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MyBatis动态SQL之映射配置
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1 映射

<mapper namespace="cn.tedu.dynamic.dao.MemberDao">
    ...
    <select id="search" resultType="Member">
        select id, nick, gender, age, city from t_member where 1 = 1
        <if test="gender != null">and gender = #{gender}</if>  \___/
        <if test="minAge != null">and age &gt;= #{minAge}</if>   |
        <if test="maxAge != null">and age &lt;= #{maxAge}</if>  防止
        <if test="city != null">and city = #{city}</if>         and
    </select>       |                 |        |                打头
    ...             |               表字段     |
</mapper>           |__________________________|
                                 |
                           HashMap的键或
                         参数实体类的属性

使用“&gt;”表示“>” \
                    避免“<>”与XML中的标签标记混淆。
使用“&lt;”表示“<” /

运行测试用例。

例程：Dynamic

2 更多条件组合

public class MemberDaoTest {
    ...
    @Test
    public void testSearch() {
        MemberDao dao = MyBatisUtil.getMapper(MemberDao.class);
        /*
        HashMap<String, Object> params = new HashMap<>();
        params.put("gender", "女");
        params.put("minAge", 20);
        params.put("maxAge", 30);
        params.put("city", "北京");
        */
        SearchParams params = new SearchParams("女", 20, 30, "北京");
        List<Member> members = dao.search(params);
        System.out.println(members);

        params = new SearchParams();
        members = dao.search(params);
        System.out.println(members);

        params = new SearchParams();
        params.setGender("男");
        members = dao.search(params);
        System.out.println(members);

        params = new SearchParams();
        params.setMinAge(25);
        params.setMaxAge(45);
        params.setCity("上海");
        members = dao.search(params);
        System.out.println(members);
    }
    ...
}

运行测试用例。

例程：Dynamic