JavaMail入門教程之解析郵件（5）

更新時間：2016年12月22日 16:19:06 作者：汪先森

這篇文章主要為大家詳細介紹了JavaMail入門教程之解析郵件的相關(guān)資料,具有一定的參考價值，感興趣的小伙伴們可以參考一下

上一篇JavaMail入門第四篇接收郵件中，控制臺打印出的內(nèi)容，我們無法閱讀，其實，讓我們自己來解析一封復雜的郵件是很不容易的，郵件里面格式、規(guī)范復雜得很。不過，我們所用的瀏覽器內(nèi)置了解析各種數(shù)據(jù)類型的數(shù)據(jù)處理模塊，我們只需要在把數(shù)據(jù)流傳輸給瀏覽器之前明確地指定該數(shù)據(jù)流屬于哪種數(shù)據(jù)類型即可，之后一切的解析操作由瀏覽器自動幫我們完成。下面這張圖可以很好的說明解析郵件的步驟

1、調(diào)用Message對象的getFrom、getSubject等方法，可以得到郵件的發(fā)件人和主題等信息，調(diào)用getContentType方法得到郵件的類型；

2、通過Message.getContentType方法的返回值判斷郵件類型，并調(diào)用Message.getContent方法得到郵件內(nèi)容。如果郵件類型為"text/plain"或者"text/html"，表示郵件內(nèi)容為純文本，此時調(diào)用Message對象的getContent方法得到郵件內(nèi)容，然后將返回對象的類型轉(zhuǎn)換成String輸出給顯示軟件即可。如果郵件類型為"multipart/*"，表示郵件內(nèi)容是一個復合類型，此時需將Message.getContent方法復合的對象轉(zhuǎn)換成Multipart。

3、調(diào)用Multipart對象的getCount方法檢測Multipart對象中封裝了多少個BodyPart對象，并通過for循環(huán)逐一取出Multipart對象中的每個BodyPart對象進行處理。

4、在處理每個BodyPart對象時，首先調(diào)用BodyPart對象的getContentType方法得到它的MIME類型，然后根據(jù)MIME類型作出如下三種情況的處理：

　　當MIME類型為"text/*"時，表示BodyPart對象中保存的是純文本數(shù)據(jù)，如上圖中的"text/plain"，此時第一BodyPart對象的getContent方法并將返回的對象轉(zhuǎn)換成String輸出給顯示軟件顯示即可。

　　當MIME類型表示的是圖片、聲音或者是附件等二進制數(shù)據(jù)時，如上圖中的"image/gif"時，此時應(yīng)調(diào)用BodyPart對象的getDataHandler方法得到了封裝了數(shù)據(jù)的DataHanlder對象，然后調(diào)用DataHandler對象的getInputStream方法獲得與數(shù)據(jù)相關(guān)聯(lián)的InputStream對象，通過這個InputStream對象中即可獲得原始的二進制數(shù)據(jù)內(nèi)容。

　　當MIME類型為"multipart/mixed"時，表示BodyPart對象中保存的是一個復合MIME消息，此時應(yīng)調(diào)用BodyPart對象的getContent方法得到封裝復合MIME消息的對象并將它轉(zhuǎn)換成Multipart類型，接著重復第3和第4個步驟操作對Multipart對象進行遞歸調(diào)用。

下面來編寫一個接收并解析帶有附件的程序

POP3Help.java

package mail;

import java.util.Properties;

import javax.mail.Folder;
import javax.mail.Session;
import javax.mail.Store;

public class POP3Help {
 public static Folder getFolder(String host, String username, String password) {
  Properties prop = new Properties();
  prop.setProperty("mail.store.protocol", "pop3");
  prop.setProperty("mail.pop3.host", host);

