Example analysis of common methods of connecting MongoDB in Java

1. Java link to MongoDB

1. Import the Mongo driver package

2. Get the Mongo link object

MongoClient mc = new MongoClient("localhost",27017);

3. Close the link

mc.close();

2. View the library and view the collection

1. Get the library object

MongoDatabase db = mc.getDatabase("myschool");

2. Get the collection of tables in the library

MongoIterable<String> listCollectionNames = db.listCollectionNames();
        
MongoCursor<String> iterator = listCollectionNames.iterator();
    while (iterator.hasNext()) {
        System.out.println(iterator.next());
    }

3 , Java adds, deletes and modifies MongoDB query

1. Add data

a. Add one piece of data

//创建对象
Student s = new Student();
s.setSid(1);
s.setSname("王俊凯");
s.setBirthday(new Date());
s.setSsex("男");
s.setClassid(2);
 
//将数据转换为json格式
Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd").create();
String json = gson.toJson(s);
 
//获取集合对象
MongoCollection<Document> collection = db.getCollection("student");
 
//添加一条数据，将json格式转换为document对象
collection.insertOne(Document.parse(json));

b. Add multiple pieces of data

//存入数据
List<Document> dlist=new ArrayList<Document>();
 
for(int i=0; i<3; i++){
    Student s = new Student();
    s.setSid(Integer.toString(i+1));
    s.setSname("王源");
    s.setBirthday(new Date());
    s.setSsex("男");
    s.setClassid(1);
    //将数据转换为json格式
    Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd").create();
    String json = gson.toJson(s);
    dlist.add(Document.parse(json));
}
 
//获取集合对象
MongoCollection<Document> collection = db.getCollection("student");
 
//添加多条数据
collection.insertMany(dlist);

2. Delete data

a. Delete one piece of data

//获取集合对象
MongoCollection<Document> collection = db.getCollection("student");
 
Student s = new Student();
s.setSid(1);
 
Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd").create();
Bson bson = Document.parse(gson.toJson(s));
 
DeleteResult deleteOne = collection.deleteOne(bson);

b. Delete multiple pieces of data

//获取集合对象
MongoCollection<Document> collection = db.getCollection("student");
 
Student s = new Student();
s.setSname("王源");
 
Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd").create();
Bson bson = Document.parse(gson.toJson(s));
 
DeleteResult deleteMany = collection.deleteMany(bson);

3. Modify data

a. Modify one piece of data

MongoCollection<Document> collection = db.getCollection("student");
 
//一个条件对象
Bson eq = Filters.eq("sname","易烊千玺");
 
//要修改的数据
Document doc = new Document();
doc.put("$set", new Document("age",22));
UpdateResult  updateone = collection.updateOne(eq, doc);
System.out.println(updateone);

b. Modify multiple pieces of data

MongoCollection<Document> collection = db.getCollection("student");
 
//多条件
Bson bson = Filters.and(Filters.gte("age", 20),Filters.lte("age", 40));
        
//要修改的数据
Document doc = new Document();        
doc.put("$set", new Document("sex","男"));
UpdateResult updateMany = collection.updateMany(bson, doc);
System.out.println(updateMany);

4. Query data

a. Search all

MongoCollection<Document> collection = db.getCollection("student");
 
FindIterable<Document> findAll = collection.find();
 
MongoCursor<Document> iterator = findAll.iterator();
 
while(iterator.hasNext()){
   System.out.println(iterator.next()); 
}

b. Query with conditions

MongoCollection<Document> collection = db.getCollection("student");
 
//一个条件对象
Bson eq = Filters.eq("sname","易烊千玺");
 
FindIterable<Document> findOne = collection.find(eq);
 
MongoCursor<Document> iterator = findOne.iterator();
 
while(iterator.hasNext()){
   System.out.println(iterator.next()); 
}

c. Fuzzy query

MongoCollection<Document> collection = db.getCollection("student");
 
//使用正则表达式进行模糊查找
Bson eq = Filters.regex("sname","易");
 
FindIterable<Document> find = collection.find(eq);
 
MongoCursor<Document> iterator = find.iterator();
 
while(iterator.hasNext()){
   System.out.println(iterator.next()); 
}

d. Paging query

MongoCollection<Document> collection = db.getCollection("student");
 
//分页查询
FindIterable<Document> find = collection.find().skip(2).limit(3);
 
MongoCursor<Document> iterator = find.iterator();
 
while(iterator.hasNext()){
   System.out.println(iterator.next()); 
}

e. Sorting query

MongoCollection<Document> collection = db.getCollection("student");
 
//排序查询  1升序   -1降序
Bson bson = new Document("sid",1);
FindIterable<Document> find = collection.find().sort(bson);
 
MongoCursor<Document> iterator = find.iterator();
 
while(iterator.hasNext()){
   System.out.println(iterator.next()); 
}

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