1 concept:
* Filter life: water purifier. Air purifier, bandit.
* Web the filter: when access to server resources, the filter may be intercepted request, perform specific functions.
* Filter effects:
The general use for completing the operation. Such as: login authentication, unified coding process, sensitive string filtering. . .
Getting Started:
Step 1:
1 define a class that implements the interface Filter
2 replication method
3 interceptor configuration path
1web.xml
2 NOTE Using @WebFilter ( "/ interception Path")
2. Filters execution process
1 performs filter
2 execution resources after release
3 final performance filters release code.
Method 3 filter lifecycle
1init: After the server is started, it will create a Filter object, and then call the init method, is performed only once. For loading resources
2doFilter: every resource request is intercepted, it will execute, execute multiple times
3destory: After the server is shut down, Filter object is destroyed. If the server is shut down properly, it will perform destory method for releasing resources.
Detailed filter configuration 4
1 specific resource path: /index.jsp only access index.jsp resources, the filter will be executed
2 interceptions directory: / user / * to access / all of the resources of the user, the filter will be executed
3 interceptor extension: * .jsp suffix is access filter will be executed when the resource jsp
4 interceptions all resources / * access any resources will be blocked
Interception way configurations: the way resources are accessed
Notes Configuration
Set dispatcherTypes property
1REQUEST: default. Direct browser requests a resource
2FORWARD: Forwarding access to resources
3INCLUDE: includes access to resources
3Error: Error Jump Resources
web.xml Configuration
* Set <dispatcherTypes> </ dispatcherTypes> tag.
Filter chain (a plurality of filter)
Execution order
Filter 1 1
2 Filter 2
3 execution resources
4 filter 2
Filter 1 5
The execution order of the filter has
1 comment Configuration: To compare string comparison rules in accordance with the class name, the small value of the first implementation
As Afileter and Bfilter it will first perform Afilter
2web.xml Configuration
Arranged in the order, the configuration of the foregoing first implementation ye
General use httpServletRequest
And httpServletRequest can get url or uri