java.util.logging

提供Java ^TM 2平台核心日志记录工具的类和接口。 日志API的中心目标是支持在客户站点维护和维护软件。

日志有四个主要的目标用途：

1. Problem diagnosis by end users and system administrators. This consists of simple logging of common problems that can be fixed or tracked locally, such as running out of resources, security failures, and simple configuration errors.
2. Problem diagnosis by field service engineers. The logging information used by field service engineers may be considerably more complex and verbose than that required by system administrators. Typically such information will require extra logging within particular subsystems.
3. Problem diagnosis by the development organization. When a problem occurs in the field, it may be necessary to return the captured logging information to the original development team for diagnosis. This logging information may be extremely detailed and fairly inscrutable. Such information might include detailed tracing on the internal execution of particular subsystems.
4. Problem diagnosis by developers. The Logging APIs may also be used to help debug an application under development. This may include logging information generated by the target application as well as logging information generated by lower-level libraries. Note however that while this use is perfectly reasonable, the logging APIs are not intended to replace the normal debugging and profiling tools that may already exist in the development environment.

The key elements of this package include:

• Logger: The main entity on which applications make logging calls. A Logger object is used to log messages for a specific system or application component.
• LogRecord: Used to pass logging requests between the logging framework and individual log handlers.
• Handler: Exports LogRecord objects to a variety of destinations including memory, output streams, consoles, files, and sockets. A variety of Handler subclasses exist for this purpose. Additional Handlers may be developed by third parties and delivered on top of the core platform.
• Level: Defines a set of standard logging levels that can be used to control logging output. Programs can be configured to output logging for some levels while ignoring output for others.
• Filter: Provides fine-grained control over what gets logged, beyond the control provided by log levels. The logging APIs support a general-purpose filter mechanism that allows application code to attach arbitrary filters to control logging output.
• Formatter: Provides support for formatting LogRecord objects. This package includes two formatters, SimpleFormatter and XMLFormatter, for formatting log records in plain text or XML respectively. As with Handlers, additional Formatters may be developed by third parties.

日志记录API提供静态和动态配置控制。 静态控制使现场服务人员能够设置特定配置，然后使用新的日志记录设置重新启动应用程序。 动态控制允许更新当前正在运行的程序中的日志记录配置。 这些API还允许为系统的不同功能区域启用或禁用日志记录。 例如，现场服务工程师可能有兴趣跟踪所有的AWT事件，但可能对套接字事件或内存管理没有兴趣。

Null Pointers

一般来说，除非在javadoc中另有说明，否则如果传递null参数，方法和构造函数将抛出NullPointerException。 这个规则的一个很大的例外是Logger类中的日志记录便利方法（配置，进入，退出，更好，更好，最好，日志，logp，logrb，严重，投掷和警告方法）将接受空值除初始Level参数外的所有参数（如果有的话）。

Related Documentation

有关控制流程的概述，请参阅 Java Logging Overview 。

Interfaces

Filter	除了日志级别提供的控制之外，还可以使用过滤器对记录的内容提供精细的纹理控制。
LoggingMXBean	日志记录工具的管理界面。

Classes

ConsoleHandler	这 Handler发布日志记录到 System.err 。
ErrorManager	可以将ErrorManager对象附加到处理程序，以处理日志记录期间处理程序上发生的任何错误。
FileHandler	简单的文件记录 Handler 。
Formatter	格式化程序提供格式化LogRecords的支持。
Handler	一个 Handler对象从 Logger需要的日志信息和出口他们。
Level	Level类定义了一组可用于控制日志记录输出的标准日志记录级别。
Logger	记录器对象用于记录特定系统或应用程序组件的消息。
LoggingPermission	旧版安全代码; 不使用。
LogManager	有一个全局LogManager对象用于维护一组关于Loggers和Log服务的共享状态。
LogRecord	LogRecord对象用于在日志记录框架和各个日志处理程序之间传递日志记录请求。
MemoryHandler	Handler缓冲内存中循环缓冲区中的请求。
SimpleFormatter	以可读的格式打印 LogRecord的简要摘要。
SocketHandler	简单的网络日志记录 Handler 。
StreamHandler	基于流的日志记录 Handler 。
XMLFormatter	将LogRecord格式化为标准的XML格式。