注意：本文并非原创，来自http://www.mkyong.com
目录：
- Mongodb
- Query document
- BasicQuery example
- findOne example
- find and $inc example
- find and $gt, $lt, $and example
- find and sorting example
- find and $regex example
- Full Example
Mongodb
Query document
Here we show you a few examples to query documents from MongoDB, by using Query, Criteria and along with some of the common operators.
> db.users.find()
{ "_id" : ObjectId("id"), "ic" : "1001", "name" : "ant", "age" : 10 }
{ "_id" : ObjectId("id"), "ic" : "1002", "name" : "bird", "age" : 20 }
{ "_id" : ObjectId("id"), "ic" : "1003", "name" : "cat", "age" : 30 }
{ "_id" : ObjectId("id"), "ic" : "1004", "name" : "dog", "age" : 40 }
{ "_id" : ObjectId("id"), "ic" : "1005", "name" : "elephant", "age" : 50 }
{ "_id" : ObjectId("id"), "ic" : "1006", "name" : "frog", "age" : 60 }
P.S This example is tested under mongo-java-driver-2.11.0.jar and spring-data-mongodb-1.2.0.RELEASE.jar
BasicQuery example
If you are familiar with the core MongoDB console find() command, just put the “raw” query inside the BasicQuery.
BasicQuery query1 = new BasicQuery("{ age : { $lt : 40 }, name : 'cat' }");
User userTest1 = mongoOperation.findOne(query1, User.class);
System.out.println("query1 - " + query1.toString());
System.out.println("userTest1 - " + userTest1);
Output
query1 - Query: { "age" : { "$lt" : 40} , "name" : "cat"}, Fields: null, Sort: { }
userTest1 - User [id=id, ic=1003, name=cat, age=30]
findOne example
findOne will return the single document that matches the query, and you can a combine few criteria with Criteria.and() method. See example 4 for more details.
Query query2 = new Query();
query2.addCriteria(Criteria.where("name").is("dog").and("age").is(40));
User userTest2 = mongoOperation.findOne(query2, User.class);
System.out.println("query2 - " + query2.toString());
System.out.println("userTest2 - " + userTest2);
Output
query2 - Query: { "name" : "dog" , "age" : 40}, Fields: null, Sort: null
userTest2 - User [id=id, ic=1004, name=dog, age=40]
find and $inc example
Find and return a list of documents that match the query. This example also shows the use of $inc operator.
List<Integer> listOfAge = new ArrayList<Integer>();
listOfAge.add(10);
listOfAge.add(30);
listOfAge.add(40);
Query query3 = new Query();
query3.addCriteria(Criteria.where("age").in(listOfAge));
List<User> userTest3 = mongoOperation.find(query3, User.class);
System.out.println("query3 - " + query3.toString());
for (User user : userTest3) {
System.out.println("userTest3 - " + user);
}
Output
query3 - Query: { "age" : { "$in" : [ 10 , 30 , 40]}}, Fields: null, Sort: null
userTest3 - User [id=id, ic=1001, name=ant, age=10]
userTest3 - User [id=id, ic=1003, name=cat, age=30]
userTest3 - User [id=id, ic=1004, name=dog, age=40]
find and $gt, $lt, $and example
Find and return a list of documents that match the query. This example also shows the use of $gt, $lt and $and operators.
Query query4 = new Query();
query4.addCriteria(Criteria.where("age").lt(40).and("age").gt(10));
List<User> userTest4 = mongoOperation.find(query4, User.class);
System.out.println("query4 - " + query4.toString());
for (User user : userTest4) {
System.out.println("userTest4 - " + user);
}
Oppss, an error message is generated, the API doen’t works in this way :)
Due to limitations of the com.mongodb.BasicDBObject, you can't add a second 'age' expression
specified as 'age : { "$gt" : 10}'. Criteria already contains 'age : { "$lt" : 40}'.
