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原文出自：http://www.mkyong.com/mongodb/spring-data-mongodb-delete-document/

返回目录：http://ysj5125094.iteye.com/blog/2192754??

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Java MongoDB : Delete document

In this tutorial, we show you how to use?collection.remove()?to delete documents from the collection.

译：在本教程中，我们将向你展示使用?collection.remove()?从集合中删除文档。

1. Test Data

Insert 10 documents from number 1 to 10 for testing.

译：插入number 为 1 到 10的 10条文档。

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for (int i=1; i <= 10; i++) {
    collection.insert(new BasicDBObject().append("number", i));
}

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2. DBCollection.remove()

See below code snippets to delete documents.（译：看下面删除文档的代码片断）

Example 1

Get first document and delete it. In this case, number = 1 is deleted.?

译：获取第一个文档并删除他，相当于删除number = 1的文档。

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	DBObject doc = collection.findOne(); //get first document
	collection.remove(doc);

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Example 2

Puts query in a?BasicDBObject. In this case, number = 2 is deleted.?

译：向BasicDBObject对象中put一个number = 2 ，再删除。

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	BasicDBObject document = new BasicDBObject();
	document.put("number", 2);
	collection.remove(document);

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And Operator?（译：and 操作符）

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Two common mistakes :（译：两个常见的错误）

1. A query like this only delete number = 3.

译：只删除number=3的。

	BasicDBObject document = new BasicDBObject();
	document.put("number", 2);
        document.put("number", 3); //override above value 2，会重写上面的值
	collection.remove(document);

2. Nice try below, but query like this will not work, it will delete NOTHING.

译：这是种不错的尝试，但是这种尝试，将不会删除任何数据。

	BasicDBObject document = new BasicDBObject();
	List<Integer> list = new ArrayList<Integer>();
	list.add(7);
	list.add(8);
	document.put("number", list);
	collection.remove(document);

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For “AND” query, you need to use “$in” or “$and” operator, see example 5.

译：使用"AND"查询，你需要使用"$in" 或 "$and"操作符，see example 5.

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Example 3

Use?BasicDBObject?directly. In this case, number = 3 is deleted.

译：直接使用BasicDBObject?对象。在这种情况下，number=3是可以删除的。

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collection.remove(new BasicDBObject().append("number", 3));

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Example 4

Puts a?$gt?operator in a?BasicDBObject?object. In this case, number = 10 is deleted.?

译：将?$gt?操作符put?BasicDBObject对象。在这种情况下，number=10是可以删除的。

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	BasicDBObject query = new BasicDBObject();
	query.put("number", new BasicDBObject("$gt", 9));
	collection.remove(query);

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Example 5

Puts a?$in?operator in a?BasicDBObject?object, constructs the query in ArrayList. In this case, number = 4 and number = 5 are deleted.?

译：put一个?$in?操作符到?BasicDBObject?对象，构建查询列表。在这种情况下，number=4和number=5被删除。

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	BasicDBObject query2 = new BasicDBObject();
	List<Integer> list = new ArrayList<Integer>();
	list.add(4);
	list.add(5);
	query2.put("number", new BasicDBObject("$in", list));
	collection.remove(query2);

More MongoDB Operators
For more operators, read this?MongoDB operators quick reference.?

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译：更多操作符，请阅读此文档（MongoDB operators quick reference.）。

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Example 6

Use cursor to delete all available documents. (Not recommended, prefer example 7)

译：使用游标，删除所有可用文档（不推荐使用，建议选择example 7）

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	DBCursor cursor = collection.find();
	while (cursor.hasNext()) {
		collection.remove(cursor.next());
	}

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Example 7

Pass an empty BasicDBObject, and the entire documents will be deleted.?

译：传递一个空的?BasicDBObject 对象，整个文档会被删除。

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collection.remove(new BasicDBObject());

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Example 8

It deletes the entire documents and drop the collection.?

译：删除所有文档及整个集合。

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collection.drop();

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Example 9

The?remove()?will returns a?WrireResult?object, it contains useful information about the remove operation. And you can uses?getN()?to get the number of documents affected.?

译：使用?remove()?命令将返回一个?WrireResult?对象，他包含删除操作的信息，你可以使用?getN()?方法得到影响文档的行数。

       WriteResult result = collection.remove(query2);
       System.out.println("Number of documents are deleted : " + result.getN());

3. Full Example

Full example to show the different ways to delete documents.?

package com.mkyong.core;
 
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;
 
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.Mongo;
import com.mongodb.MongoException;
 
/**
 * Java MongoDB : Delete document
 * @author mkyong
 */
 
public class App {
    public static void main(String[] args) {
 
      try {
 
	Mongo mongo = new Mongo("localhost", 27017);
	DB db = mongo.getDB("yourdb");
 
	// get a single collection
	DBCollection collection = db.getCollection("dummyColl");
 
	//insert number 1 to 10 for testing
	for (int i=1; i <= 10; i++) {
		collection.insert(new BasicDBObject().append("number", i));
	}
 
	//remove number = 1
	DBObject doc = collection.findOne(); //get first document
	collection.remove(doc);
 
	//remove number = 2
	BasicDBObject document = new BasicDBObject();
	document.put("number", 2);
	collection.remove(document);
 
	//remove number = 3
	collection.remove(new BasicDBObject().append("number", 3));
 
	//remove number > 9 , means delete number = 10
	BasicDBObject query = new BasicDBObject();
	query.put("number", new BasicDBObject("$gt", 9));
	collection.remove(query);
 
	//remove number = 4 and 5
	BasicDBObject query2 = new BasicDBObject();
	List<Integer> list = new ArrayList<Integer>();
	list.add(4);
	list.add(5);
	query2.put("number", new BasicDBObject("$in", list));
	collection.remove(query2);
 
	//print out the document
	DBCursor cursor = collection.find();
        while(cursor.hasNext()) {
             System.out.println(cursor.next());
        }
 
        collection.drop();
 
        System.out.println("Done");
 
      } catch (UnknownHostException e) {
	e.printStackTrace();
      } catch (MongoException e) {
	e.printStackTrace();
      }
 
   }
}

Output…?

{ "_id" : { "$oid" : "4dc7a6989e3a66c5faeee757"} , "number" : 6}
{ "_id" : { "$oid" : "4dc7a6989e3a66c5faeee758"} , "number" : 7}
{ "_id" : { "$oid" : "4dc7a6989e3a66c5faeee759"} , "number" : 8}
{ "_id" : { "$oid" : "4dc7a6989e3a66c5faeee75a"} , "number" : 9}
Done

References

1. MongoDB operators quick reference
2. MongoDB WriteResult JavaDoc

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Java MongoDB : Delete document（译）

原文：http://ysj5125094.iteye.com/blog/2212781