Mybatis-config.xml configuration file

The abstract project uses the MyBatis to manipulate the database itself before using the framework, but it is only in the stage of being used, so it makes a lot of mistakes. Recently in the finishing project and many things, have seen that familiar and unfamiliar old friends. So I want to completely understand the old friend in the end how many things I do not know. Let me also after less fan error ... mybatis config sqlsessionfactory profile database

directory [-] 1:properties property file 2:settings configuration 3:typealiases type alias (entity type alias); 4:typehandlers type handle 5 Objectfactory object Factory 6 PLU Gins plug-in 7 environments Environment 8 Mappers Mapper

In the grooming project is found the configuration of the DAO layer about the database

<configuration>
<settings>
<setting name= "cacheenabled" value= "false"/>
</settings>
<typeAliases>
<package name= "Com.desksoft.oceanus.goods.dataobject"/>
<package name= "Com.desksoft.oceanus.goods.vo"/>
</typeAliases>
</configuration>

Only a few lines of configuration are available because the Sping-mybatis implementation of the project is implemented by spring.

Think about it and know the result, using spring, of course, is the spring configuration data source datasource. Then Mybatis-config.xml content reduction that is also normal.

Why? Then you need to review what the file does. Why does the MyBatis framework require this configuration file?

Any persistence layer framework is an operational database that reads and writes database information so it's bound to have a database.

Sessionfactory used by habernate

Mybatis's Sqlsessionfactory

And so on are persistent layer Framework operations database Yes session factory

MyBatis applications are mostly using sqlsessionfactory instances, and a sqlsessionfactory instance can be obtained through Sqlsessionfactorybuilder.

The sqlsessionfactorybuilder can be obtained from an instance of a Mybatis-config.xml configuration file or a pre-defined configuration class.

The Mybatis-config.xml configuration file is a link to the configuration database, so here's a look at the tags in the file.

The MyBatis configuration file includes the following tags:

Configuration

|---Properties

|---settings

|---typealiases

|---typehandlers

|---objectfactory

|---plugins

|---environments

|---|---environment

|---|---|---transactionmanager

|---|---|__ dataSource

|__ mappers 1:properties Properties File

Properties refers to the &times in Java;. Properties

Configure the properties of the resource to specify &times;. The path to the properties,

The property's name and value are then configured under the Properties tab, and the corresponding attribute values in the properties file can be replaced. Variable using ${****} 2:settings configuration

There are a number of major configurations and descriptions of the settings configuration as follows:

Property name	Simple description	Setting the value	Default value
Cacheenabled	Global on/Off settings for all caches under this profile	true | False	True
Lazyloadingenabled	Global Settings lazy Loading. If set to ' false ', all associated will be initialized to load.	true | False	True
Aggressivelazyloading	When set to ' true ', lazy-loaded objects may be loaded by any lazy property. Otherwise, each property is loaded on demand.	true | False	True
Multipleresultsetsenabled	Allow and disallow single statements to return multiple datasets	true | False	True
Usecolumnlabel	Use column labels instead of column names. Different drives have different practices. Refer to the drive documentation, or test with these two different options.	true | False	True
Usegeneratedkeys	Allows JDBC to generate a primary key. Drive support is required. If set to true, this setting enforces the generated primary key, and some drives are incompatible but can still be executed.	true | False	False
Automappingbehavior	Specifies whether MyBatis and how to automatically map the data table fields with the properties of the object. Partial will only automatically map simple, no nested results. Full will automatically map all the complex results.	NONE, PARTIAL, Full	PARTIAL
Defaultexecutortype	Configure and set actuators, simple actuators execute other statements. The reuse executor may reuse prepared statements statements, and batch executor can execute statements and batch updates repeatedly.	Simple Reuse BATCH	Simple
Defaultstatementtimeout	Set a time limit to determine how long the drive waits for the database to respond to timeouts	Positive integers	Not Set null)

alias of type 3:typealiases (entity type alias);

Type aliases are abbreviations for Java types. is the short name of the Java object

It is only associated to the Map.xml configuration, and it is not necessary to write the full Java object name map.xml the alias is configured.

<typeAliases>
<typealias alias= "userentity" type= "com.fengyi.entity.UserEntity"/>
<typealias alias= "studententity" type= "com.fengyi.entity.StudentEntity"/>
<typealias alias= "classentity" type= "com.fengyi.entity.ClassEntity"/>
</typeAliases>

Alias property if not write default is the class name first letter lowercase

Basic types and special types of alias mapping relationships

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
Object	Object
Map	Map
HashMap	HashMap
List	List
ArrayList	ArrayList
Collection	Collection
Iterator	Iterator

4:typehandlers Type handle

Whether MyBatis sets a parameter in a preprocessing statement or extracts a value from the result set, the type processor is used to convert the obtained value to the Java type in the appropriate way.

The following table describes the default type processor.

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