MySql连接数据库——代码

MySql连接数据库——代码
按步骤
1、写配置文件db.properties

Oracle connection
url=jdbc:oracle:thin:@localhost:1521:orcl
user=scott
password=tiger
driver=oracle.jdbc.driver.OracleDriver

MySql connection
url=jdbc:mysql://localhost:3306/test #解释其中的test为连接MySQL数据库的用户名，默认为root：
user=root
password=tiger
driver=com.mysql.jdbc.Driver
此配置文件中的注释符号为#

2. DBUtil类--连接数据库

    public class DBUtil {
private static Connection conn;

private static  String driver;
private static  String url;
private  static String user;
private  static String password;
private DBUtil(){}

static {
    Properties pt = new Properties();
    InputStream is;
    try {
//          is = new FileInputStream(new File("file/db.properties"));
        is = DBUtil.class.getResourceAsStream("/db.properties");//用以上两种方法都可以，只是配置文件的位置不同。
        pt.load(is);
        url = pt.getProperty("url");
        user = pt.getProperty("user");
        password = pt.getProperty("password");
        driver = pt.getProperty("driver");



        Class.forName(driver);
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}
public static Connection getConnection(){
    if(null == conn){
        try {
            conn = DriverManager.getConnection(url, user, password);

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    return conn;
}

}

3、测试类

public class test {
ResultSet rs = null;
@Test
public void getConn() throws SQLException{
    Connection conn = DBUtil.getConnection();       
//      String sql = "select * from test_01 ";
//      String sql = "insert into test_01(userName,sex) values('rose','Lao不死');";
    String sql = "delete from test_01 where userName = 'zhangsan';";
    sql = "update test_01 set userName = 'jack123' where userName = 'jack'; ";
    PreparedStatement ps = conn.prepareStatement(sql);

    int count = ps.executeUpdate();
    System.out.println(count);
//      rs = ps.executeQuery();
//      
//      while(rs.next()){
//          System.out.println(rs.getInt(1)+","+rs.getString(2)+","+rs.getString(3));
//      }
}
}

注意：
1.加入oracle，MySQL数据库的驱动jar包之后，要对其add to build path.
2.对于获取配置文件的db.roperties还有第三种写法，就是重写一个config类，继承properties，读写文件配置。
代码如下：

    public class DBConfig extends Properties{
private static DBConfig dbConfig = null;
private DBConfig() throws IOException{
    init();
}
private void init() throws IOException {
    InputStream is = DBConfig.class.getClassLoader().getResourceAsStream("db.properties");
    this.load(is);
}
public static DBConfig getDBConfigInstance() throws IOException{
    if(dbConfig == null){
        dbConfig = new DBConfig();
    }
    return dbConfig;
}
}