Mule ESB：如何根据主题或发件人过滤电子邮件？ [英] Mule ESB: how to filter emails based on subject or sender?

问题描述

我是Mule 3.3的新功能，如果发件人字段和主题字段包含某些关键字，我正在尝试使用它从POP3服务器检索电子邮件并下载CSV附件。我已经使用了Muleoft网站上提供的示例，并且我已成功设法扫描收件箱中的新电子邮件，并且只下载CSV附件。但是，由于我无法弄清楚主题和发件人字段如何过滤电子邮件，所以我现在陷入困境。

I am new to Mule 3.3 and I am trying to use it to retrieve emails from a POP3 server and download the CSV attachments if the sender field and subject field contain certain keywords. I have used the example provided on Mulesoft website and I have successfully managed to scan my inbox for new emails and only download CSV attachments. However, I am now stuck because I can't figure out how to filter emails by subject and sender fields.

做了一些研究，我遇到了可以应用于端点的消息属性过滤器模式标签，但我不确定准确到哪个端点应用它，传入或传出。这两种方法似乎都不起作用，我找不到一个体面的例子来展示如何使用这个标签。我想实现的基本算法如下：

Doing some research I have come across a message-property-filter pattern tag that can be applied to an endpoint, but I am not sure exactly to which endpoint to apply it, incoming or outgoing. Neither approach seems to work and I can't find a decent example showing how to use this tag. The basic algorithm I want to implement is as follows:

if email is from "Bob"
  if attachment of type "CSV"
    then download CSV attachment

if email subject field contains "keyword"
  if attachment of type CSV
    then download CSV attachment

这是我到目前为止的Mule xml：

Here's the Mule xml I have so far:

<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:file="http://www.mulesoft.org/schema/mule/file" xmlns:pop3s="http://www.mulesoft.org/schema/mule/pop3s" xmlns:pop3="http://www.mulesoft.org/schema/mule/pop3" 
xmlns="http://www.mulesoft.org/schema/mule/core" 
xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" 
xmlns:spring="http://www.springframework.org/schema/beans" version="CE-3.3.1" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="
http://www.mulesoft.org/schema/mule/pop3s http://www.mulesoft.org/schema/mule/pop3s/current/mule-pop3s.xsd 
http://www.mulesoft.org/schema/mule/file http://www.mulesoft.org/schema/mule/file/current/mule-file.xsd 
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd 
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd 
http://www.mulesoft.org/schema/mule/pop3 http://www.mulesoft.org/schema/mule/pop3/current/mule-pop3.xsd ">


<expression-transformer expression="#[attachments-list:*.csv]" 
   name="returnAttachments" doc:name="Expression">
</expression-transformer>

<pop3s:connector name="POP3Connector" 
    checkFrequency="5000" 
    deleteReadMessages="false" 
    defaultProcessMessageAction="RECENT" 
    doc:name="POP3" 
    validateConnections="true">
</pop3s:connector>

<file:connector name="fileName" doc:name="File">
    <file:expression-filename-parser />
</file:connector>

<flow name="incoming-orders" doc:name="incoming-orders">

    <pop3s:inbound-endpoint user="my_username" 
        password="my_password" 
        host="pop.gmail.com" 
        port="995" 
        transformer-refs="returnAttachments"
        doc:name="GetMail" 
        connector-ref="POP3Connector" 
        responseTimeout="10000"/>
    <collection-splitter doc:name="Collection Splitter"/>

    <echo-component doc:name="Echo"/>

    <file:outbound-endpoint path="/attachments" 
        outputPattern="#[function:datestamp].csv"
        doc:name="File" responseTimeout="10000"> 
        <expression-transformer expression="payload.inputStream"/>
        <message-property-filter pattern="from=(.*)([e-mail])(.*)" caseSensitive="false"/>
    </file:outbound-endpoint>           
</flow>

什么是最好的方法解决这个问题？

What is the best way to tackle this problem?

提前感谢

推荐答案

欢迎来到骡子！几个月前，我为客户实施了类似的方案。我看看你的流程，让我们开始重构。

Welcome to Mule! A few month ago I implemented a similar proejct for a customer. I take a look at your flow, let´s start refactoring.

• 从入站端点
中删除transformer-refs =returnAttachments


• 添加您的流程的以下元素

• Remove the transformer-refs="returnAttachments" from inbound-endpoint

• Add the following elements to your flow

<pop3:inbound-endpoint ... />
<custom-filter class="com.benasmussen.mail.filter.RecipientFilter"> 
    <spring:property name="regex" value=".*bob.bent@.*" />
</custom-filter>
<expression-transformer>
    <return-argument expression="*.csv" evaluator="attachments-list" />
</expression-transformer>
<collection-splitter doc:name="Collection Splitter" />

将我的RecipientFilter作为java类添加到您的项目中。如果它们与正则表达式不匹配，所有消息将被丢弃。

Add my RecipientFilter as java class to your project. All messages will be discard if they don't match to the regex pattern.

package com.benasmussen.mail.filter;

import java.util.Collection;
import java.util.Set;
import java.util.regex.Pattern;      
import org.mule.api.MuleMessage;
import org.mule.api.lifecycle.Initialisable;
import org.mule.api.lifecycle.InitialisationException;
import org.mule.api.routing.filter.Filter;
import org.mule.config.i18n.CoreMessages;
import org.mule.transport.email.MailProperties;

public class RecipientFilter implements Filter, Initialisable
{
    private String regex;
    private Pattern pattern;

    public boolean accept(MuleMessage message)
    {
        String from = message.findPropertyInAnyScope(MailProperties.FROM_ADDRESS_PROPERTY, null);
        return isMatch(from);
    }

    public void initialise() throws InitialisationException
    {
        if (regex == null)
        {
            throw new InitialisationException(CoreMessages.createStaticMessage("Property regex is not set"), this);
        }
        pattern = Pattern.compile(regex);
    }

    public boolean isMatch(String from)
    {
        return pattern.matcher(from).matches();
    }

    public void setRegex(String regex)
    {
        this.regex = regex;
    }
}

mule表达框架是强大的，但在某些用例中，我更喜欢我自己的业务逻辑。

The mule expression framework is powerful, but in some use cases I prefer my own business logic.

• 使用应用程序属性（mule-app.properties）> < a href =http://www.mulesoft.org/documentation/display/MULE3USER/Using+Parameters+in+Your+Configuration+Files =nofollow>骡子文件

• Use application properties (mule-app.properties) > mule documentation

• MailProperties 显示所有可用的消息属性（EMail）


• 查看 mule schema doc 查看所有可用元素


• 传入的有效载荷（邮件等）由 DefaultMuleMessage （有效载荷，属性，附件）

• MailProperties shows you all available message properties (EMail)
• Take a look at the mule schema doc to see all available elements
• Incoming payload (mails, etc) are transported by an DefaultMuleMessage (Payload, Properties, Attachments)

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