???{
195?????????????????????????setmethod??=??m
196?????????????????????}
197?????????????????}
198?????????????????def?fieldvalue??=??it.getProperty(fieldname)
199?????????????????setmethod.invoke(obj,?fieldvalue)
200?????????????}
201?????????}
202
203?????????objs.add(obj)
204???}
205
206??????return??objs
207?}
208
209?println?"Id?of?the?saved?object?is?"?+?save(user)
210?println?"Found?"?+?findBy(?"edu.ecust.orm.User"?,??"id?=?'11'"?)
211?userToDelete?=?new?User(12,?"Daniel",?21)
212?delete(userToDelete)
213
posted on 2006-08-29 14:13
山風小子 閱讀(3108)
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Groovy & Grails