HelloWorld程序
学习任何程序的第一步,都是编写HelloWorld程序,我们也不例外,看下如何通过Java编写一个HelloWorld的程序。
首先,要通过Java操作Mongodb,必须先下载Mongodb的Java驱动程序,可以在这里下载。
新建立一个Java工程,将下载的驱动程序放在库文件路径下,程序代码如下:
1 package com.mkyong.core;
2 import java.net.UnknownHostException;
3 import com.mongodb.BasicDBObject;
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
10 /**
11 * Java + MongoDB Hello world Example
12 *
13 */
14 public class App {
15 public static void main(String[] args) {
16 try {
17 //实例化Mongo对象,连接27017端口
18 Mongo mongo = new Mongo("localhost", 27017);
19 //连接名为yourdb的数据库,假如数据库不存在的话,mongodb会自动建立
20 DB db = mongo.getDB("yourdb");
21 // Get collection from MongoDB, database named "yourDB"
22 //从Mongodb中获得名为yourColleection的数据集合,如果该数据集合不存在,Mongodb会为其新建立
23 DBCollection collection = db.getCollection("yourCollection");
24 // 使用BasicDBObject对象创建一个mongodb的document,并给予赋值。
25 BasicDBObject document = new BasicDBObject();
26 document.put("id", 1001);
27 document.put("msg", "hello world mongoDB in Java");
28 //将新建立的document保存到collection中去
29 collection.insert(document);
30 // 创建要查询的document
31 BasicDBObject searchQuery = new BasicDBObject();
32 searchQuery.put("id", 1001);
33 // 使用collection的find方法查找document
34 DBCursor cursor = collection.find(searchQuery);
35 //循环输出结果
36 while (cursor.hasNext()) {
37 System.out.println(cursor.next());
38 }
39 System.out.println("Done");
40 } catch (UnknownHostException e) {
41 e.printStackTrace();
42 } catch (MongoException e) {
43 e.printStackTrace();
44 }
45 }
46 }
View Code
最后,输出的结果为:
{ "_id" : { "$oid" : "4dbe5596dceace565d229dc3"} ,
"id" : 1001 , "msg" : "hello world mongoDB in Java"}
Done
在上面的例子中,演示了使用Java对Mongodb操作的重要方法和步骤,首先通过创建Mongodb对象,传入构造函数的参数是Mongodb的数据库所在地址和端口,然后使用
getDB方法获得要连接的数据库名,使用getCollection获得数据集合的名,然后通过新建立BasicDBObject对象去建立document,最后通过collection的insert方法,将建立的document保存到数据库中去。而collection的find方法,则是用来在数据库中查找document。
从Mongodb中获得collection数据集
在Mongodb中,可以通过如下方法获得数据库中的collection:
DBCollection collection = db.getCollection("yourCollection");
如果你不知道collection的名称,可以使用db.getCollectionNames()获得集合,然后再遍历,如下:
DB db = mongo.getDB("yourdb");
Set collections = db.getCollectionNames();
for(String collectionName : collections){
System.out.println(collectionName);
}
完成的一个例子如下:
package com.mkyong.core;
import java.net.UnknownHostException;
import java.util.Set;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.Mongo;
import com.mongodb.MongoException;
/**
* Java : Get collection from MongoDB
*
*/
public class GetCollectionApp {
public static void main(String[] args) {
try {
Mongo mongo = new Mongo("localhost", 27017);
DB db = mongo.getDB("yourdb");
Set<String> collections = db.getCollectionNames();
for (String collectionName : collections) {
System.out.println(collectionName);
}
DBCollection collection = db.getCollection("yourCollection");
System.out.println(collection.toString());
System.out.println("Done");
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (MongoException e) {
e.printStackTrace();
}
}
}
Mongodb中如何插入数据
下面,讲解下如何使用4种方式,将JSON数据插入到Mongodb中去。首先我们准备JSON
格式的数据,如下:
{
"database" : "mkyongDB",
"table" : "hosting",
"detail" :
{
records : 99,
index : "vps_index1",
active : "true"
}
}
}
我们希望用不同的方式,通过JAVA代码向Mongodb插入以上格式的JSON数据
第一种方法,是使用BasicDBObject,方法如下代码所示:
BasicDBObject document = new BasicDBObject();
document.put("database", "mkyongDB");
document.put("table", "hosting");
