Struts2攔截器、攔截器棧(Interceptor Stack)、全域性攔截器與方法攔截器
阿新 • • 發佈：2019-02-17
Struts2攔截器原理
Struts2攔截器是在訪問某個Action或Action的方法之前或之後實施攔截。在請求Struts2的Action時，Struts2會查詢配置檔案，並根據配置檔案例項化相應的攔截器物件。
Struts2攔截器配置
struts.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
"http://struts.apache.org/dtds/struts-2.3.dtd"> FirstInterceptor
package Interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
/**
* Created with IntelliJ IDEA.
* User: YEN
* Date: 2016/8/3
* Time: 13:59
*/
public class FirstInterceptor implements Interceptor {
private String value;
/**
* 銷燬方法
*/
@Override
public void destroy() {
System.out.println("First攔截器銷燬了");
}
/**
* 初始化方法 當程式啟動時攔截器就被初始化了
*/
@Override
public void init() {
System.out.println("First攔截器初始化了");
}
@Override
public String intercept(ActionInvocation actionInvocation) throws Exception {
//actionInvocation.invoke() 讓到達攔截器的請求繼續前進 訪問需要訪問的資源(就是放過的意思)
System.out.println("進入First攔截器");
String returnName=actionInvocation.invoke();
System.out.println("走出First攔截器");
return returnName;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}
SecondInterceptor
package Interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
/**
* Created with IntelliJ IDEA.
* User: YEN
* Date: 2016/8/3
* Time: 14:14
*/
public class SecondInterceptor implements Interceptor {
@Override
public void destroy() {
System.out.println("Second攔截器銷燬了");
}
@Override
public void init() {
System.out.println("Second攔截器初始化了");
}
@Override
public String intercept(ActionInvocation actionInvocation) throws Exception {
//actionInvocation.invoke() 讓到達攔截器的請求繼續前進 訪問需要訪問的資源(就是放過的意思)
System.out.println("進入Second攔截器");
String returnName=actionInvocation.invoke();
System.out.println("走出Second攔截器");
return returnName;
}
}
index.jsp
<a href="LoginAction.action">點選呼叫攔截器</a>
由此也可以看出，攔截器執行的順序與我們在配置檔案中定義的順序是一支的，即由外到內，而結束時則是從內到外。
攔截器棧
攔截器棧（Interceptor Stack）。Struts2攔截器棧就是將攔截器按一定的順序連線成一條鏈。在訪問被攔截的方法或欄位時，Struts2攔截器鏈中的攔截器就會按其之前定義的順序被呼叫。
可以把上面的struts.xml配置檔案格式修改為下述，這樣大大提高了Action的簡潔性：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
"http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
<package name="default" extends="struts-default">
<!--配置攔截器-->
<interceptors>
<interceptor name="FirstInterceptor" class="Interceptor.FirstInterceptor">
<param name="value" >YEN</param>
</interceptor>
<interceptor name="SecondInterceptor" class="Interceptor.SecondInterceptor"></interceptor>
<interceptor-stack name="AllInterceptor">
<interceptor-ref name="FirstInterceptor"></interceptor-ref>
<interceptor-ref name="SecondInterceptor"></interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>
</interceptor-stack>
</interceptors>
<action name="LoginAction" class="Action.LoginAction">
<interceptor-ref name="AllInterceptor"></interceptor-ref>
<result name="success">success.jsp</result>
</action>
</package>
</struts>
執行結果是一樣的。
全域性攔截器
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
"http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
<package name="default" extends="struts-default">
<!--配置攔截器-->
<interceptors>
<interceptor name="FirstInterceptor" class="Interceptor.FirstInterceptor">
<param name="value" >YEN</param>
</interceptor>
<interceptor name="SecondInterceptor" class="Interceptor.SecondInterceptor"></interceptor>
<interceptor-stack name="AllInterceptor">
<interceptor-ref name="FirstInterceptor"></interceptor-ref>
<interceptor-ref name="SecondInterceptor"></interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>
</interceptor-stack>
</interceptors>
<!--預設攔截器（全域性攔截器）-->
<default-interceptor-ref name="AllInterceptor" ></default-interceptor-ref>
<!--全域性返回頁面-->
<global-results>
<result>error.jsp</result>
</global-results>
<!--全域性Action-->
<default-action-ref name="LoginAction"></default-action-ref>
<action name="LoginAction" class="Action.LoginAction">
<interceptor-ref name="AllInterceptor"></interceptor-ref>
<result name="success">success.jsp</result>
</action>
</package>
</struts>
方法攔截器
eg:攔截add和delete方法
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
"http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
<package name="default" extends="struts-default">
<!--配置攔截器-->
<interceptors>
<!--方法攔截器配置-->
<interceptor name="MethodInterceptor" class="Interceptor.MethodFirstceptor">
<!--配置引數 ：攔截什麼方法-->
<!--includeMethods控制能訪問哪些-->
<param name="includeMethods">add,delete</param>
<!--excludeMethods控制能訪問哪些-->
<param name="excludeMethods">update</param>
</interceptors>
<action name="LoginAction" class="Action.LoginAction">
<interceptor-ref name="MethodInterceptor"></interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>
<result name="success">success.jsp</result>
</action>
</package>
</struts>package Interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;
/**
* Created with IntelliJ IDEA.
* User: YEN
* Date: 2016/8/3
* Time: 14:42
*/
/**
* 方法攔截器 針對性非常強
*/
public class MethodFirstceptor extends MethodFilterInterceptor {
@Override
protected String doIntercept(ActionInvocation aInvocation) throws Exception {
System.out.println("進入方法攔截器");
String str=aInvocation.invoke();
System.out.println("退出方法攔截器");
return str;
}
}