SMBMS项目实战（准备工作）

项目搭建

1）搭建一个maven web项目

配web.xml的时候去tomcat下面找最新的

2）配置tomcat

3）测试项目是否能跑起来

4）导入项目中可能会遇到的jar包

jsp,servlet,mysql驱动，jstl,stand

<dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.2.1</version>
      <scope>provided</scope>
    </dependency>

5）创建项目包结构

6）编写实体类

ORM映射：表-类映射

7)编写基础公共类

  7.1）数据库配置文件

 7.2）编写数据库的公共类

package com.mine.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

// 操作数据库的公共类
public class BaseDao {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;


    // 静态代码块，类加载的时候就初始化了
    static {
        Properties properties = new Properties();
        // 通过类加载器读取对应的资源
        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
        try {
            properties.load(is);  // 加载流对象
        } catch (IOException e) {
            e.printStackTrace();
        }

        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");

    }

    // 获取数据库的连接
    public static Connection getConnection()  {
        Connection connection = null; // 提升作用域
        try {
            Class.forName(driver);
             connection = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return connection;
    }

    // 编写查询公共类,要统一关闭所以把它们提到参数里面
    public static ResultSet execute(Connection connection,String sql, Object[] params, ResultSet resultSet, PreparedStatement preparedStatement) throws SQLException {
        // 预编译的sql在后面直接执行就可以了
        preparedStatement = connection.prepareStatement(sql); // 预编译sql
        for (int i = 0; i < params.length; i++) {
            // setObject
            preparedStatement.setObject(i + 1, params[i]);
        }
        resultSet = preparedStatement.executeQuery();  // 用了预编译，所以执行sql的时候不用传参
        return resultSet;
    }


    // 编写增删改公共方法

    62     // String sql 传进来要执行的sql语句
    // Object[] params  传进来的参数
    public static int execute(Connection connection, String sql, Object[] params,  PreparedStatement preparedStatement) throws SQLException {
        preparedStatement = connection.prepareStatement(sql); // 预编译sql
        for (int i = 0; i < params.length; i++) {
            // setObject
            preparedStatement.setObject(i + 1, params[i]);
        }
        int updateRows = preparedStatement.executeUpdate();
        return updateRows;
    }


    // 关闭连接释放资源
    public static boolean closeResource(Connection connection,  PreparedStatement preparedStatement, ResultSet resultSet) {
        boolean flag = true;
        if (resultSet != null) {
            try {
                resultSet.close();
                // 如果还存在，就让GC垃圾回收器回收
                resultSet=null;
            } catch (SQLException e) { // 如果关闭失败，让flag = false
                e.printStackTrace();
                flag = false;
            }
        }

        if (preparedStatement != null) {
            try {
                preparedStatement.close();
                // 如果还存在，就让GC垃圾回收器回收
                preparedStatement=null;
            } catch (SQLException e) { // 如果关闭失败，让flag = false
                e.printStackTrace();
                flag = false;
            }
        }

        if (connection != null) {
            try {
                connection.close();
                // 如果还存在，就让GC垃圾回收器回收
                connection=null;
            } catch (SQLException e) { // 如果关闭失败，让flag = false
                e.printStackTrace();
                flag = false;
            }
        }
        return flag; // 如果都释放成功返回true,只要有一个没释放就返回false

    }



}

 报错：

 出现问题原因及解决：自己在写的时候把这个函数写进了static里面

7.3)编写字符编码过滤器

package com.mine.filter;

import javax.servlet.*;
import java.io.IOException;

public class CharracterEncodingFilter implements Filter {
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
       servletRequest.setCharacterEncoding("utf-8");
       servletResponse.setCharacterEncoding("utf-8");
       filterChain.doFilter(servletRequest, servletResponse);
    }

    public void destroy() {

    }
}

注册：

<!--    字符编码过滤器-->
    <filter>
        <filter-name>CharracterEncodingFilter</filter-name>
        <filter-class>com.mine.filter.CharracterEncodingFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>CharracterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

8）导入静态资源