從文件中讀取內容併發送電子郵件

Question

我無法從文件中讀取內容，並將其作爲電子郵件的正文發送給java。但是，如果我運行代碼來發送電子郵件而不從文件中讀取內容，它會成功發送電子郵件，但在從文件正文中讀取內容時會出現問題。這將是偉大的，如果你可以幫助我下面是我正在使用的代碼

在此先感謝！

package com.example.tests; 

import java.io.BufferedReader; 
import java.io.DataInputStream; 
import java.io.FileInputStream; 
import java.io.InputStreamReader; 
import java.util.*; 
import javax.mail.*; 
import javax.mail.internet.*; 

public class sendEmail { 

    private static String USER_NAME = "zxxzz@gmail.com"; // GMail user name (just the part before "@gmail.com") 
    private static String PASSWORD = "xxxxxxx"; // GMail password 
    private static String RECIPIENT = "zxxzz@gmail.com"; 
    static String strLine = null; 
    public static void main(String[] args) { 
     String from = USER_NAME; 
     String pass = PASSWORD; 
     String[] to = { RECIPIENT }; // list of recipient email addresses 
     String subject = "Java send mail example"; 
     String body = strLine; 

     readfile(); 
     sendFromGMail(from, pass, to, subject, body); 
    } 

    private static void sendFromGMail(String from, String pass, String[] to, String subject, String body) { 
     Properties props = System.getProperties(); 
     String host = "smtp.gmail.com"; 
     props.put("mail.smtp.starttls.enable", "true"); 
     props.put("mail.smtp.host", host); 
     props.put("mail.smtp.user", from); 
     props.put("mail.smtp.password", pass); 
     props.put("mail.smtp.port", "587"); 
     props.put("mail.smtp.auth", "true"); 

     Session session = Session.getDefaultInstance(props); 
     MimeMessage message = new MimeMessage(session); 

     try { 
      message.setFrom(new InternetAddress(from)); 
      InternetAddress[] toAddress = new InternetAddress[to.length]; 

      // To get the array of addresses 
      for(int i = 0; i < to.length; i++) { 
       toAddress[i] = new InternetAddress(to[i]); 
      } 

      for(int i = 0; i < toAddress.length; i++) { 
       message.addRecipient(Message.RecipientType.TO, toAddress[i]); 
      } 

      message.setSubject(subject); 
      message.setText(body); 
      Transport transport = session.getTransport("smtp"); 
      transport.connect(host, from, pass); 
      transport.sendMessage(message, message.getAllRecipients()); 
      transport.close(); 
     } 
     catch (AddressException ae) { 
      ae.printStackTrace(); 
     } 
     catch (MessagingException me) { 
      me.printStackTrace(); 
     } 
    } 


    public static void readfile(){  
     try{ 
      // Open the file that is the first 
      // command line parameter 
      FileInputStream fstream = new FileInputStream("C:\\Sample.txt"); 
      // Get the object of DataInputStream 
      DataInputStream in = new DataInputStream(fstream); 
      BufferedReader br = new BufferedReader(new InputStreamReader(in)); 

      //Read File Line By Line 
      while ((strLine = br.readLine()) != null) { 
       // Print the content on the console 
       System.out.println (strLine); 
      } 
      //Close the input stream 
      in.close(); 
     }catch (Exception e){//Catch exception if any 
      System.err.println("Error: " + e.getMessage()); 
     } 
    } 
} 

例外，我得到：

  Exception in thread "main" java.lang.NullPointerException 
     at org.apache.geronimo.mail.util.ASCIIUtil.isAscii(ASCIIUtil.java:47) 
     at javax.mail.internet.MimeMessage.setText(MimeMessage.java:939) 
     at javax.mail.internet.MimeMessage.setText(MimeMessage.java:932) 
     at com.example.tests.sendEmail.sendFromGMail(sendEmail.java:55) 
     at com.example.tests.sendEmail.main(sendEmail.java:25) 

Answer 1

的strLine爲空！

您正確讀取該文件，但cyclinf文件的最後assignement將爲空

strLine = br.readLine()) != null 

可能的疏漏。

更換

 //Read File Line By Line 
     while ((strLine = br.readLine()) != null) { 
      // Print the content on the console 
      System.out.println (strLine); 
     } 

到

 //Read File Line By Line 
     String line; 
     strLine=""; 
     while ((line = br.readLine()) != null) { 
      // Print the content on the console 
      strLine += line; 
     } 
     System.out.println (strLine); 

或更好地利用string buffer

 //Read File Line By Line 
     String line; 
     StringBuffer buffer = new StringBuffer(""); 
     while ((line = br.readLine()) != null) { 
      // Print the content on the console 
      buffer.append(line); 
     } 
     strLine = buffer .toSTring(); 
     System.out.println (strLine); 

然後調用

sendFromGMail(from, pass, to, subject, strLine); 

Answer 2

問題是，您的body變量始終爲空。

在主要功能，改變String body = strLine;到String body = mailString;和使用另一個全局變量像mailString和readfile功能

StringBuffer mailStirng = new StringBuffer(""); 

    public static void main(String[] args) { 
      String from = USER_NAME; 
      String pass = PASSWORD; 
      String[] to = { RECIPIENT }; // list of recipient email addresses 
      String subject = "Java send mail example"; 
      readfile(); 
      String body = mailStirng.toString(); 
      sendFromGMail(from, pass, to, subject, body); 
     } 

    public static void readfile(){  
      try{ 
       // Open the file that is the first 
       // command line parameter 
       FileInputStream fstream = new FileInputStream("C:\\Sample.txt"); 
       // Get the object of DataInputStream 
       DataInputStream in = new DataInputStream(fstream); 
       BufferedReader br = new BufferedReader(new InputStreamReader(in)); 

       //Read File Line By Line 
       while ((strLine = br.readLine()) != null) { 
        // Print the content on the console 
        mailString.append(strLine); 
       } 
       //Close the input stream 
       in.close(); 
      }catch (Exception e){//Catch exception if any 
       System.err.println("Error: " + e.getMessage()); 
      } 
     } 

Answer 3

好填補它，首先，有什麼@venergiac中提到...也，你main功能，你這樣做：

final String body = strLine; // body = strLine = null 
readfile();     // initalise strLine 
sendFromGMail(from, pass, to, subject, body); // use body 

基本上，你設置body = strLine以前初始登錄strLine。 您可能還想要切換這兩行（或直接使用strLine作爲參數sendFromGmail？）。

順便說一句，在Java中Code Convention for the Java Programming Language是使用駝峯任何類名：我認爲你應該使用它，並重新命名你的類sendEmail到SendEmail :)

乾杯！