我正在开发一个程序，可以在没有用户交互的情况下发送电子邮件。为此，我使用javax.mail.Authenticator。但是，当我运行程序时，它给我空指针异常。这是我的代码：
public class Mail extends javax.mail.Authenticator {
private String _user;
private String _pass;
private String[] _to;
private String _from;
private String _port;
private String _sport;
private String _host;
private String _subject;
private String _body;
private boolean _auth;
private boolean _debuggable;
private Multipart _multipart;
public Mail() {
_host = "smtp.gmail.com"; // default smtp server
_port = "465"; // default smtp port
_sport = "465"; // default socketfactory port
_user = ""; // username
_pass = ""; // password
_from = ""; // email sent from
_subject = ""; // email subject
_body = ""; // email body
_debuggable = false; // debug mode on or off - default off
_auth = true; // smtp authentication - default on
_multipart = new MimeMultipart();
// There is something wrong with MailCap, javamail can not find a handler for the multipart/mixed part, so this bit needs to be added.
MailcapCommandMap mc = (MailcapCommandMap) CommandMap.getDefaultCommandMap();
mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html");
mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml");
mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain");
mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed");
mc.addMailcap("message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822");
CommandMap.setDefaultCommandMap(mc);
}
public Mail(String user, String pass) {
this();
_user = user;
_pass = pass;
}
public boolean send() throws Exception {
Properties props = _setProperties();
if(!_user.equals("") && !_pass.equals("") && _to.length > 0 && !_from.equals("") && !_subject.equals("") && !_body.equals("")) {
Session session = Session.getInstance(props, this);
MimeMessage msg = new MimeMessage(session);
msg.setFrom(new InternetAddress(_from));
InternetAddress[] addressTo = new InternetAddress[_to.length];
for (int i = 0; i < _to.length; i++) {
addressTo[i] = new InternetAddress(_to[i]);
}
msg.setRecipients(MimeMessage.RecipientType.TO, addressTo);
msg.setSubject(_subject);
msg.setSentDate(new Date());
// setup message body
BodyPart messageBodyPart = new MimeBodyPart();
messageBodyPart.setText(_body);
_multipart.addBodyPart(messageBodyPart);
// Put parts in message
msg.setContent(_multipart);
// send email
Transport.send(msg);
return true;
} else {
return false;
}
}
public void addAttachment(String filename) throws Exception {
BodyPart messageBodyPart = new MimeBodyPart();
DataSource source = new FileDataSource(filename);
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName(filename);
_multipart.addBodyPart(messageBodyPart);
}
@Override
public PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(_user, _pass);
}
private Properties _setProperties() {
Properties props = new Properties();
props.put("mail.smtp.host", _host);
if(_debuggable) {
props.put("mail.debug", "true");
}
if(_auth) {
props.put("mail.smtp.auth", "true");
}
props.put("mail.smtp.port", _port);
props.put("mail.smtp.socketFactory.port", _sport);
props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
props.put("mail.smtp.socketFactory.fallback", "false");
return props;
}
// the getters and setters
public String getBody() {
return _body;
}
public void setBody(String _body) {
this._body = _body;
}
public void setTo(String[] toArr) {
this._to = toArr;
}
public void setFrom(String string) {
this._from = string;
}
public void setSubject(String string) {
this._subject = string;
}
// more of the getters and setters …..
}`
这是我的主要活动：
public class AutomaticEmailActivity extends Activity {
private Mail m;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
m = new Mail("yourEmail@domain.tld", "yourpassword");
}
public void sendEmail(View view){
String[] toArr = {"toemail1@domain1.tld"}; // This is an array, you can add more emails, just separate them with a coma
m.setTo(toArr); // load array to setTo function
m.setFrom("fromEmail@domain.tld"); // who is sending the email
m.setSubject("subject");
m.setBody("your message goes here");
try {
m.addAttachment("/sdcard/myPicture.jpg"); // path to file you want to attach
if(m.send()) {
// success
Toast.makeText(AutomaticEmailActivity.this, "Email was sent successfully.", Toast.LENGTH_LONG).show();
} else {
// failure
Toast.makeText(AutomaticEmailActivity.this, "Email was not sent.", Toast.LENGTH_LONG).show();
}
} catch(Exception e) {
// some other problem
Toast.makeText(AutomaticEmailActivity.this, "There was a problem sending the email.", Toast.LENGTH_LONG).show();
}
}
} 在这里我的博客
致命的例外：主要 显示java.lang.NullPointerException 在com.example.unknown.location.MainActivity.onSensorChanged（MainActivity.java:235） 在android.hardware.SystemSensorManager $ ListenerDelegate $ 1.handleMessage（SystemSensorManager.java:256） 在android.os.Handler.dispatchMessage（Handler.java:99） 在android.os.Looper.loop（Looper.java:176） 在android.app.ActivityThread.main（ActivityThread.java:5317） at java.lang.reflect.Method.invokeNative（Native Method） 在java.lang.reflect.Method.invoke（Method.java:511） 在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1102） 在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:869） 在dalvik.system.NativeStart.main（本地方法）
运行代码时会发生以下情况：There was a problem sending the email.
我的代码中的第三个Toast，如果我用e.getMessage（）。toString替换了这个消息，它返回NullPointerException