J2EE fragmentation notes

I 've been catching up for a while.CodeYou have no time to take notes. I haven't forgotten to record it all over the past two days. It's a bit fragmented. Remember what to write.

1. batch processing data of Java. SQL. preparedstatement.

Previously, it was all inserted one by one. I thought it was too 2. So I found that the preparedstatement can be processed in batches and directly pasted with the Demo code.

 
Preparedstatement PS = conn. preparestatement (
 
 
"Insert into employees values (?, ?, ?)");
 
 
 
For(N = 0; n <100; n ++ ){
 
 
 
 
PS. setstring (name [N]);
 
 
PS. setlong (ID [N]);
 
 
PS. setint (salary [N]);
 
PS. addbatch ();
 
 
}
 
 
Ps.exe cutebatch ();
 
 
 
 
If the data volume is too large, you can limit the batch size. For example, you can submit every 1000 records once.
 
 
Preparedstatement PS = conn. preparestatement (
 
"Insert into employees values (?, ?, ?)");
 
 
Int[] Result;
 
 
IntAffectedline = 0;
 
 
For(N = 0; n <2345; n ++ ){
 
PS. setstring (name [N]);
 
 
PS. setlong (ID [N]);
 
 
PS. setint (salary [N]);
 
 
PS. addbatch ();
 
 
If(I + 1) % batch_limite = 0 ){
 
Resulteffecpstmt.exe cutebatch ();
 
 
Affectedline + = calculatesum (result );
 
 
Conn. Commit ();
 
 
PS. clearbatch ();
 
 
}
 
Resultappsps.exe cutebatch ();
 
 
Affectedline + = calculatesum (result );
 
 
}
 
 
2. Obtain the current web root directory:
 
 
Public StaticString getwebclassespath ()ThrowsUrisyntaxexception {
 
String Path = globalparameter.Class. Getresource ("/"). Touri (). getpath ();
 
 
ReturnPath;
 
 
 
 
}
 
 
 
Public StaticString getwebinfpath ()ThrowsIllegalaccessexception, urisyntaxexception {
 
 
String Path = getwebclassespath ();
 
 
If(Path. indexof ("WEB-INF")> 0 ){
 
Path = path. substring (0, path. indexof ("WEB-INF") + 8 );
 
 
}Else{
 
 
Throw NewIllegalaccessexception ("Path retrieval Error");
 
 
}
 
ReturnPath;
 
 
}
 
 
 
 
Public StaticString getwebroot ()ThrowsIllegalaccessexception, urisyntaxexception {
 
String Path = getwebclassespath ();
 
 
If(Path. indexof ("WEB-INF")> 0 ){
 
 
Path = path. substring (0, path. indexof ("WEB-INF/classes"));
 
 
}Else{
 
Throw NewIllegalaccessexception ("Path retrieval Error");
 
 
}
 
 
ReturnPath;
 
 
}
 
 
 
@ Test
 
 
Public VoidTestpath ()ThrowsIllegalaccessexception, urisyntaxexception {
 
 
System. Out. println ("Web class Path ="+ Getwebclassespath ());
 
 
System. Out. println ("WEB-INF Path ="+ Getwebinfpath ());
 
System. Out. println ("Webroot path ="+ Getwebroot ());
 
 
}
 
 
In the development environment (I am eclipse J2EE + Tomcat 7), eclipse uses a server plug-in to simulate Tomcat services, therefore, the webroot path obtained through the above method is usually D: \ workspace \. metadata \. plugins \ Org. eclipse. WST. server. such as core \ tmp0 \ wtpwebapps \ mystruts \. If a dynamically generated file is to be placed in the web directory, find it here. It seems to be a temporary folder, which has not been carefully studied. (Files first placed under the project webroot will be copied to this temporary directory, so they can all be found)
 
 
3. Bidirectional map and bimap. Support key search through value
 
 
Google collection is used, which is described here.
 
 
Usage
 
Bimap <string, string> map = hashbimap. Create ();
 
 
Map. Put ("Kafka0102","1");
 
 
System. Out. println (Map. Get ("Kafka0102"));
 
System. Out. println (Map. Inverse (). Get ("1");// The output reverse data does not provide a separate function, but needs to call inverse (). Get ()
 
 
 
 
 
 
 
 
4. I think so much about it now. I will try again later.