Struts2自定义拦截器处理全局异常

　　今天在整理之前的项目的时候想着有的action层没有做异常处理，于是想着自定义拦截器处理一下未拦截的异常。

代码:

package cn.xm.exam.action.safeHat;

import java.util.HashMap;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Controller;

import com.opensymphony.xwork2.ActionSupport;

@Controller
@Scope("prototype")
public class SafeHatAction extends ActionSupport {
    private static final Logger log = LoggerFactory.getLogger(SafeHatAction.class);
    private Map<String, Object> response;

    public SafeHatAction() {
        log.info("SafeHatAction init.........");
    }

    public String test1() {
        response = new HashMap();
        response.put("ttt", "tttttt");
        return SUCCESS;
    }
    
    public String test2() {
        response = new HashMap();
        response.put("ttt", "tttttt");
        int i = 1/0;
        return SUCCESS;
    }

    public Map<String, Object> getResponse() {
        return response;
    }

    public void setResponse(Map<String, Object> response) {
        this.response = response;
    }

}

1.异常在Action层未做处理的情况:

由于在web.xml中定义了500错误的页面，因此跳转到500页面，如下:

    <!-- 500页面 -->
    <error-page>
        <error-code>500</error-code>
        <location>/500.jsp</location>
    </error-page>

　　可是上面终究不够友好。

2.自定义拦截器处理全局异常

(1)自定义拦截器

package cn.xm.exam.interceptor;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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

public class ExceptionInterception implements Interceptor {
    private static final Logger log = LoggerFactory.getLogger(ExceptionInterception.class);
    /**
     * 
     */
    private static final long serialVersionUID = 2268867259828199826L;

    @Override
    public void destroy() {

    }

    @Override
    public void init() {

    }

    @Override
    public String intercept(ActionInvocation arg0) throws Exception {
        log.info("enter ExceptionInterception intercept ... ");
        String result = "";
        try {
            result = arg0.invoke();
            log.info("result -> {}", result);
        } catch (Throwable e) {
            log.error("未处理的异常在拦截器被拦截,class:{}", arg0.getAction().getClass(), e);
            throw new Exception(e);
        }
        log.debug("exit ExceptionInterception intercept ... ");
        return result;
    }

}

　　arg0.invoke();是调用我们的action的方法，其返回值就是action的返回值,相当于放行;捕捉到异常之后进行一个简单的异常记录之后再次抛出异常，再次抛出异常是为了跳到500页面;如果有需要可以自己再写一个页面提示错误已经被记录等信息，捕捉到异常之后返回到此页面。 

(2)struts.xml中定义拦截器

<?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>
    <constant name="struts.i18n.encoding" value="utf-8"></constant>
    <constant name="devMode" value="true"></constant>
    <constant name="struts.enable.DynamicMethodInvocation" value="true" />
    <!-- 配置拦截的后缀 -->
    <constant name="struts.action.extension" value="action,do" />
    <!-- 与spring整合 -->
    <constant name="struts.objectFactory" value="spring"></constant>

    <package name="interceptPackage" extends="json-default">

        <!-- 拦截器 -->
        <interceptors>
            <!-- 定义刚才的拦截器 -->
            <interceptor name="exceptionInterceptor"
                class="cn.xm.exam.interceptor.ExceptionInterception"></interceptor>
            <!-- 定义拦截器栈 -->
            <interceptor-stack name="myStack">
                <!-- 拦截器栈里面可以引用另外一个拦截器，也可以引用另外一个拦截器栈 -->
                <interceptor-ref name="defaultStack"></interceptor-ref>
                <interceptor-ref name="exceptionInterceptor"></interceptor-ref>
            </interceptor-stack>
        </interceptors>
        <!-- 这句是设置所有Action自动调用的拦截器堆栈 -->
        <default-interceptor-ref name="myStack" />
    </package>

    <!-- 2018-11-11引入的二开action -->
    <include file="struts/safeHat.xml"></include>

</struts>

自定义的package继承上面的package(package具有多重继承的特性，safeHalt会继承其所有父类)，例如:safeHat.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>
    <package name="safeHalt" namespace="/" extends="interceptPackage">
        <!-- 全局结果集，将response转换为json传到前台 -->
        <global-results>
            <result name="success" type="json">
                <param name="root">response</param>
            </result>
        </global-results>

        <action name="safeHat_*" class="safeHatAction" method="{1}"></action>
    </package>
</struts>

 (3)继续访问上面的错误action进行测试:

查看记录的错误日志:

2018-11-01 23:09:30 [cn.xm.exam.interceptor.ExceptionInterception]-[ERROR] 未处理的异常在拦截器被拦截,class:class cn.xm.exam.action.safeHat.SafeHatAction
java.lang.ArithmeticException: / by zero
    at cn.xm.exam.action.safeHat.SafeHatAction.test2(SafeHatAction.java:32)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at ognl.OgnlRuntime.invokeMethod(OgnlRuntime.java:871)
    at ognl.OgnlRuntime.callAppropriateMethod(OgnlRuntime.java:1294)
    at ognl.ObjectMethodAccessor.callMethod(ObjectMethodAccessor.java:68)
    at com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethodWithDebugInfo(XWorkMethodAccessor.java:117)
    at com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethod(XWorkMethodAccessor.java:108)
    at ognl.OgnlRuntime.callMethod(OgnlRuntime.java:1370)
    at ognl.ASTMethod.getValueBody(ASTMethod.java:91)
　　........

至此实现了简单的全局异常处理。 

 拦截器的使用参考我另一篇博客:https://www.cnblogs.com/qlqwjy/p/7190784.html