表結(jié)構(gòu)：
表名稱為constant
需求：
現(xiàn)在想查詢type為2徒河、3的所有數(shù)據(jù)（甚至想查詢type為1,2,3,4,5....,100的所有數(shù)據(jù)）并且返回的值是Map（key為id刚照，value為constant類）
如果采用一個(gè)一個(gè)傳參的方式進(jìn)行查詢肯定是不行的,以下是通過(guò)Mybatis提供的foreach標(biāo)簽并配合in進(jìn)行查詢
Mapper：
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.jm.dao.ConstantDao">
<resultMap id="BaseResultMap" type="com.jm.model.Constant">
<result column="id" property="id" jdbcType="BIGINT" />
<result column="key" property="key" jdbcType="VARCHAR" />
<result column="value" property="value" jdbcType="VARCHAR" />
<result column="type" property="type" jdbcType="INTEGER" />
</resultMap>
<!--此處一定要注意屬性的名稱是resultMap，并且值為“BaseResultMap”這樣就可以保證返回的Map的value是Constant的對(duì)象 -->
<select id="loadConstantByType" resultMap="BaseResultMap">
select * from constant where type in
<!-- 這里要將collection屬性的值標(biāo)記為list摔认，不然不知道傳入的參數(shù)是list separator表示分離器 item表示list中的一個(gè)元素 -->
<foreach item="item" index="index" collection="list" open="("
separator="," close=")">#{item}</foreach>
</select>
</mapper>
DAO：
import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.MapKey;
import org.springframework.stereotype.Repository;
@Repository
public interface ConstantDao {
/**
* 注釋@MapKey表示表中那個(gè)字段作為Map的key
* @return
*/
@MapKey("id")
Map<Long,Constant> loadConstantByType(List<Integer> type);
}
POJO實(shí)體類：
public class Constant {
private Long id;
private String key;
private String value;
private Integer type;
public String toString(){
StringBuffer s = new StringBuffer("Constant:{");
s.append("id:").append(this.id).append(",");
s.append("key:").append(this.key).append(",");
s.append("value:").append(this.value).append(",");
s.append("type:").append(this.type).append("}");
return s.toString();
}
public Constant() {
super();
// TODO Auto-generated constructor stub
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getKey() {
return key;
}
public void setKey(String key) {
this.key = key == null ? null : key.trim();
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value == null ? null : value.trim();
}
public Integer getType() {
return type;
}
public void setType(Integer type) {
this.type = type;
}
}
pojo中的實(shí)體類最好重寫(xiě)toString方法
junitTest:
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:spring.xml", "classpath:spring-mybatis.xml" })
public class MubatisMapTest {
@Autowired
private ConstantDao constantDao;
@Test
public void mapTest1() {
List<Integer> typeList = Arrays.asList(2,3);
Map<Long,Constant> constantMap = constantDao.loadConstantByType(typeList);
System.out.println(constantMap);
}
}
最終測(cè)試結(jié)果：
Paste_Image.png