  Session mailSession = Session.getDefaultInstance(prop, null);
  mailSession.setDebug(false);

  try {
   Store store = mailSession.getStore("pop3");
   store.connect(host, username, password);
   Folder folder = store.getFolder("inbox");
   folder.open(Folder.READ_WRITE);
   return folder;
  } catch (Exception e) {
   e.printStackTrace();
  }

  return null;
 }
}

該類用來連接和登錄POP3服務(wù)器，并返回代表郵件夾的Folder對象

index.html

<html>
 <head>
 <title>login.html</title>
 </head>
 <body>
 <form action="login.jsp" method="post">
  主機名：<input name="host" type="text"><br/>
  用戶名:<input name="username" type="text"><br/>
  密碼:<input name="password" type="password"><br/>
  <input type="submit" value="提交"> 
  <input type="reset" value="重置">
 </form>
 </body>
</html>

登錄頁面，需要用戶填寫郵件服務(wù)器的主機名，用戶名和密碼

<%@ page import="javax.mail.*,mail.*"
 contentType="text/html;charset=GB2312" %>
<%
 String host = request.getParameter("host");  
  String username = request.getParameter("username");
  String password = request.getParameter("password");
  String from = "";
  String subject = ""; 
  Folder folder = POP3Help.getFolder(host,username,password);
  session.setAttribute("folder",folder);
  Message [] messages = folder.getMessages();
  
  for(int i=0;i<messages.length;i++)
  {
   try
   {
    from = messages[i].getFrom()[0].toString();
   subject = messages[i].getSubject();
   out.print(i + 1);
%>
   發(fā)件人地址：<%=from %> 郵件主題：<%=subject %>    
   <a href="displayMsg.jsp?msgnum=<%=i+1%>">查看郵件</a><br/>
<%
  }
   catch(Exception e){}
   }
%>

獲取郵件夾中的所有郵件

displayMsg.jsp

<frameset rows="25%,*">
 <frame src="/mailDemo/DisplayHead?msgnum=<%=request.getParameter("msgnum")%>" scrolling="no">
 <frame src="/mailDemo/DisplayContent?msgnum=<%=request.getParameter("msgnum")%>" scrolling="no">
</frameset>

用于展示郵件的信息

DisplayHead.java

package mail;

import java.io.IOException;
import java.io.PrintWriter;
import java.text.DateFormat;

import javax.mail.BodyPart;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.Multipart;
import javax.mail.internet.MimeUtility;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

@SuppressWarnings("serial")
public class DisplayHead extends HttpServlet {
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  response.setContentType("text/html;charset=gb2312");
  PrintWriter out = response.getWriter();
  HttpSession session = request.getSession();
  int msgnum = Integer.parseInt(request.getParameter("msgnum"));
  Folder folder = (Folder) session.getAttribute("folder");

  try {
   Message msg = folder.getMessage(msgnum);
   String from = msg.getFrom()[0].toString();
   String subject = msg.getSubject();
   String sendDate = DateFormat.getInstance().format(msg.getSentDate());

   out.println("郵件主題：" + subject + "<br/>");
   out.println("發(fā)件人:" + from + "<br/>");
   out.println("發(fā)送日期：" + sendDate + "<br/><br/>");

   System.out.println("contentType：" + msg.getContentType());

   // 如果該郵件是組合型"multipart/*"則可能包含附件等
   if (msg.isMimeType("multipart/*")) {
    Multipart mp = (Multipart) msg.getContent();

    for (int i = 0; i < mp.getCount(); i++) {
     BodyPart bp = mp.getBodyPart(i);

     // 如果該BodyPart對象包含附件，則應(yīng)該解析出來
     if (bp.getDisposition() != null) {
      String filename = bp.getFileName();
      System.out.println("filename：" + filename);
      
      if (filename.startsWith("=?")) {
       // 把文件名編碼成符合RFC822規(guī)范
       filename = MimeUtility.decodeText(filename);
      }

      // 生成打開附件的超鏈接
      out.print("附件：");
      out.print("<a href=HandleAttach?msgnum=" + msgnum + "&&bodynum=" + i + "&&filename=" + filename
        + ">" + filename + "</a><br/>");
     }
    }
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
}

