JAVA2核心技术卷II -- 第4章. 数据库编程

1. 通用数据库连接及操作

    一般数据库连接信息存放在properties文件中

    jdbc.drivers = oracle.jdbc.driver.OracleDriver

    jdbc.url = jdbc:oracle:thin:@MyDbComputerNameOrIP:1521:DataName

    jdbc.username = dbuser

    jdbc.password = password

    链接数据库，进行操作

    写法一:

    Class.forName("oracle.jdbc.driver.OracleDriver");

    Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@MyDbComputerNameOrIP:1521:DataName",sUsr,sPwd);

    写法二:

    Properties props = new Properties();    //从属性文件中读取连接信息

    FileInpuStream in = new FileInputStream("database.properties");

    props.load(in);

    in.close();

    String drivers = props.getProperty("jdbc.drivers ");    

    System.setProperty("jdbc.drivers ", drivers);    //注册该驱动

    String url = props.getProperty("jdbc.url");     

    String username = props.getProperty("jdbc.username");  

    String password = props.getProperty("jdbc.password");

    Connection conn = DriverManager.getConnection(url, username, password);    //建立数据库连接

    try {

        Statement stat = conn.createStatement();    //创建Statement对象

        stat.execute(sql);    //可以执行任何sql操作

        ResultSet rs = stat.executeQuery();    //执行select sql操作

        ResultSet rs = stat.executeUpdate();    //执行insert, update, delete sql操作

        while (rs.next()) {rs.getString(1)    //返回当前行第一列的值}

    } finally {conn.close();}  

2. PreparedStatement预备查询语句

    当一个sql被反复执行，那么就不需要每次都创建这个查询信息，使用PreparedStatement来创建一次，然后根据每次输入的条件不同，进行操作

    String sql = "select * from books where name = ? and price = ?";

    PreparedStatement preStat = conn.perparedStatement(sql);

    preStat.setString(1, "corejava");

    preStat.setString(2, "1000");

3. 事务

    conn.setAutoCommit(false);

    conn.commit();    //执行完所有的操作之后调用

    conn.rollback();    //出现错误调用

4. 高级连接管理

    使用JNDI来建立数据库连接

    Context ctx = new InitialContext();

    DataSource ds = (DataSource)ctx.lookup("java:comp/env/jdbc/corejava");

    Connection conn = ds.getConnection();

5. LDAP轻量级目录访问协议

    Hashtable env = new Hashtable();

    env.put(Context.SECURITY_PRINCIPAL, username);

    env.put(Context.SECURITY_CREDENTIALS, password);

    DirContext initial = new InitialDirContext(env);

    DirContext context = (DirContext) initial.lookup("ldap://localhost:389");    //访问本地LDAP服务器