struts Initial Knowledge 6-Interceptor

1. Interceptor use

1.1 Custom Interceptor

• Method:

  1. Create common classes, inherit AbstractIntercepter, and implement abstract methods

  2.struts.xml configuration interceptor:

  2.1 Declare Interceptor

  2.2 Use interceptors:

  	> Note that all default interceptors do not work after configuring the interceptor
  	>
  	> Solutions:
  	>
  	> 1. Call the default stack Interceptor at every place where the interceptor is used
  	>
  	> Disadvantage: You need to call the default interceptor stack everywhere you use the interceptor
  	>
  	> 2. At your own interceptor, call the default stack interceptor group and add your own interceptor
  	>
  	> Advantages: You don't need to configure multiple interceptors in every place where interceptors are used, just configure your own interceptors.
  	>
  	> Disadvantage: You still need to use interceptors everywhere.
  	>
  	> 3. Configure intercepting XML to configure itself as the default interceptor
  	>
  	> Disadvantage: Intercept everything, and intercept anything that does not need to be intercepted.
  	>
  	> 4. Solution: There is an abstract class in the AbstractIninterceptor subclass - MethodFilterInterceptor:
  	>
  	> excludeMethod: No interception is required
  	>
  	> Include Method: Need to intercept
  	>
  	> Disadvantage: When declaring an interceptor, you don't know which methods need to be intercepted and which don't need to be intercepted.
  	>
  	> 5. Interception in Use
  

2. Processes

2.1 Execution process

• Interception - > (If there is a next interceptor, let it go to the next interceptor) - > Last interceptor let it go - > Reaching the target resource

3. Practice

3.1 Login Control

• Logon Interception Class

  public class LoginInterceptor extends MethodFilterInterceptor {
      /**
        * @Author ANGLE0
        * @Description Determine whether there are objects in the session domain
        * @Date 10:41 2019/7/28
        * @Param
        * @return
        **/
      @Override
      protected String doIntercept(ActionInvocation actionInvocation) throws Exception {
          Object obj = ActionContext.getContext().getSession().get("loginStaff");
              //Not logged in, pointing to the logon page
          if (obj == null) {
              return "login";
          }
              //Logged in
          return actionInvocation.invoke();
      }
  }
  

• strtus.xml configuration interceptor

  There are two ways to configure interceptors:

  Method 1: Define your own interceptor directly, and then configure the interceptor in action

  Method 2: Pack default interceptors and custom interceptors into stacks and then configure them into action

  • Method 1

  //Custom Interceptor
  <interceptor name="loginInterceptor" class="com.it.w.sms.web.interceptor.LoginInterceptor"></interceptor>
  
  //Reference in action
  <action name="">
  	//Reference to the default stack
  	<interceptor-ref name="defaultStack"></interceptot-ref>
  	//Call your own interceptor	
  	<interceptor-ref name="loginInterceptor"></interceptot-ref>
  </action>
  

  • Stack Packing

  <interceptors>
      <!--Custom stack-->
      <interceptor-stack name="loginInterceptorStack">
          <interceptor-ref name="default-stack"></interceptor-ref>
          <interceptor-ref name="loginInterceptor"></interceptor-ref>
      </interceptor-stack>
  </interceptors>
  

  • Declare default

  <interceptors>
      <!--3.1 Declare interceptor, register interceptor-->
      <interceptor name="loginInterceptor" class="com.it.w.sms.web.interceptor.LoginInterceptor"></interceptor>
      <!--3.2 Declare the interceptor stack, action Quote-->
      <interceptor-stack name="loginStack">
          <interceptor-ref name="default-stack"></interceptor-ref>
          <!--Configure methods that do not require interception. exculeMethod Configure methods that do not require interception"Division"-->
          <interceptor-ref name="loginInterceptor">
              <param name="excludeMethods">login</param>
          </interceptor-ref>
      </interceptor-stack>
  </interceptors>
  <!--3.3 Declare default-->
  <default-interceptor-ref name="loginStack"></default-interceptor-ref>
  
  

3.2 File Upload

Properties of uploaded files provided by 3.2.1 Struts Library

• photoFileName: Upload File Name
• photoContentType: File type

3.2.2 File Cache

• <10KB: Memory as Cache
• > 10KB: Disk temporary file as cache

3.2.3 File Processing Mode

3.2.3.1 copies

• Copy it to the specified location (temporary file processing is still in progress)

3.2.3.2 shear

• Cut the temporary file to the specified location and rename it (the temporary file has been processed and is no longer there)

3.2.4 Modification Limits Upload File Size

• Modifying Constants
• Modifying File Restrictions by Injecting Parameters

3.2.5 Multi-file Upload

3.3 File Download

3.3.1 Small bug

• The variable name of InputStream in the download action class cannot be used in
• Determine whether the picture has been P, the text is open, and whether the first voyage has been E.... Subsample