用于顯示郵件頭內(nèi)容

DisplayContent.java

package mail;

import java.io.IOException;

import javax.mail.BodyPart;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.Multipart;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

@SuppressWarnings("serial")
public class DisplayContent extends HttpServlet {
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  ServletOutputStream sos = response.getOutputStream();
  HttpSession session = request.getSession();
  int msgnum = Integer.parseInt(request.getParameter("msgnum"));
  Folder folder = (Folder) session.getAttribute("folder");

  try {
   Message msg = folder.getMessage(msgnum);
   // 郵件類型不是mixed時，表示郵件中不包含附件，直接輸出郵件內(nèi)容
   if (!msg.isMimeType("multipart/mixed")) {
    response.setContentType("message/rfc822");
    msg.writeTo(sos);
   } else {
    // 查找并輸出郵件中的郵件正文
    Multipart mp = (Multipart) msg.getContent();
    int bodynum = mp.getCount();
    for (int i = 0; i < bodynum; i++) {
     BodyPart bp = mp.getBodyPart(i);
     /*
      * MIME消息頭中不包含disposition字段， 并且MIME消息類型不為mixed時，
      * 表示當前獲得的MIME消息為郵件正文
      */
     if (!bp.isMimeType("multipart/mixed") && bp.getDisposition() == null) {
      response.setContentType("message/rfc822");
      bp.writeTo(sos);
     }
    }
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
}

用于顯示郵件正文

HandleAttact.java

package mail;

import java.io.IOException;
import java.io.InputStream;
import javax.mail.BodyPart;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.Multipart;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

@SuppressWarnings("serial")
public class HandleAttach extends HttpServlet {
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  response.setContentType("text/html");
  HttpSession session = request.getSession();
  ServletOutputStream out = response.getOutputStream();

  int msgnum = Integer.parseInt(request.getParameter("msgnum"));
  int bodynum = Integer.parseInt(request.getParameter("bodynum"));
  String filename = request.getParameter("filename");
  Folder folder = (Folder) session.getAttribute("folder");

  try {
   Message msg = folder.getMessage(msgnum);

   // 將消息頭類型設(shè)置為附件類型
   response.setHeader("Content-Disposition", "attachment;filename=" + filename);
   
   Multipart multi = (Multipart) msg.getContent();
   BodyPart bodyPart = multi.getBodyPart(bodynum);
   
   InputStream is = bodyPart.getInputStream();
   int c = 0;
   while ((c = is.read()) != -1) {
    out.write(c);
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
}

用于處理附件

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>mailDemo</display-name>
  <welcome-file-list>
  <welcome-file>index.html</welcome-file>
  <welcome-file>index.htm</welcome-file>
  <welcome-file>index.jsp</welcome-file>
  <welcome-file>default.html</welcome-file>
  <welcome-file>default.htm</welcome-file>
  <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
 
  <servlet> 
  <servlet-name>DisplayHead</servlet-name> 
  <servlet-class>mail.DisplayHead</servlet-class> 
 </servlet>  
 <servlet-mapping> 
  <servlet-name>DisplayHead</servlet-name> 
  <url-pattern>/DisplayHead</url-pattern> 
 </servlet-mapping> 
  
 <servlet> 
  <servlet-name>DisplayContent</servlet-name> 
  <servlet-class>mail.DisplayContent</servlet-class> 
 </servlet>  
 <servlet-mapping> 
  <servlet-name>DisplayContent</servlet-name> 
  <url-pattern>/DisplayContent</url-pattern> 
 </servlet-mapping>  
  
 <servlet> 
  <servlet-name>HandleAttach</servlet-name> 
  <servlet-class>mail.HandleAttach</servlet-class> 
 </servlet>  
 <servlet-mapping> 
  <servlet-name>HandleAttach</servlet-name> 
  <url-pattern>/HandleAttach</url-pattern> 
 </servlet-mapping> 
</web-app>

首先啟動tomcat服務(wù)器，然后在瀏覽器中輸入http://localhost:8080/mailDemo/index.html