Case Case [practice] Login

0 (template)

Mistakes:

 

phenomenon:

 

Error contents:

 

1

Mistakes:

 Click Save data is not modified by SQLyog;

phenomenon:

 Java code can not find the appropriate content;

Error contents:

no

 

2

Mistakes:

When a variable assignment in static code block, front and again declared variable type, in fact, lead to a new object is created;

phenomenon:

 Java code can not get to the variable content;

// this is not in fact a static code block shows the class of the same name created a new variable, the variable is non-static code block object that generated the call of the variables;

Error contents:

java.lang.IllegalArgumentException: Property 'dataSource' is required

 

3

Mistakes:

 Brackets @WebServlet ( "/ loginServlet") is not the name: delete;

phenomenon:

 This can not be called normal Servlet service;

Error contents:

404，The origin server did not find a current representation for the target resource······

 

4

Mistakes:

 When you modify Tomcat configuration error in the URL address to be deleted, and it should be modified is the deployment of the Application context;

phenomenon:

 You can not open the page properly, and the following message box pops up:

Error contents:

no