java小练习——读取数据库

布满荆棘的人生 2021-06-24 16:11 374阅读 0赞

学习笔记，如有错误，还望不吝赐教！  
参考网页：[http://www.cnblogs.com/magicianCoder/p/5506589.html][http_www.cnblogs.com_magicianCoder_p_5506589.html]

![2789632-580e37a81a66c766.png][]

data

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执行结果

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文件

第一步：下载mysql-conerctor-java-xxx-bin.jar,并且引入到Referenced Libraries中。  
第二步：写连接方式代码：

package jdbc;
    
    import java.sql.Connection;
    
    public class Values
    {
        public static String DRIVER_MYSQL = "com.mysql.jdbc.Driver";
        public static String URL = "jdbc:mysql://localhost:3306/Student?"
                + "user=root&password=0301&useUnicode=true&characterEncoding=UTF8";
    }

然后加载，连接，查询数据库，获得数据：

package jdbc;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
    
    public class TestJDBC
    {
        private Statement statement;
        
        public TestJDBC() {
            try
            {
                Class.forName(Values.DRIVER_MYSQL);     //加载JDBC驱动
                System.out.println("Driver Load Success.");
                
                Connection connection = DriverManager.getConnection(Values.URL);    //创建数据库连接对象
                statement = connection.createStatement();       //创建Statement对象
            } catch (Exception e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        
        /*
         * 根据sql查询数据库，返回一个结果集
         * 输    入:SQL语句
         * 返回值:ResultSet 查询结果
         */
        public ResultSet query(String sql) {
            ResultSet result = null;
            
            try
            {
                result = statement.executeQuery(sql);
            } catch (SQLException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            
            return result;
        }
        
        /*
         * 打印UserInfo表的数据
         * 输    入:结果集(数据表)
         * 返回值:空
         */
        public void printUserInfo(ResultSet result) {
            try
            {
                while(result.next()) {
                    System.out.println("userNname:" + result.getString(1) 
                            + ", password:" + result.getString(2));
                }
            } catch (SQLException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        
        /*
         * 执行数据操作
         * 输    入:SQL语句
         * 返回值:空
         */
        public void executeSql(String sql) {
            try
            {
                statement.execute(sql);
            } catch (SQLException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        
        public static void main(String[] args)
        {
            // TODO Auto-generated method stub
            
            String sql = "SELECT * FROM info";
            TestJDBC db = new TestJDBC();
            ResultSet result = db.query(sql);
            db.printUserInfo(result);
        }
    
    }

[http_www.cnblogs.com_magicianCoder_p_5506589.html]: https://link.jianshu.com?t=http://www.cnblogs.com/magicianCoder/p/5506589.html
[2789632-580e37a81a66c766.png]: /images/20210615/a6fb2e1d69c14003b037877e08bebd61.png
[2789632-c80c74a51ea9d3e7.png]: /images/20210615/ccdde2eb27b04e63b307ba97b2425b95.png
[2789632-af1417dd3fd2c60c.png]: /images/20210615/1c9c73c7ac654d06a1715503352c5b8c.png