Java操作MongoDB

转自::[http://www.cnblogs.com/dennisit/archive/2013/01/29/2881006.html]

步骤1:导入jar包到项目中

步骤2:操作mongodb

   

Java对mongodb的$slice操作

Java对mongodb的$eleMatch操作

Java对mongodb的$where操作

 

 

对索引的操作

创建索引

SQL:

MongoDB:         db.集合.ensureIndex({'列1':1,'列2':-1})    //1-升序  -1-降序

Java: 

Java可以通过DBCollection类的createIndex(DBObject keys)方法创建索引,它接收一个DBObject类型的参数“keys”用于表明在哪些列上创建索引.

对1列创建索引

DBCollection collection = db.getCollection("集合");
//在user集合的name列上创建索引
collection.createIndex(new BasicDBObject(“name”,1));
可以通过db.集合.getIndexes();查看索引信息

对多列创建索引

DBCollection collection = db.getCollection("集合");
BasicDBObject index = new BasicDBObject();
index.put("name", 1);
index.put("password", -1);
collection.createIndex(index);

获取索引

MongoDB:   db.集合.getIndexes();

Java:

DBCollection类的getIndexInfo();

DBCollection collection = db.getCollection(“user”);
//获取集合中的所有索引信息
List<DBObject> list = collection.getIndexInfo();
for(DBObject var : list){
      System.out.println(var);
}

 

删除索引

MongoDB:  db.集合.dropIndex({'列1':1,'列2':})

Java:

DBCollection collection = db.getCollection(“user”);

//删除集合中的指定索引信息,删除name索引,1表示删除为真
collection.dropIndex(new BasicDBObject(“name”,1));

 

//删除该集合中所有索引[_id索引不支持删除]
collection.dropIndexes();
可以通过db.user.getIndexKeys();查看user集合中的索引

 

Java对MongoDB的高级查询

 

使用QueryBuilder查询构造器对MongoDB进行高级查询

SQL语句:
select * from user where name = ‘user3’;
MongoDB:
db.user.find( { name:“user3″} );
Java代码:
DBCollection collection = db.getCollection(“user”);
//查询用户名为user3的用户
DBObject query = new QueryBuilder().put(“name”).is(“user3″).get();
DBCursor cur = collection.find(query);
while(cur.hasNext()){
       System.out.println(cur.next());
}
输出结果:
{ “_id” : { “$oid” : “50f6d250778eafb6ef5bcee7″} , “name” : “user3″ , “age” : 23.0}

 

notEquals不等于

查询user集合中用户名name值不等于user3的用户

SQL语句:
select * from user where username != ‘user3’;
MongoDB:
db.user.find( { name:{$ne:“user3″} } );
Java代码:
DBCollection collection = db.getCollection(“user”);
//查询用户名不为user3的用户
DBObject query = new QueryBuilder().put(“name”).notEquals(“user3″).get();
DBCursor cur = collection.find(query);
while(cur.hasNext()){
System.out.println(cur.next());
}
输出结果:
{ “_id” : { “$oid” : “50f6d250778eafb6ef5bcee5″} , “name” : “user1″ , “age” : 21.0}
{ “_id” : { “$oid” : “50f6d250778eafb6ef5bcee6″} , “name” : “user2″ , “age” : 22.0}
{ “_id” : { “$oid” : “50f6d250778eafb6ef5bcee8″} , “name” : “user4″ , “age” : 24.0}
{ “_id” : { “$oid” : “50f6d250778eafb6ef5bcee9″} , “name” : “user5″ , “age” : 25.0}

 

greaterThan大于

查询user集合中age大于22的用户

SQL语句:
select * from user where age > 22;
MongoDB:
db.user.find( { age:{$gt:22} } );
QueryBuilder构造:
DBObject query = new QueryBuilder().put(“age”).greaterThan(22).get();

 

 

greaterThanEquals大于等于

查询user集合中age大于等于22的用户

SQL语句:
select * from user where age >= 22;
MongoDB:
db.user.find( { age:{$gte:22} } );
QueryBuilder构造:
DBObject query = new QueryBuilder().put(“age”).greaterThanEquals(22).get();

 

lessThan小于

查询user集合中age小于22的用户

SQL语句:
select * from user where age < 22;
MongoDB:
db.user.find( { age:{$lt:22} } );
QueryBuilder构造:
DBObject query = new QueryBuilder().put(“age”).lessThan(22).get();

 

lessThanEquals小于等于

查询user集合中age小于等于22的用户

SQL语句:
select * from user where age <= 22;
MongoDB:
db.user.find( { age:{$lte:22} } );
QueryBuilder构造:
DBObject query = new QueryBuilder().put(“age”).lessThanEquals(22).get();

 

 

In范围内

查询user集合中age在23或24的记录

SQL语句:
select * from user where age in (23,24);
MongoDB:
db.user.find( { age:{$in:[23,24]} } );
Java代码:
DBCollection collection = db.getCollection(“user”);
//查询user集合中age为23或者24的用户
int[] inList = {23,24};
DBObject query = new QueryBuilder().put(“age”).in(inList).get();
DBCursor cur = collection.find(query);
while(cur.hasNext()){
System.out.println(cur.next());
}

 

 

notIn范围外

查询user集合中age不是23或24的记录

SQL语句:
select * from user where age not in (23,24);
MongoDB:
db.user.find( { age:{$nin:[23,24]} } );
Java代码:
DBCollection collection = db.getCollection(“user”);
//查询user集合中age为23或者24的用户
int[] inList = {23,24};
DBObject query = new QueryBuilder().put(“age”).notIn(inList).get();
DBCursor cur = collection.find(query);

