MyBatis 本身并不支持直接使用 LinkedHashMap,但你可以通过自定义类型处理器(TypeHandler)来实现这一需求。下面是一个简单的示例,展示了如何在 MyBatis 中结合 LinkedHashMap 实现复杂数据结构。
public class ComplexObject {
private int id;
private String name;
private LinkedHashMap<String, Object> attributes;
// 省略 getter 和 setter 方法
}
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.TypeHandler;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.LinkedHashMap;
public class ComplexObjectTypeHandler extends BaseTypeHandler<ComplexObject> {
@Override
public void setNonNullParameter(PreparedStatement ps, int i, ComplexObject parameter, JdbcType jdbcType) throws SQLException {
ps.setInt(i, parameter.getId());
ps.setString(i + 1, parameter.getName());
ps.setObject(i + 2, parameter.getAttributes());
}
@Override
public ComplexObject getNullableResult(ResultSet rs, String columnName) throws SQLException {
int id = rs.getInt(columnName);
String name = rs.getString(columnName + "_name");
LinkedHashMap<String, Object> attributes = rs.getObject(columnName + "_attributes", LinkedHashMap.class);
return new ComplexObject(id, name, attributes);
}
@Override
public ComplexObject getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
int id = rs.getInt(columnIndex);
String name = rs.getString(columnIndex + 1);
LinkedHashMap<String, Object> attributes = rs.getObject(columnIndex + 2, LinkedHashMap.class);
return new ComplexObject(id, name, attributes);
}
@Override
public ComplexObject getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
int id = cs.getInt(columnIndex);
String name = cs.getString(columnIndex + 1);
LinkedHashMap<String, Object> attributes = cs.getObject(columnIndex + 2, LinkedHashMap.class);
return new ComplexObject(id, name, attributes);
}
}
<typeHandlers>
<typeHandler handler="com.example.ComplexObjectTypeHandler" javaType="com.example.ComplexObject"/>
</typeHandlers>
<resultMap id="complexObjectResultMap" type="com.example.ComplexObject">
<id property="id" column="id"/>
<result property="name" column="name"/>
<result property="attributes" column="attributes" javaType="java.util.LinkedHashMap"/>
</resultMap>
<select id="getComplexObjectById" resultMap="complexObjectResultMap">
SELECT * FROM complex_objects WHERE id = #{id}
</select>
通过这种方式,你可以在 MyBatis 中结合 LinkedHashMap 实现复杂数据结构。