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本文是关于使用 Java 驱动程序在 MongoDB 中执行文档的批量更新。我们还将学习如何通过添加新字段、更改现有字段或数组的值或删除文档来进行更新。

先决条件

对于本篇文章，我们将使用你必须遵循的以下工具。

使用 Java 批量更新 MongoDB 中的文档

当我们需要更新数据库中的多个文档时，批量更新很有用。现在，问题是，我们要如何更新文档？

我们是否想通过添加新字段、更新现有字段或数组的值或删除文档来进行更新？要了解所有这些场景，让我们创建一个集合并插入两个文档。

创建集合：

db.createCollection('supervisor');

插入第一个文档：

db.supervisor.insertOne(
    {
          "firstname": "Mehvish",
          "lastname": "Ashiq",
          "gender": "Female",
          "contact" : {
              "email":"mehvishofficial@gmail.com",
              "phone" : [
                  {
                      "type" : "official",
                      "number" : "123456789"
                  },
                  {
                       "type" : "personal",
                       "number" : "124578369"
                  },
               ]
          },
          "entries" : [
              { "_id" : 1, "itemsperday" : [ 1,3,4,5,6,7 ] },
              { "_id" : 2, "itemperday" : [ 2,3,4,5,2,7 ] },
              { "_id" : 3, "itemperday" : [ 5,0,0,4,0,1 ] }
           ]
    }
);

插入第二个文件：

db.supervisor.insertOne(
    {
          "firstname": "Tahir",
          "lastname": "Raza",
          "gender": "Male",
          "contact" : {
              "email":"tahirraza@gmail.com",
              "phone" : [
                  {
                      "type" : "official",
                      "number" : "123478789"
                  },
                  {
                       "type" : "personal",
                       "number" : "122378369"
                  },
               ]
          },
          "entries" : [
              { "_id" : 1, "itemsperday" : [ 4,5,6,7,4,6 ] },
              { "_id" : 2, "itemperday" : [ 2,3,2,7,5,2 ] },
              { "_id" : 3, "itemperday" : [ 5,0,0,1,0,0 ] }
           ]
    }
);

填充集合后，你可以使用 db.supervisor.find().pretty(); 查看插入的文档。我们将从简单的解决方案开始，然后转向一些棘手但有趣的解决方案。

使用 updateMany() 通过向现有文档添加新字段来执行批量更新

示例代码：

//write your package where you want to save your source file
package com.voidtesting.javamongobulkupdateexample;

// import necessary libraries
import com.mongodb.BasicDBObject;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.client.MongoClients;
import com.mongodb.client.MongoCollection;
import org.bson.Document;

// Example_1
public class Example_1 {

    // main method
    public static void main(String[] args) {
        // Replace the connection string with your own connection string
        var uri = "mongodb://localhost:27017";

        // try block
        try ( MongoClient mongoClient = MongoClients.create(uri)) {

            // print message if connection is successfully established
            System.out.println("Connected successfully to server.");

            // get the specified database from the MongoDB server
            MongoDatabase database = mongoClient.getDatabase("bulkUpdate");

            // get the specified collection from the selected database
            MongoCollection<Document> collection = database.getCollection("supervisor");

            // update documents by adding a new field and its value
            collection.updateMany(new BasicDBObject(),
                    new BasicDBObject("$set",
                    new BasicDBObject("status", "Good")));

            // print a new line
            System.out.println();

            // iterate over all documents of the selected collection
            // to print in Java IDE
            collection.find().forEach(doc -> {
                System.out.println(doc.toBsonDocument());
                System.out.println();
            });// end forEach

        } // end try block

        // print error if unable to execute a command
        catch (MongoException error) {
            System.err.println("An error occurred while running a command: " + error);
        }// end catch block