You can’t use Criteria.and() to add multiple criteria into the same field, to fix it, use Criteria.andOperator(), see updated example :
Query query4 = new Query();
query4.addCriteria(
Criteria.where("age").exists(true)
.andOperator(
Criteria.where("age").gt(10),
Criteria.where("age").lt(40)
)
);
List<User> userTest4 = mongoOperation.find(query4, User.class);
System.out.println("query4 - " + query4.toString());
for (User user : userTest4) {
System.out.println("userTest4 - " + user);
}
Output
query4 - Query: { "age" : { "$lt" : 40} , "$and" : [ { "age" : { "$gt" : 10}}]}, Fields: null, Sort: null
userTest4 - User [id=51627a0a3004cc5c0af72964, ic=1002, name=bird, age=20]
userTest4 - User [id=51627a0a3004cc5c0af72965, ic=1003, name=cat, age=30]
find and sorting example
Find and sort the result.
Query query5 = new Query();
query5.addCriteria(Criteria.where("age").gte(30));
query5.with(new Sort(Sort.Direction.DESC, "age"));
List<User> userTest5 = mongoOperation.find(query5, User.class);
System.out.println("query5 - " + query5.toString());
for (User user : userTest5) {
System.out.println("userTest5 - " + user);
}
Output
query5 - Query: { "age" : { "$gte" : 30}}, Fields: null, Sort: { "age" : -1}
userTest5 - User [id=id, ic=1006, name=frog, age=60]
userTest5 - User [id=id, ic=1005, name=elephant, age=50]
userTest5 - User [id=id, ic=1004, name=dog, age=40]
userTest5 - User [id=id, ic=1003, name=cat, age=30]
find and $regex example
Find by regular expression pattern.
Query query6 = new Query();
query6.addCriteria(Criteria.where("name").regex("D.*G", "i"));
List<User> userTest6 = mongoOperation.find(query6, User.class);
System.out.println("query6 - " + query6.toString());
for (User user : userTest6) {
System.out.println("userTest6 - " + user);
}
Output
query6 - Query: { "name" : { "$regex" : "D.*G" , "$options" : "i"}}, Fields: null, Sort: null
userTest6 - User [id=id, ic=1004, name=dog, age=40]
Full Example
A full example to combine everything from example 1 to 6.
SpringMongoConfig.java
package com.mkyong.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.mongodb.core.MongoTemplate;
import com.mongodb.MongoClient;
/**
* Spring MongoDB configuration file
*
*/
@Configuration
public class SpringMongoConfig{
public @Bean
MongoTemplate mongoTemplate() throws Exception {
MongoTemplate mongoTemplate =
new MongoTemplate(new MongoClient("127.0.0.1"),"yourdb");
return mongoTemplate;
}
}
User.java
package com.mkyong.model;
import java.util.Date;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.index.Indexed;
import org.springframework.data.mongodb.core.mapping.Document;
import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.format.annotation.DateTimeFormat.ISO;
@Document(collection = "users")
public class User {
@Id
private String id;
@Indexed
private String ic;
private String name;
private int age;
//getter, setter and constructor methods
}
QueryApp.java
package com.mkyong.core;
import java.util.ArrayList;
import java.util.List;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.data.domain.Sort;
import org.springframework.data.mongodb.core.MongoOperations;
import org.springframework.data.mongodb.core.query.BasicQuery;
import org.springframework.data.mongodb.core.query.Criteria;
import org.springframework.data.mongodb.core.query.Query;
import com.mkyong.config.SpringMongoConfig;
import com.mkyong.model.User;
/**
* Query example
*
* @author mkyong
*
*/
public class QueryApp {
public static void main(String[] args) {
ApplicationContext ctx =
new AnnotationConfigApplicationContext(SpringMongoConfig.class);
MongoOperations mongoOperation =
(MongoOperations) ctx.getBean("mongoTemplate");
// insert 6 users for testing
List<User> users = new ArrayList<User>();
User user1 = new User("1001", "ant", 10);
User user2 = new User("1002", "bird", 20);
User user3 = new User("1003", "cat", 30);
User user4 = new User("1004", "dog", 40);
