Struts2 源码分析-----拦截器源码解析 --- ParametersInterceptor

@Override
public String doIntercept(ActionInvocation invocation) throws Exception {
    Object action = invocation.getAction();//获取当前执行的Action对象
    if (!(action instanceof NoParameters)) {//判断Action是否实现了NoParameters接口，实现该接口表示该Action没有任何请求参数
        ActionContext ac = invocation.getInvocationContext();//获取ActionContext对象
        final Map<String, Object> parameters = retrieveParameters(ac);//获取请求参数Map
        //省略...
        if (parameters != null) {//如果请求参数不为null
            Map<String, Object> contextMap = ac.getContextMap();//获取ActionContext内部的context Map，即OgnlContext对象
            try {
                //省略...
                ValueStack stack = ac.getValueStack();//获取值栈
                setParameters(action, stack, parameters);//为值栈设置参数
            } finally {
                //省略...
            }
        }
    }
    return invocation.invoke();//调用下一个拦截器
}

protected void setParameters(Object action, ValueStack stack, final Map<String, Object> parameters) {
    ParameterNameAware parameterNameAware = (action instanceof ParameterNameAware)
            ? (ParameterNameAware) action : null;//判断Action有无实现ParameterNameAware接口
 
    Map<String, Object> params;
    Map<String, Object> acceptableParameters;//合法参数集合
    //判断参数设置是否有序，ordered默认为false，即无序
    if (ordered) {
        params = new TreeMap<String, Object>(getOrderedComparator());//如果有序则要获取比较器
        acceptableParameters = new TreeMap<String, Object>(getOrderedComparator());
        params.putAll(parameters);
    } else {
        params = new TreeMap<String, Object>(parameters);
        acceptableParameters = new TreeMap<String, Object>();
    }
    //迭代请求参数
    for (Map.Entry<String, Object> entry : params.entrySet()) {
        String name = entry.getKey();
        //判断参数是否合法，如果Action实现了ParameterNameAware则acceptableName(name)返回true且parameterNameAware.acceptableParameterName(name)
        //也返回true该参数才是合法的；如果Action没有实现ParameterNameAware则参数是否合法由acceptableName(name)方法决定
        boolean acceptableName = acceptableName(name)  && (parameterNameAware == null  || parameterNameAware.acceptableParameterName(name));
        //如果参数合法
        if (acceptableName) {
            acceptableParameters.put(name, entry.getValue());//把合法参数添加到合法参数集合中
        }
    }
 
    ValueStack newStack = valueStackFactory.createValueStack(stack);
    //省略...
    for (Map.Entry<String, Object> entry : acceptableParameters.entrySet()) {//迭代合法参数
        String name = entry.getKey();//参数名
        Object value = entry.getValue();//参数值
        try {
            newStack.setValue(name, value);//将该参数设置到ValueStack中
        } catch (RuntimeException e) {
            //省略...
        }
    }
    //省略...
    //看该方法的名称是将合法参数添加到ActionContext中，但在该拦截器中，该方法为空实现，无任何代码
    //该方法被声明为protected，即子类可以覆盖该方法以改变行为
    addParametersToContext(ActionContext.getContext(), acceptableParameters);
}

protected boolean acceptableName(String name) {
    //调用isAccepted与isExcluded方法判断
    if (isAccepted(name) && !isExcluded(name)) {
        return true;
    }
    return false;
} 

protected boolean isAccepted(String paramName) {
    if (!this.acceptParams.isEmpty()) {
        for (Pattern pattern : acceptParams) {
            Matcher matcher = pattern.matcher(paramName);
            if (matcher.matches()) {
                return true;
            }
        }
        return false;
    } else
        return acceptedPattern.matcher(paramName).matches();
}
 
protected boolean isExcluded(String paramName) {
    if (!this.excludeParams.isEmpty()) {
        for (Pattern pattern : excludeParams) {
            Matcher matcher = pattern.matcher(paramName);
            if (matcher.matches()) {
                return true;
            }
        }
    }
    return false;
}