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分享java mail 接收邮件，为什么 subject 为 null
如题，使用 java mail，读取邮箱收件箱的邮件，能读出正确的邮件数目来，也能读到 content，但 getSubject() 却返回 null，事实是邮件确实是有 subject 的，中英文都不行。还有 getFrom() 也是 null，代码如下，请指教，谢谢！
public class MailReceiverTest {
public static void main(String[] args) throws Exception {
String pop3Server = "mail.xxxxxx.com";
String protocol = "pop3";
String user = "xxx@xxxxxx.com";
String pwd = "xxxxxx";
Properties props = new Properties();
props.setProperty("mail.store.protocol", protocol);
props.setProperty("mail.pop3.host", pop3Server);
Session session = Session.getInstance(props);
session.setDebug(true);
Store store = session.getStore();
store.connect(pop3Server, user, pwd);
Folder folder = store.getFolder("INBOX");
folder.open(Folder.READ_ONLY);
try {
Message [] messages = folder.getMessages();
// 此处 mailCounts 数量为 2，与我收件箱中一致，正确
int mailCounts = messages.length;
for(int i = 0; i < mailCounts; i++) {
String subject = messages[i].getSubject(); // subject 为 null，为何 ？
String from = (messages[i].getFrom()[0]).toString();
System.out.println("第 " + (i+1) + "封邮件的主题：" + subject);
System.out.println("第 " + (i+1) + "封邮件的发件人地址：" + from);
}
} finally {
folder.close(false);
store.close();
}
}
}
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Java碎碎念 2015-06-24
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刚执行了代码，可以取到主题，楼主换个邮箱服务器试试。
I_am_a_java_CaiNiao 2015-06-24
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这是收邮件啊，需要设置主题吗？不明白
爱跳舞的铅笔头 2015-06-24
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再好好看看代码，是不是主题没有设置上啊
I_am_a_java_CaiNiao 2015-06-24
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找到原因了，我项目中还用到了 axis2，axis2的 jar 包与 javamail 有冲突，把 axis2 的jar 包全去掉就正常了。
不过现在问题是我确实需要 axis2，不行就分两个项目了，唉。。。
I_am_a_java_CaiNiao 2015-06-24
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以下是调试日志：
Loading javamail.default.providers from jar:file:/C:/Users/tianxiang/.m2/repository/javax/mail/mail/1.4.7/mail-1.4.7.jar!/META-INF/javamail.default.providers
DEBUG: loading new provider protocol=imap, className=com.sun.mail.imap.IMAPStore, vendor=Oracle, version=null
DEBUG: loading new provider protocol=imaps, className=com.sun.mail.imap.IMAPSSLStore, vendor=Oracle, version=null
DEBUG: loading new provider protocol=smtp, className=com.sun.mail.smtp.SMTPTransport, vendor=Oracle, version=null
DEBUG: loading new provider protocol=smtps, className=com.sun.mail.smtp.SMTPSSLTransport, vendor=Oracle, version=null
DEBUG: loading new provider protocol=pop3, className=com.sun.mail.pop3.POP3Store, vendor=Oracle, version=null
DEBUG: loading new provider protocol=pop3s, className=com.sun.mail.pop3.POP3SSLStore, vendor=Oracle, version=null
DEBUG: getProvider() returning provider protocol=pop3; type=javax.mail.Provider$Type@a54f742; class=com.sun.mail.pop3.POP3Store; vendor=Oracle
DEBUG POP3: mail.pop3.rsetbeforequit: false
DEBUG POP3: mail.pop3.disabletop: false
DEBUG POP3: mail.pop3.forgettopheaders: false
DEBUG POP3: mail.pop3.cachewriteto: false
DEBUG POP3: mail.pop3.filecache.enable: false
DEBUG POP3: mail.pop3.keepmessagecontent: false
DEBUG POP3: mail.pop3.starttls.enable: false
DEBUG POP3: mail.pop3.starttls.required: false
DEBUG POP3: mail.pop3.apop.enable: false
DEBUG POP3: mail.pop3.disablecapa: false
DEBUG POP3: connecting to host "mail.sinotrans-mingzhou.com", port 110, isSSL false
+OK sinotrans-mingzhou.com POP3 MDaemon 14.0.3 ready <MDAEMON-F201506241428.AA2816603MD4765@sinotrans-mingzhou.com>
CAPA
+OK Capability list follows
TOP
USER
UIDL
.
