JDBC 通过读取配置文件 链接数据库

一    准备工作

1  安装 MySQL  

2  下载JDBC所需要的包

3   安装好JDK

二   操作步骤

1  创建一个web项目，把对应的包和配置文件放在适当的位置，通常情况如下

 jdbc.properties里面的内容

Driver=com.mysql.jdbc.Driver  驱动名字 JDBC驱动： 
url=jdbc:sqlserver://+数据库地址+;DatabaseName=数据库名字 
userName=用户名 
password=密码

2 在类里面去读取jdbc.properties 的内容 以及书写  链接数据库 关闭数据库 的方法

package com.bowei.utl;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class JdbcUtl {
    // 数据库驱动
    private static String Driver = "";
    // 数据库地址
    private static String url = "";
    // 数据库用户名
    private static String userName = "";
    // 数据库密码
    private static String password = "";
  static {
        Properties p = new Properties();
        try {
            // 通过相对路径加载文件
            String path=(Thread.currentThread().getContextClassLoader().getResource("").getFile()).substring(1);
            path=java.net.URLDecoder.decode(path,"utf-8");
            path=path.replace('/', '\'); // 将/换成  
            path=path.replace("file:", ""); //去掉file:  
            path=path.replace("classes\", ""); //去掉class   
            path+="sof/jdbc.properties";  //路径
            p.load(new FileInputStream(new File(path)));
            // 用getProperty方法通过关键字获取信息
            Driver = p.getProperty("Driver");
            url = p.getProperty("url");
            userName = p.getProperty("userName");
            password = p.getProperty("password");
          
            
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
//get set
    public static String getDriver() {
        return Driver;
    }

    public static void setDriver(String driver) {
        Driver = driver;
    }

    public static String getUrl() {
        return url;
    }

    public static void setUrl(String url) {
        JdbcUtl.url = url;
    }

    public static String getUserName() {
        return userName;
    }

    public static void setUserName(String userName) {
        JdbcUtl.userName = userName;
    }

    public static String getPassword() {
        return password;
    }

    public static void setPassword(String password) {
        JdbcUtl.password = password;
    }
    // 获取数据库连接
    public static Connection getConn() {
        Connection conn = null;
        try {
            // 加载驱动
            Class.forName(Driver);
            // 获取数据库连接
            conn = DriverManager.getConnection(url, userName, password);

        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return conn;
    }

    // 关闭数据库资源
    public static void closeAll(ResultSet rs, Statement stat, Connection conn) {
        /* 分别按顺序关闭数据库的结果集资源，Statement 对象资源以及Connection 连接数据库对象 */
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (stat != null) {
            try {
                stat.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }
}

下面是增删查改的方法：（此处省略的学生类的代码，自己写）

insert

private static int insert(Student student) {
    Connection conn=JdbcUtl.getConn();
      Statement st=null;
      ResultSet rs = null;
    int i = 0;
    String sql = "insert into students (Name,Sex,Age) values(?,?,?)";
    PreparedStatement pstmt;
    try {
        pstmt = (PreparedStatement) conn.prepareStatement(sql);
        pstmt.setString(1, student.getName());
        pstmt.setString(2, student.getSex());
        pstmt.setString(3, student.getAge());
        i = pstmt.executeUpdate();
        pstmt.close();
    }  finally {
            JdbcUtl.closeAll(rs, st, conn);//释放资源
        }
    return i;
}

update

private static int update(Student student) {
Connection conn=JdbcUtl.getConn();

int i = 0;  
4 String sql = "update students set Age='" + student.getAge() + "' where Name='" + student.getName() + "'";  
5  PreparedStatement pstmt;  
6 try {  
7 pstmt = (PreparedStatement) conn.prepareStatement(sql);  
8 i = pstmt.executeUpdate();  
9 System.out.println("resutl: " + i); 

 pstmt.close(); 

 conn.close(); 

} catch (SQLException e) { 

 e.printStackTrace(); 

 } 

return i; 

}

select

private static Integer getAll() {
    Connection conn =JdbcUtl.getConn();
    String sql = "select * from students";
    PreparedStatement pstmt;
    try {
        pstmt = (PreparedStatement)conn.prepareStatement(sql);
        ResultSet rs = pstmt.executeQuery();
        int col = rs.getMetaData().getColumnCount();
        System.out.println("============================");
        while (rs.next()) {
            for (int i = 1; i <= col; i++) {
                System.out.print(rs.getString(i) + "	");
                if ((i == 2) && (rs.getString(i).length() < 8)) {
                    System.out.print("	");
                }
             }
            System.out.println("");
        }
            System.out.println("============================");
    } catch (SQLException e) {
        e.printStackTrace();
    }
    return null;
}

delete

private static int delete(String name) {
    Connection conn = JdbcUtl.getConn();
    int i = 0;
    String sql = "delete from students where Name='" + name + "'";
    PreparedStatement pstmt;
    try {
        pstmt = (PreparedStatement) conn.prepareStatement(sql);
        i = pstmt.executeUpdate();
        System.out.println("resutl: " + i);
        pstmt.close();
        conn.close();
    } catch (SQLException e) {
        e.printStackTrace();
    }
    return i;
}