MyBatis Series -05-sqlmapconfig.xml Detailed

MyBatis Global configuration file Sqlmapconfig.xml, the configuration is as follows:

Properties (Attributes)

Settings (Global configuration parameters)

Typealiases (Type alias)

Typehandlers (Type processor)

Objectfactory (Object Factory)

Plugins (plug-in)

Environments (Environment collection Property object)

Environment (Environment sub-Property object)

TransactionManager (transaction Management)

DataSource (data source)

Mappers (Mapper)

5.1 Properties Property

Demand:

To configure the database connection parameters separately in Db.properties, you only need to load the Db.properties property values in Sqlmapconfig.xml.

You do not need to hard-code database connection parameters in Sqlmapconfig.xml.

The database connection parameters are only configured in Db.properties, because it is convenient to manage the parameters uniformly, and other XML can refer to the db.properties.

Load the properties file in Sqlmapconfig.xml:

Properties Features:

Note: MyBatis will load the properties in the following order:

• Attributes defined in the properties element are first read.
• It then reads the properties of the resource or URL loaded in the property element, overwriting properties that have been read with the same name.
• Finally read the property passed by the ParameterType, which overrides the Read property with the same name.

Suggestions:

Do not add any attribute values in the properties element, only the attribute values are defined in the property file.

Defining attribute names in the properties file is specific, such as: XXXXX.XXXXX.XXXX

5.2 Settings Global parameter configuration

<!--global configuration parameters, when needed and set-

<!--<settings>

</settings>

The MyBatis framework can adjust some of the running parameters at run time.

For example: Turn on level Two cache, turn on lazy loading.

Global parameters will affect the running behavior of MyBatis.

5.3 typealiases (alias) key 5.3.1 Requirements

In Mapper.xml, defining a lot of statement,statement requires parametertype specifying the type of input parameter, the type of mapping that needs to be resulttype to specify the output result.

If you enter a type full path when specifying a type, it is inconvenient to develop, you can define some aliases for the type specified by ParameterType or Resulttype, and the alias definition in mapper.xml to facilitate development.

5.3.2 MyBatis Default Support aliases

Alias	Types of mappings
_byte	Byte
_long	Long
_short	Short
_int	Int
_integer	Int
_double	Double
_float	Float
_boolean	Boolean
String	String
Byte	Byte
Long	Long
Short	Short
Int	Integer
Integer	Integer
Double	Double
Float	Float
Boolean	Boolean
Date	Date
Decimal	BigDecimal
BigDecimal	BigDecimal

5.3.3 Custom alias 5.3.3.1 single alias definition

In Sqlmapconfig.xml:

   <!---   <typealiases>      <!-- define type for a single alias      : path to type alias      :       alias--       <   Type= "Cn.itcast.mybatis.po.User"  alias= "User"/>    </typealiases>

Reference aliases in Usermapper.xml:

   <id= "Finduserbyusername"  parametertype= "Java.lang.String" Resulttype = "User" >       SELECT * from USER WHERE username like '%${value}% '   </SELECT> 

5.3.3.2 Bulk alias definition

<!---   <typealiases>      <!-- The bulk alias definition      Specifies the package name, MyBatis automatically scans the PO class in the package, automatically defines the alias, and the alias is the class name (either      uppercase or lowercase)-      < Name = "Cn.itcast.mybatis.po"/></      Typealiases>

5.4 Typehandlers (Type processor)

The conversion of JDBC type and Java type is done through typehandlers in MyBatis.

Typically, MyBatis provides a type processor that meets daily needs and does not require customization.

MyBatis supports type processors:

Type processor	Java Type	JDBC Type
Booleantypehandler	Boolean,boolean	Any of the compatible Boolean values
Bytetypehandler	Byte,byte	Any compatible number or byte type
Shorttypehandler	Short,short	Any compatible number or short integer
Integertypehandler	Integer,int	Any compatible number and integral type
Longtypehandler	Long,long	Any compatible number or long integer
Floattypehandler	Float,float	Any compatible digital or single-precision floating-point type
Doubletypehandler	Double,double	Any compatible digital or double-precision floating-point type
Bigdecimaltypehandler	BigDecimal	Any compatible number or decimal decimal type
Stringtypehandler	String	char and varchar types
Clobtypehandler	String	CLOB and LongVarChar types
Nstringtypehandler	String	nvarchar and nchar types
Nclobtypehandler	String	NCLOB type
Bytearraytypehandler	Byte[]	Any compatible byte stream type
Blobtypehandler	Byte[]	Blob and LongVarBinary types
Datetypehandler	Date (Java.util)	Timestamp type
Dateonlytypehandler	Date (Java.util)	Date type
Timeonlytypehandler	Date (Java.util)	Time Type
Sqltimestamptypehandler	Timestamp (java.sql)	Timestamp type
Sqldatetypehandler	Date (java.sql)	Date type
Sqltimetypehandler	Time (java.sql)	Time Type
Objecttypehandler	Any	Other or unspecified type
Enumtypehandler	Enumeration type	varchar-any compatible string type as a code store (not an index).

5.5 mappers (map configuration) 5.5.1 load a single mapping file via resource

   < mappers >      <  resource= "Usermapper.xml"/>   </mappers >

5.5.2 loading a single mapper via the Mapper interface

   < mappers >      <!-- loading a single mapping file via the Mapper interface      follows some specifications: The Mapper interface class name and the Mapper.xml mapping file name need to be consistent, and the upper specification in one directory is the premise that the      Mapper proxy method       is used  --      <class= " Cn.itcast.mybatis.mapper.UserMapper "/>   </mappers> 

According to the specification above, Mapper.java and Mapper.xml are placed in a directory with the same name.

5.5.3 Bulk Load mapper (recommended)

   < mappers >      <!-- Bulk Load Mapper      Specifies the package name of the Mapper interface, MyBatis automatically scans all mapper interfaces underneath the package for loading      Follow some specifications: You need to keep the Mapper interface class name and the Mapper.xml mapping file name consistent, and the upper specification in one directory is the premise that you are      using       the Mapper proxy method--       <name= "Cn.itcast.mybatis.mapper"/>   </ mappers >

MyBatis Series -05-sqlmapconfig.xml Detailed