java数据库编程

java连接数据库

创建lib文件夹并导入mysql驱动jar包

加载驱动

Class.forName("com.mysql.jdbc.Driver");

获取连接对象

private static String url = "jdbc:mysql:///wtu?useUnicode=true&characterEncoding=utf-8"; private static String userName = "root"; private static String password = "root"; private static Connection con; con = DriverManager.getConnection(url,userName,password);

获取执行对象

//获取静态执行对象 Statement stmt = conn.createStatement(); //获取动态执行对象 String sql="..." PreparedStatement pstmt = conn.prepareStatement(sql);

执行sql语句

pstmt.executeUpadte() //执行更改（增删修改） pstmt.executeQuary() //执行查询

补充JDBC2.0批处理

package jdbc2batchprocessing; import utils.JdbcUtils; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.Timestamp; //批处理，一次处理多条数据 public class BatchProcessingTest { public static void main(String[] args) throws Exception { Connection conn = JdbcUtils.getConn(); String sql = "INSERT INTO test VALUES(?,?,?,?,?)"; PreparedStatement pstmt = conn.prepareStatement(sql); int num = 130,age=32; for (int i = 0; i < 8; i++) { pstmt.setString(1,String.valueOf(num)); pstmt.setString(2,"李兴华"+i); pstmt.setInt(3,age); pstmt.setString(4,"女"); pstmt.setTimestamp(5,new Timestamp(new java.util.Date().getTime())); pstmt.addBatch(); num++; age++; } int[] temps = pstmt.executeBatch(); System.out.println("更新了"+temps.length+"条数据"); pstmt.close(); conn.close(); } }

结果集元数据MetaData

package metadata; import utils.JdbcUtils; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.ResultSetMetaData; //结果集元数据 public class ResultMetaDataTest { public static void main(String[] args) throws Exception { Connection conn = JdbcUtils.getConn(); String sql = "SELECT * FROM test WHERE num=107"; PreparedStatement pstmt = conn.prepareStatement(sql); ResultSet rs = pstmt.executeQuery(); //获取元数据对象 ResultSetMetaData md = rs.getMetaData(); //通过元数据获取结果集的列数 int count = md.getColumnCount(); while (rs.next()){ for (int i=1;i<=count;i++){ //获取每个单元格的数据 Object value = rs.getObject(i); //通过元数据获取列名 String columnName = md.getColumnName(i); System.out.println(columnName+":"+value); } } rs.close(); pstmt.close(); conn.close(); } }