Java连接MySQL数据库,并进行增删改查
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1、具体的代码实现
import java.sql.*; public class DatabaseService { /** * Create Connection * * @param dbtype * @param username * @param password * @param url * @return * @throws Exception */ public static Connection connectDBDriver(String dbtype, String username, String password, String url) throws Exception { Connection conn = null; try { if (dbtype.equals("mysql")) { Class.forName("com.mysql.jdbc.Driver").newInstance(); } else if (dbtype.equals("oracle")) { Class.forName("oracle.jdbc.driver.OracleDriver").newInstance(); } else { } conn = DriverManager.getConnection(url, username, password); } catch (Exception e) { e.printStackTrace(); } return conn; } /** * close DB * * @param conn * @throws Exception */ public void closeDBDriver(Connection conn) throws Exception { try { conn.close(); } catch (Exception e) { /* ignore close errors */ e.printStackTrace(); } } /** * get ResultSet * * @param conn * @param sql * @return * @throws Exception */ private static ResultSet getResultSet(Connection conn, String sql) throws Exception { ResultSet resultSet = null; try { // PreparedStatement pstmt; // ResultSet rset; //任意的前后滚动;设置为只读类型的参数 Statement statement = conn.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY); // pstmt = conn.prepareStatement(sql); resultSet = statement.executeQuery(sql); } catch (Exception e) { e.printStackTrace(); } return resultSet; } /** * get ColumnCount * * @param resultSet * @return * @throws Exception */ private static int getColumnCount(ResultSet resultSet) throws Exception { int columnCount = 0; try { // ResultSet resultSet = this.getResultSet(conn, sql); //getMetaData() 获取此 ResultSet 对象的列的编号、类型和属性 //getColumnCount() 返回此 ResultSet 对象中的列数。 columnCount = resultSet.getMetaData().getColumnCount(); if (columnCount == 0) { } } catch (Exception e) { e.printStackTrace(); } return columnCount; } /** * get ColumnCount * * @param conn * @param sql * @return * @throws Exception */ public static int getColumnCount(Connection conn, String sql) throws Exception { int columnCount = 0; try { // ResultSet resultSet = this.getResultSet(conn, sql); columnCount = getResultSet(conn, sql).getMetaData() .getColumnCount(); if (columnCount == 0) { } } catch (Exception e) { e.printStackTrace(); } return columnCount; } /** * get RowCount * * @param conn * @param sql * @return * @throws Exception */ public int getRowCount(Connection conn, String sql) throws Exception { int rowCount = 0; try { ResultSet resultSet = getResultSet(conn, sql); // boolean last() 将光标移动到此 ResultSet 对象的最后一行。 resultSet.last(); // boolean last() 将光标移动到此 ResultSet 对象的最后一行。 rowCount = resultSet.getRow(); if (rowCount == 0) { } } catch (Exception e) { e.printStackTrace(); } return rowCount; } /** * get RowCount * * @param resultSet * @return * @throws Exception */ private static int getRowCount(ResultSet resultSet) throws Exception { int rowCount = 0; try { resultSet.last(); rowCount = resultSet.getRow(); if (rowCount == 0) { } } catch (Exception e) { e.printStackTrace(); } return rowCount; } /** * get data by row index and col index * * @param conn * @param sql * @param row * @param col * @return * @throws Exception */ public static String getData(Connection conn, String sql, int row, int col) throws Exception { String data = null; int rownum = 0; int rowcount = 0; int colcount = 0; try { ResultSet resultSet = getResultSet(conn, sql); colcount = getColumnCount(resultSet); rowcount = getRowCount(resultSet); //beforeFirst() 将光标移动到此 ResultSet 对象的开头,正好位于第一行之前。 resultSet.beforeFirst(); if (rowcount > 0) { if (row <= 0 || row > rowcount) { } else { if (col <= 0 || col > colcount) { } else { while (resultSet.next()) { rownum++; if (rownum == row) { data = resultSet.getString(col); break; } } } } } else { } } catch (Exception e) { e.printStackTrace(); } return data; } /** * get data by row index and col index * * @param conn * @param sql * @param row * @param field * @return * @throws Exception */ public static String getData(Connection conn, String sql, int row, String field) throws Exception { String data = null; int rownum = 0; int rowcount = 0; // int colcount = 0; try { ResultSet resultSet = getResultSet(conn, sql); // colcount = getColumnCount(resultSet); rowcount = getRowCount(resultSet); resultSet.beforeFirst(); if (rowcount > 0) { if (row <= 0 || row > rowcount) { } else { while (resultSet.next()) { rownum++; if (rownum == row) { data = resultSet.getString(field); break; } } } } else { } } catch (Exception e) { e.printStackTrace(); } return data; } // executeUpdate方法可以执行新增、更新、删除三种sql语句 public static int executeUpdate(Connection conn, String sql) { Statement stmt = null; try { stmt = conn.createStatement(); stmt.executeUpdate(sql); int updateCount = stmt.getUpdateCount(); return updateCount; } catch (Exception e) { e.printStackTrace(); } finally { if (stmt != null) { try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } } return 0; } }
2、调用函数实现增删改查
public class JdbcData { public static void main(String[] args) { Connection connection = databaseService.connectDBDriver("mysql","username","password","URL"); String sql = "XXXX‘"; //查询数据,获取到数据 String data = DatabaseService.getData(connection, sql,1,1); String sqlstatus = "XXXX"; //update数据 DatabaseService.executeUpdate(connection,sqlstatus); } }
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