    }// end main method
}//end Example_1

输出：

{
    "_id": {"$oid": "62a866e592fd89ad9c4932ed"},
    "firstname": "Mehvish",
    "lastname": "Ashiq",
    "gender": "Female",
    "contact": {
        "email": "mehvishofficial@gmail.com",
        "phone": [
            { "type": "official", "number": "123456789"},
            {"type": "personal", "number": "124578369"}
         ]
     },
     "entries": [
         {"_id": 1.0, "itemsperday": [1.0, 3.0, 4.0, 5.0, 6.0, 7.0]},
         {"_id": 2.0, "itemperday": [2.0, 3.0, 4.0, 5.0, 2.0, 7.0]},
         {"_id": 3.0, "itemperday": [5.0, 0.0, 0.0, 4.0, 0.0, 1.0]}
     ],
     "status": "Good"
}

{
    "_id": {"$oid": "62a8670192fd89ad9c4932ee"},
    "firstname": "Tahir",
    "lastname": "Raza",
    "gender": "Male",
    "contact": {
        "email": "tahirraza@gmail.com",
        "phone": [
            {"type": "official", "number": "123478789"},
            {"type": "personal", "number": "122378369"}
         ]
     },
     "entries": [
         {"_id": 1.0, "itemsperday": [4.0, 5.0, 6.0, 7.0, 4.0, 6.0]},
         {"_id": 2.0, "itemperday": [2.0, 3.0, 2.0, 7.0, 5.0, 2.0]},
         {"_id": 3.0, "itemperday": [5.0, 0.0, 0.0, 1.0, 0.0, 0.0]}
     ],
     "status": "Good"
}

我们已经为你格式化了输出（如上所示），但你将在 IDE 上每行看到一个文档。我们也可以使用 db.supervisor.find().pretty(); 在 mongo shell 上查看更新的文档。

对于此示例代码，我们使用 mongo 集合对象的 updateMany() 方法，该方法接受 filter 查询和 update 语句来更新匹配的文档。在这里，我们不是过滤文档，而是向所有现有文档添加一个名为 status 的新字段（参见上面给出的输出）。

使用 updateMany() 对匹配过滤器的多个文档中的现有字段执行批量更新

示例代码：

//write your package where you want to save your source file
package com.voidtesting.javamongobulkupdateexample;

// import necessary libraries
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.client.MongoClients;
import com.mongodb.client.MongoCollection;
import static com.mongodb.client.model.Filters.eq;
import static com.mongodb.client.model.Updates.combine;
import static com.mongodb.client.model.Updates.set;
import org.bson.Document;

// Example_2
public class Example_2 {

    // main method
    public static void main(String[] args) {
        // Replace the connection string with your own connection string
        var uri = "mongodb://localhost:27017";

        // try block
        try ( MongoClient mongoClient = MongoClients.create(uri)) {

            // print message if connection is successfully established
            System.out.println("Connected successfully to server.");

            // get the specified database from the MongoDB server
            MongoDatabase database = mongoClient.getDatabase("bulkUpdate");

            // get the specified collection from the selected database
            MongoCollection<Document> collection = database.getCollection("supervisor");

            // update the filtered documents by updating the existing field
            collection.updateMany(eq("gender", "Female"),combine(set("gender", "F")));
            collection.updateMany(eq("gender", "Male"),combine(set("gender", "M")));

            System.out.println();
            // iterate over all documents of the selected collection
            // to print in Java IDE
            collection.find().forEach(doc -> {
                System.out.println(doc.toBsonDocument());
                System.out.println();
            });// end forEach

        } // end try block

        // print error if unable to execute a command
        catch (MongoException error) {
            System.err.println("An error occurred while running a command: " + error);
        }// end catch block

    }// end main method
}//end Example_2

输出：

{
    "_id": {"$oid": "62a866e592fd89ad9c4932ed"},
    "firstname": "Mehvish",
    "lastname": "Ashiq",
    "gender": "F",
    "contact": {
        "email": "mehvishofficial@gmail.com",
        "phone": [
            { "type": "official", "number": "123456789"},
            {"type": "personal", "number": "124578369"}
         ]
     },
     "entries": [
         {"_id": 1.0, "itemsperday": [1.0, 3.0, 4.0, 5.0, 6.0, 7.0]},
         {"_id": 2.0, "itemperday": [2.0, 3.0, 4.0, 5.0, 2.0, 7.0]},
         {"_id": 3.0, "itemperday": [5.0, 0.0, 0.0, 4.0, 0.0, 1.0]}
     ],
     "status": "Good"
}

