ibatis.net 学习笔记
现在的使用IBatis。顺序可以是这样，首先项目经理会分析整个项目，可以分成为几个对象，每个对象具有什么属性，什么方法。同时会用visio画出UML图来。这样可以说把面向对象的优势完全体现出来了。 然后程序员会根据UML图来操作对象，实现每个对象的属性和方法。这样就可以完全脱离数据库，去考虑程序的问题。这种开发方式特别适合于团队开发，团队中有专门的人去负责数据的建立，他可以根据项目中的Maps图清晰的知道每个数据表中的字段
- Separating SQL code from programming code
- Passing input parameters to the library classes and extracting the output
- Separating data access classes from business logic classes
- Caching often-used data until it changes
- Managing transactions and threading
So, how do you decide whether to OR/M or to DataMap? As always, the best advice is to implement a representative part of your project using either approach, and then decide. But, in general, OR/M is a good thing when you
-
Have complete control over your database implementation
-
Do not have a Database Administrator or SQL guru on the team
-
Need to model the problem domain outside the database as an object graph.
Likewise, the best time to use a Data Mapper, like iBATIS, is when:
-
You do not have complete control over the database implementation, or want to continue to access a legacy database as it is being refactored.
-
You have database administrators or SQL gurus on the team.
-
The database is being used to model the problem domain, and the application's primary role is to help the client use the database model.
Table 3.1. The six statement-type elements
| Statement Element | Attributes | Child Elements | Methods |
|---|---|---|---|
| <statement> | id parameterClass resultClass listClass parameterMap resultMap cacheModel |
All dynamic elements |
Insert Update Delete All query methods |
| <insert> | id parameterClass parameterMap |
All dynamic elements <selectKey> <generate> |
Insert Update Delete |
| <update> | id parameterClass parameterMap extends |
All dynamic elements <generate> |
Insert Update Delete |
| <delete> | id parameterClass parameterMap extends |
All dynamic elements <generate> |
Insert Update Delete |
| <select> | id parameterClass resultClass listClass parameterMap resultMap cacheModel extends |
All dynamic elements <generate> |
All query methods |
| <procedure> | id parameterMap resultClass resultMap cacheModel |
All dynamic elements |
Insert Update Delete All query |
存储过程Stored Procedures
<!--
Microsot SQL Server
-->
< procedure id ="SwapEmailAddresses" parameterMap ="swap-params" >
ps_swap_email_address
</ procedure >
...
< parameterMap id ="swap-params" >
< parameter property ="email1" column ="First_Email" />
< parameter property ="email2" column ="Second_Email" />
</ parameterMap >
<!-- Oracle with MS OracleClient provider -->
< procedure id ="InsertCategory" parameterMap ="insert-params" >
prc_InsertCategory
</ procedure >
...
< parameterMap id ="insert-params" >
< parameter property ="Name" column ="p_Category_Name" />
< parameter property ="GuidString" column ="p_Category_Guid" dbType ="VarChar" />
< parameter property ="Id" column ="p_Category_Id" dbType ="Int32" type ="Int" />
</ parameterMap >
< procedure id ="SwapEmailAddresses" parameterMap ="swap-params" >
ps_swap_email_address
</ procedure >
...
< parameterMap id ="swap-params" >
< parameter property ="email1" column ="First_Email" />
< parameter property ="email2" column ="Second_Email" />
</ parameterMap >
<!-- Oracle with MS OracleClient provider -->
< procedure id ="InsertCategory" parameterMap ="insert-params" >
prc_InsertCategory
</ procedure >
...
