Data Access 之 MyBatis（八）- MyBatis 通用 Mapper（Part C）

public interface CustMapper<T> extends SelectOneMapper<T> {
}
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<bean id="mapperScannerConfigurer" class="tk.mybatis.spring.mapper.MapperScannerConfigurer">
    <!--指定接口所在的包-->
    <property name="basePackage" value="com.citi.mapper"></property>
    <!--配置自定义的CustMapper<T>接口-->
    <property name="properties">
        <value>
            mappers=com.citi.common.CustMapper
        </value>
    </property>
</bean>
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public interface TeacherMapper extends CustMapper<Teacher> {
}
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@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:application.xml")
public class TeacherMapperTest {
    @Resource
    private TeacherMapper teacherMapper;
    @Test
    public void selectOne(){
        // 构造查询条件
        Teacher record = new Teacher();
        record.setGrade("三年二班");
        record.setName("stark");
        Teacher teacher = teacherMapper.selectOne(record);
        System.out.println("查询到的内容为：" + teacher);
    }
}
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@RegisterMapper
public interface BatchUpdateMapper<T> {
    @UpdateProvider(type = BatchUpdateProvider.class, method = "dynamicSQL")
    void batchUpdate(List<T> tList);
}
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public class BatchUpdateProvider extends MapperTemplate {
    // 构造器
    public BatchUpdateProvider(Class<?> mapperClass, MapperHelper mapperHelper) {
        super(mapperClass, mapperHelper);
    }
}
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<foreach item="record" collection="list" separator=";">
    UPDATE porsche
    <set>
    por_name = #{porsche.porName},
    por_price = #{porsche.porPrice},
    por_stock = #{porsche.porStock},
    </set>
    por_id = #{porsche.por_id}
</foreach>
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public String batchUpdate(MappedStatement ms){
    // 1.新建一条SQL语句
    StringBuilder sql = new StringBuilder();
    // 2.拼接 foreach标签开头
    sql.append("<foreach item="record" collection="list" separator=";" >");
    // 获取实体类对象
    Class<?> entityClass = getEntityClass(ms);
    String updateClause = SqlHelper.updateTable(entityClass,tableName(entityClass));
    // 3.拼接 "UPDATE 表名 "
    sql.append(updateClause);
    // 4.拼接set标签开头
    sql.append("<set>");
    // 获取字段名称的集合
    Set<EntityColumn> columns = EntityHelper.getColumns(entityClass);
    // 声明主键字段
    String idColumn = null;
    String idColumnHolder = null;
    // 遍历字段
    for (EntityColumn entityColumn : columns) {
        // 判断是否是主键，是主键要放在WHERE子句后面
        boolean isPrimaryKey = entityColumn.isId();
        System.out.println(isPrimaryKey);
        if (isPrimaryKey){
            idColumn = entityColumn.getColumn();
            System.out.println(idColumn);
            idColumnHolder = entityColumn.getColumnHolder("record");
        } else {
            // 返回类似如下字符串"(实体类.属性，jdbcType=NUMERIC,typeHandler=MyTypeHandler)"
            // 获取字段名和属性名
            String column = entityColumn.getColumn();
            String columnHolder = entityColumn.getColumnHolder("record");
            // 5.拼接por_name = #{porsche.porName},
            sql.append(column).append("=").append(columnHolder).append(",");
        }
    }
    // 6.拼接set标签结尾
    sql.append("</set>");
    // 7.拼接where子句
    sql.append("where ").append(idColumn).append("=").append(idColumnHolder);
    // 8.拼接 foreach标签结尾
    sql.append("</foreach>");
    // 9.返回SQL语句
    return sql.toString();
}
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public interface CustMapper<T> extends SelectOneMapper<T>,BatchUpdateMapper<T> {
}
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@Test
public void batchUpdate(){
    List<Teacher> teacherList = new ArrayList<>();
    for (int i = 7; i < 10; i++) {
        Teacher teacher = new Teacher();
        teacher.setId(i);
        teacher.setGrade("五年" + i + "班");
        teacher.setName("Ultron " + i);
        teacher.setAddress("New York");
        teacher.setBirthDate(new Date());
        teacherList.add(teacher);
    }
    teacherMapper.batchUpdate(teacherList);
}
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@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
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