1. 使用List<Map.Entry<String, String>> params作为传入参数

  • service层：
    public List<Student> getMultiStudentInMap(List<Map.Entry<String, String>> params, long percentage) {        System.out.println(params);        return studentMapper.selectForeachEntry(params, percentage);    }
  • mapper.java
    public List<Student> selectForeachEntry(@Param("params") List<Map.Entry<String, String>> params, @Param("percentage") long percentage);
  • mapper.xml
    <!-- 在foreach中，传入参数为Map或Map.Entry对象时，index是键，item是值 -->    <select id="selectForeachEntry" resultMap="studentResult">        select * from test_student t where t.percentage = #{percentage}        <if test="params.size() > 0">            and (            <foreach item="param" index="index" collection="params" separator=" or ">                (t.name = #{index} and t.branch = #{param})             </foreach>            )        </if>    </select>
  • 调用方法：
        List<Map.Entry<String, String>> idList = new ArrayList<>();        Map<String, String> map = new TreeMap<>();        map.put("name_1", "a");        map.put("name_2", "b");        map.put("name_3", "c");        Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();        while (it.hasNext()) {            idList.add(it.next());        }                List<Student> students = studentDao.getMultiStudentInMap(idList, 0);
  • mybatis生成的结果：
==> Preparing: select * from test_student t where t.percentage = ? and ( (t.name = ? and t.branch = ?) or (t.name = ? and t.branch = ?) or (t.name = ? and t.branch = ?) ) ==> Parameters: 0(Long), name_1(String), a(String), name_2(String), b(String), name_3(String), c(String)<== Total: 0
  • 缺点：

使用Map生成Map.Entry有局限性，key值不能重复。不使用Map，就需要自己实现Map.Entry接口： class MyEntry implements Map.Entry<String, String> {...}

2. 自定义键值对的类

  • Pair类：
public class Pair<K, V> {    private K key;    private V value;}
  • service层：
    public List<Student> getMultiStudentByPairList(List<Pair<String, String>> myentryList, long percentage) {        System.out.println(myentryList);        return studentMapper.selectByPairList(myentryList, percentage);    }
  • mapper.java
    public List<Student> selectByPairList(@Param("pairs") List<Pair<String, String>> pairs, @Param("percentage") long percentage);
  • mapper.xml
    <!-- 在foreach中，传入参数为List/Set对象时，index是当前迭代的序号，item是当前迭代的元素 -->    <select id="selectByPairList" resultMap="studentResult">        select * from test_student t where t.percentage = #{percentage}        <if test="pairs.size() > 0">            and (            <foreach item="pair" index="index" collection="pairs" separator=" or ">                (t.name = #{pair.key} and t.branch = #{pair.value})             </foreach>            )        </if>    </select>
  • 调用方法：
        List<Pair<String, String>> myentryList = new ArrayList<>();        myentryList.add(new Pair<String, String>("name_1", "a"));        myentryList.add(new Pair<String, String>("name_2", "b"));        myentryList.add(new Pair<String, String>("name_3", "c"));                List<Student> students = studentDao.getMultiStudentByPairList(myentryList, 0);
  • mybatis生成的结果：
==> Preparing: select * from test_student t where t.percentage = ? and ( (t.name = ? and t.branch = ?) or (t.name = ? and t.branch = ?) or (t.name = ? and t.branch = ?) ) ==> Parameters: 0(Long), name_1(String), a(String), name_2(String), b(String), name_3(String), c(String)<== Total: 0