这破站 Spring Setter注入(Setter injection)和构造注入(Constructor injection)
平时使用Spring少不了各种注入，大部分时候都是直接在属性上@Autowired就完了，偶尔看到在构造方法上注入的也知道怎么回事。今天忽然想到这俩有什么区别，了解了下使用场景。
Java8 Lambda map()和flatMap()
在使用lambda的map时候看到了flatMap这个方法，之前知道和map不一样，但是一直没管它，这次又想起来，就找了点资料看了下。
UTF-8 BOM
在使用Notepad++转换编码时，转为UTF-8可以选择“UTF-8”和“UTF-8 BOM”这两种，有点好奇这俩有什么区别，于是查了会资料。
Spring Boot data-mongodb连接MongoDB数据库失败
用了spring-boot-starter-data-mongodb模块后，连接本机的Mongodb一直失败，用户也创建了，密码也设了，就是连不上啊。
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>总是报错：
com.mongodb.MongoSecurityException: Exception authenticating MongoCredential{mechanism=null, userName='test', source='test', password=<hidden>, mechanismProperties={}}
at com.mongodb.connection.SaslAuthenticator.wrapException(SaslAuthenticator.java:162)
at com.mongodb.connection.SaslAuthenticator.access$200(SaslAuthenticator.java:39)
at com.mongodb.connection.SaslAuthenticator$1.run(SaslAuthenticator.java:68)
at com.mongodb.connection.SaslAuthenticator$1.run(SaslAuthenticator.java:46)
at com.mongodb.connection.SaslAuthenticator.doAsSubject(SaslAuthenticator.java:168)
at com.mongodb.connection.SaslAuthenticator.authenticate(SaslAuthenticator.java:46)
at com.mongodb.connection.DefaultAuthenticator.authenticate(DefaultAuthenticator.java:32)
at com.mongodb.connection.InternalStreamConnectionInitializer.authenticateAll(InternalStreamConnectionInitializer.java:122)
at com.mongodb.connection.InternalStreamConnectionInitializer.initialize(InternalStreamConnectionInitializer.java:52)
at com.mongodb.connection.InternalStreamConnection.open(InternalStreamConnection.java:127)
at com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:114)
at java.lang.Thread.run(Thread.java:748)
Caused by: com.mongodb.MongoCommandException: Command failed with error 18: 'Authentication failed.' on server localhost:27017. The full response is { "ok" : 0.0, "errmsg" : "Authentication failed.", "code" : 18, "codeName" : "AuthenticationFailed" }
at com.mongodb.connection.ProtocolHelper.getCommandFailureException(ProtocolHelper.java:164)
at com.mongodb.connection.InternalStreamConnection.receiveCommandMessageResponse(InternalStreamConnection.java:295)
at com.mongodb.connection.InternalStreamConnection.sendAndReceive(InternalStreamConnection.java:255)
at com.mongodb.connection.CommandHelper.sendAndReceive(CommandHelper.java:84)
at com.mongodb.connection.CommandHelper.executeCommand(CommandHelper.java:34)
at com.mongodb.connection.SaslAuthenticator.sendSaslContinue(SaslAuthenticator.java:123)
at com.mongodb.connection.SaslAuthenticator.access$100(SaslAuthenticator.java:39)
at com.mongodb.connection.SaslAuthenticator$1.run(SaslAuthenticator.java:65)
... 9 common frames omittedChrome禁止地址栏显示历史记录
已经有很多人吐槽过这个设置了，搜索过的历史有多少人会在去搜？而且这玩意之前还能通过chrome://flags关闭，更新到86版本后直接就不让关了，脑残Google？真就为所欲为。