org.springframework.aop.framework.adapter.ThrowsAdviceInterceptor.java Source code

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Here is the source code for org.springframework.aop.framework.adapter.ThrowsAdviceInterceptor.java

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/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.aop.framework.adapter;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.aop.AfterAdvice;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * Interceptor to wrap an after-throwing advice.
 *
 * <p>The signatures on handler methods on the {@code ThrowsAdvice}
 * implementation method argument must be of the form:<br>
 *
 * {@code void afterThrowing([Method, args, target], ThrowableSubclass);}
 *
 * <p>Only the last argument is required.
 *
 * <p>Some examples of valid methods would be:
 *
 * <pre class="code">public void afterThrowing(Exception ex)</pre>
 * <pre class="code">public void afterThrowing(RemoteException)</pre>
 * <pre class="code">public void afterThrowing(Method method, Object[] args, Object target, Exception ex)</pre>
 * <pre class="code">public void afterThrowing(Method method, Object[] args, Object target, ServletException ex)</pre>
 *
 * <p>This is a framework class that need not be used directly by Spring users.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 */
public class ThrowsAdviceInterceptor implements MethodInterceptor, AfterAdvice {

    private static final String AFTER_THROWING = "afterThrowing";

    private static final Log logger = LogFactory.getLog(ThrowsAdviceInterceptor.class);

    private final Object throwsAdvice;

    /** Methods on throws advice, keyed by exception class */
    private final Map<Class<?>, Method> exceptionHandlerMap = new HashMap<>();

    /**
     * Create a new ThrowsAdviceInterceptor for the given ThrowsAdvice.
     * @param throwsAdvice the advice object that defines the exception
     * handler methods (usually a {@link org.springframework.aop.ThrowsAdvice}
     * implementation)
     */
    public ThrowsAdviceInterceptor(Object throwsAdvice) {
        Assert.notNull(throwsAdvice, "Advice must not be null");
        this.throwsAdvice = throwsAdvice;

        Method[] methods = throwsAdvice.getClass().getMethods();
        for (Method method : methods) {
            if (method.getName().equals(AFTER_THROWING)
                    && (method.getParameterCount() == 1 || method.getParameterCount() == 4) && Throwable.class
                            .isAssignableFrom(method.getParameterTypes()[method.getParameterCount() - 1])) {
                // Have an exception handler
                this.exceptionHandlerMap.put(method.getParameterTypes()[method.getParameterCount() - 1], method);
                if (logger.isDebugEnabled()) {
                    logger.debug("Found exception handler method: " + method);
                }
            }
        }

        if (this.exceptionHandlerMap.isEmpty()) {
            throw new IllegalArgumentException(
                    "At least one handler method must be found in class [" + throwsAdvice.getClass() + "]");
        }
    }

    public int getHandlerMethodCount() {
        return this.exceptionHandlerMap.size();
    }

    /**
     * Determine the exception handle method. Can return null if not found.
     * @param exception the exception thrown
     * @return a handler for the given exception type
     */
    @Nullable
    private Method getExceptionHandler(Throwable exception) {
        Class<?> exceptionClass = exception.getClass();
        if (logger.isTraceEnabled()) {
            logger.trace("Trying to find handler for exception of type [" + exceptionClass.getName() + "]");
        }
        Method handler = this.exceptionHandlerMap.get(exceptionClass);
        while (handler == null && exceptionClass != Throwable.class) {
            exceptionClass = exceptionClass.getSuperclass();
            handler = this.exceptionHandlerMap.get(exceptionClass);
        }
        if (handler != null && logger.isDebugEnabled()) {
            logger.debug("Found handler for exception of type [" + exceptionClass.getName() + "]: " + handler);
        }
        return handler;
    }

    @Override
    public Object invoke(MethodInvocation mi) throws Throwable {
        try {
            return mi.proceed();
        } catch (Throwable ex) {
            Method handlerMethod = getExceptionHandler(ex);
            if (handlerMethod != null) {
                invokeHandlerMethod(mi, ex, handlerMethod);
            }
            throw ex;
        }
    }

    private void invokeHandlerMethod(MethodInvocation mi, Throwable ex, Method method) throws Throwable {
        Object[] handlerArgs;
        if (method.getParameterCount() == 1) {
            handlerArgs = new Object[] { ex };
        } else {
            handlerArgs = new Object[] { mi.getMethod(), mi.getArguments(), mi.getThis(), ex };
        }
        try {
            method.invoke(this.throwsAdvice, handlerArgs);
        } catch (InvocationTargetException targetEx) {
            throw targetEx.getTargetException();
        }
    }

}