Third, MyBatis series: Mapper mapping uses POJO entities to receive data and incoming parameters

1. First define an entity User type that receives the data, and a userquery type for the input parameter.

1  Public classUser {2      Public intID;3      PublicString username;4      PublicDate birthday;5      PublicString sex;6      PublicString address;7 }8  Public classUserQuery {9     PrivateString Orderbyclause;Ten     PrivateList<criteria>Oredcriteria; One      Public voidAddusernamelike (String username) { AOredcriteria.add (NewCriteria ("username like", username)); -     } -      Public voidAddsexgreaterthan (intvalue) { theOredcriteria.add (NewCriteria ("Sex >", value)); -     } -      Public classCriteria { -         PrivateString Conditia; +         PrivateObject value; -          PublicCriteria (String Conditia, Object value) { +              This. Conditia =Conditia; A              This. Value =value; at         } -     } -}

2, now need to configure a more complex mapper mapping file

• Defines Resultmap, which is used to map entity properties to SQL fields. The final Pojo returned here is the User type.
• The ID represents the mapping of the primary key attribute and the field, if multiple primary keys are required to define multiple IDs;
• Result represents the mapping of other properties and fields;
• The SQL fragment is defined, such as: User_columns, User_where, so it can be referenced in any SQL script, and is easy to maintain;
• The ${alias} placeholder is defined in User_colums , and the value of the placeholder is defined when the fragment is referenced;
• User_where the SQL fragment used to define the query criteria, foreach is used to loop a collection that repeats the SQL statements within the section.
• The Oredcriteria value is the member name of UserQuery,
• The criteria is the private variable name in the statement.
• Separator= "and" means that the stitching statement is separated by an and.
• When you define select, UserQuery is used as an incoming parameter, and the return type uses the Resultmap type UserMap;
• Use include to introduce a SQL fragment, and you can set property values for others;
• Use if test to determine, satisfy the condition to use the IF section of the SQL statement;

1 <?XML version= "1.0" encoding= "UTF-8"?>2 <!DOCTYPE Mapper Public "-//mybatis.org//dtd mapper 3.3//en"3 "Http://mybatis.org/dtd/mybatis-3-mapper.dtd">4 <Mappernamespace= "Test">5     <Resultmaptype= "Cn.xleos.mybatis.po.User"ID= "UserMap">6         <IDcolumn= "id" Property= "id" />7         <resultcolumn= "username" Property= "username" />8         <resultcolumn= "Birthday" Property= "Birthday" />9         <resultcolumn= "Sex" Property= "Sex" />Ten         <resultcolumn= "Address" Property= "Address" /> One     </Resultmap> A     <SQLID= "User_columns"> - ${alias}id, ${alias}username, ${alias}birthday, - ${alias}sex, ${alias}address, ${alias}attrs the     </SQL> -     <SQLID= "User_where"> -         <where> -             <foreachCollection= "Oredcriteria"Item= "Criteria"Separator= "and"> + (${criteria.condition} #{criteria.value}) -             </foreach> +         </where> A     </SQL> at     <SelectID= "Getuserbyquery"ParameterType= "Cn.xleos.mybatis.po.UserQuery" - Resultmap= "UserMap"> - SELECT -         <includerefID= "User_columns"> -             < Propertyname= "Alias"value="" /> -         </include> in From user -         <ifTest= "_parameter! = null"> to             <includerefID= "User_where" /> +         </if> -         <ifTest= "Oredcriteria! = null"> the ORDER by ${orderbyclause} *         </if> $     </Select>Panax Notoginseng </Mapper>

3, through the unit test to see how the results

The first thing to do is to create a userquery query Pojo object, and then add conditions and sort fields;
Since the return type is already specified in the Mapper mapping file, multiple records are returned as list<user> types;

1  Public classMybatismappertest {2 @Test3      Public voidqueryusertest () {4Sqlsession sqlsession =sqlsessionfactory.opensession ();5         Try {6UserQuery UserQuery =Newuserquery ();7Userquery.setorderbyclause ("Birthday");8Userquery.addusernamelike ("Zhang%");9             Tenlist<user> users = sqlsession.selectlist ("Test.getuserbyquery", userquery); One System.out.println (users); A}finally { - sqlsession.close (); -         } the     } -}

The resulting SQL script can be seen through the trace log as follows, resulting in the same as expected:
DEBUG [main]-==> preparing:select ID, username, birthday, sex, address from user WHERE (username like?) Order BY Birthday
DEBUG [main]-==> Parameters: Zhang% (String)

Third, MyBatis series: Mapper mapping uses POJO entities to receive data and incoming parameters