GMail Mailbox Reader with IMAP

This time I will show you how to read a Gmail mailbox using IMAP protocol and Java Mail. With IMAP you will have access to a specific folders in your GMail account such as:

• INBOX
• Gmail
• Gmail/All
• Gmail/Sent Mail
• Gmail/Starred
• Gmail/Drafts
• Gmail/Important
• Gmail/Spam
• Gmail/Trash

First you need to define your build.gradle as follow:

def configurationDirectory = "${System.getProperty('user.home')}/.mailbox-reader"

buildscript {
  ext {
    springBootVersion = '1.5.1.RELEASE'
    cglibVersion = '3.2.4'
    javaMailVersion = '1.4'
  }
  repositories {
    mavenCentral()
  }
  dependencies {
    classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
  }
}

apply plugin: "groovy"
apply plugin: "application"
apply plugin: 'org.springframework.boot'

jar {
  baseName = 'mailbox-reader'
  version = '0.0.1-SNAPSHOT'
}

sourceCompatibility = 1.8

repositories {
  mavenCentral()
}

dependencies {
  compile 'org.springframework.boot:spring-boot-starter'
  compile 'org.codehaus.groovy:groovy'
  compile "javax.mail:mail:$javaMailVersion"
  testCompile 'org.springframework.boot:spring-boot-starter-test'
  testCompile 'org.spockframework:spock-spring'
  testCompile "cglib:cglib-nodep:$cglibVersion"
}

task settingEnvironment(type:Copy) {
  from configurationDirectory
  into 'src/main/resources'
  include "application.properties"  
}

processResources.dependsOn "settingEnvironment"

This is the IMAP mailbox reader implementation

package com.jos.dem.mailbox.reader.service.impl

import org.springframework.stereotype.Service
import org.springframework.beans.factory.annotation.Value
import org.springframework.beans.factory.annotation.Autowired

import javax.mail.Folder
import javax.mail.Message
import javax.mail.MessagingException
import javax.mail.NoSuchProviderException
import javax.mail.Session
import javax.mail.Store
import javax.annotation.PostConstruct

import com.jos.dem.mailbox.reader.service.InboxReader

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

@Service
class InboxReaderImap implements InboxReader {

  @Value('${username}')
  String username
  @Value('${password}')
  String password
  @Value('${imap.server}')
  String server
  @Value('${imap.port}')
  String port

  Properties properties = new Properties()
  Folder sentFolder
  Store store

  Logger log = LoggerFactory.getLogger(this.class)
	
  @PostConstruct
  void setup() {
  	properties.put("mail.imap.host", server);
  	properties.put("mail.imap.port", port);
  	properties.put("mail.store.protocol", "imaps");
  	Session emailSession = Session.getDefaultInstance(properties)
  	Store store = emailSession.getStore('imaps')
  	store.connect(server, username, password)
  	sentFolder = store.getFolder('[Gmail]/Sent Mail')
  	sentFolder.open(Folder.READ_ONLY)
  	log.info "Inbox Type: ${sentFolder.getType()}"
  	log.info "Folders: ${store.getDefaultFolder().list('*')}"
  }

  void read(){
  	Message[] messages = sentFolder.getMessages();
	log.info("messages.length---" + messages.length);
	for (int i = 0; i < messages.length; i++) {
	  Message message = messages[i];
	  log.info("--------------------------------")
	  log.info("Email Number " + (i + 1))
	  log.info("From: " + message.getFrom()[0])
	  log.info("Subject: " + message.getSubject())
	}
	sentFolder.close(false)
  }  
	
}

javax.mail.Folder has this types:

• HOLDS_FOLDER = 1
• HOLDS_MESSAGES = 1
• READ_ONLY = 1
• READ_WRITE = 2

Output

Inbox Type: 3
Reading message
messages.length---1
--------------------------------
Email Number 1
From: contact@josdem.io
Subject: Hello from Jmailer!

Configuration

In your computer’s home directory: ${home}, create a directory called: .mailbox-reader then inside create a file called application.properties with this content

username=user@gmail.com
password=secret
pop3.server=pop.gmail.com
pop3.port=995
imap.server=imap.gmail.com
imap.port=993

Build

gradle build

Run

 java -jar build/libs/mailbox-reader-0.0.1-SNAPSHOT.jar

To download the code:

git clone https://github.com/josdem/java-topics.git
cd mailbox-reader

Return to the main article