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driver=com.mysql.jdbc.Driverurl=jdbc:mysql://localhost:3306/testusername=rootpassword=

package com.test;import java.io.IOException;import java.io.InputStream;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.Properties;public class JdbcUtils {	private static String driver = null;    private static String url = null;    private static String username = null;    private static String password = null;    // 加载驱动，获取数据库连接信息    static {        try {            // 加载配置文件            InputStream in = JdbcUtils.class.getClassLoader().getResourceAsStream("DB.properties");            Properties properties = new Properties();            properties.load(in);            driver = properties.getProperty("driver");            url = properties.getProperty("url");            username = properties.getProperty("username");            password = properties.getProperty("password");            // 加载驱动            Class.forName(driver);        } catch (IOException e) {            e.printStackTrace();        } catch (ClassNotFoundException e) {            e.printStackTrace();        }    }    /**     * 获取数据库连接     * @throws SQLException     */    public static Connection getConnection() {        try {            return DriverManager.getConnection(url, username, password);        } catch (SQLException e) {            e.printStackTrace();        }        return null;    }    /**     * 释放资源     * @param connection     * @param preparedStatement     * @param resultSet     */    public static void releaseDB(Connection connection, PreparedStatement preparedStatement, ResultSet resultSet) {        if (connection != null) {            try {                connection.close();            } catch (SQLException e) {                e.printStackTrace();            }        }        if (preparedStatement != null) {            try {                preparedStatement.close();            } catch (SQLException e) {                e.printStackTrace();            }        }        if (resultSet != null) {            try {                resultSet.close();            } catch (SQLException e) {                e.printStackTrace();            }        }    }}

3、增删改查

package com.test;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;public class JdbcTest {	public void insert() {		Connection connection = null;		PreparedStatement preparedStatement = null;		try {			// 获取连接			connection = JdbcUtils.getConnection();			// 准备sql语句			String sql = "INSERT INTO user(id,name,age) VALUES(?,?,?)";			// 获取PrepareStatement对象			preparedStatement = connection.prepareStatement(sql);			// 填充占位符			preparedStatement.setInt(1, 6);			preparedStatement.setString(2, "小A");			preparedStatement.setInt(3, 25);			// 执行sql			int num = preparedStatement.executeUpdate();// 返回影响到的行数			System.out.println("一共影响到" + num + "行");		} catch (SQLException e) {			e.printStackTrace();		} finally {			JdbcUtils.releaseDB(connection, preparedStatement, null);		}	}	public void update() {		Connection connection = null;		PreparedStatement preparedStatement = null;		try {			// 获取连接			connection = JdbcUtils.getConnection();			// 准备sql语句			String sql = "update user set age = ? where name = ?";			// 获取PrepareStatement对象			preparedStatement = connection.prepareStatement(sql);			// 填充占位符						preparedStatement.setInt(1, 30);			preparedStatement.setString(2, "小A");			// 执行sql			int num = preparedStatement.executeUpdate();// 返回影响到的行数			System.out.println("一共影响到" + num + "行");		} catch (SQLException e) {			e.printStackTrace();		} finally {			JdbcUtils.releaseDB(connection, preparedStatement, null);		}	}	public void query() {        Connection connection = null;        PreparedStatement preparedStatement = null;        ResultSet resultSet = null;        try {            connection = JdbcUtils.getConnection();            String sql = "SELECT name,age FROM user";            preparedStatement = connection.prepareStatement(sql);            resultSet = preparedStatement.executeQuery();            // 遍历结果集            while (resultSet.next()) {                String name = resultSet.getString(1);                Integer age = resultSet.getInt(2);                                System.out.println("name:" + name + ", age:" + age);            }        } catch (Exception e) {        	e.printStackTrace();        } finally {            JdbcUtils.releaseDB(connection, preparedStatement, resultSet);        }    }	public void delete() {        Connection connection = null;        PreparedStatement preparedStatement = null;        try {            connection = JdbcUtils.getConnection();            String sql = "DELETE FROM user WHERE id = ?";            preparedStatement = connection.prepareStatement(sql);            preparedStatement.setInt(1, 6);            int num = preparedStatement.executeUpdate();            System.out.println("一共影响到" + num + "行");        } catch (Exception e) {        	e.printStackTrace();        } finally {            JdbcUtils.releaseDB(connection, preparedStatement, null);        }    }	}

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