{
    "_id": {"$oid": "62a8670192fd89ad9c4932ee"},
    "firstname": "Tahir",
    "lastname": "Raza",
    "gender": "M",
    "contact": {
        "email": "tahirraza@gmail.com",
        "phone": [
            {"type": "official", "number": "123478789"},
            {"type": "personal", "number": "122378369"}
         ]
     },
     "entries": [
         {"_id": 1.0, "itemsperday": [4.0, 5.0, 6.0, 7.0, 4.0, 6.0]},
         {"_id": 2.0, "itemperday": [2.0, 3.0, 2.0, 7.0, 5.0, 2.0]},
         {"_id": 3.0, "itemperday": [5.0, 0.0, 0.0, 1.0, 0.0, 0.0]}
     ],
     "status": "Good"
}

此代码示例与上一个示例类似，但我们正在更新与过滤器匹配的所有文档中特定字段的值。

我们使用 updateMany() 对 gender 等于 Female 且 gender 等于 Male 的所有文档执行批量更新。我们将 "gender": "Female" 和 "gender": "Male" 分别更改为 "gender":"F" 和 "gender":"M"。

到目前为止，我们已经了解了如何使用 updateMany() 方法添加新字段或更新第一级现有字段的值。接下来，我们将学习使用 updateMany() 对满足过滤器查询的嵌入式文档进行批量更新。

使用 updateMany() 对匹配过滤器的嵌入文档执行批量更新

示例代码：

//write your package where you want to save your source file
package com.voidtesting.javamongobulkupdateexample;

// import necessary libraries
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.client.MongoClients;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.model.UpdateOptions;
import org.bson.Document;
import org.bson.conversions.Bson;

// Example_3
public class Example_3 {

    // main method
    public static void main(String[] args) {
        // Replace the connection string with your own connection string
        var uri = "mongodb://localhost:27017";

        // try block
        try ( MongoClient mongoClient = MongoClients.create(uri)) {
            // print message if connection is successfully established
            System.out.println("Connected successfully to server.");

            // get the specified database from the MongoDB server
            MongoDatabase database = mongoClient.getDatabase("bulkUpdate");

            // get the specified collection from the selected database
            MongoCollection<Document> collection = database.getCollection("supervisor");
            // filter
            Bson where = new Document().append("contact.phone.type", "official");
            // update
            Bson update = new Document().append("contact.phone.$.type", "assistant");
            // set
            Bson set = new Document().append("$set", update);

            // update collection
            collection.updateMany(where, set, new UpdateOptions());


            // iterate over all documents of the selected collection
            // to print in Java IDE
            collection.find().forEach(doc -> {
                System.out.println(doc.toBsonDocument());
                System.out.println();
            }); // end forEach

        } // end try block

        // print error if unable to execute a command
        catch (MongoException error) {
            System.err.println("An error occurred while running a command: " + error);
        }// end catch block

    }// end main method
}//end Example_3

输出：

{
    "_id": {"$oid": "62a866e592fd89ad9c4932ed"},
    "firstname": "Mehvish",
    "lastname": "Ashiq",
    "gender": "F",
    "contact": {
        "email": "mehvishofficial@gmail.com",
        "phone": [
            { "type": "assistant", "number": "123456789"},
            {"type": "personal", "number": "124578369"}
         ]
     },
     "entries": [
         {"_id": 1.0, "itemsperday": [1.0, 3.0, 4.0, 5.0, 6.0, 7.0]},
         {"_id": 2.0, "itemperday": [2.0, 3.0, 4.0, 5.0, 2.0, 7.0]},
         {"_id": 3.0, "itemperday": [5.0, 0.0, 0.0, 4.0, 0.0, 1.0]}
     ],
     "status": "Good"
}

