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一伸刃、在Spring中使用遠(yuǎn)程調(diào)用
Spring集成了多個可以遠(yuǎn)程調(diào)用的技術(shù)枷邪。遠(yuǎn)程調(diào)用支持開發(fā)遠(yuǎn)程服務(wù)哄辣，用普通的POJO即可實(shí)現(xiàn)。目前Spring支持以下幾個遠(yuǎn)程調(diào)用技術(shù)：
- Remote Method Invocation (RMI)
- Spring HTTP invoker
- Hessian
- Burlap
- Java Message Service(JMS)贩猎，在底層使用JMS作為協(xié)議
- Advanced Message Queuing Protocol(AMQP)收夸，在底層使用AMQP作為協(xié)議
Spring自動發(fā)現(xiàn)功能不適用于遠(yuǎn)程接口蜗顽，主要是為了避免對遠(yuǎn)程調(diào)用者開啟太多的入口布卡。
當(dāng)討論Spring的遠(yuǎn)程調(diào)用能力時我們使用以下實(shí)體類和相應(yīng)的services：
public class Account implements Serializable{
private String name;
public String getName(){
return name;
}
public void setName(String name) {
this.name = name;
}
}
public interface AccountService {
public void insertAccount(Account account);
public List<Account> getAccounts(String name);
}
public class AccountServiceImpl implements AccountService {
public void insertAccount(Account acc) {
// do something...
}
public List<Account> getAccounts(String name) {
// do something...
}
}
使用RMI的就不翻譯了，性能不太好雇盖。只翻譯一個Hessian忿等。Burlap與Hessian配置方式一樣，只需要把Hessian這個詞換成Burlap就行了崔挖。AMQP看這里贸街。關(guān)于它Spring另外有個項(xiàng)目。
1.1 使用Hessian通過HTTP遠(yuǎn)程調(diào)用services
Hessian提供了一個二進(jìn)制基于HTTP的遠(yuǎn)程調(diào)用協(xié)議狸相。更多信息請查看薛匪。
Hessian通過HTTP溝通，我們可以自定義一個servlet脓鹃。你可以輕松的寫出如下這樣的一個servlet來曝露你的服務(wù)逸尖。
<servlet>
<servlet-name>remoting</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>remoting</servlet-name>
<url-pattern>/remoting/*</url-pattern>
</servlet-mapping>
然后在WEB-INF文件夾創(chuàng)建一個remoting-servlet.xml配置文件
1.1.1 使用HessianServiceExporter曝露你的beans
我們將會在remoting-servlet.xml配置文件中創(chuàng)建一個HessianServiceExporter來曝露你的服務(wù)：
<bean id="accountService" class="example.AccountServiceImpl"></bean>
<bean name="/AccountService" class="org.springframework.remoting.caucho.HessianServiceExporter">
<property name="service" ref="accountService"/>
<property name="serviceInterface" value="example.AccountService"/>
</bean>
現(xiàn)在我們?nèi)?zhǔn)備在客戶端連接服務(wù)。沒有顯式的處理器映射被指定瘸右，那么BeanNameUrlHandlerMapping將會被使用娇跟，因此，這個服務(wù)將會曝露在DispatcherServlet的映射下并且以bean名稱（也就是/AccountService）命名的URL：http://HOST:8080/remoting/AccountService
1.1.2 在客戶端連接服務(wù)
使用HessianProxyFactoryBean我們可以在客戶端鏈接服務(wù)太颤。SimpleObject使用AccountService來管理賬戶：
<bean class="example.SimpleObject">
<property name="accountService" ref="accountService"/>
</bean>
<bean id="accountService" class="org.springframework.remoting.caucho.HessianProxyFactoryBean">
<property name="serviceUrl" value="http://remotehost:8080/remoting/AccountService"/>
<property name="serviceInterface" value="example.AccountService"/>
</bean>
1.2 對使用Hessian或者Burlap曝露的服務(wù)應(yīng)用HTTP基本身份驗(yàn)證
Hessian 和 Burlap的協(xié)議都是基于HTTP的苞俘，你可以很輕松的使用HTTP基本身份驗(yàn)證，例如：
<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping">
<property name="interceptors" ref="authorizationInterceptor"/>
</bean>
<bean id="authorizationInterceptor"
class="org.springframework.web.servlet.handler.UserRoleAuthorizationInterceptor">
<property name="authorizedRoles" value="administrator,operator"/>
</bean>
在這個應(yīng)用程序上下文中這個攔截器只允許administrators 和 operators這兩個角色調(diào)用bean方法龄章。
具體文檔也沒說吃谣，有興趣可以自行搜索，Apache Shiro也可以使用做裙。
