（一）使用Query和Criteria类
假设数据库状态如下：
[{"_id" : ObjectId("5b9a10d25ef6a842e429df6e"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "zhangsan",
"age" : "30"},
{"_id" : ObjectId("5b9a244d5ef6a8ae118f1fc4"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "lisi",
"age" : "25"},
{"_id" : ObjectId("5b9f74485ef6a831080b3d19"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "wangwu",
"age" : "20"}]
1、is查询
Query query = new Query();
query.addCriteria(Criteria.where("name").is("zhangsan"));
User user = mongoTemplate.find(query, User.class);
结果返回：
{"_id" : ObjectId("5b9a10d25ef6a842e429df6e"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "zhangsan",
"age" : "30"}
2、正则查询
Query query = new Query();
query.addCriteria(Criteria.where("name").regex("^w"));
User user = mongoTemplate.find(query, User.class);
结果返回：
{"_id" : ObjectId("5b9f74485ef6a831080b3d19"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "wangwu",
"age" : "20"}
3、lt和gt
lt(小于)、gt(大于)、lte(小于等于)、gte(大于等于)
Query query = new Query();
query.addCriteria(Criteria.where("age").lt("35").gt("20"));
List<User> user = mongoTemplate.find(query, User.class);
结果返回：
[{"_id" : ObjectId("5b9a10d25ef6a842e429df6e"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "zhangsan",
"age" : "30"},
{"_id" : ObjectId("5b9a244d5ef6a8ae118f1fc4"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "lisi",
"age" : "25"}]
4、结果排序
Query query = new Query();
query.with(new Sort(Sort.Direction.ASC, "age"));
List<User> user = mongoTemplate.find(query, User.class);
结果返回：
[{"_id" : ObjectId("5b9f74485ef6a831080b3d19"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "wangwu",
"age" : "20"},
{"_id" : ObjectId("5b9a244d5ef6a8ae118f1fc4"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "lisi",
"age" : "25"},
{"_id" : ObjectId("5b9a10d25ef6a842e429df6e"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "zhangsan",
"age" : "30"}]
5、分页
Query query = new Query();
PageRequest pageRequest = PageReqest.of(0, 2);
query.with(pageRequest);
结果返回两页大小为2的页面。
（二）生成的查询方法
需要在接口上继承MongoRepository，如下：
public interface UserRepository extends MongoRepository<User, String> {
......
}
与MongoRepository相关接口
1、通过FindBy查询
使用FindBy通过entity实体属性查询
User findByName(String name)；
User user = userRepository.findByName("zhangsan");得到跟1.1一样的结果
2、StartingWith和EndingWith
List<User> findByNameStartingWith(String regex);
List<User> findByNameEndingWith(String regex);
List<User> user = userRepository.findByNameStartingWith("z");
List<User> user = userRepository.findByNameEndingWith("n");
两个查询得到一样的结果
{"_id" : ObjectId("5b9a10d25ef6a842e429df6e"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "zhangsan",
"age" : "30"}
3、Between
List<User> findByAgeBetween(int gt, int lt);
List<User> user = userRepository.findByAgeBetween(20, 35);得到跟1.3一样的结果
4、Like模糊查询
List<User> findByNameLike(String name);
List<User> user = userRepository.findByNameLike("n");
结果返回：
[{"_id" : ObjectId("5b9a10d25ef6a842e429df6e"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "zhangsan",
"age" : "30"},
{"_id" : ObjectId("5b9f74485ef6a831080b3d19"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "wangwu",
"age" : "20"}]
5、OrderBy排序
在2.4模糊查询上按年龄递增排序
List<User> findByNameLikeOrderByAgeAsc(String name);
List<User> user = userRepository.findByNameLikeOrderByAgeAsc("n");
结果返回：
[{"_id" : ObjectId("5b9f74485ef6a831080b3d19"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "wangwu",
"age" : "20"},
{"_id" : ObjectId("5b9a10d25ef6a842e429df6e"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "zhangsan",
"age" : "30"}]
6、使用Top和First限制查询的结果大小
User findTopByOrderByAgeDesc();
User user = userRepository.findTopByOrderByAgeDesc();
结果返回：
{"_id" : ObjectId("5b9a10d25ef6a842e429df6e"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "zhangsan",
"age" : "30"}
List<User> findFirst2ById(String id);
List<User> user = userRepository.findFirst2ById(String id);
结果返回：
[{"_id" : ObjectId("5b9a10d25ef6a842e429df6e"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "zhangsan",
"age" : "30"},
{"_id" : ObjectId("5b9a244d5ef6a8ae118f1fc4"),
"_class" : "com.ceshi.mongo.entity.User",
"name" : "lisi",
"age" : "25"}]
7、分页
Page<User> findAll(PageAble pageable);
Page<User> page = userRepository.findAll(PageRequest.of(0, 2));
（三）使用@Query注解
1、对2.1使用@Query注解查询
@Query("{ `name` : ?0 }")
User findByName(String name)；
占位符?0引用方法的第一个参数。
2、正则表达式
对2.4使用@Query注解查询
@Query("{ `name` : { $regex : ?0 }}")
List<User> findByRegexName(String regex);
3、对2.3使用@Query注解查询
@Query("{ `age` : { $gt : ?0 , $lt : ?1 }}")
List<User> findByAgeBetween(int gt, int lt);
4、使用查询语法
@Query(value = "select * from User u where u.age>?1 and u.age<?2")
List<User> findByAgeBetween(int gt, int lt);
like表达式
@Query(value = "select * from User u where u.name like %:name%")
Lise<User> findByName(@Param("name") String name);
使用@Param注解注入参数
@Query(value = "select * from User u where u.name = :name and u.age = :age")
Lise<User> findByNamedParam(@Param("name") String name, @Param("age") Int age);
