Apache Pluto和Velocity集成教程示例
时间：2020-02-23 14:29:41 来源:igfitidea点击:
Velocity是Apache Software Foundation的一个项目，在Apache Velocity Engine下发布，其中它被视为模板引擎，它提供模板语言来引用Java代码中定义的对象。
Velocity的主要目的是确保Web应用程序中表示层和业务层之间的清晰分隔，这与我们之前使用的众多表示技术类似。
但是，您使用JSP和Servlet开发的Portlet用于注册员工，并且使用JSP作为表示层，使用Standard Portlet作为控制器，并使用Servlet处理注册业务。
这次将使用相同的示例，只是有所不同，因为Velocity模板和Velocity Portlet将分别替换您使用的JSP和Standard Portlet。
本教程将向您提供一个完整的场景，说明如何使用Velocity模板获取功能全面的Portlet，该Portlet可用于将员工保存在数据库中。
项目结构
其中您将获得整个创建项目的完整描述：
员工表
在开始研究在应用程序中集成Velocity模板的方式之前，请先浏览一下用于保留员工的Employee表和用于在数据库中创建Table的SQL语句。
Employee.SQL
CREATE TABLE `employee` ( `EMP_ID` int(11) NOT NULL AUTO_INCREMENT, `EMP_NAME` varchar(45) DEFAULT NULL, `EMP_JOB` varchar(45) DEFAULT NULL, `EMP_SALARY` int(11) DEFAULT NULL, PRIMARY KEY (`EMP_ID`) ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
员工模式
根据MVC(模型-视图-控制器)设计模式，数据必须保留在模型内部，因为它将在应用程序的不同组件(即视图和控制器)之间来回发送。
由于我们只有一个Employee Table，因此Employee模型将如下所示：
Employee.java
package com.theitroad.data;
public class Employee {
private int id;
private String name;
private String job;
private int salary;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
public int getSalary() {
return salary;
}
public void setSalary(int salary) {
this.salary = salary;
}
}
RegisterEmployeePortlet速度Portlet
Velocity Portlet的创建并不是一件复杂的任务，因为您可能熟悉这里介绍的许多类型的Portlet。
像任何普通的Portlet一样，您的Velocity应该如下所示：
RegisterEmployeePortlet.java
package com.theitroad.portlet;
import java.io.IOException;
import javax.portlet.ActionRequest;
import javax.portlet.ActionResponse;
import javax.portlet.PortletException;
import javax.portlet.PortletRequestDispatcher;
import javax.portlet.RenderRequest;
import javax.portlet.RenderResponse;
public class RegisterEmployeePortlet extends org.apache.portals.bridges.velocity.GenericVelocityPortlet {
public void doView(RenderRequest request, RenderResponse response) throws PortletException, IOException {
//Check the status parameter
if(request.getParameter("status") == null){
//In case it's null, return into default view that's already defined in the portlet.xml viewPage
super.doView(request, response);
}
else {
//In case, the status value is success
if(request.getParameter("status").equals("success")){
PortletRequestDispatcher dispatcher = this.getPortletContext().getRequestDispatcher("/register/success.vm");
//delegate the view into success.vm
dispatcher.include(request, response);
}
else {
//In case, the status value is failure
PortletRequestDispatcher dispatcher = this.getPortletContext().getRequestDispatcher("/register/failure.vm");
//delegate the view into failure.vm
dispatcher.include(request, response);
}
}
}
public void processAction(ActionRequest request, ActionResponse response) throws PortletException, IOException{
//Create request dispatcher
PortletRequestDispatcher dispatcher = this.getPortletContext().getNamedDispatcher("RegisterEmployeeServlet");
try {
//Include
dispatcher.include(request, response);
//Set render parameter
response.setRenderParameter("status", "success");
}
catch(Exception ex){
//Set render parameter
response.setRenderParameter("status", "failed");
response.setRenderParameter("exception", ex.getMessage());
}
}
}
以下是上述代码的详细说明：
您的Portlet应该扩展org.apache.portals.bridges.velocity.GenericVelocityPortlet。
像任何标准Portlet一样，您有机会覆盖必需的方法。
通常，您可以访问不同类型的请求/响应。
正如您可以像在《 JSP&Servlet教程》中那样将请求委托到JSP视图中一样，您可以使用Velocity标记模板执行相同的操作。
由于我们拥有默认的ViewPage值作为初始参数，因此super.doView的调用将为registerEmployee.vm提供处理请求的机会。
根据状态参数，您可能会访问success.vm或者failure.vm。
您可以在项目中使用定义的路径来引用Velocity模板，因为它们被视为与您处理过的任何演示技术一样。
我们建议的路径是/register/registerEmployee.vm、/register/success.vm和/register/faliure.vm。
RegisterEmployeePortlet速度Portlet描述符
幸运的是，在Portlet部署描述符(Portlet.xml)中定义Portlet时，您不必知道很多细节。
但是，像任何标准Portlet一样，您的Portlet.xml应该如下所示：
portlet.xml
