我正在尝试发送没有Gmail的电子邮件并使用javax.mail。特别是，我使用两个文件：
mailSender.java和MainActivity。
mailSender.java ：
package com.polito.gmail;
import java.util.Date;
import java.util.Properties;
import javax.activation.CommandMap;
import javax.activation.MailcapCommandMap;
import javax.mail.BodyPart;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
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;
public class mailSender extends javax.mail.Authenticator {
private String _user;
private String _pass;
private String[] destAddr = {"user1@hotmail.it", "user2@gmail.com"};
private String fromAddr = "from@gmail.com";
private String _port;
private String _sport;
private String _host;
private String _subject = "New Mail";
private String _body;
private boolean _auth;
private boolean _debuggable;
private Multipart _multipart;
public mailSender() {
_host = "smtp.gmail.com"; // default smtp server
_port = "465"; // default smtp port
_sport = "465"; // default socketfactory port
_user = ""; // username
_pass = ""; // password
_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 mailSender(String user, String pass) {
this();
_user = user;
_pass = pass;
}
public boolean send() throws Exception {
Properties props = _setProperties();
if (!_user.equals("") && !_pass.equals("") && destAddr.length > 0
&& !fromAddr.equals("") && !_subject.equals("")
&& !_body.equals("")) {
Session session = Session.getInstance(props, this);
MimeMessage msg = new MimeMessage(session);
msg.setFrom(new InternetAddress(fromAddr));
InternetAddress[] addressTo = new InternetAddress[destAddr.length];
for (int i = 0; i < destAddr.length; i++) {
addressTo[i] = new InternetAddress(destAddr[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;
}
}
@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", "false");
}
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;
}
在 MainActivity.java ：
mailSender sender = new mailSender("from@gmail.com","password");
sender.setBody(prepareBody());
try {
if(sender.send()) {
Toast.makeText(MainActivity.this, "Mail send", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(MainActivity.this, "Mail not send", Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
Log.e("error", String.valueOf(e.getMessage()));
}
我在清单文件中插入INTERNET权限并正确ping smtp.gmail.com，但应用程序会生成此异常：
01-10 11:06:52.238: E/AndroidRuntime(2001): FATAL EXCEPTION: main
01-10 11:06:52.238: E/AndroidRuntime(2001): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.polito.gmail/com.polito.gmail.MainActivity}: java.lang.NullPointerException
01-10 11:06:52.238: E/AndroidRuntime(2001): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2185)
01-10 11:06:52.238: E/AndroidRuntime(2001): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2210)
01-10 11:06:52.238: E/AndroidRuntime(2001): at android.app.ActivityThread.access$600(ActivityThread.java:142)
01-10 11:06:52.238: E/AndroidRuntime(2001): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1208)
01-10 11:06:52.238: E/AndroidRuntime(2001): at android.os.Handler.dispatchMessage(Handler.java:99)
01-10 11:06:52.238: E/AndroidRuntime(2001): at android.os.Looper.loop(Looper.java:137)
01-10 11:06:52.238: E/AndroidRuntime(2001): at android.app.ActivityThread.main(ActivityThread.java:4931)
01-10 11:06:52.238: E/AndroidRuntime(2001): at java.lang.reflect.Method.invokeNative(Native Method)
01-10 11:06:52.238: E/AndroidRuntime(2001): at java.lang.reflect.Method.invoke(Method.java:511)
01-10 11:06:52.238: E/AndroidRuntime(2001): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
01-10 11:06:52.238: E/AndroidRuntime(2001): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558)
01-10 11:06:52.238: E/AndroidRuntime(2001): at dalvik.system.NativeStart.main(Native Method)
01-10 11:06:52.238: E/AndroidRuntime(2001): Caused by: java.lang.NullPointerException
01-10 11:06:52.238: E/AndroidRuntime(2001): at com.polito.gmail.MainActivity.onCreate(MainActivity.java:48)
01-10 11:06:52.238: E/AndroidRuntime(2001): at android.app.Activity.performCreate(Activity.java:5008)
01-10 11:06:52.238: E/AndroidRuntime(2001): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
01-10 11:06:52.238: E/AndroidRuntime(2001): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2139)
01-10 11:06:52.238: E/AndroidRuntime(2001): ... 11 more
有什么问题？
答案 0 :(得分：0)
试试这可能对你有帮助。
mailSender sender = new mailSender("from@gmail.com","password");
sender.setBody(prepareBody());
try {
if(sender.send()) {
Toast.makeText(MainActivity.this, "Mail send", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(MainActivity.this, "Mail not send", Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
if(e.getMessage() != null)
Log.e("error", String.valueOf(e.getMessage()));
}
答案 1 :(得分：0)
您的代码似乎是正确的，请检查您是否收到了邮件。发生异常是因为没有与异常相关的消息。试试这个以避免NullPointerException：
Log.e("error", String.valueOf(e));
更新： 为了更好地使用javamail进行异常处理的逻辑，请遵循：
try {
sender.send();
Toast.makeText(MainActivity.this, "Mail send", Toast.LENGTH_LONG).show();
}
catch (Exception e) {
if (e.toString().equals("java.lang.NullPointerException"))
Toast.makeText(MainActivity.this, "Mail not send: Mail settings not configured", Toast.LENGTH_LONG).show();
else if (e.toString().equals("javax.mail.AuthenticationFailedException"))
Toast.makeText(MainActivity.this, "Mail not send: Wrong Username or Password", Toast.LENGTH_LONG).show();
else if (e.toString().equals("Invalid Addresses"))
Toast.makeText(MainActivity.this, "Mail not send: Invalid Address(es)", Toast.LENGTH_LONG).show();
else
Toast.makeText(MainActivity.this, "Mail not send", Toast.LENGTH_LONG).show();
}