{
    "_id": {"$oid": "62a8670192fd89ad9c4932ee"},
    "firstname": "Tahir",
    "lastname": "Raza",
    "gender": "M",
    "contact": {
        "email": "tahirraza@gmail.com",
        "phone": [
            {"type": "assistant", "number": "123478789"},
            {"type": "personal", "number": "122378369"}
         ]
     },
     "entries": [
         {"_id": 1.0, "itemsperday": [4.0, 5.0, 6.0, 7.0, 4.0, 6.0]},
         {"_id": 2.0, "itemperday": [2.0, 3.0, 2.0, 7.0, 5.0, 2.0]},
         {"_id": 3.0, "itemperday": [5.0, 0.0, 0.0, 1.0, 0.0, 0.0]}
     ],
     "status": "Good"
}

在这个 Java 程序中，我们使用 updateMany() 方法对匹配过滤器查询的嵌入文档执行批量更新。

在这里，我们将 contact.phone.type 的值从 official 更新为 assistant。要访问文档数组，我们使用位置运算符 ($) 来更新满足过滤器查询的第一个数组值。

在使用位置运算符时，我们还可以指定应该更新哪些数组元素。我们可以指定要更新的第一个、所有或特定的数组元素。

为了通过位置运算符指定数组元素，我们使用 dot notation，一种用于导航 BSON 对象的属性访问语法。我们通过以下方式使用位置运算符来更新第一个、所有或指定的数组元素。

使用 bulkWrite() API 更新与过滤查询匹配的现有文档

示例代码：

//write your package where you want to save your source file
package com.voidtesting.javamongobulkupdateexample;

// import necessary libraries
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.client.MongoClients;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.model.DeleteOneModel;
import com.mongodb.client.model.UpdateManyModel;
import com.mongodb.client.model.WriteModel;
import java.util.ArrayList;
import java.util.List;
import org.bson.Document;

// Example_4
public class Example_4 {

    // main method
    public static void main(String[] args) {
        // Replace the connection string with your own connection string
        var uri = "mongodb://localhost:27017";

        // try block
        try ( MongoClient mongoClient = MongoClients.create(uri)) {
            // print message if connection is successfully established
            System.out.println("Connected successfully to server.");

            // get the specified database from the MongoDB server
            MongoDatabase database = mongoClient.getDatabase("bulkUpdate");

            // get the specified collection from the selected database
            MongoCollection<Document> collection = database.getCollection("supervisor");

            // create object
            List<WriteModel<Document>> writes = new ArrayList<>();

            // delete the document matching the filter
            writes.add(new DeleteOneModel<>(new Document("firstname", "Tahir")));

            // update document matching the filter
            writes.add(new UpdateManyModel<>(
                    new Document("status", "Good"), // filter
                    new Document("$set", new Document("status", "Excellent")) // update
            ));

            // bulk write
            collection.bulkWrite(writes);

            // iterate over all documents of the selected collection
            // to print in Java IDE
            collection.find().forEach(doc -> {
                System.out.println(doc.toBsonDocument());
                System.out.println();
            });// end forEach

        } // end try block
        catch (MongoException me) {
            System.err.println("An error occurred while running a command: " + me);
        }// end catch block
    }// end main method

}// end Example_4

输出：

{
    "_id": {"$oid": "62a866e592fd89ad9c4932ed"},
    "firstname": "Mehvish",
    "lastname": "Ashiq",
    "gender": "F",
    "contact": {
        "email": "mehvishofficial@gmail.com",
        "phone": [
            {"type": "assistant", "number": "123456789"},
            {"type": "personal", "number": "124578369"}
        ]
     },
     "entries": [
         {"_id": 1.0, "itemsperday": [1.0, 3.0, 4.0, 5.0, 6.0, 7.0]},
         {"_id": 2.0, "itemperday": [2.0, 3.0, 4.0, 5.0, 2.0, 7.0]},
         {"_id": 3.0, "itemperday": [5.0, 0.0, 0.0, 4.0, 0.0, 1.0]}
     ],
     "status": "Excellent"
}

在此示例中，我们使用 bulkWrite()API 一次执行多个操作（删除和更新）。DeleteOneModel() 用于删除匹配过滤器的文档，而我们使用 UpdateManyModel() 更新所有匹配过滤器的文档中已存在字段的值。