BasicDBObject documentDetail = new BasicDBObject();
documentDetail.put("records", "99");
documentDetail.put("index", "vps_index1");
documentDetail.put("active", "true");
document.put("detail", documentDetail);
collection.insert(document);
第二种方法是使用BasicDBObjectBuilder对象,如下代码所示:
BasicDBObjectBuilder documentBuilder = BasicDBObjectBuilder.start()
.add("database", "mkyongDB")
.add("table", "hosting");
BasicDBObjectBuilder documentBuilderDetail = BasicDBObjectBuilder.start()
.add("records", "99")
.add("index", "vps_index1")
.add("active", "true");
documentBuilder.add("detail", documentBuilderDetail.get());
collection.insert(documentBuilder.get());
第三种方法是使用Map对象,代码如下:
new HashMap();
documentMap.put("database", "mkyongDB");
documentMap.put("table", "hosting");
Map documentMapDetail =new HashMap();
documentMapDetail.put("records", "99");
documentMapDetail.put("index", "vps_index1");
documentMapDetail.put("active", "true");
documentMap.put("detail", documentMapDetail);
collection.insert(new BasicDBObject(documentMap));
第四种方法,也就是最简单的,即直接插入JSON格式数据
String json ="{'database' : 'mkyongDB','table' : 'hosting',"+
"'detail' : {'records' : 99, 'index' : 'vps_index1', 'active' : 'true'}}}";
DBObject dbObject =(DBObject)JSON.parse(json);
collection.insert(dbObject);
这里使用了JSON的parse方法,将解析后的JSON字符串转变为DBObject对象后再直接插入到collection中去。
完整的代码如下所示:
1 packagecom.mkyong.core;
2 importjava.net.UnknownHostException;
3 importjava.util.HashMap;
4 importjava.util.Map;
5 importcom.mongodb.BasicDBObject;
6 importcom.mongodb.BasicDBObjectBuilder;
7 importcom.mongodb.DB;
8 importcom.mongodb.DBCollection;
9 importcom.mongodb.DBCursor;
10 importcom.mongodb.DBObject;
11 importcom.mongodb.Mongo;
12 importcom.mongodb.MongoException;
13 importcom.mongodb.util.JSON;
14 /**
15 * Java MongoDB : Insert a Document
16 *
17 */
18 publicclass InsertDocumentApp {
19 publicstaticvoid main(String[] args){
20 try{
21 Mongo mongo =new Mongo("localhost", 27017);
22 DB db = mongo.getDB("yourdb");
23 // get a single collection
24 DBCollection collection = db.getCollection("dummyColl");
25 // BasicDBObject example
26 System.out.println("BasicDBObject example...");
27 BasicDBObject document =new BasicDBObject();
28 document.put("database", "mkyongDB");
29 document.put("table", "hosting");
30 BasicDBObject documentDetail =new BasicDBObject();
31 documentDetail.put("records", "99");
32 documentDetail.put("index", "vps_index1");
33 documentDetail.put("active", "true");
34 document.put("detail", documentDetail);
35 collection.insert(document);
36 DBCursor cursorDoc = collection.find();
37 while(cursorDoc.hasNext()){
38 System.out.println(cursorDoc.next());
39 }
40 collection.remove(new BasicDBObject());
41 // BasicDBObjectBuilder example
42 System.out.println("BasicDBObjectBuilder example...");
43 BasicDBObjectBuilder documentBuilder = BasicDBObjectBuilder.start()
44 .add("database", "mkyongDB")
45 .add("table", "hosting");
46 BasicDBObjectBuilder documentBuilderDetail = BasicDBObjectBuilder.start()
47 .add("records", "99")
48 .add("index", "vps_index1")
49 .add("active", "true");
50 documentBuilder.add("detail", documentBuilderDetail.get());
51 collection.insert(documentBuilder.get());
52 DBCursor cursorDocBuilder = collection.find();
53 while(cursorDocBuilder.hasNext()){
54 System.out.println(cursorDocBuilder.next());
55 }
56 collection.remove(new BasicDBObject());
57 // Map example
