Query查询操作

org.springframework.data.mongodb.core.MongoTemplate

MongoTemplate对MongoDB的CRUD操作

1. 查询操作mongoTemplate.find (query, entityClass)
   参数说明:
   entityClass：实体class,也就是要把文档转换成对应的实体
   query :
   query查询语句的实现方式有两种
           第一种实现方式
           mongoTemplate.find (new Query(new Criteria("onumber").is("002")),entityClass)
           第二种实现方式
           Criteria是标准查询的接口，可以引用静态的Criteria.where的把多个条件组合在一起，
           就可以轻松地将多个方法标准和查询连接起来，方便我们操作查询语句
           mongoTemplate.find (new Query(Criteria.where("onumber").is("002")),entityClass)
           即：查询条件onumber="002"

           多个条件组合查询
           例如：onumber="002" and cname="zcy"
           Query query=new Query()
           query.addCriteria(new Criteria("onumber").is("002"));
           query.addCriteria(new Criteria("cname").is("zcy1"));
           = mongoTemplate.find (query,entityClass);


       public static void main(String[] args) {
Query query = new Query();
query.addCriteria(new Criteria("onumber").is("002"));
query.addCriteria(new Criteria("cname").is("zcy1"));
// Query: { "onumber" : "002" , "cname" : "zcy1"}, Fields: null, Sort: null
System.err.println(query.toString());
Query query2 = new Query(Criteria.where("onumber").is("002").and("cname").is("zcy"));
// Query: { "onumber" : "002" , "cname" : "zcy"}, Fields: null, Sort: null
System.out.println(query2.toString());
}

           第二种实现方式
           mongoTemplate.find (new Query(Criteria.where("onumber").is("002").and("cname").is("zcy")),entityClass)


       源码:
       where:
   public static Criteria where(String key) {
       return new Criteria(key);
   }

   is:
   public Criteria is(Object o) {

       if (!isValue.equals(NOT_SET)) {
           throw new InvalidMongoDbApiUsageException(
                   "Multiple 'is' values declared. You need to use 'and' with multiple criteria");
       }

       if (lastOperatorWasNot()) {
           throw new InvalidMongoDbApiUsageException("Invalid query: 'not' can't be used with 'is' - use 'ne' instead.");
       }

       this.isValue = o;
       return this;
   }
       and:
   public Criteria and(String key) {
       return new Criteria(this.criteriaChain, key);
   }

   public <T> List<T> find(Query query, Class<T> entityClass) {
       return find(query, entityClass, determineCollectionName(entityClass));
   }





   例如：onumber="002" or cname="zcy"

@RestController
@Api
@RequestMapping(value = "/v1.0")
public class DemoController {

@PostMapping(value = "/query")
public Response query(@RequestParam(value = "name", required = false) String name,
@RequestParam(value = "age", required = false) String age) {

Response response = new Response();
try {
MLoggerUtils.info("{},{}", name, age);
Query query = new Query();
List<Criteria> list = new ArrayList<Criteria>();
Criteria criteria = new Criteria();
Criteria[] criterias = {};
if (StringUtils.isNotEmpty(name)) {
list.add(new Criteria("name").is(name));
}
if (StringUtils.isNotEmpty(name)) {
list.add(new Criteria("age").is(age));
}
if (CollectionUtils.isNotEmpty(list)) {
criteria.orOperator(list.toArray(criterias));
}

query.addCriteria(criteria);
MLoggerUtils.info("param{}", query.toString());
} catch (Exception e) {
// TODO: handle exception
}
return null;
}
public static void main(String[] args) {
Query query = new Query();
query.addCriteria(new Criteria("onumber").is("002"));
query.addCriteria(new Criteria("cname").is("zcy1"));
// Query: { "onumber" : "002" , "cname" : "zcy1"}, Fields: null, Sort:
// null
System.err.println(query.toString());
Query query2 = new Query(Criteria.where("onumber").is("002").and("cname").is("zcy"));
// Query: { "onumber" : "002" , "cname" : "zcy"}, Fields: null, Sort:
// null
System.out.println(query2.toString());

Query query3 = new Query(new Criteria().orOperator(Criteria.where("onumber").is("002"), Criteria.where("cname").is("zcy")));
System.out.println(query3.toString());
// Query: { "$or" : [ { "onumber" : "002"} , { "cname" : "zcy"}]},
// Fields: null, Sort: null
}

}

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