Introduction to related operations of Struts interceptor (with code)

This article brings you an introduction to the relevant operations of the Struts interceptor (with code). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

How to implement aop

Used to implement action before and after execution

Generally used for transaction operations.

Generally used for certain unauthorized operations When the page is accessed, interception operations are performed to intercept illegal access.

Out-of-the-box interceptor

<!-- 拦截器 -->
<interceptor-ref name="params"/>  <!-- 传递属性拦截器 -->
<interceptor-ref name="timer"/> <!-- 测算执行时间 -->

Must have passing attributes for this interceptor

The running output log is as follows

2019-03-24 03:50:19.231 [DEBUG] com.opensymphony.xwork2.ognl.SecurityMemberAccess.isAccessible(SecurityMemberAccess.java:67) - Checking access for [target: com.ming.HelloWorldAction@33e67d25, member: public java.lang.String com.ming.HelloWorldAction.getName(), property: name]
2019-03-24 03:50:19.232 [INFO ] com.opensymphony.xwork2.interceptor.TimerInterceptor.doLog(TimerInterceptor.java:205) - Executed action [//hello!execute] took 12 ms.

You can see that this action takes 12ms to run in total

Custom interceptor

You need to inherit this abstract class and implement its method. com.opensymphony.xwork2.interceptor.AbstractInterceptor abstract class

The code is as follows

package com.ming;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;

public class MyInterceptor extends AbstractInterceptor {
    /**
     * Override to handle interception
     *
     * @param invocation
     */
    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        return null;
    }
}

Implement the interceptor method of this class

package com.ming;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class MyInterceptor extends AbstractInterceptor {
    /**
     * Override to handle interception
     *
     * @param invocation
     */
    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        Logger logger = LogManager.getLogger();
        // 执行结果前
        String output = "hi before";
        logger.info(output);
        
        // 开始执行Action
        String result = invocation.invoke();
        
        // 执行结果后
        output = "hi after";
        logger.info(output);
        
        // 继续传递到下一个拦截器
        return result;
    }
}

Change the configuration file

<!-- 拦截器 -->
<interceptor-ref name="params"/>  <!-- 传递属性拦截器 -->
<interceptor-ref name="timer"/> <!-- 测算执行时间 -->


/HelloWorld.jsp
/error.html

Effect As follows

The console output is as follows

2019-03-24 04:37:24.086 [DEBUG] com.opensymphony.xwork2.ognl.SecurityMemberAccess.isAccessible(SecurityMemberAccess.java:67) - Checking access for [target: com.ming.HelloWorldAction@5121691d, member: public void com.ming.HelloWorldAction.setName(java.lang.String), property: name]
2019-03-24 04:37:24.087 [INFO ] com.ming.MyInterceptor.intercept(MyInterceptor.java:19) - hi before
2019-03-24 04:37:24.089 [DEBUG] com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:430) - Executing action method = execute
2019-03-24 04:37:24.106 [DEBUG] com.opensymphony.xwork2.ognl.SecurityMemberAccess.isAccessible(SecurityMemberAccess.java:67) - Checking access for [target: com.ming.HelloWorldAction@5121691d, member: public java.lang.String com.ming.HelloWorldAction.execute() throws java.lang.Exception, property: null]
2019-03-24 04:37:24.143 [DEBUG] com.opensymphony.xwork2.ognl.SecurityMemberAccess.isAccessible(SecurityMemberAccess.java:67) - Checking access for [target: org.apache.struts2.result.ServletDispatcherResult@2e4369c6, member: public void org.apache.struts2.result.StrutsResultSupport.setLocation(java.lang.String), property: location]
2019-03-24 04:37:24.143 [DEBUG] com.opensymphony.xwork2.ognl.SecurityMemberAccess.isAccessible(SecurityMemberAccess.java:67) - Checking access for [target: org.apache.struts2.result.ServletDispatcherResult@2e4369c6, member: public void org.apache.struts2.result.StrutsResultSupport.setLocation(java.lang.String), property: location]
2019-03-24 04:37:24.150 [DEBUG] org.apache.struts2.result.ServletDispatcherResult.doExecute(ServletDispatcherResult.java:127) - Forwarding to location: /error.html
2019-03-24 04:37:24.158 [DEBUG] com.opensymphony.xwork2.conversion.impl.InstantiatingNullHandler.nullPropertyValue(InstantiatingNullHandler.java:98) - Entering nullPropertyValue [target=[com.ming.HelloWorldAction@5121691d, com.opensymphony.xwork2.DefaultTextProvider@2e34626e], property=struts]
2019-03-24 04:37:24.175 [INFO ] com.ming.MyInterceptor.intercept(MyInterceptor.java:26) - hi after
2019-03-24 04:37:24.176 [INFO ] com.opensymphony.xwork2.interceptor.TimerInterceptor.doLog(TimerInterceptor.java:205) - Executed action [//hello!execute] took 89 ms.

It can be seen that since 3 interceptors are configured, the interceptors are executed sequentially.
Two operations are performed before and after execution

This is aspect-oriented programming
You can add transaction locks here. The locks can be implemented with redis. When multiple tomcat instances read the database at the same time, the locking operation is performed and redis is used to achieve the purpose of locking

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