58 System.out.println("Map example...");
59 Map documentMap =new HashMap();
60 documentMap.put("database", "mkyongDB");
61 documentMap.put("table", "hosting");
62 Map documentMapDetail =new HashMap();
63 documentMapDetail.put("records", "99");
64 documentMapDetail.put("index", "vps_index1");
65 documentMapDetail.put("active", "true");
66 documentMap.put("detail", documentMapDetail);
67 collection.insert(new BasicDBObject(documentMap));
68 DBCursor cursorDocMap = collection.find();
69 while(cursorDocMap.hasNext()){
70 System.out.println(cursorDocMap.next());
71 }
72 collection.remove(new BasicDBObject());
73 // JSON parse example
74 System.out.println("JSON parse example...");
75 String json ="{'database' : 'mkyongDB','table' : 'hosting',"+
76 "'detail' : {'records' : 99, 'index' : 'vps_index1', 'active' : 'true'}}}";
77 DBObject dbObject =(DBObject)JSON.parse(json);
78 collection.insert(dbObject);
79 DBCursor cursorDocJSON = collection.find();
80 while(cursorDocJSON.hasNext()){
81 System.out.println(cursorDocJSON.next());
82 }
83 collection.remove(new BasicDBObject());
84 }catch(UnknownHostException e){
85 e.printStackTrace();
86 }catch(MongoException e){
87 e.printStackTrace();
88 }
89 }
90 }
View Code
更新Document
假设如下的JSON格式的数据已经保存到Mongodb中去了,现在要更新相关的数据。
{"_id" : {"$oid" : "x"} , "hosting" : "hostA" , "type" : "vps" , "clients" : 1000}
{"_id" : {"$oid" : "x"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 100}
{"_id" : {"$oid" : "x"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}
假设现在要将hosting中值为hostB的进行更新,则可以使用如下的方法:
new BasicDBObject();
newDocument.put("hosting", "hostB");
newDocument.put("type", "shared host");
newDocument.put("clients", 111);
collection.update(new BasicDBObject().append("hosting", "hostB"), newDocument);
可以看到,这里依然使用了BasicDBObject对象,并为其赋值了新的值后,然后使用collection的update方法,即可更新该对象。
更新后的输出如下:
{"_id" : {"$oid" : "x"} , "hosting" : "hostA" , "type" : "vps" , "clients" : 1000}
{"_id" : {"$oid" : "x"} , "hosting" : "hostB" , "type" : "shared host" , "clients" : 111}
{"_id" : {"$oid" : "x"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}
另外,还可以使用mongodb中的$inc修饰符号去对某个值进行更新,比如,要将hosting值为hostB的document的clients的值得更新为199(即100+99=199),可以这样:
new BasicDBObject().append("$inc",
new BasicDBObject().append("clients", 99));
collection.update(new BasicDBObject().append("hosting", "hostB"), newDocument);
则输出如下:
{"_id" : {"$oid" : "x"} , "hosting" : "hostA" , "type" : "vps" , "clients" : 1000}
{"_id" : {"$oid" : "x"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 199}
{"_id" : {"$oid" : "x"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}
接下来,讲解$set修饰符的使用。比如要把hosting中值为hostA的document中的
type的值进行修改,则可以如下实现:
new BasicDBObject().append("$set",
new BasicDBObject().append("type", "dedicated server"));
collection.update(new BasicDBObject().append("hosting", "hostA"), newDocument3);
则输出如下,把type的值从vps改为dedicated server:
{"_id" : {"$oid" : "x"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 100}
{"_id" : {"$oid" : "x"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}
{"_id" : {"$oid" : "x"} , "hosting" : "hostA" , "clients" : 1000 , "type" : "dedicated server"}
要注意的是,如果不使用$set的修饰符,而只是如下代码:
new BasicDBObject().append("type", "dedicated server");
collection.update(new BasicDBObject().append("hosting", "hostA"), newDocument3);
则会将所有的三个document的type类型都改为dedicated server了,因此要使用$set以更新特定的document的特定的值。