< parameterMap id ="insert-params" >
< parameter property ="Name" column ="p_Category_Name" />
< parameter property ="GuidString" column ="p_Category_Guid" dbType ="VarChar" />
< parameter property ="Id" column ="p_Category_Id" dbType ="Int32" type ="Int" />
</ parameterMap >
Reusing SQL Fragments重用sql【注意加载顺序比如sql在另外的map中】
<
sql
id
="selectItem_fragment"
>
FROM items
WHERE parentid = 6
</ sql >
< select id ="selectItemCount" resultClass ="int" >
SELECT COUNT(*) AS total
< include refid ="selectItem_fragment" />
</ select >
< select id ="selectItems" resultClass ="Item" >
SELECT id, name
< include refid ="selectItem_fragment" />
</ select >
FROM items
WHERE parentid = 6
</ sql >
< select id ="selectItemCount" resultClass ="int" >
SELECT COUNT(*) AS total
< include refid ="selectItem_fragment" />
</ select >
< select id ="selectItems" resultClass ="Item" >
SELECT id, name
< include refid ="selectItem_fragment" />
</ select >
When writing Sql, you often encounter duplicate fragments of SQL. iBATIS offers a simple yet powerful attribute to reuse them.
<select id="GetAllAccounts" resultMap="indexed-account-result"> select Account_ID, Account_FirstName, Account_LastName, Account_Email from Accounts </select> <select id="GetAllAccountsOrderByName" extends="GetAllAccounts" resultMap="indexed-account-result"> order by Account_FirstName </select>
Escaping XML symbols去除xml特殊标记
<![CDATA[
SELECT * FROM PERSON WHERE AGE > #value#
]]>
Auto-Generated Keys自动生成主键标识符
<!
—Oracle SEQUENCE Example using .NET 1.1 System.Data.OracleClient --
>
< insert id ="insertProduct-ORACLE" parameterClass ="product" >
< selectKey resultClass ="int" type ="pre" property ="Id" >
SELECT STOCKIDSEQUENCE.NEXTVAL AS VALUE FROM DUAL
</ selectKey >
insert into PRODUCT (PRD_ID,PRD_DESCRIPTION) values (#id#,#description#)
</ insert >
<! — Microsoft SQL Server IDENTITY Column Example -- >
< insert id ="insertProduct-MS-SQL" parameterClass ="product" >
insert into PRODUCT (PRD_DESCRIPTION)
values (#description#)
< selectKey resultClass ="int" type ="post" property ="id" >
select @@IDENTITY as value
</ selectKey >
</ insert >
<!-- MySQL Example -->
< insert id ="insertProduct-MYSQL" parameterClass ="product" >
insert into PRODUCT (PRD_DESCRIPTION)
values (#description#)
< selectKey resultClass ="int" type ="post" property ="id" >
select LAST_INSERT_ID() as value
</ selectKey >
</ insert >
< insert id ="insertProduct-ORACLE" parameterClass ="product" >
< selectKey resultClass ="int" type ="pre" property ="Id" >
SELECT STOCKIDSEQUENCE.NEXTVAL AS VALUE FROM DUAL
</ selectKey >
insert into PRODUCT (PRD_ID,PRD_DESCRIPTION) values (#id#,#description#)
</ insert >
<! — Microsoft SQL Server IDENTITY Column Example -- >
< insert id ="insertProduct-MS-SQL" parameterClass ="product" >
insert into PRODUCT (PRD_DESCRIPTION)
values (#description#)
< selectKey resultClass ="int" type ="post" property ="id" >
select @@IDENTITY as value
</ selectKey >
</ insert >
<!-- MySQL Example -->
< insert id ="insertProduct-MYSQL" parameterClass ="product" >
insert into PRODUCT (PRD_DESCRIPTION)
values (#description#)
< selectKey resultClass ="int" type ="post" property ="id" >
select LAST_INSERT_ID() as value
</ selectKey >
</ insert >
自动生成简单sql
3.3.3.4.
<
generate
>
tag
You can use iBATIS to execute any SQL statement your application requires. When the requirements for a statement are simple and obvious, you may not even need to write a SQL statement at all. The < generate > tag can be used to create simple SQL statements automatically, based on a < parameterMap > element. The four CRUD statement types (insert, select, update, and delete) are supported. For a select, you can select all or select by a key (or keys). Example 3.8 shows an example of generating the usual array of CRUD statements.
