抢街饭 通过本文主要向大家介绍了java spring拦截器,java拦截器,java过滤器和拦截器,java中拦截器的作用,java登录拦截器等相关知识,希望对您有所帮助,也希望大家支持linkedu.com www.linkedu.com
本文实例讲述了Java中的拦截器、过滤器、监听器用法。分享给大家供大家参考，具体如下：
一、拦截器 ：是在面向切面编程的就是在你的service或者一个方法，前调用一个方法，或者在方法后调用一个方法比如动态代理就是拦截器的简单实现，在你调用方 法前打印出字符串（或者做其它业务逻辑的操作），也可以在你调用方法后打印出字符串，甚至在你抛出异常的时候做业务逻辑的操作。
1.Struts2拦截器是在访问某个Action或Action的某个方法，字段之前或之后实施拦截，并且Struts2拦截器是可插拔的，拦截器是ＡＯＰ的一种实现。
2.拦截器栈（Interceptor Stack）Struts2拦截器栈就是将拦截器按一定的顺序联结成一条链。在访问被拦截的方法或字段时，Struts2拦截器链中的拦截器就会按其之前定义的顺序被调用。
package com.lzw.struts.Interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;
public class MyInterceptor extends MethodFilterInterceptor {
private static final long serialVersionUID = -6410044851077844880L;
/**
* 在struts.xml <param name="lzw">struts</param>
*/
private String lzw;
public String getLzw() {
return lzw;
}
public void setLzw(String lzw) {
this.lzw = lzw;
}
@Override
public void destroy() {
System.out.println("destroy!");
}
@Override
public void init() {
System.out.println("init!");
}
@Override
protected String doIntercept(ActionInvocation invocation) throws Exception {
System.out.println("MyInterceptor-start");
System.out.println(lzw);
String result = invocation.invoke();
System.out.println("MyInterceptor-end");
return result;
}
}
</div>
package com.lzw.struts.Interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;
public class FirstInterceptor extends MethodFilterInterceptor {
private static final long serialVersionUID = 1L;
@Override
protected String doIntercept(ActionInvocation invocation) throws Exception {
System.out.println("FirstInterceptor-Start");
String result = invocation.invoke();
System.out.println("FirstInterceptor-End");
return result;
}
}
</div>
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">
<struts>
<!--开发模式开关，本地可以设为true帮助调试问题，部署到服务器上设为false-->
<constant name="struts.devMode" value="false"/>
<!--务必配上该属性，否则会导致AOP注入异常-->
<constant name="struts.objectFactory.spring.autoWire.alwaysRespect" value="true"/>
<constant name="struts.i18n.encoding" value="UTF-8" />
<constant name="struts.multipart.maxSize" value="1000000000"/>
<package name="strutsLzw" extends="struts-default" namespace="/">
<interceptors>
<interceptor name="lzwInterceptorA" class="com.lzw.struts.Interceptor.MyInterceptor">
<param name="lzw">struts</param>
</interceptor>
<interceptor name="lzwInterceptorB" class="com.lzw.struts.Interceptor.FirstInterceptor">
</interceptor>
<!-- 定义自己的拦截器栈 -->
<interceptor-stack name="myStack">
<interceptor-ref name="lzwInterceptorA"></interceptor-ref>
<interceptor-ref name="lzwInterceptorB"></interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>
</interceptor-stack>
</interceptors>
<!-- 全局的每个action都会拦截 -->
<default-interceptor-ref name="myStack"></default-interceptor-ref>
<!-- 增加method="lzwTest" 执行LoginAction的lzwTest方法 否则执行execute方法 -->
<action name="login" class="com.lzw.struts.action.LoginAction" method="lzwTest">
<result name="success">/result.jsp</result>
<result name="failer">/error.jsp</result>
<result name="input">/error.jsp</result>
</action>
</package>
</struts>
</div>
或者：
<?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="strutsLzw" extends="struts-default">
<interceptors>
<interceptor name="lzwInterceptor" class="com.lzw.struts.Interceptor.MyInterceptor">
<param name="lzw">struts</param>
</interceptor>
</interceptors>
<!-- 增加method="lzwTest" 执行LoginAction的lzwTest方法 否则执行execute方法 -->
<action name="login" class="com.lzw.struts.action.LoginAction" method="lzwTest">
<result name="success">/result.jsp</result>
<result name="failer">/error.jsp</result>
<result name="input">/error.jsp</result>
<interceptor-ref name="lzwInterceptor"></interceptor-ref>
<!--增加defaultStack 否则 验证拦截器不执行，也就是 validate 方法不执行-->
<interceptor-ref name="defaultStack"></interceptor-ref>
</action>
</package>
</struts>
</div>
web.xml中加入：
<filter>
<filter-name>struts2</filter-name>
<!-- 已经过时了<filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class> -->
<filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
<init-param>
<param-name>actionPackages</param-name>
<param-value>com.lzw.struts.action</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>struts2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</div>
package com.lzw.struts.action;
import com.opensymphony.xwork2.ActionSupport;
public class LoginAction extends ActionSupport{
private static final long serialVersionUID = 1L;
private String username;
private String password;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String execute() throws Exception {
System.out.println("=====execute=====");
if ("hello".equals(this.getUsername().trim()) && "world".equals(this.getPassword().trim())) {
return "success";
} else {
this.addFieldError("username", "username or password error");
return "failer";
}
}
@Override
public void validate() {
System.out.println("=====validate=====");
if (null == this.getUsername() || "".equals(this.getUsername().trim())) {
this.addFieldError("username", "username required");
}
if (null == this.getPassword() || "".equals(this.getPassword().trim())) {
this.addFieldError("password", "password required");
}
}
public String lzwTest() {
System.out.println("======Test====");
return SUCCESS;
}
}
</div>