<?xml version="1.0" encoding="UTF-8"?> <portlet-app xmlns="https://java.sun.com/xml/ns/portlet/portlet-app_2_0.xsd" version="2.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://java.sun.com/xml/ns/portlet/portlet-app_2_0.xsd"> <portlet> <display-name>Register Employee</display-name> <portlet-name>RegisterEmployee</portlet-name> <portlet-class>com.theitroad.portlet.RegisterEmployeePortlet </portlet-class> <description>Employee Registration</description> <init-param> <name>ViewPage</name> <value>/register/registerEmployee.vm</value> </init-param> <supports> <mime-type>text/html</mime-type> <portlet-mode>VIEW</portlet-mode> </supports> <portlet-info> <title>Employee Registration</title> <keywords>employee, registration</keywords> <short-title>Employee Registration</short-title> </portlet-info> </portlet> </portlet-app>
这是上面输入的代码的详细说明：
您应该定义ViewPage初始参数，以使Portlet通过其包含的页面访问后立即显示registerEmployee.vm。
与ViewPage类似，您可以添加EditPage和HelpPage。
支持不同的视图需要您调整支持元素。
应用程序部署描述符和Maven构建文件
您可能会询问定义的速度模板是如何执行的，因为没有明确声明其完成方式。
实际上，事实上，已定义的Servlet将处理Velocity Templates解释过程，因此一旦您的Portlet将请求委托给任何以* .vm结尾的Velocity资源中，Velocity Servlet将被执行并返回HTML输出。
在下面查看部署描述符(web.xml)：
web.xml
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "https://java.sun.com/dtd/web-app_2_3.dtd" > <web-app> <display-name>Employee Registration</display-name> <servlet> <servlet-class>com.theitroad.servlet.RegisterEmployeeServlet</servlet-class> <servlet-name>RegisterEmployeeServlet</servlet-name> </servlet> <servlet-mapping> <servlet-name>RegisterEmployeeServlet</servlet-name> <url-pattern>/registerEmployeeServlet</url-pattern> </servlet-mapping> <!-- Define Velocity Servlet --> <servlet> <servlet-name>velocity</servlet-name> <servlet-class>org.apache.portals.bridges.velocity.BridgesVelocityViewServlet</servlet-class> </servlet> <!-- Map *.vm files to Velocity --> <servlet-mapping> <servlet-name>velocity</servlet-name> <url-pattern>*.vm</url-pattern> </servlet-mapping> </web-app>
您会注意到，BridgesVelocityServlet已与映射元素结合使用。
让我们看一下使用过的Maven构建文件：
pom.xml
<project xmlns="https://maven.apache.org/POM/4.0.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 https://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.theitroad</groupId>
<artifactId>VelocityBridge</artifactId>
<packaging>war</packaging>
<version>0.0.1-SNAPSHOT</version>
<name>VelocityBridge</name>
<url>https://maven.apache.org</url>
<properties>
<deployFolder>D:/Apache Pluto/pluto-2.0.3/webapps</deployFolder>
</properties>
<dependencies>
<!-- Java Portlet Specification V2.0 -->
<dependency>
<groupId>org.apache.portals</groupId>
<artifactId>portlet-api_2.0_spec</artifactId>
<version>1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.4</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jsp-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>commons-beanutils</groupId>
<artifactId>commons-beanutils</artifactId>
<version>1.7.0</version>
</dependency>
<dependency>
<groupId>commons-collections</groupId>
<artifactId>commons-collections</artifactId>
<version>3.1</version>
</dependency>
<dependency>
<groupId>commons-digester</groupId>
<artifactId>commons-digester</artifactId>
<version>1.7</version>
</dependency>
<dependency>
<groupId>commons-digester</groupId>
<artifactId>commons-digester</artifactId>
<version>1.7</version>
</dependency>
<dependency>
<groupId>org.apache.velocity</groupId>
<artifactId>velocity</artifactId>
<version>1.5</version>
</dependency>
<dependency>
<groupId>org.apache.velocity</groupId>
<artifactId>velocity-tools</artifactId>
<version>2.0</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
<dependency>
<groupId>org.apache.pluto</groupId>
<artifactId>pluto-taglib</artifactId>
<version>1.1.7</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.32</version>
</dependency>
<dependency>
<groupId>org.apache.portals.bridges</groupId>
<artifactId>portals-bridges-velocity</artifactId>
<version>2.0</version>
</dependency>
<dependency>
<groupId>org.apache.portals.bridges</groupId>
<artifactId>portals-bridges-common</artifactId>
<version>2.0</version>
</dependency>
</dependencies>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<!-- bind 'pluto2:assemble' goal to 'process-resources' lifecycle -->
<!-- This plugin will read your portlet.xml and web.xml and injects required
lines -->
<plugin>
<groupId>org.apache.portals.pluto</groupId>