DEBUG POP3: authentication command trace suppressed
DEBUG POP3: authentication command succeeded
STAT
+OK 0 0
QUIT
+OK stx@sinotrans-mingzhou.com sinotrans-mingzhou.com POP3 Server signing off (mailbox empty)
I_am_a_java_CaiNiao 2015-06-24
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换了好几个邮箱，都是老问题。
获取的其他属性（From, To, Date...）也都是null，除了 getContent 是有内容的。
Java碎碎念 2015-06-24
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JavaMail version 1.4.7
I_am_a_java_CaiNiao 2015-06-24
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我换了 qq 邮箱，还是不行。你用的 jar 包是什么版本的？我的是：
<dependency>
<groupId>javax.mail</groupId>
<artifactId>mail</artifactId>
<version>1.4.7</version>
</dependency>
利用Java发送邮件（含附件）的例子
1、邮件发送的配置propertity文件内容如下：（utils.properties文件放在src下面）
emailsmtp=smtp.qq.comemailaddress=459104018@qq.comemailpass=******2、读取配置文件的类文件（ReadPropertity.java）
import java.io.IOException;import java.util.Properties;public class ReadPropertity { static Properties props = new Properties(); static { try { props.load(ReadPropertity.class.getClassLoader().getResourceAsStream( "utils.properties")); } catch (IOException e1) { e1.printStackTrace(); } } public static String getProperty(String key) { return props.getProperty(key); }}3、邮件处理类（EmailHandle.java）import java.util.Iterator;import java.util.LinkedList;import java.util.List;import java.util.Properties;import javax.activation.DataHandler;import javax.activation.FileDataSource;import javax.mail.BodyPart;import javax.mail.Message;import javax.mail.Multipart;import javax.mail.Session;import javax.mail.Transport;import javax.mail.internet.InternetAddress;import javax.mail.internet.MimeBodyPart;import javax.mail.internet.MimeMessage;import javax.mail.internet.MimeMultipart;import javax.mail.internet.MimeUtility;/*** 本程序用java来实现Email的发送， 所用到的协议为：smtp*
Company: 疯狂的IT人
* time:2013-04-05* @author www.crazyiter.com* @date * @version 1.0 */public class EmailHandle { private MimeMessage mimeMsg; //邮件对象 private Session session; //发送邮件的Session会话 private Properties props;//邮件发送时的一些配置信息的一个属性对象 private String sendUserName; //发件人的用户名 private String sendUserPass; //发件人密码 private Multipart mp;//附件添加的组件 private List files = new LinkedList();//存放附件文件 public EmailHandle(String smtp) { sendUserName = ""; sendUserPass = ""; setSmtpHost(smtp);// 设置邮件服务器 createMimeMessage(); // 创建邮件 } public void setSmtpHost(String hostName) { if (props == null) props = System.getProperties(); props.put("mail.smtp.host", hostName); } public boolean createMimeMessage(){ try { // 用props对象来创建并初始化session对象 session = Session.getDefaultInstance(props, null); } catch (Exception e) { System.err.println("获取邮件会话对象时发生错误！" + e); return false; } try { mimeMsg = new MimeMessage(session); // 用session对象来创建并初始化邮件对象 mp = new MimeMultipart();// 生成附件组件的实例 } catch (Exception e) { return false; } return true; } /** * 设置SMTP的身份认证 */ public void setNeedAuth(boolean need) { if (props == null) props = System.getProperties(); if (need) props.put("mail.smtp.auth", "true"); else props.put("mail.smtp.auth", "false"); } /** * 进行用户身份验证时，设置用户名和密码 */ public void setNamePass(String name, String pass) { sendUserName = name; sendUserPass = pass; } /** * 设置邮件主题 * @param mailSubject * @return */ public boolean setSubject(String mailSubject) { try { mimeMsg.setSubject(mailSubject); } catch (Exception e) { return false; } return true; } /** * 设置邮件内容,并设置其为文本格式或HTML文件格式，编码方式为UTF-8 * @param mailBody * @return */ public boolean setBody(String