如果要更新多个document中相同的值,可以使用$multi,比如,要把所有vps为type的document,将它们的clients的值更新为888,可以如下实现:
new BasicDBObject().append("$set",
new BasicDBObject().append("clients", "888"));
collection.update(new BasicDBObject().append("type", "vps"), updateQuery, false, true);
输出如下:
{"_id" : {"$oid" : "x"} , "hosting" : "hostA" , "clients" : "888" , "type" : "vps"}
{"_id" : {"$oid" : "x"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 100}
{"_id" : {"$oid" : "x"} , "hosting" : "hostC" , "clients" : "888" , "type" : "vps"}
最后,还是给出更新document的完整例子:
1 package com.liao;
2 import java.net.UnknownHostException;
3 import com.mongodb.BasicDBObject;
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 publicclass UpdateDocumentApp {
10 publicstaticvoid printAllDocuments(DBCollection collection){
11 DBCursor cursor = collection.find();
12 while (cursor.hasNext()) {
13 System.out.println(cursor.next());
14 }
15 }
16 publicstaticvoid removeAllDocuments(DBCollection collection){
17 collection.remove(new BasicDBObject());
18 }
19 publicstaticvoid insertDummyDocuments(DBCollection collection){
20 BasicDBObject document = new BasicDBObject();
21 document.put("hosting", "hostA");
22 document.put("type", "vps");
23 document.put("clients", 1000);
24 BasicDBObject document2 = new BasicDBObject();
25 document2.put("hosting", "hostB");
26 document2.put("type", "dedicated server");
27 document2.put("clients", 100);
28 BasicDBObject document3 = new BasicDBObject();
29 document3.put("hosting", "hostC");
30 document3.put("type", "vps");
31 document3.put("clients", 900);
32 collection.insert(document);
33 collection.insert(document2);
34 collection.insert(document3);
35 }
36 publicstaticvoid main(String[] args) {
37 try {
38 Mongo mongo = new Mongo("localhost", 27017);
39 DB db = mongo.getDB("yourdb");
40 DBCollection collection = db.getCollection("dummyColl");
41 System.out.println("Testing 1...");
42 insertDummyDocuments(collection);
43 //find hosting = hostB, and update it with new document
44 BasicDBObject newDocument = new BasicDBObject();
45 newDocument.put("hosting", "hostB");
46 newDocument.put("type", "shared host");
47 newDocument.put("clients", 111);
48 collection.update(new BasicDBObject().append("hosting", "hostB"), newDocument);
49 printAllDocuments(collection);
50 removeAllDocuments(collection);
51 System.out.println("Testing 2...");
52 insertDummyDocuments(collection);
53 BasicDBObject newDocument2 = new BasicDBObject().append("$inc",
54 new BasicDBObject().append("clients", 99));
55 collection.update(new BasicDBObject().append("hosting", "hostB"), newDocument2);
56 printAllDocuments(collection);
57 removeAllDocuments(collection);
58 System.out.println("Testing 3...");
59 insertDummyDocuments(collection);
60 BasicDBObject newDocument3 = new BasicDBObject().append("$set",
61 new BasicDBObject().append("type", "dedicated server"));
62 collection.update(new BasicDBObject().append("hosting", "hostA"), newDocument3);
63 printAllDocuments(collection);
64 removeAllDocuments(collection);
65 System.out.println("Testing 4...");
66 insertDummyDocuments(collection);
67 BasicDBObject updateQuery = new BasicDBObject().append("$set",
68 new BasicDBObject().append("clients", "888"));
69 collection.update(
70 new BasicDBObject().append("type", "vps"), updateQuery, false, true);
71 printAllDocuments(collection);