<artifactId>maven-pluto-plugin</artifactId>
<version>2.1.0-M3</version>
<executions>
<execution>
<phase>generate-resources</phase>
<goals>
<goal>assemble</goal>
</goals>
</execution>
</executions>
</plugin>
<!-- configure maven-war-plugin to use updated web.xml -->
<!-- This plugin will make sure your WAR will contain the updated web.xml -->
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>2.1.1</version>
<configuration>
<webXml>${project.build.directory}/pluto-resources/web.xml</webXml>
</configuration>
</plugin>
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<id>copy</id>
<phase>integration-test</phase>
<configuration>
<tasks>
<copy file="target/${project.artifactId}.war" tofile="${deployFolder}/${project.artifactId}.war"
</tasks>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
<execution>
<id>delete</id>
<phase>clean</phase>
<configuration>
<tasks>
<delete file="${deployFolder}/${project.artifactId}.war"
<delete dir="${deployFolder}/${project.artifactId}"
</tasks>
<detail>true</detail>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
速度模板(视图)
如前所述，您可以使用Velocity Templates代替默认的JSP来呈现您请求的视图。
与JSP类似，在Velocity模板中定义了一个隐式对象，以便在开发视图时使用。
让我们看一下创建的视图，看看必须注意的主要事项。
registeremployee.vm
<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Register Employee</title> </head> <body> <form action="$renderResponse.createActionURL()" method="POST"> <table width="100%"> <tr width="60%"> <td>Enter Employee ID:</td> <td><input name="employeeID" </td> </tr> <tr width="60%"> <td>Enter Employee Name:</td> <td><input name="employeeName" </td> </tr> <tr width="60%"> <td>Enter Employee Job:</td> <td><input name="employeeJob" </td> </tr> <tr width="60%"> <td>Enter Employee Salary:</td> <td><input name="employeeSalary" </td> </tr> <tr width="60%" align="center"> <td colspan="2"><input type="submit" value="Register" </td> </tr> </table> </form> </body> </html>
以下是上面列出的代码的详细说明：
您可能需要的隐式对象是RenderRequest，RenderResponse和PortletConfig。
您应该分别使用$renderRequest，$renderResponse和$portletConfig来引用这些对象。
由于这些对象是Java对象，因此，它们具有所有相关的功能，就像在标准Portlet中调用它们一样。
我们通过调用$renderResponse.createActionURL()创建了一个actionUrl。
success.vm
<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Register Employee</title> </head> <portlet:renderURL var="registerAnother"> <portlet:param name="status" value="initiate" </portlet:renderURL> <img src="$renderRequest.getContextPath()/images/success.jpg" name="$renderResponse.getNamespace()Success" <body> Congratulations ! you've just add a new employee<br<a href="$renderResponse.createRenderURL()">Register Another</a> </body> </html>
failure.vm
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Register Employee</title>
</head>
<body>
Unfortunately ! you Jan not be able of registering a new employee cause the reason below
<br
<br
<img src="$renderRequest.getContextPath()/images/failed.jpg" name="$renderResponse.getNamespace()Failed"
<span style="font-size:small ;font-style: italic;color: red;font-weight: bold;">
$renderRequest.getParameter("exception")
<br
<br
<a href="$renderResponse.createRenderURL()">Try Again</a>
</body>
</html>
这里是成功和失败速度模板的详细说明：
我们使用$renderRequest.getContextPath()来指定正在运行的应用程序的上下文。
为了获得安全的代码，由于速度模板可能包含相同JavaScript变量/代码，因此您可以使用$renderReponse.getNamespace()来创建唯一的标识符。
您可以通过调用$renderRequest.getParamater()来访问特定的请求属性。
$renderResponse()。
createRenderURL()用于针对您的Portlet渲染请求。
注册员工业务处理程序
处理员工注册业务不是Portlet的任务，因为在将您的组件映射到MVC设计时，它被视为控制器。
无论您使用的是哪种Portlet，我们都有一个单独的Servlet负责处理注册过程；提取请求的参数，并调用数据库实用程序以保存员工。
RegisterEmployeeServlet.java
package com.theitroad.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;
import com.theitroad.dao.EmployeeDAO;
import com.theitroad.data.Employee;
public class RegisterEmployeeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
Logger logger = Logger.getLogger(RegisterEmployeeServlet.class);
public RegisterEmployeeServlet() {
super();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//Create employee
Employee employee = new Employee();
//Fill in required data from the request sent
employee.setId(Integer.parseInt(request.getParameter("employeeID")));
