java map reduce，mybatis擴展ResultMap

我們可以從一個<resultMap>中擴展出一個新的<resultMap>,這樣原先<resultMap>屬性就可以繼承過來了。

<resultMap?type="Student"?id="StudentResult"><id?property="studId"?column="stud_id"?/><result?property="name"?column="name"?/><result?property="email"?column="email"?/><result?property="phone"?column="phone"?/>
</resultMap>
<resultMap?type="Student"?id="StudentWithAddre***esult"?extends="StudentResult"><result?property="address.addrId"?column="addr_id"?/><result?property="address.street"?column="street"?/><result?property="address.city"?column="city"?/><result?property="address.state"?column="state"?/><result?property="address.zip"?column="zip"?/><result?property="address.country"?column="country"?/>
</resultMap>

這樣id為StudentResult的<resultMap>就擴展了id為StudentResult的<resultMap>

如果你指向映射student表中的內容，你可以使用id為StudentResult的<resultMap>

<select?id="findStudentById"?parameterType="int"?resultMap="StudentResult">SELECT?*?FROM?STUDENTS?WHERE?STUD_ID=#{studId}
</select>

java map reduce，如果你想要映射Student和Address表中的數據，你可以使用id為StudentWithAddre***esult的<resultMap>

<select?id="selectStudentWithAddress"?parameterType="int"?resultMap="StudentWithAddre***esult">SELECT?STUD_ID,?NAME,?EMAIL,?PHONE,?A.ADDR_ID,?STREET,?CITY,STATE,?ZIP,?COUNTRYFROM?STUDENTS?S?LEFT?OUTER?JOIN?ADDRESSES?A?ONS.ADDR_ID=A.ADDR_IDWHERE?STUD_ID=#{studId}
</select>