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java连接mysql

程序员文章站 2024-01-27 12:04:46
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1.首先要下载数据驱动jar包地址:http://www.mysql.com/downloads/connector/j/
2.将jar导入myeclipse中,点击添加jar包
3.创建一个ConnectionDB.java文件

/*
 * 连接数据库
 */
public class ConnectionDB {
     /**  
     * 数据库驱动类名称  
     */    
    private static final String DRIVER = "com.mysql.jdbc.Driver";    

    /**  
     * 连接字符串  
     */    
    private static final String URLSTR = "jdbc:mysql://localhost:3306/shop";

    /**  
     * 用户名  
     */    
    private static final String USERNAME = "root";    

    /**  
     * 密码  
     */    
    private static final String USERPASSWORD = "admin";   

    /**  
     * 创建数据库连接对象  
     */    
    private Connection connnection = null;    

    /**  
     * 创建PreparedStatement对象  
     */    
    private PreparedStatement preparedStatement = null;    

    /**  
     * 创建结果集对象  
     */    
    private ResultSet resultSet = null;    

    /**
     *加载数据库的驱动
     */
    static {    
        try {    
            Class.forName(DRIVER);    
        } catch (ClassNotFoundException e) {    
            e.printStackTrace();
        }    
    }    

    /**  
     * 获取数据库连接
     * @return 数据库连接  
     */    
    public Connection getConnection() {    
        try {    
            //获取连接    
            connnection = DriverManager.getConnection(URLSTR, USERNAME,USERPASSWORD);    
        } catch (SQLException e) {    
            System.out.println(e.getMessage());    
        }    
        return connnection;    
    }    

    /**  
     * insert update delete SQL语句的执行的统一方法  
     * @param sql SQL语句  
     * @param params 参数数组,若没有参数则为null  
     * @return 受影响的行数  
     */    
    public int executeUpdate(String sql, Object[] params) {    
        // 受影响的行数    
        int affectedLine = 0;         
        try {    
            //获得连接    
            connnection = this.getConnection();    
            //调用SQL     
            preparedStatement = connnection.prepareStatement(sql);      
            // 参数赋值    
            if (params != null) {    
                for (int i = 0; i < params.length; i++) {    
                    preparedStatement.setObject(i + 1, params[i]);    
                }    
            }    
            // 执行    
            affectedLine = preparedStatement.executeUpdate();    
        } catch (SQLException e) {    
            System.out.println(e.getMessage());    
        } finally {    
            // 释放资源    
            closeAll();    
        }    
        return affectedLine;    
    }  

    /**  
     * SQL 查询将查询结果直接放入ResultSet中  
     * @param sql SQL语句  
     * @param params 参数数组,若没有参数则为null  
     * @return 结果集  
     */    
    private ResultSet executeQueryRS(String sql, Object[] params) {    
        try {    
            // 获得连接    
            connnection = this.getConnection();    
            // 调用SQL    
            preparedStatement = connnection.prepareStatement(sql);    
            // 参数赋值    
            if (params != null) {    
                for (int i = 0; i < params.length; i++) {    
                    preparedStatement.setObject(i + 1, params[i]);    
                }    
            }    
            // 执行    
            resultSet = preparedStatement.executeQuery();    
        } catch (SQLException e) {    
            System.out.println(e.getMessage());    
        }    
        return resultSet;    
    }  

    /**  
     * 获取结果集,并将结果放在List中   
     * @param sql  SQL语句           
     * @return List  结果集                       
     */ 
    public List<Object> excuteQuery(String sql, Object[] params) {    
        // 执行SQL获得结果集    
        ResultSet rs = executeQueryRS(sql, params);    

        // 创建ResultSetMetaData对象    
        ResultSetMetaData rsmd = null;    

        // 结果集列数    
        int columnCount = 0;    
        try {    
            rsmd = rs.getMetaData();    

            // 获得结果集列数    
            columnCount = rsmd.getColumnCount();    
        } catch (SQLException e1) {    
            System.out.println(e1.getMessage());    
        }    

        // 创建List    
        List<Object> list = new ArrayList<Object>();    

        try {    
            // 将ResultSet的结果保存到List中    
            while (rs.next()) {    
                Map<String, Object> map = new HashMap<String, Object>();    
                for (int i = 1; i <= columnCount; i++) {    
                    map.put(rsmd.getColumnLabel(i), rs.getObject(i));    
                }    
                list.add(map);    
            }    
        } catch (SQLException e) {    
            System.out.println(e.getMessage());    
        } finally {    
            closeAll();    
        }    
        return list;    
    }  

    /**  
     * 关闭所有资源  
     */    
    private void closeAll() {    
        // 关闭结果集对象    
        if (resultSet != null) {    
            try {    
                resultSet.close();    
            } catch (SQLException e) {    
                System.out.println(e.getMessage());    
            }    
        }    
        // 关闭PreparedStatement对象    
        if (preparedStatement != null) {    
            try {    
                preparedStatement.close();    
            } catch (SQLException e) {    
                System.out.println(e.getMessage());    
            }    
        }    
        // 关闭Connection 对象    
        if (connnection != null) {    
            try {    
                connnection.close();    
            } catch (SQLException e) {    
                System.out.println(e.getMessage());    
            }    
        }       
    }    
}

4.直接传入sql语句即可
5.调用

public static void main(String[] args) {

        ConnectionDB connectionDB=new ConnectionDB();
        String sql="select * from person";
        List<Object> excuteQuery = connectionDB.excuteQuery(sql, null);
        for (int i = 0; i < excuteQuery.size(); i++) {
            Map<String, Object> map = (Map<String, Object>) excuteQuery.get(i);
            System.out.println(map.get("id"));
        }
    }

6.结果
java连接mysql