今天使用mongo-java-drive寫連接mongo的客戶端，着實被上面那個錯坑了一把。回顧一下解決過程：
報錯：
1 com.mongodb.MongoTimeoutException: Timed out after 30000 ms while waiting to connect. Client view of cluster state is {type=UNKNOWN, servers=[{address=localhost:27017, type=UNKNOWN, state=CONNECTING, exception={com.mongodb.MongoSocketWriteException: Exception sending message}, caused by {javax.net.ssl.SSLHandshakeException: Remote host closed connection during handshake}, caused by {java.io.EOFException: SSL peer shut down incorrectly}}] 2 at com.mongodb.connection.BaseCluster.getDescription(BaseCluster.java:167) 3 at com.mongodb.client.internal.MongoClientDelegate.getConnectedClusterDescription(MongoClientDelegate.java:106) 4 at com.mongodb.client.internal.MongoClientDelegate.createClientSession(MongoClientDelegate.java:77) 5 at com.mongodb.client.internal.MongoClientDelegate$DelegateOperationExecutor.getClientSession(MongoClientDelegate.java:185) 6 at com.mongodb.client.internal.MongoClientDelegate$DelegateOperationExecutor.execute(MongoClientDelegate.java:152) 7 at com.mongodb.client.internal.MongoCollectionImpl.executeSingleWriteRequest(MongoCollectionImpl.java:894) 8 at com.mongodb.client.internal.MongoCollectionImpl.executeInsertOne(MongoCollectionImpl.java:443) 9 at com.mongodb.client.internal.MongoCollectionImpl.insertOne(MongoCollectionImpl.java:427) 10 at com.mongodb.client.internal.MongoCollectionImpl.insertOne(MongoCollectionImpl.java:421) 11 at com.czb.chargepile.core.MongeTemplate.insert(MongeTemplate.java:59) 12 at com.czb.chargepile.manage.X01Manager.insert(X01Manager.java:17) 13 at manage.X01ManagerTest.main(X01ManagerTest.java:21)
分析：mongodb數據庫連接超時，也就是客戶端連不上mongo
代碼：
1 MongoCredential credential = MongoCredential.createCredential(user, databaseName, password); 2 3 mongoClient = MongoClients.create( 4 5 MongoClientSettings.builder() 6 7 .applyToSslSettings(builder -> builder.enabled(true)) 8 9 .applyToClusterSettings(builder -> 10 11 builder.hosts(Arrays.asList(new ServerAddress("localhost", 27017)))) 12 13 .credential(credential) 14 15 .build()); 16 17 MongoDatabase database = mongoClient.getDatabase(databaseName);
解決：
1、看到錯誤，首先想到的是用戶名密碼不對，為了確保密碼無誤，重新設置了mongo的密碼，然而並未好使
2、檢查用戶所屬數據庫是否正確，經過檢查，發現完全匹配
檢查mongo-java-drive版本是否和mongo版本匹配，發現完全匹配
4、最后開始懷疑上面的代碼有問題，找官方文檔https://mongodb.github.io/mongo-java-driver/3.8/driver/tutorials/authentication/，從這里找到了新的寫法，先無腦拷貝，然后運行，發現這里寫法是成功的，與自己的代碼對比，發現我的代碼多了一行
1 .applyToSslSettings(builder -> builder.enabled(true))
回到我代碼，去掉，發現成功了。又回去看官方文檔，找到端倪
如果使用那個選項，傳輸過程會使用TLS/SSL對傳輸層進行加密，但是我的mongo服務是沒有對應設置的，所以導致連接不上。