MyBatis GeneratorXML Configuration File Reference 1

本文介绍了MyBatis Generator的基本配置方法,通过一个XML配置文件示例,详细解释了如何设置数据库连接信息、生成对象的方式及对应表等内容。此外,还提供了关于文件中各个元素及其属性的具体说明。

http://mybatis.org/generator/configreference/xmlconfig.html

最常见用例中, MyBatis Generator (MBG) 靠XML配置文件来驱动。配置文件告诉MBG以下信息:

  • 如何连接数据库;
  • 需要产生哪些对象,以及怎么产生;
  • 用哪些表来产生对象。

下面是个MBG配置文件的例子,查看关于元素和属性值的更多信息,需要查阅单独的页面。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
  PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
  "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

<generatorConfiguration>
  <classPathEntry location="/Program Files/IBM/SQLLIB/java/db2java.zip" />

  <context id="DB2Tables" targetRuntime="MyBatis3">
    <jdbcConnection driverClass="COM.ibm.db2.jdbc.app.DB2Driver"
        connectionURL="jdbc:db2:TEST"
        userId="db2admin"
        password="db2admin">
    </jdbcConnection>

    <javaTypeResolver >
      <property name="forceBigDecimals" value="false" />
    </javaTypeResolver>

    <javaModelGenerator targetPackage="test.model" targetProject="\MBGTestProject\src">
      <property name="enableSubPackages" value="true" />
      <property name="trimStrings" value="true" />
    </javaModelGenerator>

    <sqlMapGenerator targetPackage="test.xml"  targetProject="\MBGTestProject\src">
      <property name="enableSubPackages" value="true" />
    </sqlMapGenerator>

    <javaClientGenerator type="XMLMAPPER" targetPackage="test.dao"  targetProject="\MBGTestProject\src">
      <property name="enableSubPackages" value="true" />
    </javaClientGenerator>

    <table schema="DB2ADMIN" tableName="ALLTYPES" domainObjectName="Customer" >
      <property name="useActualColumnNames" value="true"/>
      <generatedKey column="ID" sqlStatement="DB2" identity="true" />
      <columnOverride column="DATE_FIELD" property="startDate" />
      <ignoreColumn column="FRED" />
      <columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" />
    </table>

  </context>
</generatorConfiguration>

一下是关于这个文件的重要提示:

  • 文件指定用来连接数据库的legacy DB2 CLI驱动,并且指定驱动的位置。
  • The Java Type Resolver should not force the use of BigDecimal fields - this means that integral types (Short, Integer, Long, etc.) will be substituted if possible. This feature is an attempt to make database DECIMAL and NUMERIC columns easier to deal with.
  • The Java model generator should use sub-packages. This means that the generated model objects will be placed in a package called test.model.db2admin in this case (because the table is in the DB2ADMIN schema). If the enableSubPackages attribute was set to false, then the package would be test.model. The Java model generator should also trim strings. This means that the setters for any String properties will call the trim function - this is useful if your database might return blank characters at the end of character columns.
  • The SQL Map generator should use sub-packages. This means that the generated XML files will be placed in a package called test.xml.db2admin in this case (because the table is in the DB2ADMIN schema). If the enableSubPackages attribute was set to false, then the package would be test.xml.
  • The DAO generator should use sub-packages. This means that the generated DAO classes will be placed in a package called test.dao.db2admin in this case (because the table is in the DB2ADMIN schema). If the enableSubPackages attribute was set to false, then the package would be test.dao. The DAO generator should generate mapper interfaces that reference an XML configuration for MyBatis.
  • The file specifies only one table will be introspected, but many more could be specified. Important notes about the specified table include:
    • The generated objects will be based on the name Customer (CustomerKey, Customer, CustomerMapper, etc.) - rather than on the table name.
    • Actual column names will be used as properties. If this property were set to false (or not specified), then MBG would attempt to camel case the column names. In either case, the name can be overridden by the <columnOverride> element
    • The column has a generated key, it is an identity column, and the database type is DB2. This will cause MBG to generate the proper <selectKey> element in the generated <insert> statement so that the newly generated key can be returned (using DB2 specific SQL).
    • The column DATE_FIELD will be mapped to a property called startDate. This will override the default property which would be DATE_FIELD in this case, or dateField if the useActualColumnNames property was set to false.
    • The column FRED will be ignored. No SQL will list the field, and no Java property will be generated.
    • The column LONG_VARCHAR_FIELD will be treated as a VARCHAR field, regardless of the actual data type.
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MyBatis provides the `parameterMap` element as a way to map complex parameter objects to the SQL statement parameters. It is used when you have a complex object with multiple properties and you want to map them to the corresponding parameters in your SQL statement. To use the `parameterMap`, you need to define it in your MyBatis XML configuration file. Here's an example: ```xml <!-- Define the parameterMap --> <parameterMap id="myParameterMap" type="com.example.MyParameterObject"> <parameter property="param1" jdbcType="VARCHAR"/> <parameter property="param2" jdbcType="INTEGER"/> <!-- more parameters... --> </parameterMap> <!-- Use the parameterMap in your SQL statement --> <select id="myQuery" parameterMap="myParameterMap"> SELECT * FROM my_table WHERE column1 = #{param1} AND column2 = #{param2} <!-- more conditions... --> </select> ``` In the above example, `com.example.MyParameterObject` is a Java class representing the complex parameter object. The `parameterMap` element defines the mappings between the properties of `MyParameterObject` and the SQL statement parameters. Each `parameter` element specifies the property name and the corresponding JDBC type. You can then reference the `parameterMap` in your SQL statement using the `parameterMap` attribute of the statement. The `#{param1}` and `#{param2}` placeholders will be replaced with the values from the corresponding properties of the parameter object. Note that starting from MyBatis 3, it is recommended to use annotation-based parameter mapping (`@Param` annotation) or inline parameter mapping (`#{property}`) instead of `parameterMap` for simplicity and better readability.
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