User user5 = new User("1005", "elephant",50);
User user6 = new User("1006", "frog", 60);
users.add(user1);
users.add(user2);
users.add(user3);
users.add(user4);
users.add(user5);
users.add(user6);
mongoOperation.insert(users, User.class);
System.out.println("Case 1 - find with BasicQuery example");
BasicQuery query1 = new BasicQuery("{ age : { $lt : 40 }, name : 'cat' }");
User userTest1 = mongoOperation.findOne(query1, User.class);
System.out.println("query1 - " + query1.toString());
System.out.println("userTest1 - " + userTest1);
System.out.println("\nCase 2 - find example");
Query query2 = new Query();
query2.addCriteria(Criteria.where("name").is("dog").and("age").is(40));
User userTest2 = mongoOperation.findOne(query2, User.class);
System.out.println("query2 - " + query2.toString());
System.out.println("userTest2 - " + userTest2);
System.out.println("\nCase 3 - find list $inc example");
List<Integer> listOfAge = new ArrayList<Integer>();
listOfAge.add(10);
listOfAge.add(30);
listOfAge.add(40);
Query query3 = new Query();
query3.addCriteria(Criteria.where("age").in(listOfAge));
List<User> userTest3 = mongoOperation.find(query3, User.class);
System.out.println("query3 - " + query3.toString());
for (User user : userTest3) {
System.out.println("userTest3 - " + user);
}
System.out.println("\nCase 4 - find list $and $lt, $gt example");
Query query4 = new Query();
// it hits error
// query4.addCriteria(Criteria.where("age").lt(40).and("age").gt(10));
query4.addCriteria(
Criteria.where("age").exists(true).andOperator(
Criteria.where("age").gt(10),
Criteria.where("age").lt(40)
)
);
List<User> userTest4 = mongoOperation.find(query4, User.class);
System.out.println("query4 - " + query4.toString());
for (User user : userTest4) {
System.out.println("userTest4 - " + user);
}
System.out.println("\nCase 5 - find list and sorting example");
Query query5 = new Query();
query5.addCriteria(Criteria.where("age").gte(30));
query5.with(new Sort(Sort.Direction.DESC, "age"));
List<User> userTest5 = mongoOperation.find(query5, User.class);
System.out.println("query5 - " + query5.toString());
for (User user : userTest5) {
System.out.println("userTest5 - " + user);
}
System.out.println("\nCase 6 - find by regex example");
Query query6 = new Query();
query6.addCriteria(Criteria.where("name").regex("D.*G", "i"));
List<User> userTest6 = mongoOperation.find(query6, User.class);
System.out.println("query6 - " + query6.toString());
for (User user : userTest6) {
System.out.println("userTest6 - " + user);
}
mongoOperation.dropCollection(User.class);
}
}
Output
Case 1 - find with BasicQuery example
query1 - Query: { "age" : { "$lt" : 40} , "name" : "cat"}, Fields: null, Sort: { }
userTest1 - User [id=id, ic=1003, name=cat, age=30]
Case 2 - find example
query2 - Query: { "name" : "dog" , "age" : 40}, Fields: null, Sort: null
userTest2 - User [id=id, ic=1004, name=dog, age=40]
Case 3 - find list $inc example
query3 - Query: { "age" : { "$in" : [ 10 , 30 , 40]}}, Fields: null, Sort: null
userTest3 - User [id=id, ic=1001, name=ant, age=10]
userTest3 - User [id=id, ic=1003, name=cat, age=30]
userTest3 - User [id=id, ic=1004, name=dog, age=40]
Case 4 - find list $and $lt, $gt example
query4 - Query: { "age" : { "$lt" : 40} , "$and" : [ { "age" : { "$gt" : 10}}]}, Fields: null, Sort: null
userTest4 - User [id=id, ic=1002, name=bird, age=20]
userTest4 - User [id=id, ic=1003, name=cat, age=30]
Case 5 - find list and sorting example
query5 - Query: { "age" : { "$gte" : 30}}, Fields: null, Sort: { "age" : -1}
userTest5 - User [id=id, ic=1006, name=frog, age=60]
userTest5 - User [id=id, ic=1005, name=elephant, age=50]
userTest5 - User [id=id, ic=1004, name=dog, age=40]
userTest5 - User [id=id, ic=1003, name=cat, age=30]
Case 6 - find by regex example
query6 - Query: { "name" : { "$regex" : "D.*G" , "$options" : "i"}}, Fields: null, Sort: null
userTest6 - User [id=id, ic=1004, name=dog, age=40]