mailBody) { try { BodyPart bp = new MimeBodyPart(); bp.setContent(""+ mailBody, "text/html;charset=UTF-8"); // 在组件上添加邮件文本 mp.addBodyPart(bp); } catch (Exception e) { System.err.println("设置邮件正文时发生错误！" + e); return false; } return true; } /** * 增加发送附件 * @param filename * 邮件附件的地址，只能是本机地址而不能是网络地址，否则抛出异常 * @return */ public boolean addFileAffix(String filename) { try { BodyPart bp = new MimeBodyPart(); FileDataSource fileds = new FileDataSource(filename); bp.setDataHandler(new DataHandler(fileds)); bp.setFileName(MimeUtility.encodeText(fileds.getName(),"utf-8",null)); // 解决附件名称乱码 mp.addBodyPart(bp);// 添加附件 files.add(fileds); } catch (Exception e) { System.err.println("增加邮件附件：" + filename + "发生错误！" + e); return false; } return true; } public boolean delFileAffix(){ try { FileDataSource fileds = null; for(Iterator it = files.iterator() ;it.hasNext();) { fileds = (FileDataSource)it.next(); if(fileds != null && fileds.getFile() != null){ fileds.getFile().delete(); } } }catch (Exception e) { return false; } return true; } /** * 设置发件人地址 * @param from * 发件人地址 * @return */ public boolean setFrom(String from) { try { mimeMsg.setFrom(new InternetAddress(from)); } catch (Exception e) { return false; } return true; } /** * 设置收件人地址 * @param to收件人的地址 * @return */ public boolean setTo(String to) { if (to == null) return false; try { mimeMsg.setRecipients(Message.RecipientType.TO,InternetAddress.parse(to)); } catch (Exception e) { return false; } return true; } /** * 发送附件 * @param copyto * @return */ public boolean setCopyTo(String copyto) { if (copyto == null) return false; try { mimeMsg.setRecipients(javax.mail.Message.RecipientType.CC,InternetAddress.parse(copyto)); } catch (Exception e) { return false; } return true; } /** * 发送邮件 * @return */ public boolean sendEmail() throws Exception{ mimeMsg.setContent(mp); mimeMsg.saveChanges(); System.out.println("正在发送邮件...."); Session mailSession = Session.getInstance(props, null); Transport transport = mailSession.getTransport("smtp"); // 连接邮件服务器并进行身份验证 transport.connect((String) props.get("mail.smtp.host"), sendUserName,sendUserPass); // 发送邮件 transport.sendMessage(mimeMsg, mimeMsg.getRecipients(Message.RecipientType.TO)); System.out.println("发送邮件成功！"); transport.close(); return true; }}4、邮件发送的类文件（SendEmail.java）/*** 发送邮件测试*Company: 疯狂的IT人
* time:2013-04-05* @author www.crazyiter.com* @date * @version 1.0 */public class SendEmail { public SendEmail() { } /***以后需要两个参数：接收方地址 、 内容***/ public static void send(String subject, String toaddress,String content)throws Exception { String hostName = ReadPropertity.getProperty("emailsmtp"); String fromAddress = ReadPropertity.getProperty("emailaddress"); String fromAPass = ReadPropertity.getProperty("emailpass"); EmailHandle emailHandle = new EmailHandle(hostName); emailHandle.setFrom(fromAddress); emailHandle.setNeedAuth(true); emailHandle.setSubject(subject); emailHandle.setBody(content); emailHandle.setTo(toaddress); emailHandle.setFrom(fromAddress); emailHandle.addFileAffix("D:/myself/help/txt/java环境变量.txt");// 附件文件路径 emailHandle.setNamePass(fromAddress, fromAPass); emailHandle.sendEmail(); } public static void main(String[] args) { try { SendEmail.send("带附件的邮件测试","459104018@qq.com","测试内容疯狂的IT人"); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } }}5、发送邮件需要的jar包：activation.jarmail-plugin.jarmail.jar6、打包下载： 疯狂的IT人整理java邮件发送（源码）.rar 下载地址： http://www.crazyiter.com/bbs/forum.php?mod=attachment&aid=MjF8MzQzOTYzZjB8MTM2NTE3NjczMHwxfDExNDA%3D
