javaMail實現收發郵件（五）

時間  2019-11-13
標籤 javamail 實現 收發 郵件 欄目 Java 简体版
原文   原文鏈接

控制檯打印出的內容，咱們沒法閱讀，其實，讓咱們本身來解析一封複雜的郵件是很不容易的，郵件裏面格式、規範複雜得很。不過，咱們所用的瀏覽器內置瞭解析各類數據類型的數據處理模塊，咱們只須要在把數據流傳輸給瀏覽器以前明確地指定該數據流屬於哪一種數據類型便可，以後一切的解析操做由瀏覽器自動幫咱們完成。下面這張圖能夠很好的說明解析郵件的步驟：html

一、調用Message對象的getFrom、getSubject等方法，能夠獲得郵件的發件人和主題等信息，調用getContentType方法獲得郵件的類型；
二、經過Message.getContentType方法的返回值判斷郵件類型，並調用Message.getContent方法獲得郵件內容。若是郵件類型爲"text/plain"或者"text/html"，表示郵件內容爲純文本，此時調用Message對象的getContent方法獲得郵件內容，而後將返回對象的類型轉換成String輸出給顯示軟件便可。若是郵件類型爲"multipart/*"，表示郵件內容是一個複合類型，此時需將Message.getContent方法複合的對象轉換成Multipart。
三、調用Multipart對象的getCount方法檢測Multipart對象中封裝了多少個BodyPart對象，並經過for循環逐一取出Multipart對象中的每一個BodyPart對象進行處理。
四、在處理每一個BodyPart對象時，首先調用BodyPart對象的getContentType方法獲得它的MIME類型，而後根據MIME類型做出以下三種狀況的處理：當MIME類型爲"text/*"時，表示BodyPart對象中保存的是純文本數據，如上圖中的"text/plain"，此時第一BodyPart對象的getContent方法並將返回的對象轉換成String輸出給顯示軟件顯示便可。
當MIME類型表示的是圖片、聲音或者是附件等二進制數據時，如上圖中的"image/gif"時，此時應調用BodyPart對象的getDataHandler方法獲得了封裝了數據的DataHanlder對象，而後調用DataHandler對象的getInputStream方法得到與數據相關聯的InputStream對象，經過這個InputStream對象中便可得到原始的二進制數據內容。
當MIME類型爲"multipart/mixed"時，表示BodyPart對象中保存的是一個複合MIME消息，此時應調用BodyPart對象的getContent方法獲得封裝複合MIME消息的對象並將它轉換成Multipart類型，接着重複第3和第4個步驟操做對Multipart對象進行遞歸調用。java

編寫一個接收並解析帶有附件的程序

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;
    }
}
POP3Help.java

該類用來鏈接和登陸POP3服務器，並返回表明郵件夾的Folder對象web

<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>
index.html

登陸頁面，須要用戶填寫郵件服務器的主機名，用戶名和密碼瀏覽器

<%@ 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){}
          }
%>
login.jsp

獲取郵件夾中的全部郵件服務器

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

用於展現郵件的信息session

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("發件人:" + from + "<br/>");
            out.println("發送日期：" + sendDate + "<br/><br/>");

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

            // 若是該郵件是組合型"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);

                    // 若是該BodyPart對象包含附件，則應該解析出來
                    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規範
                            filename = MimeUtility.decodeText(filename);
                        }

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

用於顯示郵件頭內容app

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，直接輸出郵件內容
            if (!msg.isMimeType("multipart/mixed")) {
                response.setContentType("message/rfc822");
                msg.writeTo(sos);
            } else {
                // 查找並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， 而且MIME消息類型不爲mixed時，
                     * 表示當前得到的MIME消息爲郵件正文
                     */
                    if (!bp.isMimeType("multipart/mixed") && bp.getDisposition() == null) {
                        response.setContentType("message/rfc822");
                        bp.writeTo(sos);
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
DisplayContent.java

用於顯示郵件正文jsp

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);

            // 將消息頭類型設置爲附件類型
            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();
        }
    }
}
HandleAttact.java

用於處理附件ide

<?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>
web.xml
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