Ethereum mapping length

1. The main network mapping of wicc is the process of replacing erc20 token with wicc on the public chain of the base chain. The main network mapping of the public chain is the symbol of the real use of the public chain. After the main network mapping, all kinds of applications and development based on the public chain can really start, and really enter the service life of the public chain.

2. EOS will end crowdfunding at 06:59:59 Beijing time on June 2, 2018. You need to complete the mapping as soon as possible before that time, and replace the EOS based on Ethereum with EOS main network token,
otherwise, the EOS will be cleared at that time, and the EOS based on Ethereum network will stop transferring within 23 hours after crowdfunding.

3. Yesterday, I wrote a log about udev, sysfs, and continue today.

4. < servlet>< br /> & lt; servlet-name> aaaaa</ servlet-name>< br /> & lt; servlet-class> com.bdqn</ servlet-class>< br /></ servlet>< br />< servlet-mapping>< br /> & lt; servlet-name> aaaaa</ servlet-name>< br /> & lt; url-pattern> ac</ url-pattern>< br /></ servlet-mapping>
the servlet name in the servlet should be consistent with the servlet name in the servlet mapping
the location of the class you want to connect to is written as a package in the servlet class. The name of the class
URL pattern is the name you want to enter in the browser
for example, if you type http://localhost : 8080 / project name / AC
the server will find the URL pattern first, and the name is a Which servlet mapping of C, and then find the servlet name of the servlet mapping, and then find the servlet with the same servlet name, and then find the servlet class of the servlet, so as to find the processing class
(limited level, a lot of nonsense, but it should be clear)

5. Please read and understand the ant style path matching syntax carefully. Here * matches to one level, such as ABC. Do * * /... Can match to sub URL address of any length

6. The fourth parameter of the function createfilemapping() specifies the byte size of the created file mapping object. The parameter type is DWORD, that is, the maximum size of the file mapping object is 2147483648 bytes, that is, 2G

the file size is really related to the virtual memory. After all, it is necessary to open up the same memory space as the file size inside the process

if you want a file larger than 2G, you can't use the file mapping object method. You can use a simple file method, such as reading n bytes from the source file in turn and writing them to the destination file in turn.

7. 1) Assigned
the primary key is generated by an external program without hibernate

2) Hilo
the primary key generation mechanism implemented by hi / Lo algorithm requires additional database tables to save the primary key generation history

3) seqhilo
similar to Hilo, the primary key generation mechanism implemented by hi / Lo algorithm is only that the primary key history
state is saved in sequence, which is suitable for databases supporting sequence, such as Oracle

4) increment
primary keys are incremented in numerical order. The implementation mechanism of this method is to maintain
a variable in the current application instance to save the current maximum value, and then every time you need to generate a primary key,
add 1 to this value as the primary key
the possible problem in this way is: if there are multiple instances accessing the same data
library, because each instance maintains its own primary key state, different instances may generate the same primary key, resulting in plicate primary keys. Therefore, if there are multiple real
instances in the same database, this method must be avoided

5) identity
uses the primary key generation mechanism provided by the database. For example, the primary key generation mechanism in DB2, SQL server and MySQL


6) sequence
uses the sequence mechanism provided by the database to generate the primary key. Such as
sequence in ORALCE

7) native
according to the underlying database, hibernate uses one of identity, Hilo and sequence as the primary key generation method

8) uuid.hex
hibernate generates a hexadecimal value (represented by a 32-bit string after encoding) as the primary key based on the 128 bit unique value generation algorithm

9) uuid.string
is similar to uuid.hex, except that the generated primary key is not encoded (length 16). Problems may occur in some
databases (such as PostgreSQL)

10) foreign
uses the field of the external table as the primary key
generally speaking, using uuid.hex to generate the primary key will provide the best performance and database platform adaptability< In addition, common databases, such as Oracle, DB2, SQL server and MYSQL, provide an easy-to-use primary key generation mechanism (auto increase field or sequence). We can use the method of generator class = native to generate the primary key provided by the database< However, it is worth noting that the primary key generation mechanism provided by some databases may not be the best in efficiency,
a large number of concurrent insert data may cause interlocking between tables
the primary key generation mechanism provided by the database is often achieved by saving the current primary key status in an internal table (for example, for a self incrementing primary key, the current maximum value and incremental value are maintained in the internal table).
after each insertion of data, the maximum value will be read, and then the incremental value will be added as the primary key of the new record, In this way, one insert operation may lead to multiple table read / write operations in the data
library, accompanied by data lock / unlock operation, which has a great impact on performance
therefore, uuid.hex is recommended as the primary key generation
mechanism for systems with high concurrent insert requirements.

8. This is the object relation mapping file * *. HBM. XML between hibernate and database< br />< class name=" c.lw.model.Changeroll" table=" changeroll" catalog=" sms"& gt;
indicates that the class c.lw.model.changeroll corresponds to the table changeroll in the database instance SMS

& lt; id name=" id" type=" java.lang.Integer"& gt; < br />< column name=" id" /& gt; < br />< generator class=" native" /& gt; < br /></ id>
the primary key of the changeroll table is ID, which is generated by the database itself. The corresponding field ID in the c.lw.model.changeroll class is Java. Lang.integer

& lt; many-to-one name=" systemuser" class=" c.lw.model.Systemuser" fetch=" select"& gt; < br />< column name=" student" /& gt; < br /></ many-to-one>
many to one relationship: multiple changerolls, corresponding to one student. This is the object relation mapping file * *. HBM. XML between hibernate and database< br />< class name=" c.lw.model.Changeroll" table=" changeroll" catalog=" sms"& gt;
indicates that the class c.lw.model.changeroll corresponds to the table changeroll in the database instance SMS

& lt; id name=" id" type=" java.lang.Integer"& gt; < br />< column name=" id" /& gt; < br />< generator class=" native" /& gt; < br /></ id>
the primary key of the changeroll table is ID, which is generated by the database itself. The corresponding c.lw.model.changeroll class contains the field systemuser, effect = & quot; of type c.lw.model.systemuser; select" When querying the corresponding table of c.lw.model.systemuser through changeroll table, select method is used (another method is join, you can check the difference between them yourself). The corresponding field in the changeroll table is named student.

& lt; property name=" changetype" type=" java.lang.String"& gt; < br />< column name=" changetype" length=" 20" /& gt; < br /></ property>
the java.lang.string field in the c.lw.model.changeroll class corresponds to the changetype field in the changeroll table, with a maximum length of 20
the last property means the same as this

the answer is a bit messy. There are many descriptions about hibernate configuration files on the Internet, you can search them yourself.