Servlets - 发送电子邮件( Sending Email)
使用Servlet发送电子邮件很简单，但首先应该在您的计算机上安装JavaMail API和Java Activation Framework (JAF) 。
您可以从Java的标准网站下载最新版本的JavaMail (Version 1.2) 。
您可以从Java的标准网站下载最新版本的JAF (Version 1.1.1) 。
下载并解压缩这些文件，在新创建的顶级目录中，您将找到两个应用程序的jar文件。 您需要在CLASSPATH中添加mail.jar和activation.jar文件。
发送简单电子邮件
以下是从您的计算机发送简单电子邮件的示例。 这里假设您的localhost已连接到互联网并且足以发送电子邮件。 同时确保CLASSPATH中的Java Email API包和JAF包中的所有jar文件都可用。
// File Name SendEmail.java
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;
public class SendEmail extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// Recipient's email ID needs to be mentioned.
String to = "abcd@gmail.com";
// Sender's email ID needs to be mentioned
String from = "web@gmail.com";
// Assuming you are sending email from localhost
String host = "localhost";
// Get system properties
Properties properties = System.getProperties();
// Setup mail server
properties.setProperty("mail.smtp.host", host);
// Get the default Session object.
Session session = Session.getDefaultInstance(properties);
// Set response content type
response.setContentType("text/html");
PrintWriter out = response.getWriter();
try {
// Create a default MimeMessage object.
MimeMessage message = new MimeMessage(session);
// Set From: header field of the header.
message.setFrom(new InternetAddress(from));
// Set To: header field of the header.
message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
// Set Subject: header field
message.setSubject("This is the Subject Line!");
// Now set the actual message
message.setText("This is actual message");
// Send message
Transport.send(message);
String title = "Send Email";
String res = "Sent message successfully....";
String docType =
"<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";
out.println(docType +
"<html>\n" +
"<head><title>" + title + "</title></head>\n" +
"<body bgcolor = \"#f0f0f0\">\n" +
"<h1 align = \"center\">" + title + "</h1>\n" +
"<p align = \"center\">" + res + "</p>\n" +
"</body>
</html>"
);
} catch (MessagingException mex) {
mex.printStackTrace();
}
}
}
现在让我们编译上面的servlet并在web.xml中创建以下条目
....
<servlet>
<servlet-name>SendEmail</servlet-name>
<servlet-class>SendEmail</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>SendEmail</servlet-name>
<url-pattern>/SendEmail</url-pattern>
</servlet-mapping>
....
现在使用URL http:// localhost:8080/SendEmail调用此servlet，该URL将向给定的电子邮件ID abcd@gmail.com发送电子邮件，并显示以下响应 -
<h1 align="center">Send Email</h1>
<p align="center">Sent message successfully....</p>
如果您要向多个收件人发送电子邮件，则可以使用以下方法指定多个电子邮件ID -
void addRecipients(Message.RecipientType type, Address[] addresses)
throws MessagingException
以下是参数的说明 -
type - 将设置为TO，CC或BCC。 这里CC表示碳复制，BCC表示黑碳复制。 示例Message.RecipientType.TO
addresses - 这是电子邮件ID的数组。 在指定电子邮件ID时，您需要使用InternetAddress（）方法。
发送HTML电子邮件
以下是从您的计算机发送HTML电子邮件的示例。 这里假设您的localhost已连接到互联网并且足以发送电子邮件。 同时，确保CLASSPATH中的Java Email API包和JAF包中的所有jar文件都可用。
此示例与前一个示例非常相似，不同之处在于我们使用setContent（）方法设置第二个参数为“text/html”的内容，以指定HTML内容包含在消息中。
使用此示例，您可以发送与您喜欢的HTML内容一样大的内容。
// File Name SendEmail.java
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;
public class SendEmail extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// Recipient's email ID needs to be mentioned.
String to = "abcd@gmail.com";
// Sender's email ID needs to be mentioned
String from = "web@gmail.com";
// Assuming you are sending email from localhost
String host = "localhost";
// Get system properties
Properties properties = System.getProperties();
// Setup mail server
properties.setProperty("mail.smtp.host", host);
// Get the default Session object.
Session session = Session.getDefaultInstance(properties);
// Set response content type
response.setContentType("text/html");
PrintWriter out = response.getWriter();
try {
// Create a default MimeMessage object.
MimeMessage message = new MimeMessage(session);
// Set From: header field of the header.
message.setFrom(new InternetAddress(from));
// Set To: header field of the header.
message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
// Set Subject: header field
message.setSubject("This is the Subject Line!");
// Send the actual HTML message, as big as you like
message.setContent("<h1>This is actual message</h1>", "text/html" );
// Send message
Transport.send(message);
String title = "Send Email";
String res = "Sent message successfully....";
String docType =
"<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";
out.println(docType +
"<html>\n" +
"<head><title>" + title + "</title></head>\n" +
"<body bgcolor = \"#f0f0f0\">\n" +
"<h1 align = \"center\">" + title + "</h1>\n" +
"<p align = \"center\">" + res + "</p>\n" +
"</body>
</html>"
);
} catch (MessagingException mex) {
mex.printStackTrace();
}
}
}
编译并运行上面的servlet以在给定的电子邮件ID上发送HTML消息。
在电子邮件中发送附件
以下是从您的计算机发送包含附件的电子邮件的示例。 这里假设您的localhost已连接到互联网并且足以发送电子邮件。
// File Name SendEmail.java
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;
public class SendEmail extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// Recipient's email ID needs to be mentioned.
String to = "abcd@gmail.com";
// Sender's email ID needs to be mentioned
String from = "web@gmail.com";
// Assuming you are sending email from localhost
String host = "localhost";
// Get system properties
Properties properties = System.getProperties();
// Setup mail server
properties.setProperty("mail.smtp.host", host);
// Get the default Session object.
Session session = Session.getDefaultInstance(properties);
// Set response content type
response.setContentType("text/html");
PrintWriter out = response.getWriter();
try {
// Create a default MimeMessage object.
MimeMessage message = new MimeMessage(session);
// Set From: header field of the header.
message.setFrom(new InternetAddress(from));
// Set To: header field of the header.
message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
// Set Subject: header field
message.setSubject("This is the Subject Line!");
// Create the message part
BodyPart messageBodyPart = new MimeBodyPart();
// Fill the message
messageBodyPart.setText("This is message body");
// Create a multipar message
Multipart multipart = new MimeMultipart();
// Set text message part
multipart.addBodyPart(messageBodyPart);
// Part two is attachment
messageBodyPart = new MimeBodyPart();
String filename = "file.txt";
DataSource source = new FileDataSource(filename);
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName(filename);
multipart.addBodyPart(messageBodyPart);
// Send the complete message parts
message.setContent(multipart );
// Send message
Transport.send(message);
String title = "Send Email";
String res = "Sent message successfully....";
String docType =
"<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";
out.println(docType +
"<html>\n" +
"<head><title>" + title + "</title></head>\n" +
"<body bgcolor = \"#f0f0f0\">\n" +
"<h1 align = \"center\">" + title + "</h1>\n" +
"<p align = \"center\">" + res + "</p>\n" +
"</body>
</html>"
);
} catch (MessagingException mex) {
mex.printStackTrace();
}
}
}
编译并运行上面的servlet，将文件作为附件发送，并在给定的电子邮件ID上发送消息。
用户认证部分
如果需要向电子邮件服务器提供用户ID和密码以进行身份验证，则可以按如下方式设置这些属性 -
props.setProperty("mail.user", "myuser");
props.setProperty("mail.password", "mypwd");
其余的电子邮件发送机制将保持如上所述。
