### 实验目的
了解如何使用 Java 连接
MongoDB 数据库，进行基本的增删改查操作。
### 实验环境
- JDK 1.8 及以上
-
MongoDB 数据库
- Maven 或 Gradle 用于依赖管理
### 实验步骤
#### 1. 添加依赖
如果使用 Maven，在 `pom.xml` 中添加以下依赖：
```xml
<dependency>
<groupId>org.
mongodb</groupId>
<artifactId>mongo-java-driver</artifactId>
<version>4.7.1</version>
</dependency>
```
#### 2. 连接
MongoDB
```java
import com.
mongodb.client.MongoClients;
import com.
mongodb.client.MongoClient;
import com.
mongodb.client.MongoDatabase;
public class ConnectTo
MongoDB {
public static void main(String[] args) {
// 连接到
MongoDB 服务器
MongoClient mongoClient = MongoClients.create("
mongodb://localhost:27017");
// 选择数据库
MongoDatabase database = mongoClient.getDatabase("testdb");
System.out.println("Connected to the database successfully");
}
}
```
#### 3. 插入文档
```java
import com.
mongodb.client.MongoClients;
import com.
mongodb.client.MongoClient;
import com.
mongodb.client.MongoCollection;
import com.
mongodb.client.MongoDatabase;
import org.bson.Document;
public class InsertDocument {
public static void main(String[] args) {
MongoClient mongoClient = MongoClients.create("
mongodb://localhost:27017");
MongoDatabase database = mongoClient.getDatabase("testdb");
MongoCollection<Document> collection = database.getCollection("testcollection");
Document document = new Document("name", "John")
.append("age", 30)
.append("city", "New York");
collection.insertOne(document);
System.out.println("Document inserted successfully");
}
}
```
#### 4. 查询文档
```java
import com.
mongodb.client.MongoClients;
import com.
mongodb.client.MongoClient;
import com.
mongodb.client.MongoCollection;
import com.
mongodb.client.MongoDatabase;
import org.bson.Document;
import com.
mongodb.client.FindIterable;
public class QueryDocument {
public static void main(String[] args) {
MongoClient mongoClient = MongoClients.create("
mongodb://localhost:27017");
MongoDatabase database = mongoClient.getDatabase("testdb");
MongoCollection<Document> collection = database.getCollection("testcollection");
FindIterable<Document> documents = collection.find();
for (Document document : documents) {
System.out.println(document.toJson());
}
}
}
```
#### 5. 更新文档
```java
import com.
mongodb.client.MongoClients;
import com.
mongodb.client.MongoClient;
import com.
mongodb.client.MongoCollection;
import com.
mongodb.client.MongoDatabase;
import org.bson.Document;
import com.
mongodb.client.model.Filters;
import com.
mongodb.client.model.Updates;
public class UpdateDocument {
public static void main(String[] args) {
MongoClient mongoClient = MongoClients.create("
mongodb://localhost:27017");
MongoDatabase database = mongoClient.getDatabase("testdb");
MongoCollection<Document> collection = database.getCollection("testcollection");
collection.updateOne(Filters.eq("name", "John"), Updates.set("age", 31));
System.out.println("Document updated successfully");
}
}
```
#### 6. 删除文档
```java
import com.
mongodb.client.MongoClients;
import com.
mongodb.client.MongoClient;
import com.
mongodb.client.MongoCollection;
import com.
mongodb.client.MongoDatabase;
import org.bson.Document;
import com.
mongodb.client.model.Filters;
public class DeleteDocument {
public static void main(String[] args) {
MongoClient mongoClient = MongoClients.create("
mongodb://localhost:27017");
MongoDatabase database = mongoClient.getDatabase("testdb");
MongoCollection<Document> collection = database.getCollection("testcollection");
collection.deleteOne(Filters.eq("name", "John"));
System.out.println("Document deleted successfully");
}
}
```
### 实验注意事项
- 确保
MongoDB 服务器已启动，并且监听的端口正确。
- 在进行数据库操作时，要处理可能出现的异常，如网络异常、数据库连接异常等。
- 对于
MongoDB 的权限管理，要合理设置用户权限，避免数据泄露。
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