JAVA：JDBC连接MySQL数据库

痛定思痛。 2022-06-16 12:15 402阅读 0赞

一、下载mysql连接包,放到项目中

a)        首先要到mysql官网下载Connector/J地址是：

[http://www.mysql.com/downloads/connector/j/][http_www.mysql.com_downloads_connector_j]

![Center][]

![Center 1][]

b)        解压后的文件夹是：

![Center 2][]

c)        拷贝到工程中：

![Center 3][]

d)        鼠标右键：Add to Build Path

![Center 4][]

二、新建一个DBHelper类用来打开或关闭数据库：

package com.db;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.SQLException;
    
    public class DBHelper {
    	public static final String url = "jdbc:mysql://127.0.0.1/xxxxx";
    	public static final String name = "com.mysql.jdbc.Driver";
    	public static final String user = "root";
    	public static final String password = "123456";
    
    	public Connection conn = null;
    	public PreparedStatement pst = null;
    
    	public DBHelper(String sql) {
    		try {
    			Class.forName(name);// 指定连接类型
    			conn = DriverManager.getConnection(url, user, password);// 获取连接
    			pst = conn.prepareStatement(sql);// 准备执行语句
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    
    	public void close() {
    		try {
    			this.conn.close();
    			this.pst.close();
    		} catch (SQLException e) {
    			e.printStackTrace();
    		}
    	}
    }

三、新建一个HelloJDBC类用来执行查询操作：

package com.db;
    
    import java.sql.ResultSet;
    import java.sql.SQLException;
    
    public class HelloJDBC {
    	static String sql = null;  
        static DBHelper db1 = null;  
        static ResultSet ret = null;  
        
        public void query() {
        	 sql = " select * from zduser ";//SQL语句  
             db1 = new DBHelper(sql);//创建DBHelper对象  
       
             try {  
                 ret = db1.pst.executeQuery();//执行语句，得到结果集  
                 while (ret.next()) {  
                     String uid = ret.getString(1);  
                     String ufname = ret.getString(2);  
                     String ulname = ret.getString(3);  
                     String udate = ret.getString(4);  
                     System.out.println(uid + "\t" + ufname + "\t" + ulname + "\t" + udate );  
                 }//显示数据  
             } catch (SQLException e) {  
                 e.printStackTrace();  
             } finally {
            	 try {
    				ret.close();
    				db1.close();//关闭连接  
    			} catch (SQLException e) {
    				e.printStackTrace();
    			}  
            	 
             }
             
        }
        
    }

四、执行main方法报错了

a)        错误信息：com/mysql/jdbc/Driver : Unsupported major.minor version 52.0

b)        原因：是因为我的jdk和mysql提供的jar包不匹配，重新下载一个mysql连接jar包，如图：

![Center 5][]

替换即可。

五、重新运行main程序，执行正确。

[http_www.mysql.com_downloads_connector_j]: http://www.mysql.com/downloads/connector/j/
[Center]: /images/20220616/63f48b2b1cb84ac5a784d547e377b97d.png
[Center 1]: /images/20220616/ce51315ce4de47c8ad93f79d6478c2b0.png
[Center 2]: /images/20220616/df08ebb789dd437d90e14a502f4685bc.png
[Center 3]: /images/20220616/956a28db4b1f461382f5072760d2335d.png
[Center 4]: /images/20220616/f6de68151a59444abe2f2d91e3f0088d.png
[Center 5]: /images/20220616/4b428f62f41a4b778962c24a8780f51c.png