72 removeAllDocuments(collection);
73 System.out.println("Done");
74 } catch (UnknownHostException e) {
75 e.printStackTrace();
76 } catch (MongoException e) {
77 e.printStackTrace();
78 }
79 }
80 }
View Code
查询Document
下面学习如何查询document,先用下面的代码往数据库中插入1-10数字:
for(int i=1; i <=10; i++){
collection.insert(new BasicDBObject().append("number", i));
}
接下来,看下如下的例子:
1) 获得数据库中的第一个document:
DBObject doc = collection.findOne();
System.out.println(dbObject);
输出为:
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80bd"} , "number" : 1}
2)获得document的集合
DBCursor cursor = collection.find();
while(cursor.hasNext()){
System.out.println(cursor.next());
}
这里,使用collection.find()方法,获得当前数据库中所有的documents对象集合
然后通过对DBCursor对象集合的遍历,即可输出当前所有documents。输出如下:
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80bd"} , "number" : 1}
//..........中间部分省略,为2到9的输出
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80c6"} , "number" : 10}
3) 获取指定的document
比如要获得number=5的document对象内容,可以使用collection的find方法即可,如下:
new BasicDBObject();
query.put("number", 5);
DBCursor cursor = collection.find(query);
while(cursor.hasNext()){
System.out.println(cursor.next());
}
即输出:
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80c1"} , "number" : 5}
4) 使用in操作符号
在mongodb中,也可以使用in操作符,比如要获得number=9和number=10的document对象,可以如下操作:
new BasicDBObject();
List list =new ArrayList();
list.add(9);
list.add(10);
query.put("number", new BasicDBObject("$in", list));
DBCursor cursor = collection.find(query);
while(cursor.hasNext()){
System.out.println(cursor.next());
}
这里使用了一个List,并将list传入到BasicDBObject的构造函数中,并使用了in操作符号,输出如下:
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80c5"} , "number" : 9}
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80c6"} , "number" : 10}
5) 使用>,<等比较符号
在mongodb中,也可以使用比如>,<等数量比较符号,比如要输出number>5的document集合,则使用“$gt”即可,同理,小于关系则使用$lt,例子如下:
new BasicDBObject();
query.put("number", new BasicDBObject("$gt", 5));
DBCursor cursor = collection.find(query);
while(cursor.hasNext()){
System.out.println(cursor.next());
}
输出如下:
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80c2"} , "number" : 6}
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80c3"} , "number" : 7}
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80c4"} , "number" : 8}
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80c5"} , "number" : 9}
{"_id" : {"$oid" : "4dc7f7b7bd0fb9a86c6c80c6"} , "number" : 10}
也可以多个比较符号一起使用,比如要输出number>5和number<8的document,则如下:
BasicDBObject query =new BasicDBObject();
query.put("number", new BasicDBObject("$gt", 5).append("$lt", 8));
DBCursor cursor = collection.find(query);
while(cursor.hasNext()){
System.out.println(cursor.next());
}
同样,如果是不等于的关系的话,可以使用$ne操作符,如下:
new BasicDBObject();
query5.put("number", new BasicDBObject("$ne", 8));
DBCursor cursor6 = collection.find(query5);
while(cursor6.hasNext()){
System.out.println(cursor6.next());
}
以上输出number=8之外的所有document。
删除document
下面我们学习如何删除document,依然以上面的已插入的1-10的documents集合为例说明:
1) 删除第一个document
DBObject doc = collection.findOne();
collection.remove(doc);
2) 删除指定的document
比如删除number=2的document,如下方法:
new BasicDBObject();
document.put("number", 2);
collection.remove(document);
要注意的是,如下的方法将只会删除number=3的document。
new BasicDBObject();
document.put("number", 2);
document.put("number", 3);
collection.remove(document);
3) 使用in 操作符号指定删除document
下面的例子将同时删除number=4和number=5的document,使用的是in操作符
