本章将教您如何使用Struts 2以简单的步骤访问数据库. Struts是一个MVC框架而不是数据库框架,但它为JPA/Hibernate集成提供了出色的支持.我们将在后面的章节中讨论hibernate集成,但在本章中我们将使用普通的旧JDBC来访问数据库.
本章的第一步是设置和填充我们的数据库.我在这个例子中使用MySQL作为我的数据库.我在我的机器上安装了MySQL,并创建了一个名为"struts_tutorial"的新数据库.我创建了一个名为 login 的表,并用一些值填充它.下面是我用来创建和填充表格的脚本.
我的MYSQL数据库有默认用户名"root"和"root123"密码
CREATE TABLE `struts_tutorial`.`login` ( `user` VARCHAR( 10 ) NOT NULL , `password` VARCHAR( 10 ) NOT NULL , `name` VARCHAR( 20 ) NOT NULL , PRIMARY KEY ( `user` ) ) ENGINE = InnoDB; INSERT INTO `struts_tutorial`.`login` (`user`, `password`, `name`) VALUES ('scott', 'navy', 'Scott Burgemott');
下一步是下载 MySQL Connector jar文件,并将此文件放在项目的WEB-INF\lib文件夹中.完成此操作后,我们现在可以创建操作类了.
操作类具有与列对应的属性在数据库表中.我们将用户,密码和名称作为字符串属性.在action方法中,我们使用用户和密码参数来检查用户是否存在,如果是,我们在下一个屏幕中显示用户名.
如果用户输入了错误的信息,我们再次将它们发送到登录屏幕.
以下是 LoginAction.java 文件的内容 :
package com.it1352.struts2; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import com.opensymphony.xwork2.ActionSupport; public class LoginAction extends ActionSupport { private String user; private String password; private String name; public String execute() { String ret = ERROR; Connection conn = null; try { String URL = "jdbc:mysql://localhost/struts_tutorial"; Class.forName("com.mysql.jdbc.Driver"); conn = DriverManager.getConnection(URL, "root", "root123"); String sql = "SELECT name FROM login WHERE"; sql+=" user = ? AND password = ?"; PreparedStatement ps = conn.prepareStatement(sql); ps.setString(1, user); ps.setString(2, password); ResultSet rs = ps.executeQuery(); while (rs.next()) { name = rs.getString(1); ret = SUCCESS; } } catch (Exception e) { ret = ERROR; } finally { if (conn != null) { try { conn.close(); } catch (Exception e) { } } } return ret; } public String getUser() { return user; } public void setUser(String user) { this.user = user; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getName() { return name; } public void setName(String name) { this.name = name; } }
现在,让我们创建一个JSP文件 index.jsp 收集用户名和密码.将根据数据库检查此用户名和密码.
<%@ page language = "java" contentType = "text/html; charset = ISO-8859-1" pageEncoding = "ISO-8859-1"%> <%@ taglib prefix = "s" uri = "/struts-tags"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>Login</title> </head> <body> <form action = "loginaction" method = "post"> User:<br/><input type = "text" name = "user"/><br/> Password:<br/><input type = "password" name = "password"/><br/> <input type = "submit" value = "Login"/> </form> </body> </html>
现在让我们创建 success.jsp 文件,该文件将被调用如果动作返回SUCCESS,但是如果从动作返回ERROR,我们将有另一个视图文件.
<%@ page contentType = "text/html; charset = UTF-8" %> <%@ taglib prefix = "s" uri = "/struts-tags" %> <html> <head> <title>Successful Login</title> </head> <body> Hello World, <s:property value = "name"/> </body> </html>
如果从操作返回ERROR,以下将是视图文件 error.jsp .
<%@ page contentType = "text/html; charset = UTF-8" %> <%@ taglib prefix = "s" uri = "/struts-tags" %> <html> <head> <title>Invalid User Name or Password</title> </head> <body> Wrong user name or password provided. </body> </html>
最后,让我们使用struts.xml配置文件将所有内容放在一起,如下所示 :
<?xml version = "1.0" Encoding = "UTF-8"?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"> <struts> <constant name = "struts.devMode" value = "true" /> <package name = "helloworld" extends = "struts-default"> <action name = "loginaction" class = "com.IT屋.struts2.LoginAction" method = "execute"> <result name = "success">/success.jsp</result> <result name = "error">/error.jsp</result> </action> </package> </struts>
以下是 web.xml 文件的内容 :
<?xml version = "1.0" Encoding = "UTF-8"?> <web-app xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" xmlns = "http://java.sun.com/xml/ns/javaee" xmlns:web = "http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation = "http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id = "WebApp_ID" version = "3.0"> <display-name>Struts 2</display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <filter> <filter-name>struts2</filter-name> <filter-class> org.apache.struts2.dispatcher.FilterDispatcher </filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
现在,右键单击项目名称,然后单击导出> WAR文件以创建War文件.然后在Tomcat的webapps目录中部署此WAR.最后,启动Tomcat服务器并尝试访问URL http://localhost:8080/HelloWorldStruts2/index.jsp .这将生成以下屏幕 :
输入错误的用户名和密码.你应该看下一页.
现在输入 scott 作为用户名,输入 navy 作为密码.你应该看下一页.