SendGridでメールを送受信するサンプル

InboundMailServlet.java

package herokuSamples.web.mail;

import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.HashMap;
import java.io.UnsupportedEncodingException;
import java.io.InputStream;
import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.annotation.WebServlet;

import herokuSamples.util.TemplateEngine;
import herokuSamples.util.FileUtils;
import herokuSamples.util.Cache;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import java.lang.reflect.Type;
import com.google.gson.reflect.TypeToken;

@WebServlet(name="InboundMailServlet", urlPatterns={"/inboundMail"})
public class InboundMailServlet extends HttpServlet {

    private static Map<String, Object> initParams() {
        Map<String, Object> params = new HashMap<String, Object>();
        params.put("title", "インバウンドメール");
        return params;
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
        if ("true".equals(req.getParameter("delete"))) {
            Cache.remove("latestMail");
            res.sendRedirect("/inboundMail");
            return;
        }
        Map<String, Object> params = initParams();
        String mail = (String)Cache.get("latestMail");
        if (mail == null) {
            mail = "No mail";
        }
        params.put("mail", mail);
        TemplateEngine.merge(res, "mail/inboundMail.html", params);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
        ServletFileUpload upload = new ServletFileUpload(new DiskFileItemFactory());
        try {
            ReceivedMail mail = new ReceivedMail(upload.parseRequest(req));
            int attachmentCount = mail.getAttachmentCount();

            StringBuilder buf = new StringBuilder();
            buf.append("From: ").append(mail.getFrom()).append("\n")
                .append("To: ").append(mail.getTo()).append("\n")
                .append("Subject: ").append(mail.getSubject()).append("\n")
                .append("AttachmentCount: " + attachmentCount).append("\n");
            for (int i=0; i<attachmentCount; i++) {
                buf.append("Attachment").append(i+1).append(": ")
                    .append(mail.getAttachmentName(i)).append("\n");
            }
            String body = mail.getTextBody();
            buf.append("\n").append(body);
            Cache.set("latestMail", buf.toString(), 7200);
            System.out.println(buf.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static class ReceivedMail {
        private List<FileItem> items;
        private Map<String, String> charsets = null;
        private Map<String, AttachmentInfo> attachmentInfo = null;

        public ReceivedMail(List<FileItem> items) {
            this.items = items;
        }

        public String getCharset(String name) {
            if (this.charsets == null) {
                FileItem item = getFileItem("charsets");
                if (item == null) {
                    this.charsets = new HashMap<String, String>();
                } else {
                    Type type = new TypeToken<Map<String, String>>() {}.getType();
                    try {
                        this.charsets = new Gson().fromJson(item.getString("utf-8"), type);
                    } catch (UnsupportedEncodingException e) {
                        throw new IllegalStateException(e);
                    }
                }
            }
            return this.charsets.get(name);
        }

        public AttachmentInfo getAttachmentInfo(int n) {
            if (this.attachmentInfo == null) {
                String json = getValue("attachment-info");
                if (json == null) {
                    this.attachmentInfo = new HashMap<String, AttachmentInfo>();
                } else {
                    Type type = new TypeToken<Map<String, AttachmentInfo>>() {}.getType();
                    this.attachmentInfo = new Gson().fromJson(json, type);
                }
            }
            return this.attachmentInfo.get("attachment" + (n + 1));
        }

        public String getValue(String name) {
            for (FileItem item : items) {
                if (item.getFieldName().equals(name)) {
                    try {
                        String charset = getCharset(name);
                        return item.getString(charset == null ? "utf-8" : charset);
                    } catch (UnsupportedEncodingException e) {
                        throw new IllegalStateException(e);
                    }
                }
            }
            return null;
        }

        public FileItem getFileItem(String name) {
            for (FileItem item : items) {
                if (item.getFieldName().equals(name)) {
                    return item;
                }
            }
            return null;
        }

        public List<String> keys() {
            List<String> list = new ArrayList<String>();
            for (FileItem item : items) {
                list.add(item.getFieldName());
            }
            return list;
        }

        public String getHeaders() { return getValue("headers");}
        public String getTextBody() { return getValue("text");}
        public String getHtmlBody() { return getValue("html");}
        public String getFrom() { return getValue("from");}
        public String getTo() { return getValue("to");}
        public String getCc() { return getValue("cc");}
        public String getSubject() { return getValue("subject");}

        public int getAttachmentCount() {
            String n = getValue("attachments");
            return n == null ? 0 : Integer.parseInt(n);
        }

        public InputStream getAttachmentStream(int n) throws IOException {
            FileItem item = getFileItem("attachment" + (n + 1));
            return item != null && !item.isFormField() ? item.getInputStream() : null;
        }

        public String getAttachmentName(int n) {
            AttachmentInfo info = getAttachmentInfo(n);
            return info != null ? info.getName() : null;
        }

    }

    public static class AttachmentInfo {
        private String filename;
        private String name;
        private String type;

        public String getFilename() { return this.filename;}
        public String getName() { return this.name;}
        public String getType() { return this.type;}
    }
}

MailServlet.java

package herokuSamples.web.mail;

import java.util.Arrays;
import java.util.Map;
import java.util.HashMap;
import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.annotation.WebServlet;

import herokuSamples.util.TemplateEngine;
import jp.co.flect.sendgrid.SendGridClient;
import jp.co.flect.sendgrid.SendGridException;
import jp.co.flect.sendgrid.model.WebMail;

@WebServlet(name="MailServlet", urlPatterns={"/mail"})
public class MailServlet extends HttpServlet {

    private static final String DEFAULT_MAIL_FROM = "test@ht.flectdev.com";

    private static Map<String, Object> initParams() {
        String from = System.getenv("MAIL_FROM");
        if (from == null) {
            from = DEFAULT_MAIL_FROM;
        }
        Map<String, Object> params = new HashMap<String, Object>();
        params.put("title", "メール送信");
        params.put("message", "");
        params.put("to", "");
        params.put("subject", "");
        params.put("body", "");
        params.put("from", from);
        return params;
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
        Map<String, Object> params = initParams();
        TemplateEngine.merge(res, "mail/mail.html", params);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
        Map<String, Object> params = initParams();
        req.setCharacterEncoding("utf-8");

        String from = (String)params.get("from");
        String to = req.getParameter("to");
        String subject = req.getParameter("subject");
        String body = req.getParameter("body");
        params.put("to", to);
        params.put("subject", subject);
        params.put("body", body);
        try {
            sendMail(from, to, subject, body);
            params.put("message", "メールを送信しました。");
        } catch (Exception e) {
            params.put("message", "メールを送信できませんでした。: " + e.getMessage());
        }
        TemplateEngine.merge(res, "mail/mail.html", params);
    }

    private void sendMail(String from, String to, String subject, String body) throws IOException, SendGridException {
        String username = System.getenv("SENDGRID_USERNAME");
        String password = System.getenv("SENDGRID_PASSWORD");
        SendGridClient client = new SendGridClient(username, password);
        WebMail mail = new WebMail();
        mail.setFrom(from);
        mail.setToList(Arrays.asList(to.split(",")));
        mail.setSubject(subject);
        mail.setText(body);
        client.mail(mail);
    }
}