Java如何操作MongoDB常用API文档

collection.find().projection(fields(include("username","pwd"),excludeId()));//返回username与pwd字段且不返回_id字段
Document doc = new Document().append("_id", 0).append("username",1).append("pwd",1);//指定查询字段，0为不包含此字段，1为包含此字段
FindIterable<Document> findIterable = collection.find().projection(doc);

Document myDoc = collection.find(and(eq("username","liuchao"),eq("pwd","12345"))).first();
//此方法需包含头文件import static com.mongodb.client.model.Filters.*;
Document myDoc = collection.find(new Document("username", "liuchao").append("pwd", "12345")).first();
//无需包含上面的头文件

FindIterable<Document> iterable = collection.find().sort(ascending("title"));//按title升序排列
FindIterable<Document> iterable = collection.find().sort(ascending("title","Words"));//按title和words升序排列
FindIterable<Document> iterable = collection.find().sort(descending("title"));//按title降序排列
FindIterable<Document> iterable = collection.find().sort(new Document("time",-1));//按time降序排列

MongoCursor<Document> cursor = collection.find(new Document("username","liuchao")).sort(new Document("time",-1)).limit(n).iterator();
//对满足条件username=“liuchao”的结果进行降序排列，并获取前n条数据。（n=0获取全部）

    <!--MongoDB相关依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mongodb</groupId>
            <artifactId>mongodb-driver-sync</artifactId>
        </dependency>

    <dependency>
      <groupId>org.mongodb</groupId>
      <artifactId>mongodb-driver</artifactId>
      <version>3.8.2</version>
      <scope>compile</scope>
    </dependency>

#springboot MongoDB配置
spring.data.mongodb.username=用户名
spring.data.mongodb.password=密码
spring.data.mongodb.authentication-database=一般是admin
spring.data.mongodb.database=数据库名
spring.data.mongodb.port=端口号，默认27017
spring.data.mongodb.host=主机ip

     @Autowired
    private MongoTemplate mongoTemplate;
     
     public void saveStudent(Student student)
    {
        //返回的结果是保存的对象本身, 所以一般不写
        Student result = mongoTemplate.save(student);
    }

    
    public void delStudentByObjectId(ObjectId id)
    {
        //构造查询条件
        Query query = Query.query(Criteria.where("id").is(id));
        //删除操作(常用API)
        mongoTemplate.remove(query, Student.class);
    }

     
    public Student findStudent(ObjectId id)
    {
        Query query = Query.query(Criteria.where("id").is(id));
        //常用API
        Student student = mongoTemplate.findOne(query, Student.class);
        return student;
    }

     public List<Student> findList()
    {
        //第一个参数可以理解为查出的结果应该封装到怎样的对象中,第二个参数可以理解为表名(也可以不写)
        return mongoTemplate.findAll(Student.class, "tb_student");
    }

    public List<Student> findByCondition()
    {
        //构造查询条件
        Query query=Query.query(Criteria.where("id").ne(1));
        //执行查找操作,最后一个参数可以省略(在实体类上已经加上了注解,指定了对应的表名也就是document的名字)
        List<Student> list = mongoTemplate.find(query, Student.class, "tb_student");
        return list;
    }