Solve the problem of cannot be cast to javax.servlet.Filter error _jsp programming

Cannot is cast to javax.servlet.Filter error, cause Servlet-api.jar conflict

Use MAVEN to develop a Web application that complains when it starts:

Jar not loaded. For a Servlet Spec 2.3, section 9.7.2. Offending Class:javax/servlet/servlet.class

And then output the error:

Serious: Exception starting filter Encodingfilter
java.lang.ClassCastException: Org.springframework.web.filter.CharacterEncodingFilter cannot be cast to
 Javax.servlet.Filter

The cause of the problem is that after Server-:tomcat startup, the jar packets in the Tomcat/lib directory are read into memory, and if the WebApps directory has the same package in the Web-inf/lib directory, it will fail to load.

Similar problems can occur between different versions of packages

The way to solve this problem is to use the <scope> tag for Servlet-ap.jar, compile it with Servlet-api and JSP-API, but without these two dependencies when packing

As follows:

<dependency>
 <groupId>javax.servlet</groupId>
 <artifactid>servlet-api</ artifactid>
 <version>2.4</version>
 <scope>provided</scope>
</ Dependency>

<dependency> <scope>, which mainly manages the deployment of dependencies. Currently <scope> can use 5 values:

* Compile, default, applies to all phases, and is published along with the project.
* provided, similar to compile, expects JDK, containers, or users to provide this dependency. such as Servlet.jar.
* Runtime, used only at run time, such as JDBC driver, applicable to run and test phase.
* Test, used only during testing, for compiling and running test code. Will not be published with the project.
* System, similar to provided, needs to explicitly provide jar,maven that contains dependencies and does not find it in repository.

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