employee.setName(request.getParameter("employeeName"));
employee.setJob(request.getParameter("employeeJob"));
employee.setSalary(Integer.parseInt(request.getParameter("employeeSalary")));
try {
//Asking employeeDAO creating the employee against registered database
Employee createdEmployee = EmployeeDAO.getInstance().createEmployee(employee);
//Print out the created employee information
logger.info("Employee Created"+createdEmployee);
} catch (Exception e) {
//Log the exception
logger.error("Employee Creation Failed", e);
//Throw another exception for notifying the Portlet
throw new ServletException(e);
}
}
}
数据库实用程序
由于我们的应用程序已访问数据库以使雇员实例得以持久保存，因此请使用我们拥有的最佳实践来处理数据库代码，这一点很重要，EmployeeDAO和ConnectionUtility都是用于安全且异步地访问数据库的类。
EmployeeDAO.java
package com.theitroad.dao;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import com.theitroad.dao.utility.ConnectionUtility;
import com.theitroad.data.Employee;
public class EmployeeDAO {
public static EmployeeDAO employeeDAO = null;
private EmployeeDAO(){
}
public static EmployeeDAO getInstance(){
synchronized(EmployeeDAO.class){
if(employeeDAO == null){
employeeDAO = new EmployeeDAO();
}
}
return employeeDAO;
}
public Employee createEmployee(Employee employee) throws SQLException, IllegalAccessException, IOException, ClassNotFoundException{
//Get connection instance
Connection connection = ConnectionUtility.getInstance().getConnection();
//Create Prepared Statement
PreparedStatement query = connection.prepareStatement("INSERT INTO EMPLOYEE VALUES (?,?,?,?)");
//Set variables
query.setInt(1, employee.getId());
query.setString(2, employee.getName());
query.setString(3, employee.getJob());
query.setInt(4, employee.getSalary());
try {
//Execute
query.execute();
//Return employee instance
return employee;
}
catch(Exception e){
//Close statement
query.close();
//Close connection
connection.close();
//Throw another exception for notifying the Servlet
throw new SQLException(e);
}
}
public boolean deleteEmployee(Employee employee){
return false;
}
public boolean updateEmployee(Employee employee, int employeeId){
return false;
}
}
ConnectionUtility.java
package com.theitroad.dao.utility;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
public class ConnectionUtility {
private static ConnectionUtility connectionUtiliy = null;
private Connection connection = null;
private ConnectionUtility() {
}
public static ConnectionUtility getInstance() throws IOException, IllegalAccessException, SQLException, ClassNotFoundException{
//Synchronized against connectionUtility instance
synchronized(ConnectionUtility.class){
//Check whether the connectionUtility is null or not
if(connectionUtiliy == null){
//Create a properties instance
Properties properties = new Properties();
//Load properties from classpath
properties.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("connection.properties"));
//Set connection with connectionUtility
connectionUtiliy = new ConnectionUtility();
//Load driver class
Class.forName("com.mysql.jdbc.Driver");
//Create connection
connectionUtiliy.setConnection(DriverManager.getConnection("jdbc:mysql://localhost:3306/theitroad", properties));
}
return connectionUtiliy;
}
}
public Connection getConnection() throws ClassNotFoundException, SQLException, IOException {
if(connection.isClosed()){
//Create a properties instance
Properties properties = new Properties();
//Load properties from classpath
properties.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("connection.properties"));
//Load driver class
Class.forName("com.mysql.jdbc.Driver");
//Create connection
connectionUtiliy.setConnection(DriverManager.getConnection("jdbc:mysql://localhost:3306/theitroad", properties));
}
return connection;
}
public void setConnection(Connection connection) {
this.connection = connection;
}
}
员工注册演示
我们假设您有一个正在运行的Apache Pluto实例，同时您还创建了一个名为theitroad的Portal页面，并且您熟悉了将Portlet部署到Portal页面中的方式。
如果您是第一次听到此消息，那么有必要返回到我们的Apache Pluto简介来完成所有相关的事情。
一旦用户激活了注册动作，Portlet的processAction方法将被执行，然后将注册Register Servlet。
系统会立即通知用户注册操作的结果以及注册操作是否成功完成。
