首先是对MongoDB用户和权限的设置，如果不设置用户的话，直接使用mongo命令就可以进入客户端shell界面进行操作了，但是如果没有设置用户的话，总感觉少了点什么，于是经过半天的查找和实践，差不多把用户和权限弄明白了。总结如下：
如果按照以下这个指令安装的话：
mongod --install --dbpath "C:Program Filesmongodbdatadb" --logpath "C:Program FilesmongodbdatalogMongoDB.log"
如下：
c:Program Filesmongodbin>mongod --install --dbpath "C:Program Filesmongodbdatadb" --logpath "C:Program FilesmongodbdatalogMongoDB.log"
Fri Apr 05 13:47:43.164
Fri Apr 05 13:47:43.168 warning: 32-bit servers don't have journaling enabled by default. Please use --journal if you want durability.
Fri Apr 05 13:47:43.169
Fri Apr 05 13:47:43.169 Trying to install Windows service 'MongoDB'
Fri Apr 05 13:47:43.170 There is already a service named 'MongoDB', aborting
c:Program Filesmongodbin>net start MongoDB
Mongo DB 服服务务已已经经启启动动成成功功。。
c:Program Filesmongodbin>mongo
MongoDB shell version: 2.4.1
connecting to: test
Server has startup warnings:
Fri Apr 05 13:48:02.516 [initandlisten]
Fri Apr 05 13:48:02.516 [initandlisten] ** NOTE: This is a 32 bit MongoDB binary.
Fri Apr 05 13:48:02.516 [initandlisten] ** 32 bit builds are limited to less than 2GB of data (or less with --journal).
Fri Apr 05 13:48:02.516 [initandlisten] ** Note that journaling defaults to off for 32 bit and is currently off.
Fri Apr 05 13:48:02.516 [initandlisten] ** See http://dochub.mongodb.org/core/32bit
Fri Apr 05 13:48:02.516 [initandlisten]
> show dbs
admin (empty)
local 0.03125GB
>
可以看到有两个默认的数据库admin和local
实例1：创建一个用户名为root，密码为admin的用户，如下：
> use admin
switched to db admin
> db.addUser("root","admin")
{
"user" : "root",
"readOnly" : false,
"pwd" : "bde0d84f6749c235a6b4e36d945eb666",
"_id" : ObjectId("515e662430d89f61f6991c91")
}
> show collections
Fri Apr 05 13:50:36.685 JavaScript execution failed: error: {
"$err" : "not authorized for query on admin.system.namespaces",
"code" : 16550
} at src/mongo/shell/query.js:L128
>
说明：使用以上指令show collections的时候，发现报错了。是因为没有权限。做如下操作：
> db.auth("root","admin");
1
说明：返回1表示验证成功了，返回0表示验证失败。
此时，输入以下指令：show collections则可以看到admin下的集合了。
> show collections
system.indexes
system.users
> db.system.users.find()
{ "_id" : ObjectId("515e662430d89f61f6991c91"), "user" : "root", "readOnly" : false, "pwd" : "bde0d84f6749c235a6b4e36d945eb666" }
>
实例2：在用户名为root，密码为admin的用户下创建一个student数据库，并在student数据库中创建一个stu的集合并插入一个文档，如下：
> use student
switched to db student
> db.stu.insert({"name":"maoyuanjun","age":25,"sex":"male"})
> db.stu.find()
{ "_id" : ObjectId("515e676630d89f61f6991c92"), "name" : "maoyuanjun", "age" : 25, "sex" : "male" }
退出服务器，重新登陆如下：
c:Program Filesmongodbin>mongo
MongoDB shell version: 2.4.1
connecting to: test
> show dbs
Fri Apr 05 13:58:05.420 JavaScript execution failed: listDatabases failed:{ "ok" : 0, "errmsg" : "unauthorized" }
at src/mongo/shell/mongo.js:L46
出错原因：是没有权限。则先判断是否有权限，如下：
> use admin
switched to db admin
> db.auth("root","admin")
1
> show dbs
admin 0.0625GB
local 0.03125GB
student 0.0625GB
>
这时，我们可以看到用户root，密码admin的用户下多了一个student数据库。
实例3：在创建一个用户
c:Program Filesmongodbin>mongo
MongoDB shell version: 2.4.1
connecting to: test
> use admin
switched to db admin
直接添加用户会报错：
> db.addUser("test","123456")
Fri Apr 05 14:01:31.404 JavaScript execution failed: error: { "$err" : "not authorized for query on admin.system.users", "code" : 16550 } at src/mongo/shell/query.js:L128
做权限的判断：
> db.auth("root","admin");
1
> use admin
switched to db admin
> db.addUser("test",123456)
{
"user" : "test",
"readOnly" : false,
"pwd" : "c8ef9e7ab00406e84cfa807ec082f59e",
"_id" : ObjectId("515e68e2be252e81c5dee198")
}
> show collections
system.indexes
system.users
> db.system.users.find()
{ "_id" : ObjectId("515e662430d89f61f6991c91"), "user" : "root", "readOnly" : fa
lse, "pwd" : "bde0d84f6749c235a6b4e36d945eb666" }
{ "_id" : ObjectId("515e68e2be252e81c5dee198"), "user" : "test", "readOnly" : fa
lse, "pwd" : "c8ef9e7ab00406e84cfa807ec082f59e" }
>