二岗憋、在Spring中使用郵件
首先添加第三方依賴：
<dependency>
<groupId>javax.mail</groupId>
<artifactId>javax.mail-api</artifactId>
<version>1.5.6</version>
</dependency>
<dependency>
<groupId>javax.activation</groupId>
<artifactId>activation</artifactId>
<version>1.1.1</version>
</dependency>
org.springframework.mail包是Spring Framework email支持的根級別包。發(fā)送郵件的核心接口是MailSender菇用；SimpleMailMessage類封裝了封裝一個簡單郵件的屬性例如發(fā)件人澜驮、收件人陷揪。 這個包還提供了一個統(tǒng)一的郵件異常MailException惋鸥。
org.springframework.mail.javamail.JavaMailSender接口添加了JavaMail的特性，例如MIME信息支持悍缠。JavaMailSender還為JavaMail MIME消息的準(zhǔn)備活動提供了一個回調(diào)接口org.springframework.mail.javamail.MimeMessagePreparator卦绣。
2.1 用法
我們假設(shè)這里有一個業(yè)務(wù)接口叫做OrderManager：
public interface OrderManager {
void placeOrder(Order order);
}
2.1.1 MailSender 和 SimpleMailMessage的基本用法
import org.springframework.mail.MailException;
import org.springframework.mail.MailSender;
import org.springframework.mail.SimpleMailMessage;
public class SimpleOrderManager implements OrderManager {
private MailSender mailSender;
private SimpleMailMessage templateMessage;
public void setMailSender(MailSender mailSender) {
this.mailSender = mailSender;
}
public void setTemplateMessage(SimpleMailMessage templateMessage) {
this.templateMessage = templateMessage;
}
public void placeOrder(Order order) {
// Do the business calculations...
// Call the collaborators to persist the order...
// 創(chuàng)建一個線程安全的template message副本并且自定義它
SimpleMailMessage msg = new SimpleMailMessage(this.templateMessage);
msg.setTo(order.getCustomer().getEmailAddress());
msg.setText(
"Dear " + order.getCustomer().getFirstName()
+ order.getCustomer().getLastName()
+ ", thank you for placing order. Your order number is "
+ order.getOrderNumber());
try{
this.mailSender.send(msg);
}
catch (MailException ex) {
// 簡單的輸出它，然后繼續(xù)
System.err.println(ex.getMessage());
}
}
}
下面是一些bean定義：
<bean id="mailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">
<property name="host" value="mail.mycompany.com"/>
</bean>
<!-- 這是一個template message飞蚓，使用默認(rèn)狀態(tài)預(yù)加載它 -->
<bean id="templateMessage" class="org.springframework.mail.SimpleMailMessage">
<!-- 發(fā)件人 -->
<property name="from" value="customerservice@mycompany.com"/>
<!-- 郵件主題 -->
<property name="subject" value="Your order"/>
</bean>
<bean id="orderManager" class="com.mycompany.businessapp.support.SimpleOrderManager">
<property name="mailSender" ref="mailSender"/>
<property name="templateMessage" ref="templateMessage"/>
</bean>
2.1.2 使用JavaMailSender 和 MimeMessagePreparator
這是另一個OrderManager實(shí)現(xiàn)滤港，使用的了MimeMessagePreparator回調(diào)接口。請注意mailSender參數(shù)是JavaMailSender類型，這樣我們便可使用JavaMail的MimeMessage類：
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMessage;
import org.springframework.mail.MailException;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessagePreparator;
public class SimpleOrderManager implements OrderManager {
private JavaMailSender mailSender;
public void setMailSender(JavaMailSender mailSender) {
this.mailSender = mailSender;
}
public void placeOrder(final Order order) {
// Do the business calculations...
// Call the collaborators to persist the order...
