【MongoDB for Java】Java操作MongoDB

package com.hoo.test; 2 3 import java.net.UnknownHostException; 4 import com.mongodb.DB; 5 import com.mongodb.DBCollection; 6 import com.mongodb.DBCursor; 7 import com.mongodb.Mongo; 8 import com.mongodb.MongoException; 9 import com.mongodb.util.JSON; 10 11 /** 12 * MongoDB 简单示例 13 */ 14 public class SimpleTest { 15 16 public static void main(String[] args) throws UnknownHostException, MongoException { 17 Mongo mg = new Mongo(); 18 //查询所有的Database 19 for (String name : mg.getDatabaseNames()) { 20 System.out.println("dbName: " + name); 21 } 22 23 DB db = mg.getDB("test"); 24 //查询所有的聚集集合 25 for (String name : db.getCollectionNames()) { 26 System.out.println("collectionName: " + name); 27 } 28 29 DBCollection users = db.getCollection("users"); 30 31 //查询所有的数据 32 DBCursor cur = users.find(); 33 while (cur.hasNext()) { 34 System.out.println(cur.next()); 35 } 36 System.out.println(cur.count()); 37 System.out.println(cur.getCursorId()); 38 System.out.println(JSON.serialize(cur)); 39 } 40 }

 

2、 完成CRUD操作，首先建立一个MongoDB4CRUDTest.java，基本测试代码如下：

 1 package com.hoo.test;
 2  
 3 import java.net.UnknownHostException;
 4 import java.util.ArrayList;
 5 import java.util.List;
 6 import org.bson.types.ObjectId;
 7 import org.junit.After;
 8 import org.junit.Before;
 9 import org.junit.Test;
10 import com.mongodb.BasicDBObject;
11 import com.mongodb.Bytes;
12 import com.mongodb.DB;
13 import com.mongodb.DBCollection;
14 import com.mongodb.DBCursor;
15 import com.mongodb.DBObject;
16 import com.mongodb.Mongo;
17 import com.mongodb.MongoException;
18 import com.mongodb.QueryOperators;
19 import com.mongodb.util.JSON;
20  
21 /**
22  * 实现MongoDB的CRUD操作
23  */
24 public class MongoDB4CRUDTest {
25     
26     private Mongo mg = null;
27     private DB db;
28     private DBCollection users;
29     
30     @Before
31     public void init() {
32         try {
33             mg = new Mongo();
34             //mg = new Mongo("localhost", 27017);
35         } catch (UnknownHostException e) {
36             e.printStackTrace();
37         } catch (MongoException e) {
38             e.printStackTrace();
39         }
40         //获取temp DB；如果默认没有创建，mongodb会自动创建
41         db = mg.getDB("temp");
42         //获取users DBCollection；如果默认没有创建，mongodb会自动创建
43         users = db.getCollection("users");
44     }
45     
46     @After
47     public void destory() {
48         if (mg != null)
49             mg.close();
50         mg = null;
51         db = null;
52         users = null;
53         System.gc();
54     }
55     
56     public void print(Object o) {
57         System.out.println(o);
58     }
59 }

 

3、 添加操作

在添加操作之前，我们需要写个查询方法，来查询所有的数据。代码如下：

 1 /**
 2  * 查询所有数据
 3  */
 4 private void queryAll() {
 5     print("查询users的所有数据：");
 6     //db游标
 7     DBCursor cur = users.find();
 8     while (cur.hasNext()) {
 9         print(cur.next());
10     }
11 }
12  
13 @Test
14 public void add() {
15     //先查询所有数据
16     queryAll();
17     print("count: " + users.count());
18     
19     DBObject user = new BasicDBObject();
20     user.put("name", "hoojo");
21     user.put("age", 24);
22     //users.save(user)保存，getN()获取影响行数
23     //print(users.save(user).getN());
24     
25     //扩展字段，随意添加字段，不影响现有数据
26     user.put("sex", "男");
27     print(users.save(user).getN());
28     
29     //添加多条数据，传递Array对象
30     print(users.insert(user, new BasicDBObject("name", "tom")).getN());
31     
32     //添加List集合
33     List<DBObject> list = new ArrayList<DBObject>();
34     list.add(user);
35     DBObject user2 = new BasicDBObject("name", "lucy");
36     user.put("age", 22);
37     list.add(user2);
38     //添加List集合
39     print(users.insert(list).getN());
40     
41     //查询下数据，看看是否添加成功
42     print("count: " + users.count());
43     queryAll();
44 }

 

4、 删除数据

1 @Test
2 public void remove() {
3     queryAll();
4     print("删除id = 4de73f7acd812d61b4626a77：" + users.remove(new BasicDBObject("_id", new ObjectId("4de73f7acd812d61b4626a77"))).getN());
5     print("remove age >= 24: " + users.remove(new BasicDBObject("age", new BasicDBObject("$gte", 24))).getN());
6 }