Example 3.10. Creating the "usual suspects" with the < generate > tag
< parameterMaps >
< parameterMap id ="insert-generate-params" >
< parameter property ="Name" column ="Category_Name" />
< parameter property ="Guid" column ="Category_Guid" dbType ="UniqueIdentifier" />
</ parameterMap >
< parameterMap id ="update-generate-params" extends ="insert-generate-params" >
< parameter property ="Id" column ="Category_Id" />
</ parameterMap >
< parameterMap id ="delete-generate-params" >
< parameter property ="Id" column ="Category_Id" />
< parameter property ="Name" column ="Category_Name" />
</ parameterMap >
< parameterMap id ="select-generate-params" >
< parameter property ="Id" column ="Category_Id" />
< parameter property ="Name" column ="Category_Name" />
< parameter property ="Guid" column ="Category_Guid" dbType ="UniqueIdentifier" />
</ parameterMap >
</ parameterMaps >
< statements >
< update id ="UpdateCategoryGenerate" parameterMap ="update-generate-params" >
< generate table ="Categories" by ="Category_Id" />
</ update >
< delete id ="DeleteCategoryGenerate" parameterMap ="delete-generate-params" >
< generate table ="Categories" by ="Category_Id, Category_Name" />
</ delete >
< select id ="SelectByPKCategoryGenerate" resultClass ="Category" parameterClass ="Category"
parameterMap ="select-generate-params" >
< generate table ="Categories" by ="Category_Id" />
</ select >
< select id ="SelectAllCategoryGenerate" resultClass ="Category"
parameterMap ="select-generate-params" >
< generate table ="Categories" />
</ select >
< insert id ="InsertCategoryGenerate" parameterMap ="insert-generate-params" >
< selectKey property ="Id" type ="post" resultClass ="int" >
select @@IDENTITY as value
</ selectKey >
< generate table ="Categories" />
</ insert >
</ statements >
You can use iBATIS to execute any SQL statement your application requires. When the requirements for a statement are simple and obvious, you may not even need to write a SQL statement at all. The < generate > tag can be used to create simple SQL statements automatically, based on a < parameterMap > element. The four CRUD statement types (insert, select, update, and delete) are supported. For a select, you can select all or select by a key (or keys). Example 3.8 shows an example of generating the usual array of CRUD statements.
Example 3.10. Creating the "usual suspects" with the < generate > tag
< parameterMaps >
< parameterMap id ="insert-generate-params" >
< parameter property ="Name" column ="Category_Name" />
< parameter property ="Guid" column ="Category_Guid" dbType ="UniqueIdentifier" />
</ parameterMap >
< parameterMap id ="update-generate-params" extends ="insert-generate-params" >
< parameter property ="Id" column ="Category_Id" />
</ parameterMap >
< parameterMap id ="delete-generate-params" >
< parameter property ="Id" column ="Category_Id" />
< parameter property ="Name" column ="Category_Name" />
</ parameterMap >
< parameterMap id ="select-generate-params" >
< parameter property ="Id" column ="Category_Id" />
< parameter property ="Name" column ="Category_Name" />
< parameter property ="Guid" column ="Category_Guid" dbType ="UniqueIdentifier" />
</ parameterMap >
</ parameterMaps >
< statements >
< update id ="UpdateCategoryGenerate" parameterMap ="update-generate-params" >
< generate table ="Categories" by ="Category_Id" />
</ update >
< delete id ="DeleteCategoryGenerate" parameterMap ="delete-generate-params" >
< generate table ="Categories" by ="Category_Id, Category_Name" />
</ delete >
< select id ="SelectByPKCategoryGenerate" resultClass ="Category" parameterClass ="Category"
parameterMap ="select-generate-params" >
< generate table ="Categories" by ="Category_Id" />
</ select >
< select id ="SelectAllCategoryGenerate" resultClass ="Category"
parameterMap ="select-generate-params" >
< generate table ="Categories" />
</ select >
< insert id ="InsertCategoryGenerate" parameterMap ="insert-generate-params" >
< selectKey property ="Id" type ="post" resultClass ="int" >
select @@IDENTITY as value
</ selectKey >
< generate table ="Categories" />
</ insert >
</ statements >
| Attribute | Description | Required |
|---|---|---|
| table | specifies the table name to use in the SQL statement. | yes |
| by | specifies the columns to use in a WHERE clause | no |
If you want to cache the result of a query, you can specify a Cache Model as part of the <statement> element. Example 3.15 shows a <cacheModel> element and a corresponding <statement>.