MimeMessagePreparator preparator = new MimeMessagePreparator() {
public void prepare(MimeMessage mimeMessage) throws Exception {
mimeMessage.setRecipient(Message.RecipientType.TO,
new InternetAddress(order.getCustomer().getEmailAddress()));
mimeMessage.setFrom(new InternetAddress("mail@mycompany.com"));
mimeMessage.setText(
"Dear " + order.getCustomer().getFirstName() + " "
+ order.getCustomer().getLastName()
+ ", thank you for placing order. Your order number is "
+ order.getOrderNumber());
}
};
try {
this.mailSender.send(preparator);
}
catch (MailException ex) {
// 簡單的輸出它溅漾，然后繼續(xù)
System.err.println(ex.getMessage());
}
}
}
更多信息請參考JavaMail的javadoc山叮。
2.1.3 使用JavaMail MimeMessageHelper
// 在現(xiàn)實(shí)中這里是通過依賴注入獲得的
JavaMailSenderImpl sender = new JavaMailSenderImpl();
sender.setHost("mail.host.com");
MimeMessage message = sender.createMimeMessage();
MimeMessageHelper helper = new MimeMessageHelper(message);
helper.setTo("test@host.com");
helper.setText("Thank you for ordering!");
sender.send(message);
發(fā)送附件與內(nèi)聯(lián)資源
附件好理解，內(nèi)聯(lián)資源舉個例子可以是圖片或者Excel顯式在你的郵件正文中而不是作為一個附件顯示添履。
附件
下面這個例子展示了如何使用MimeMessageHelper來發(fā)送一封郵件并且使用一張圖片作為附件：
// 在現(xiàn)實(shí)中這里是通過依賴注入獲得的
JavaMailSenderImpl sender = new JavaMailSenderImpl();
sender.setHost("mail.host.com");
MimeMessage message = sender.createMimeMessage();
// 使用true標(biāo)識指明你需要一個multipart信息
MimeMessageHelper helper = new MimeMessageHelper(message, true);
helper.setTo("test@host.com");
helper.setText("Check out this image!");
// 讓我們添加一個附件
FileSystemResource file = new FileSystemResource(new File("c:/Sample.jpg"));
helper.addAttachment("CoolImage.jpg", file);
sender.send(message);
內(nèi)聯(lián)資源
JavaMailSenderImpl sender = new JavaMailSenderImpl();
sender.setHost("mail.host.com");
MimeMessage message = sender.createMimeMessage();
// use the true flag to indicate you need a multipart message
MimeMessageHelper helper = new MimeMessageHelper(message, true);
helper.setTo("test@host.com");
// use the true flag to indicate the text included is HTML
helper.setText("<html><body><img src='cid:identifier1234'></body></html>", true);
// let's include the infamous windows Sample file (this time copied to c:/)
FileSystemResource res = new FileSystemResource(new File("c:/Sample.jpg"));
helper.addInline("identifier1234", res);
sender.send(message);
一個基于Velocity的例子
要使用Velocity來創(chuàng)建你的郵件模版屁倔，你首先要將Velocity的類庫引入。
創(chuàng)建模版頁面：
# in the com/foo/package
<html>
<body>
<h3>Hi ${user.userName}, welcome to the Chipping Sodbury On-the-Hill message boards!</h3>
<div>
Your email address is <a href="mailto:${user.emailAddress}">${user.emailAddress}</a>.
</div>
</body>
</html>
配置：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="mailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">
<property name="host" value="mail.csonth.gov.uk"/>
</bean>
<bean id="registrationService" class="com.foo.SimpleRegistrationService">
<property name="mailSender" ref="mailSender"/>
<property name="velocityEngine" ref="velocityEngine"/>
</bean>
<bean id="velocityEngine" class="org.springframework.ui.velocity.VelocityEngineFactoryBean">
<property name="velocityProperties">
<value>
resource.loader=class
class.resource.loader.class=org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader
</value>
</property>
</bean>
</beans>
package com.foo;
import org.apache.velocity.app.VelocityEngine;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.mail.javamail.MimeMessagePreparator;
import org.springframework.ui.velocity.VelocityEngineUtils;
import javax.mail.internet.MimeMessage;
import java.util.HashMap;
import java.util.Map;
public class SimpleRegistrationService implements RegistrationService {
private JavaMailSender mailSender;
private VelocityEngine velocityEngine;
public void setMailSender(JavaMailSender mailSender) {
this.mailSender = mailSender;
}
public void setVelocityEngine(VelocityEngine velocityEngine) {
this.velocityEngine = velocityEngine;
}
public void register(User user) {
// Do the registration logic...
sendConfirmationEmail(user);
}
private void sendConfirmationEmail(final User user) {
MimeMessagePreparator preparator = new MimeMessagePreparator() {
public void prepare(MimeMessage mimeMessage) throws Exception {
MimeMessageHelper message = new MimeMessageHelper(mimeMessage);
message.setTo(user.getEmailAddress());
message.setFrom("webmaster@csonth.gov.uk"); // could be parameterized...
Map model = new HashMap();
model.put("user", user);
String text = VelocityEngineUtils.mergeTemplateIntoString(
velocityEngine, "com/dns/registration-confirmation.vm", model);
message.setText(text, true);
}
};
this.mailSender.send(preparator);
}
}
未完暮胧，待續(xù)...
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