01.使用Java連接MongoDB

Java操作MongoDB

操作系統：Win10 1803
jdk環境：jdk1.8.201
運行軟件：Idea Ultima Education 2019.1
項目框架：Maven
MongoDB版本：MongoDB 4.0.5

搭建基礎Java Maven項目

1.創建Maven項目

這裏默認大家都會創建maven項目，如果不會搭建的話可以安照自己使用的IDE參考對應的博客
+Idea開發Maven項目
+ Idea配置Maven環境
+ Idea搭建Maven項目

• Eclipse開發Maven項目
  • Eclipse配置Maven環境
  • Eclipse創建Maven項目

2.配置Maven pom.xml

• 導入java連接MongoDB需要的jar包

     <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>3.8.1</version>
          <scope>test</scope>
      </dependency>
      
      <dependency>
          <groupId>org.mongodb</groupId>
          <artifactId>mongo-java-driver</artifactId>
          <version>3.10.1</version>
      </dependency>
  

• 爲了方便所以我添加了一些輔助jar包

  <dependencies>
      <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>3.8.1</version>
          <scope>test</scope>
      </dependency>
      <dependency>
          <groupId>org.mongodb</groupId>
          <artifactId>mongo-java-driver</artifactId>
          <version>3.10.1</version>
      </dependency>
      <!--1.0.8 輔助工具 -->
      <dependency>
          <groupId>com.0opslab</groupId>
          <artifactId>0opslab-utils</artifactId>
          <version>1.0.8</version>
          <exclusions>
              <exclusion>
                  <groupId>javax.servlet</groupId>
                  <artifactId>javax.servlet-api</artifactId>
              </exclusion>
          </exclusions>
      </dependency>
  
      <!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
      <dependency>
          <groupId>com.alibaba</groupId>
          <artifactId>fastjson</artifactId>
          <version>1.2.56</version>
      </dependency>
  
  </dependencies>
  <build>
      <!-- 放行所有配置文件 -->
      <resources>
          <resource>
              <directory>src/main/java</directory><!--所在的目錄-->
              <includes><!--包括目錄下的.properties,.xml文件都會掃描到-->
                  <include>**/*.properties</include>
                  <include>**/*.xml</include>
              </includes>
              <filtering>false</filtering>
          </resource>
          <resource>
              <directory>src/main/resources</directory>
              <includes>
                  <include>**/*.properties</include>
                  <include>**/*.xml</include>
              </includes>
              <filtering>true</filtering>
          </resource>
      </resources>
  </build>
  

創建MongoDB數據庫連接對象

1.創建一個簡單測試類，來創建一個簡單的數據庫連接

• 數據庫連接核心代碼

//創建一個MongoDB連接對象 MongoClient
MongoClient mongoClient = new MongoClient("127.0.0.1",27017);
//然後創建一個數據庫操作對象通過mongoClient.getDatabase(你的庫名)獲取
MongoDatabase mongoDatabase = mongoClient.getDatabase("test");

• 這裏我創建了一個測試類查看能否連接上MongoDB中的test庫
  需要被連接的test數據庫

測試後結果
  

2.封裝數據庫連接操作

因爲每次要連接數據庫的時候都需要寫這兩行代碼，何不如將這兩行代碼封裝成類並且通過配置文件獲取MongoDB連接字符串，並且將其設置爲單例模式從而提升代碼運行效率呢

1. 將數據庫連接操作封裝成一個對象（Connection），並且設爲單例模式
   Connection.java

import com.mongodb.MongoClient;
import com.mongodb.client.MongoDatabase;

public class Connection {


    private ConnectionProperty connectionProperty;
    private static Connection connection;
    private MongoClient mongoClient;
    private Connection(){
        connectionProperty = new ConnectionProperty();
    }

    public void setConnectionProperty(ConnectionProperty connectionProperty) {
        this.connectionProperty = connectionProperty;
    }

    /**
     *
     * @return 返回MongoDB數據庫操作連接對象MongoDataBase,爲增加對數據庫的操作安全性所以沒有將此對象設置爲單例對象
     * @throws Exception 拋出數據庫連接異常
     */
    public MongoDatabase getMongodb() throws Exception {
        //創建一個數據庫連接對象
        mongoClient = new MongoClient(connectionProperty.getHost(),connectionProperty.getPort());
        //獲取數據庫操作對象,並連接數據庫
        MongoDatabase mongodb = mongoClient.getDatabase(connectionProperty.getDatabase());
        if (mongodb.getName()!=null)
            return mongodb;
        else
            throw new Exception("數據庫連接出錯");
    }

    public static Connection getInstance() {
        if (connection != null)
            return connection;
        else{
            connection = new Connection();
        }
        return connection;
    }
}

2. 將讀取配置文件的類封裝成一個對象(ConnectionProperty)，並且將其設爲參數傳入數據庫連接對象中
   ConnectionProperty.java

import com.opslab.util.PropertiesUtil;

import java.net.URL;

public class ConnectionProperty {

    private String host;
    private int port;
    private String database;
    private String path = "src/main/resources/properties/db.properties";

    public String getPath() {
        return path;
    }

    public void setPath(String path) {
        this.path = path;
    }

    public String getHost() {
        return host;
    }

    public int getPort() {
        return port;
    }

    public String getDatabase() {
        return database;
    }

    public ConnectionProperty(){
        UpdateProperty(path);
    }

    public void UpdateProperty(String path){
        this.path = path;
        PropertiesUtil propertiesUtil = new PropertiesUtil();
        try{
            host = propertiesUtil.GetValueByKey(path,"mongodb.host");
            port = Integer.parseInt(propertiesUtil.GetValueByKey(path,"mongodb.port"));
            database = propertiesUtil.GetValueByKey(path,"mongodb.database");
        }catch (Exception e){
            //這裏添加一層文件保護，爲防止讀取不到配置文件導致出錯
            e.printStackTrace();
        }
    }
}

3. 創建db.properties
   db.properties

mongodb.host = 127.0.0.1
mongodb.port = 27017
mongodb.database = test

4. 項目代碼框架
   db.properties存放在/src/main/resources/properties
   

未完待續。。。。。