Example 3.17. A <cacheModel> element with its corresponding <statement>
<cacheModel id="product-cache" implementation="LRU"> <flushInterval hours="24"/> <flushOnExecute statement="insertProduct"/> <flushOnExecute statement="updateProduct"/> <flushOnExecute statement="deleteProduct"/> <property name="size" value="1000" /> </cacheModel> <statement id="selectProductList" parameterClass="int" cacheModel="product-cache"> select * from PRODUCT where PRD_CAT_ID = #value# </statement>
Example 3.46. Resolving complex properties with a join 表连接问题 用resultMapping
<resultMaps>
<resultMap id="select-product-result" class="product">
<result property="id" column="PRD_ID"/>
<result property="description" column="PRD_DESCRIPTION"/>
<result property="category" resultMapping="Category.CategoryResult" />
</resultMap>
</resultMaps>
<statements>
<statement id="selectProduct" parameterClass="int" resultMap="select-product-result">
select *
from PRODUCT, CATEGORY
where PRD_CAT_ID=CAT_ID
and PRD_ID = #value#
</statement>
</statements>
Example 3.48. N+1 Select Lists (1:M and M:N), example of problem 在大数据量时候有问题的sql
<resultMaps> <resultMap id="select-category-result" class="Category"> <result property="Id" column="CAT_ID"/> <result property="Description" column="CAT_DESCRIPTION"/> <result property="ProductList" column="CAT_ID" select="selectProductsByCatId"/> </resultMap> <resultMap id="Product-result" class="Product"> <result property="Id" column="PRD_ID"/> <result property="Description" column="PRD_DESCRIPTION"/> </resultMap> <resultMaps> <statements> <!-- This statement executes 1 time --> <statement id="selectCategory" parameterClass="int" resultMap="select-category-result"> select * from CATEGORY where CAT_ID = #value# </statement> <!-- This statement executes N times (once for each category returned above) and returns a list of Products (1:M) --> <statement id="selectProductsByCatId" parameterClass="int" resultMap="select-product-result"> select * from PRODUCT where PRD_CAT_ID = #value# </statement> </statements>iBATIS fully solves the N+1 selects problem. Here is the same example solved :
Example 3.49. N+1 Select Lists (1:M and M:N) resolution
<sqlMap namespace="ProductCategory"> <resultMaps> <resultMap id="Category-result" class="Category" groupBy="Id"> <result property="Id" column="CAT_ID"/> <result property="Description" column="CAT_DESCRIPTION"/> <result property="ProductList" resultMapping="ProductCategory.Product-result"/> </resultMap> <resultMap id="Product-result" class="Product"> <result property="Id" column="PRD_ID"/> <result property="Description" column="PRD_DESCRIPTION"/> </resultMap> <resultMaps> <statements> <!-- This statement executes 1 time --> <statement id="SelectCategory" parameterClass="int" resultMap="Category-result"> select C.CAT_ID, C.CAT_DESCRIPTION, P.PRD_ID, P.PRD_DESCRIPTION from CATEGORY C left outer join PRODUCT P on C.CAT_ID = P.PRD_CAT_ID where CAT_ID = #value# </statement>Example 3.50. Mapping a composite key 组合键
<resultMaps> <resultMap id="select-order-result" class="order"> <result property="id" column="ORD_ID"/> <result property="customerId" column="ORD_CST_ID"/> ... <result property="payments" column="itemId=ORD_ID, custId=ORD_CST_ID" select="selectOrderPayments"/> </resultMap> <resultMaps> <statements> <statement id="selectOrderPayments" resultMap="select-payment-result"> select * from PAYMENT where PAY_ORD_ID = #itemId# and PAY_CST_ID = #custId# </statement> </statements>
xml 中的方法是全局的 在那个xml里面都能访问所以要保持方法id的唯一性
ibatis的优点
1.学习简单 最简单的持久层框架
2.自己写相应的sql语句
3.分离数据库设计和对象模型的设计减少耦合
不使用ibatis的情况
1、对应用程序和数据库拥有完全的控制权
2、
nullValue
<resultMaps>
<resultMap id="SelectproductResult" class="productEntity">
<result property="Id" column="Id" />
<result property="Name" column="Name" />
<result property="UserId" column="UserId" nullValue="0" />
</resultMap>
</resultMaps>
组合键的使用
<resultMaps>
<resultMap id="select-order-result" class="order">
<result property="id" column="ORD_ID"/>
<result property="customerId" column="ORD_CST_ID"/>
...
