Java MyBatis 返回类型

Java►MyBatis , 评论

返回单个结果

Map

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<select id="selectMap" resultType="java.util.Map">
    SELECT id, name, email FROM user LIMIT 1   
</select>
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@MapKey("id")
Map<Long, Object> selectMap();
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@Test
public void selectMap() {
    Map<Long, Object> map = mapper.selectMap();
    System.out.println(JSON.toJSONString(map));
}

返回结果 

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{"1":{"name":"ifan","id":1,"email":"ifan@qq.com"}}

LinkedHashMap

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<select id="selectLinkedHashMap" resultType="java.util.LinkedHashMap">
    SELECT id, name, email FROM user LIMIT 1 
</select>
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LinkedHashMap<String, Object> selectLinkedHashMap();  
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LinkedHashMap<String, Object> linkedHashMap = mapper.selectLinkedHashMap();

返回结果

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{"id":1,"name":"ifan","email":"ifan@qq.com"}

返回多个结果

List<Map>

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<select id="selectMapList" resultType="java.util.Map">
    SELECT id, name, email FROM user LIMIT 1
</select>
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List<Map<String, Object>> selectMapList();
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List<Map<String, Object>> maps = mapper.selectMapList();

返回结果

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[
	{"id":1,"name":"ifan","email":"ifan@qq.com"}
	{"id":2,"name":"ifan","email":"ifan@qq.com"}
	{"id":3,"name":"ifan","email":"ifan@qq.com"}
]

Map<Map>

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<select id="selectMapMap" resultType="java.util.Map">
    SELECT id, name, email FROM user LIMIT 1
</select>
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@MapKey("id")
Map<String, Map<String, Object>> selectMapMap();
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Map<String, Map<String, Object>> stringMapMap = mapper.selectMapMap();

返回结果

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{
	"1":{"id":1,"name":"ifan","email":"ifan@qq.com"},
	"2":{"id":2,"name":"ifan","email":"ifan@qq.com"},
	"3":{"id":3,"name":"ifan","email":"ifan@qq.com"},
}

List<LinkedHashMap>

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<select id="selectListLinkedHashMap" resultType="java.util.LinkedHashMap">
    SELECT id, name, email FROM user LIMIT 1
</select>
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List<LinkedHashMap<String, Object>> selectListLinkedHashMap();    
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List<LinkedHashMap<String, Object>> linkedHashMap = mapper.selectListLinkedHashMap();
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[
	{"id":1,"name":"ifan","email":"ifan@qq.com"},
	{"id":2,"name":"ifan","email":"ifan@qq.com"},
	{"id":3,"name":"ifan","email":"ifan@qq.com"},
]

Map<LinkedHashMap>

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<select id="selectMapLinkedHashMap" resultType="java.util.LinkedHashMap">
    SELECT id, name, email FROM user LIMIT 1
</select>
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@MapKey("id")
Map<String, LinkedHashMap<String, Object>> selectMapLinkedHashMap();
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Map<String, LinkedHashMap<String, Object>> mapLinkedHashMaps = mapper.selectMapLinkedHashMap();
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{
	"1":{"id":1,"name":"ifan","email":"ifan@qq.com"},
	"2":{"id":2,"name":"ifan","email":"ifan@qq.com"},
	"3":{"id":3,"name":"ifan","email":"ifan@qq.com"},
}

List<Pair<Integer, Long>>

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<select id="countByAuthor" resultType="javafx.util.Pair">
    SELECT id, name, email FROM user LIMIT 1
</select>
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List<Pair<Integer, Long>> countByAuthor();
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List<Pair<Integer, Long>> list = mapper.countByAuthor();
Map<Integer, Long> map = list.stream().collect(Collectors.toMap(Pair::getKey, Pair::getValue));

返回结果

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{"ifan": 1, "fan":2}

iFan在路上啊

个人简介。