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preface Congratulations to all the friends who read this article for successfully unlocking the advanced feature plug-in version of RabbitMQ series Content of delay queue 🎁 Through this article, you will clearly understand: what is delay queue? Delay queue usage scenario? How to install the BBU # exchange # Q plug-in? 😄 At the end ...

There are some points to pay attention to when using @ Transactional: Spring will roll back (RuntimeException) and its subclasses by default. When an Exception and its subclasses are encountered, it will not roll back@Transactional annotations should only be applied to public methods, which is determined by the nature of Spring AOP @For the Tr ...

1. Concept of abnormality: • when the program is running, if the Python interpreter encounters an error, it will stop the execution of the program and prompt some error messages, which is an exception • the action that the program stops executing and prompts an error message is usually called: raise exception During program devel ...

1. Basic data type typepositionbytecharacteristicData rangebyte81-2 ^ 7 ~ 2 ^ 7, the first digit indicates positive and negativechar1620 ~ 2^16-1short162-2 ^ 15 ~ 2 ^ 15-1, the first digit indicates positive and negativeint324Default type of integer in java-2 ^ 31 ~ 2 ^ 31-1, the first digit indicates positive and negativelong648Add L at the ...

Log specification (code out efficiency: detailed explanation of Alibaba Java development manual) 1. [mandatory] the API in the log system (Log4j, Logback) cannot be directly used in the application, but the API in the log framework SLF4J should be used. The log framework in facade mode is used, which is conducive to the unification of maintena ...

1.ADC Sample and hold? F28335 chip contains ADC peripherals to realize the conversion from analog quantity to digital quantity. ADC conversion includes sample and hold quantization and coding; Sampling is to convert the continuous quantity in time into the discrete quantity in time, and save the sampling results until the next sampling is cal ...

Website recommendation ts-playground ts Chinese Manual Introduction to ts Type basis Strong type and weak type Strongly typed language: it is not allowed to change the data type of a variable unless it is castWeakly typed language: variables can be assigned different data types Static type and dynamic type Statically typed language: det ...

Day 1 This section mainly explains some compiling environments of JAVA and some confusing basic knowledge. James Gosling received a bachelor's degree in computer science from the University of Calgary in Canada in 1977 and a doctor's degree in computer science from Carnegie Mellon University in 1983. After graduation, he worked at IBM and de ...

1. python standard library: python 3.9.4 (1)format(): format(value[, format_spec]) Convert # value # to # format_ "Formatted" representation of spec # control. format_ The interpretation of spec ， depends on the type of ， value ， argument, but most built-in types use standard formatting syntax: Format specification Mini lan ...

1, Recycle bin for HDFS There is a recycle bin in our windows system. If you want to restore deleted files, you can restore them here. HDFS also has a recycle bin. HDFS will create a recycle bin directory for each user: / user / user name / Trash /, every file / directory deleted by the user on the Shell command line will enter the correspond ...