<result property="payments" column="itemId=ORD_ID, custId=ORD_CST_ID"
select="selectOrderPayments"/>
</resultMap>
<resultMaps>
<statements>
<statement id="selectOrderPayments" resultMap="select-payment-result">
select * from PAYMENT
where PAY_ORD_ID = #itemId#
and PAY_CST_ID = #custId#
</statement>
</statements>
ibatis高级特性
数据关联
延迟加载
动态映射
事务管理
缓存
重用sql
<sql id="selectall">
select * from selectall
</sql>
<select id="selectallbyname">
<include refid="selectall"/> where name="11"
</select >
配置的重用
Extends
resultMapping
过滤特殊字符
>= 号 <![CDATA[>=]]>
parameterClass
parameterMap
Example 3.18. An external Parameter Map
<parameterMap id="parameterMapIdentifier" [class="fullyQualifiedClassName, assembly|typeAlias"] [extends="[sqlMapNamespace.]parameterMapId"]> <parameter property ="propertyName" [column="columnName"] [direction="Input|Output|InputOutput"] [dbType="databaseType"] [type="propertyCLRType"] [nullValue="nullValueReplacement"] [size="columnSize"] [precision="columnPrecision"] [scale="columnScale"] [typeHandler="fullyQualifiedClassName, assembly|typeAlias"] <parameter ... ... /> <parameter ... ... /> </parameterMap>Example 3.19. A typical <parameterMap> element
<parameterMap id="insert-product-param" class="Product"> <parameter property="description" /> <parameter property="id"/> </parameterMap> <statement id="insertProduct" parameterMap="insert-product-param"> insert into PRODUCT (PRD_DESCRIPTION, PRD_ID) values (?,?); </statement>
resultClass
resultMap（局部的在其他xml中引用得加上相应的命名空间）
Example 3.26. The structure of a <resultMap> element.
<resultMap id="resultMapIdentifier" [class="fullyQualifiedClassName, assembly|typeAlias"] [extends="[sqlMapNamespace.]resultMapId"]> <constructor > <argument property="argumentName" column="columnName" [columnIndex="columnIndex"] [dbType="databaseType"] [type="propertyCLRType"] [resultMapping="resultMapName"] [nullValue="nullValueReplacement"] [select="someOtherStatementName"] [typeHandler="fullyQualifiedClassName, assembly|typeAlias"] /> </constructor > <result property="propertyName" column="columnName" [columnIndex="columnIndex"] [dbType="databaseType"] [type="propertyCLRType"] [resultMapping="resultMapName"] [nullValue="nullValueReplacement"] [select="someOtherStatementName"] [lazyLoad="true|false"] [typeHandler="fullyQualifiedClassName, assembly|typeAlias"] /> <result ... .../> <result ... .../> // Inheritance support <discriminator column="columnName" [type|typeHandler="fullyQualifiedClassName, assembly|typeAlias"] /> <subMap value="discriminatorValue" resultMapping="resultMapName" /> <subMap .../> </resultMap>
Cache Models
Example 3.51. Configuation a cache using the Cache Model element
<cacheModel id="product-cache" implementation="LRU" readOnly="true" serialize="false"> <flushInterval hours="24"/> <flushOnExecute statement="insertProduct"/> <flushOnExecute statement="updateProduct"/> <flushOnExecute statement="deleteProduct"/> <property name="CacheSize" value="100"/> </cacheModel>
Cache Implementation
