MyBatis Mapper Agent use method detailed _java

MyBatis Introduction

MyBatis is an excellent persistence layer framework that supports common SQL queries, stored procedures, and advanced mappings. MyBatis eliminates the manual setting of almost all JDBC code and parameters and the retrieval encapsulation of the result set. MyBatis can use simple XML or annotations for configuration and raw mappings, mapping interfaces and Java Pojo (Plain old Java Objects, normal Java objects) to records in the database.

The following focuses on the use of Mapper agent method.

The tasks that a developer needs to accomplish:

Mapper.xml mapping files and Mapper.java

Two. Development specification

1, in Mapper.xml namespace equals Mapper interface address.

2, the Mapper.java interface in the method name and Mapper.xml statement ID consistent

3, the method input parameter type in the Mapper.java interface is consistent with the type specified by ParameterType in statement in Mapper.xml.

4, the method return value type in the Mapper.java interface is consistent with the type specified by Resulttype in statement in Mapper.xml.

Mapper.java sample

Query user information based on ID public user
finduserbyid (int id) throws Exception;

Mapper.xml sample

<select id= "Finduserbyid" parametertype= "int" resulttype= "user" >
select * from user WHERE Id=#{value}
</select>

5. Loading Mapper.xml in Sqlmapconfig.xml

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

Or

<mappers>
<!--bulk Load Mapper
Specifies the package name of the Mapper interface, MyBatis automatically scans all mapper interfaces underneath the package to load
Follow some specifications: The Mapper interface class name and the Mapper.xml mapping file name need to be consistent, and the premise of the top specification in a directory is that the
Mapper proxy method is used
-->
<package Name= "Cn.itcast.mybatis.mapper"/>
</mappers>

The above is a small set to introduce the MyBatis Mapper agent use method, I hope to help you, if you have any questions please give me a message, small series will promptly reply to everyone. Here also thank you very much for the cloud Habitat Community website support!