new BasicDBObject();
List list =new ArrayList();
list.add(4);
list.add(5);
query2.put("number", new BasicDBObject("$in", list));
collection.remove(query2);
4) 使用“$gt”删除大于某个值的document
new BasicDBObject();
query.put("number", new BasicDBObject("$gt", 9));
collection.remove(query);
以上会删除number=10的document。
5) 删除所有的document
DBCursor cursor = collection.find();
while(cursor.hasNext()){
collection.remove(cursor.next());
}
保存图片到Mongodb
下面将讲解如何使用Java MongoDB GridFS API去保存图片等二进制文件到Monodb,关于Java MongoDB GridFS API的详细论述,请参考http://www.mongodb.org/display/DOCS/GridFS+Specification
1)保存图片
代码段如下:
String newFileName ="mkyong-java-image";
File imageFile =newFile("c:\\JavaWebHosting.png");
GridFS gfsPhoto =new GridFS(db, "photo");
GridFSInputFile gfsFile = gfsPhoto.createFile(imageFile);
gfsFile.setFilename(newFileName);
gfsFile.save();
这里,将c盘下的JavaWebHosting.png保存到mongodb中去,并命名为mkyong-java-image。
2) 读取图片信息
代码段如下
String newFileName ="mkyong-java-image";
GridFS gfsPhoto =new GridFS(db, "photo");
GridFSDBFile imageForOutput = gfsPhoto.findOne(newFileName);
System.out.println(imageForOutput);
将会输出JSON格式的结果;
{
"_id" :
{
"$oid" : "4dc9511a14a7d017fee35746"
} ,
"chunkSize" : 262144 ,
"length" : 22672 ,
"md5" : "1462a6cfa27669af1d8d21c2d7dd1f8b" ,
"filename" : "mkyong-java-image" ,
"contentType" : null ,
"uploadDate" :
{
"$date" : "2011-05-10T14:52:10Z"
} ,
"aliases" : null
}
可以看到,输出的是文件的属性相关信息。
3) 输出已保存的所有图片
下面代码段,输出所有保存在photo命名空间下的图片信息:
new GridFS(db, "photo");
DBCursor cursor = gfsPhoto.getFileList();
while(cursor.hasNext()){
System.out.println(cursor.next());
}
4) 从数据库中读取一张图片并另存
下面的代码段,从数据库中读取一张图片并另存为另外一张图片到磁盘中
String newFileName ="mkyong-java-image";
GridFS gfsPhoto =new GridFS(db, "photo");
GridFSDBFile imageForOutput = gfsPhoto.findOne(newFileName);
imageForOutput.writeTo("c:\\JavaWebHostingNew.png");
5) 删除图片
String newFileName ="mkyong-java-image";
GridFS gfsPhoto =new GridFS(db, "photo");
gfsPhoto.remove(gfsPhoto.findOne(newFileName));
如何将JSON数据格式转化为DBObject格式
在mongodb中,可以使用com.mongodb.util.JSON类,将JSON格式的字符串转变为DBObject对象。MongoDB for JAVA驱动中提供了用于向数据库中存储普通对象的接口DBObject,当一个文档从MongoDB中取出时,它会自动把文档转换成DBObject接口类型,要将它实例化为需要的对象。比如:
{
'name' : 'mkyong',
'age' : 30
}
这样的JSON格式字符串,转换方法为:
DBObject dbObject =(DBObject) JSON.parse("{'name':'mkyong', 'age':30}");
完整的代码如下:
packagecom.mkyong.core;
importjava.net.UnknownHostException;
importcom.mongodb.DB;
importcom.mongodb.DBCollection;
importcom.mongodb.DBCursor;
importcom.mongodb.DBObject;
importcom.mongodb.Mongo;
importcom.mongodb.MongoException;
importcom.mongodb.util.JSON;
/**
* Java MongoDB : Convert JSON data to DBObject
*
*/
publicclass App {
publicstaticvoid main(String[] args){
try{
Mongo mongo =new Mongo("localhost", 27017);
DB db = mongo.getDB("yourdb");
DBCollection collection = db.getCollection("dummyColl");
DBObject dbObject =(DBObject) JSON
.parse("{'name':'mkyong', 'age':30}");
collection.insert(dbObject);
DBCursor cursorDoc = collection.find();
while(cursorDoc.hasNext()){
System.out.println(cursorDoc.next());
}
System.out.println("Done");
}catch(UnknownHostException e){
e.printStackTrace();
}catch(MongoException e){
e.printStackTrace();
}
}
}
则输出为:
{"_id" : {"$oid" : "4dc9ebb5237f275c2fe4959f"} , "name" : "mkyong" , "age" : 30}
Done
可以看到,将JSON格式的数据类型直接转换为mongodb中的文档类型并输出。
小结:
本文学习了如何使用Mongodb for JAVA驱动,对mongodb进行日常的数据库操作,比如增加,删除和修改,下一篇教程中,将指导学习Spring对mongodb的操作。