MEMORY：MEMORY cache使用reference类型来管理cache的行为。也就是说，垃圾收集器可以决定谁可以停留在缓存中。MEMORY cache是应用程序一个很好的选择（没有对象重用的识别模式。与内存较少的应用程序）
LRU：
最少使用的优先被删除
FIFO：FIFO的缓存实现使用先进先出算法来确定如何从缓存中自动删除对象。当Cache满时，最古老的对象将被从缓存中删除。
FIFO缓存有利于使用这种模式（一个特定的查询接连几次被引用，但后来一段时间可能不用）。
Dynamic SQL动态sql语句
Table 3.7. Binary conditional attributes
Element Description <isEqual> Checks the equality of a property and a value, or another property. Example Usage: <isEqual prepend="AND" property="status" compareValue="Y"> MARRIED = ‘TRUE' </isEqual><isNotEqual> Checks the inequality of a property and a value, or another property. Example Usage: <isNotEqual prepend="AND" property="status" compareValue="N"> MARRIED = ‘FALSE' </isNotEqual><isGreaterThan> Checks if a property is greater than a value or another property. Example Usage: <isGreaterThan prepend="AND" property="age" compareValue="18"> ADOLESCENT = ‘FALSE' </isGreaterThan><isGreaterEqual> Checks if a property is greater than or equal to a value or another property. Example Usage: <isGreaterEqual prepend="AND" property="shoeSize" compareValue="12"> BIGFOOT = ‘TRUE' </isGreaterEqual><isLessEqual> Checks if a property is less than or equal to a value or another property. Example Usage: <isLessEqual prepend="AND" property="age" compareValue="18"> ADOLESCENT = ‘TRUE' </isLessEqual>
Table 3.8. Unary conditional attributes
| Element | Description |
|---|---|
| <isPropertyAvailable> | Checks if a property is available (i.e is a property of the parameter object). Example Usage: <isPropertyAvailable property="id" > ACCOUNT_ID=#id# </isPropertyAvailable> |
| <isNotPropertyAvailable> | Checks if a property is unavailable (i.e not a property of the parameter object). Example Usage: <isNotPropertyAvailable property="age" > STATUS='New' </isNotEmpty> |
| <isNull> | Checks if a property is null. Example Usage: <isNull prepend="AND" property="order.id" > ACCOUNT.ACCOUNT_ID = ORDER.ACCOUNT_ID(+) </isNotEmpty> |
| <isNotNull> | Checks if a property is not null. Example Usage: <isNotNull prepend="AND" property="order.id" > ORDER.ORDER_ID = #order.id# </isNotEmpty> |
| <isEmpty> | Checks to see if the value of a Collection, String property is null or empty ("" or size() < 1). Example Usage: <isEmpty property="firstName" > LIMIT 0, 20 </isNotEmpty> |
| <isNotEmpty> | Checks to see if the value of a Collection, String property is not null and not empty ("" or size() < 1). Example Usage: <isNotEmpty prepend="AND" property="firstName" > FIRST_NAME LIKE '%$FirstName$%' </isNotEmpty> |
Table 3.9. Testing to see if a parameter is present
| Element | Description |
|---|---|
| <isParameterPresent> | Checks to see if the parameter object is present (not null).<isParameterPresent prepend="AND"> EMPLOYEE_TYPE = #empType# </isParameterPresent> |
| <isNotParameterPresent> | Checks to see if the parameter object is not present (null). Example Usage:<isNotParameterPresent prepend="AND"> EMPLOYEE_TYPE = ‘DEFAULT' </isNotParameterPresent> |
1.IBatis.Net 中的数据类型转换 http://www.cnblogs.com/aaa6818162/archive/2011/05/21/2053019.html
2.存储过程的使用
3.调试时获取sql语句 GetStatementName