下面是一个示例,它使用了结果集章节中描述的几个 getInt 和 getString 方法。此示例与导航结果集部分中解释的前面示例非常相似。
该示例代码是根据前面章节中的环境和数据库设置编写的。
复制并粘贴以下示例到JDBCExample.java中,如下编译并运行:
//步骤1.导入所需的软件包 import java.sql.*; public class JDBCExample { // JDBC驱动程序名称和数据库URL static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; static final String DB_URL = "jdbc:mysql://localhost/EMP"; // 数据库凭证 static final String USER = "username"; static final String PASS = "password"; public static void main(String[] args) { Connection conn = null; Statement stmt = null; try{ //步骤2:注册JDBC驱动程序 Class.forName("com.mysql.jdbc.Driver"); //步骤3:建立连接 System.out.println("Connecting to database..."); conn = DriverManager.getConnection(DB_URL,USER,PASS); //步骤4:执行查询以创建陈述 // RS示例的必需参数。 System.out.println("Creating statement..."); stmt = conn.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY); String sql; sql = "SELECT id, first, last, age FROM Employees"; ResultSet rs = stmt.executeQuery(sql); // 将光标移到最后一行。 System.out.println("Moving cursor to the last..."); rs.last(); //步骤5:从结果集中提取数据 System.out.println("Displaying record..."); //按列名检索 int id = rs.getInt("id"); int age = rs.getInt("age"); String first = rs.getString("first"); String last = rs.getString("last"); //显示值 System.out.print("ID: " + id); System.out.print(", Age: " + age); System.out.print(", First: " + first); System.out.println(", Last: " + last); // 将光标移到第一行。 System.out.println("Moving cursor to the first row..."); rs.first(); //步骤6:从结果集中提取数据 System.out.println("Displaying record..."); //按列名检索 id = rs.getInt("id"); age = rs.getInt("age"); first = rs.getString("first"); last = rs.getString("last"); //显示值 System.out.print("ID: " + id); System.out.print(", Age: " + age); System.out.print(", First: " + first); System.out.println(", Last: " + last); // 将光标移到第一行。 System.out.println("Moving cursor to the next row..."); rs.next(); //步骤7:从结果集中提取数据 System.out.println("Displaying record..."); id = rs.getInt("id"); age = rs.getInt("age"); first = rs.getString("first"); last = rs.getString("last"); //显示值 System.out.print("ID: " + id); System.out.print(", Age: " + age); System.out.print(", First: " + first); System.out.println(", Last: " + last); //步骤8:清理环境 rs.close(); stmt.close(); conn.close(); }catch(SQLException se){ //处理JDBC错误 se.printStackTrace(); }catch(Exception e){ //处理Class.forName的错误 e.printStackTrace(); }finally{ //最终阻止用于关闭资源 try{ if(stmt!=null) stmt.close(); }catch(SQLException se2){ } try{ if(conn!=null) conn.close(); }catch(SQLException se){ se.printStackTrace(); } } System.out.println("Goodbye!"); } }//结束JDBCExample
现在让我们编译上面的示例,如下所示:
C:\>javac JDBCExample.java C:\>
运行时JDBCExample,它将产生以下结果-
C:\>java JDBCExample Connecting to database... Creating statement... Moving cursor to the last... Displaying record... ID: 103, Age: 30, First: Sumit, Last: Mittal Moving cursor to the first row... Displaying record... ID: 100, Age: 18, First: Zara, Last: Ali Moving cursor to the next row... Displaying record... ID: 101, Age: 25, First: Mahnaz, Last: Fatma Goodbye! C:\>