 

and逻辑与

查询user集合中age大于22并且性别为”man“的用户

SQL语句:
select * from user where sex = ‘man’ and age > 20;
MongoDB:
db.user.find({sex:“man”,age:{$gt:20}});
Java代码:
//查询user集合中age大于22并且性别为”man“的用户
DBObject query = new QueryBuilder().put(“sex”).is(“man”).and(“age”).greaterThan(20).get();

 

正则表达式

查询name以user开头的记录

SQL语句:
select * from user where name like ‘user%’;
MongoDB:
db.user.find({name:/^user.*/});
Java代码:
DBCollection collection = db.getCollection(“user”);
Pattern pattern = Pattern.compile(“^user”);
BasicDBObject query = new BasicDBObject(“name”,pattern);

 

分页查询

mongoDB中通过skip()和limit()结合实现分页

public static void main(String[] args) {

Mongo mongo = null;
try {
//通过连接字符串得到一个数据库实例的连接
mongo = new Mongo(“127.0.0.1″,27017);
} catch (Exception e) {
e.printStackTrace();
}
//连接超级用户
DB db = mongo.getDB(“mydb”);
//指定安全授权信息[超级用户的用户名为root,密码为root123]
db.authenticate(“mydbusr”, “123”.toCharArray());

 

int perNum = 10; //每页显示的数目
int count = 0; //数据库中总共记录数目
int pageNum = 0; //分页后的页数

DBCollection collection = db.getCollection(“user”);

count

= (int)collection.getCount(); //总共记录数
pageNum = (count-1)/perNum + 1; //计算总共页数

System.out.println(“数据库”+collection+”中共有”+count+”条记录,每页显示”+perNum+”条记录,可显示”+pageNum+”页”);

 

//循环分页打印
for(int i=0; i<pageNum; i++){
System.out.println(“————第” + (i+1) + “页数据————“);
DBCursor cur = collection.find().skip(i*perNum).limit(perNum);
while(cur.hasNext()){
System.out.println(cur.next());
}
}
}

 

 

Java操作GridFS

 

插入数据

使用GridFS类的createFile(File file)方法可以将大文件保存到MongoDB中,该方法接收一个参数,表示本地文件路径

public static void main(String[] args) {
Mongo mongo = null;
try {
mongo = new Mongo(“127.0.0.1″,27017);
} catch (Exception e) {
// TODO: handle exception
}
DB db = mongo.getDB(“mydb”);
db.authenticate(“mydbusr”, “123”.toCharArray());

 

File zipFile

= new File(“D:/freemarker源码.rar”); //创建文件对象
//将文件存放到file数据库中
GridFS gfs = new GridFS(db,”file”);

 

//创建大文件对象输入流
GridFSInputFile gfsFile = null;
try {
//将本地文件存储到mongo中
gfsFile = gfs.createFile(zipFile);
} catch (Exception e) {
e.printStackTrace();
}
//设置存储的文件名
gfsFile.setFilename(“demozip”);
gfsFile.save();
}
在mydb数据库下查看存储的文件信息
> db
mydb
> show collections;
file.chunks
file.files
system.indexes
system.users
user
> db.file.files.findOne();
{
“_id” : ObjectId(“50f780a7de886482c92a56c9″),
“chunkSize” : NumberLong(262144),
“length” : NumberLong(83711),
“md5″ : “51f235ccf838511eb0f53633dbca22b3″,
“filename” : “demozip”,
“contentType” : null,
“uploadDate” : ISODate(“2013-01-17T04:40:07.240Z”),
“aliases” : null
}

 

查询数据

因为上传了一个zip文档,为了方便观察,使用GridFS类的findOne(DBObject query)方法,按文件名查找数据库中的GridFS对象信息,该方法结束1个参数,代表查询条件.

DB db = mongo.getDB(“mydb”);
db.authenticate(“mydbusr”, “123”.toCharArray());

 

//将文件存放到file数据库中
GridFS gfs = new GridFS(db,”file”);

 

//查询GridFS数据,按照文件名查询 db.file.files.findOne({filename:”demozip”});
GridFSDBFile zipfile = gfs.findOne(“demozip”);
System.out.println(zipfile);

 

读取并保存数据

首先用find或者findOne方法找到GridFS对象,再用writeTo方法将数据写到本地.

DB db = mongo.getDB(“mydb”);
db.authenticate(“mydbusr”, “123”.toCharArray());

 

GridFS gfs

= new GridFS(db,”file”);

 

//查询GridFS数据,按照文件名查询 db.file.files.find({filename:”demozip”});
GridFSDBFile zipfile = gfs.findOne(“demozip”);
System.out.println(“服务器端文件MD5值为:” + zipfile.getMD5());
try {
//将读取到的文件写到本地
zipfile.writeTo(“E:/downgidfs.zip”);
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
控制台输出:服务器端文件MD5值为:51f235ccf838511eb0f53633dbca22b3
验证下载到的文件的MD5
E:>md5sum downgidfs.zip
51f235ccf838511eb0f53633dbca22b3 *downgidfs.zip

 

删除数据

Java中使用remove(DBObject query)来实现移除数据

GridFS gfs = new GridFS(db,”file”);
//查询GridFS数据,按照文件名查询 db.file.files.find({filename:”demozip”});
GridFSDBFile zipfile = gfs.findOne(“demozip”);
//删除查询到的GridFS数据
gfs.remove(zipfile);