Java操作MongoDB模糊查询和分页查询_java mongodb模糊查询

我会详细讲解Java操作MongoDB模糊查询和分页查询的完整攻略,并且包含两条示例说明.

第一段：MongoDB模糊查询

在MongoDB中使用$regex运算符实现模糊查询.以下是使用Java驱动程序实现MongoDB模糊查询的步骤：

创建MongoClient和MongoDatabase实例

MongoClient mongoClient = new MongoClient("localhost", 27017);
MongoDatabase database = mongoClient.getDatabase("test");

获取MongoCollection对象

MongoCollection collection = database.getCollection("collection_name");

创建正则表达式

Pattern pattern = Pattern.compile("query_string");
Bson regex = Filters.regex("field_name", pattern);

构建查询条件并查询

FindIterable iterable = collection.find(regex);
MongoCursor cursor = iterable.iterator();
while (cursor.hasNext()) {
System.out.println(doc);
}

以下是一个完整的示例：

MongoClient mongoClient = new MongoClient("localhost", 27017);
MongoDatabase database = mongoClient.getDatabase("test");
MongoCollection collection = database.getCollection("users");
//查询username中包含"John"的所有文档
Pattern pattern = Pattern.compile("John");
Bson regex = Filters.regex("username", pattern);
FindIterable iterable = collection.find(regex);
MongoCursor cursor = iterable.iterator();
while (cursor.hasNext()) {
System.out.println(doc);
}

第二段：MongoDB分页查询

在MongoDB中使用skip和limit方法实现分页查询.以下是使用Java驱动程序实现MongoDB分页查询的步骤：

MongoClient mongoClient = new MongoClient("localhost", 27017);
MongoDatabase database = mongoClient.getDatabase("test");

MongoCollection collection = database.getCollection("collection_name");

构建查询条件、设置分页参数并查询

int skip = (pageNo - 1) * pageSize;
FindIterable iterable = collection.find().skip(skip).limit(pageSize);
MongoCursor cursor = iterable.iterator();
while (cursor.hasNext()) {
System.out.println(doc);
}

MongoClient mongoClient = new MongoClient("localhost", 27017);
MongoDatabase database = mongoClient.getDatabase("test");
MongoCollection collection = database.getCollection("users");
//查询第2页,每页显示5条记录
int pageNo = 2;
int pageSize = 5;
int skip = (pageNo - 1) * pageSize;
FindIterable iterable = collection.find().skip(skip).limit(pageSize);
MongoCursor cursor = iterable.iterator();
while (cursor.hasNext()) {
System.out.println(doc);
}

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