5、 修改数据

 1 @Test
 2 public void modify() {
 3     print("修改：" + users.update(new BasicDBObject("_id", new ObjectId("4dde25d06be7c53ffbd70906")), new BasicDBObject("age", 99)).getN());
 4     print("修改：" + users.update(
 5             new BasicDBObject("_id", new ObjectId("4dde2b06feb038463ff09042")), 
 6             new BasicDBObject("age", 121),
 7             true,//如果数据库不存在，是否添加
 8             false//多条修改
 9             ).getN());
10     print("修改：" + users.update(
11             new BasicDBObject("name", "haha"), 
12             new BasicDBObject("name", "dingding"),
13             true,//如果数据库不存在，是否添加
14             true//false只修改第一天，true如果有多条就不修改
15             ).getN());
16     
17     //当数据库不存在就不修改、不添加数据，当多条数据就不修改
18     //print("修改多条：" + coll.updateMulti(new BasicDBObject("_id", new ObjectId("4dde23616be7c19df07db42c")), new BasicDBObject("name", "199")));
19 }

6、 查询数据：

　　mongoDB不支持联合查询、子查询，这需要我们自己在程序中完成。将查询的结果集在Java查询中进行需要的过滤即可。

 1 @Test
 2 public void query() {
 3     //查询所有
 4     //queryAll();
 5     
 6     //查询id = 4de73f7acd812d61b4626a77
 7     print("find id = 4de73f7acd812d61b4626a77: " + users.find(new BasicDBObject("_id", new ObjectId("4de73f7acd812d61b4626a77"))).toArray());
 8     
 9     //查询age = 24
10     print("find age = 24: " + users.find(new BasicDBObject("age", 24)).toArray());
11     
12     //查询age >= 24
13     print("find age >= 24: " + users.find(new BasicDBObject("age", new BasicDBObject("$gte", 24))).toArray());
14     print("find age <= 24: " + users.find(new BasicDBObject("age", new BasicDBObject("$lte", 24))).toArray());
15     
16     print("查询age!=25：" + users.find(new BasicDBObject("age", new BasicDBObject("$ne", 25))).toArray());
17     print("查询age in 25/26/27：" + users.find(new BasicDBObject("age", new BasicDBObject(QueryOperators.IN, new int[] { 25, 26, 27 }))).toArray());
18     print("查询age not in 25/26/27：" + users.find(new BasicDBObject("age", new BasicDBObject(QueryOperators.NIN, new int[] { 25, 26, 27 }))).toArray());
19     print("查询age exists 排序：" + users.find(new BasicDBObject("age", new BasicDBObject(QueryOperators.EXISTS, true))).toArray());
20     
21     print("只查询age属性：" + users.find(null, new BasicDBObject("age", true)).toArray());
22     print("只查属性：" + users.find(null, new BasicDBObject("age", true), 0, 2).toArray());
23     print("只查属性：" + users.find(null, new BasicDBObject("age", true), 0, 2, Bytes.QUERYOPTION_NOTIMEOUT).toArray());
24     
25     //只查询一条数据，多条去第一条
26     print("findOne: " + users.findOne());
27     print("findOne: " + users.findOne(new BasicDBObject("age", 26)));
28     print("findOne: " + users.findOne(new BasicDBObject("age", 26), new BasicDBObject("name", true)));
29     
30     //查询修改、删除
31     print("findAndRemove 查询age=25的数据，并且删除: " + users.findAndRemove(new BasicDBObject("age", 25)));
32     
33     //查询age=26的数据，并且修改name的值为Abc
34     print("findAndModify: " + users.findAndModify(new BasicDBObject("age", 26), new BasicDBObject("name", "Abc")));
35     print("findAndModify: " + users.findAndModify(
36         new BasicDBObject("age", 28), //查询age=28的数据
37         new BasicDBObject("name", true), //查询name属性
38         new BasicDBObject("age", true), //按照age排序
39         false, //是否删除，true表示删除
40         new BasicDBObject("name", "Abc"), //修改的值，将name修改成Abc
41         true, 
42         true));
43     
44     queryAll();
45 }

7、 其他操作

 1 public void testOthers() {
 2     DBObject user = new BasicDBObject();
 3     user.put("name", "hoojo");
 4     user.put("age", 24);
 5     
 6     //JSON 对象转换        
 7     print("serialize: " + JSON.serialize(user));
 8     //反序列化
 9     print("parse: " + JSON.parse("{ \"name\" : \"hoojo\" , \"age\" : 24}"));
10     
11     print("判断temp Collection是否存在: " + db.collectionExists("temp"));
12     
13     //如果不存在就创建
14     if (!db.collectionExists("temp")) {
15         DBObject options = new BasicDBObject();
16         options.put("size", 20);
17         options.put("capped", 20);
18         options.put("max", 20);
19         print(db.createCollection("account", options));
20     }
21     
22     //设置db为只读
23     db.setReadOnly(true);
24     
25     //只读不能写入数据
26     db.getCollection("test").save(user);
27 }

 

【MongoDB for Java】Java操作MongoDB

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