javaweb使用Thymeleaf 最凝练的CRUD项目-上

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://192.168.198.100:3306/view-demo
username=root
password=atguigu
initialSize=10
maxActive=20
maxWait=10000

public class JDBCUtil {// 将数据源对象设置为静态属性，保证大对象的单一实例private static DataSource dataSource;static {// 1.创建一个用于存储外部属性文件信息的Properties对象Properties properties = new Properties();// 2.使用当前类的类加载器加载外部属性文件：jdbc.propertiesInputStream inputStream = JDBCUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");try {// 3.将外部属性文件jdbc.properties中的数据加载到properties对象中properties.load(inputStream);// 4.创建数据源对象dataSource = DruidDataSourceFactory.createDataSource(properties);} catch (Exception e) {e.printStackTrace();}}/*** 从数据源中获取数据库连接* @return 数据库连接对象*/public static Connection getConnection() {Connection connection = null;try {connection = dataSource.getConnection();} catch (SQLException e) {e.printStackTrace();throw new RuntimeException(e);}return connection;}/*** 释放数据库连接* @param connection 要执行释放操作的连接对象*/public static void releaseConnection(Connection connection) {if (connection != null) {try {connection.close();} catch (SQLException e) {e.printStackTrace();throw new RuntimeException(e);}}}}

public class DemoTest {@Testpublic void testConnection() {Connection connection = JDBCUtil.getConnection();System.out.println("connection = " + connection);}}

public class BaseDao<T> {private QueryRunner queryRunner = new QueryRunner();/*** 通用的增删改方法* @param sql* @param param* @return*/public int update(String sql, Object ... param) {Connection connection = JDBCUtil.getConnection();int count = 0;try {count = queryRunner.update(connection, sql, param);} catch (SQLException e) {e.printStackTrace();throw new RuntimeException(e);} finally {// 关闭数据库连接JDBCUtil.releaseConnection(connection);}return count;}/*** 查询单个对象的通用方法* @param clazz* @param sql* @param param* @return*/public T getBean(Class<T> clazz, String sql, Object ... param) {Connection connection = JDBCUtil.getConnection();T bean = null;try {bean = queryRunner.query(connection, sql, new BeanHandler<>(clazz), param);} catch (SQLException e) {e.printStackTrace();throw new RuntimeException(e);} finally {// 关闭数据库连接JDBCUtil.releaseConnection(connection);}return bean;}/*** 查询集合对象的通用方法* @param clazz* @param sql* @param param* @return*/public List<T> getBeanList(Class<T> clazz, String sql, Object ... param) {Connection connection = JDBCUtil.getConnection();List<T> beanList = null;try {beanList = queryRunner.query(connection, sql, new BeanListHandler<>(clazz), param);} catch (SQLException e) {e.printStackTrace();throw new RuntimeException(e);} finally {// 关闭数据库连接JDBCUtil.releaseConnection(connection);}return beanList;}
}

public class ViewBaseServlet extends HttpServlet {private TemplateEngine templateEngine;@Overridepublic void init() throws ServletException {// 1.获取ServletContext对象ServletContext servletContext = this.getServletContext();// 2.创建Thymeleaf解析器对象ServletContextTemplateResolver templateResolver = new ServletContextTemplateResolver(servletContext);// 3.给解析器对象设置参数// ①HTML是默认模式，明确设置是为了代码更容易理解templateResolver.setTemplateMode(TemplateMode.HTML);// ②设置前缀String viewPrefix = servletContext.getInitParameter("view-prefix");templateResolver.setPrefix(viewPrefix);// ③设置后缀String viewSuffix = servletContext.getInitParameter("view-suffix");templateResolver.setSuffix(viewSuffix);// ④设置缓存过期时间（毫秒）templateResolver.setCacheTTLMs(60000L);// ⑤设置是否缓存templateResolver.setCacheable(true);// ⑥设置服务器端编码方式templateResolver.setCharacterEncoding("utf-8");// 4.创建模板引擎对象templateEngine = new TemplateEngine();// 5.给模板引擎对象设置模板解析器templateEngine.setTemplateResolver(templateResolver);}protected void processTemplate(String templateName, HttpServletRequest req, HttpServletResponse resp) throws IOException {// 1.设置响应体内容类型和字符集resp.setContentType("text/html;charset=UTF-8");// 2.创建WebContext对象WebContext webContext = new WebContext(req, resp, getServletContext());// 3.处理模板数据templateEngine.process(templateName, webContext, resp.getWriter());}
}

<!-- 在上下文参数中配置视图前缀和视图后缀 -->
<context-param><param-name>view-prefix</param-name><param-value>/WEB-INF/view/</param-value>
</context-param>
<context-param><param-name>view-suffix</param-name><param-value>.html</param-value>
</context-param>