1：构造一个操作数据库的工具类，可以获得连接和释放连接
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public class DBUtil { private static Connection conn = null; static { //静态初始块 try { Class.forName("com.mysql.jdbc.Driver"); conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test", "root", "064319"); //初始化获取连接 } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } } /** * 释放连接 * @param rs * @param psmt * @param conn * @throws SQLException */ public static void closeAll(ResultSet rs, PreparedStatement psmt, Connection conn) throws SQLException { if(rs != null) { rs.close(); } if(psmt != null) { psmt.close(); } if(conn != null) { conn.close(); } } /** * 获取连接 * @return */ public static Connection getConnection() { return conn; } /** * 根据表的名字来获得表的列信息 * @param tableName */ public static void getTableColumnInfoByTableName(String tableName) { Connection conn = getConnection(); ResultSet rs = null; PreparedStatement psmt = null; String sql = "select * from " + tableName; try { psmt = conn.prepareStatement(sql); rs = psmt.executeQuery(); ResultSetMetaData resultSetMetaData = rs.getMetaData(); for(int i = 1; i<= resultSetMetaData.getColumnCount(); i++) { System.out.println(resultSetMetaData.getColumnName(i)); } } catch (SQLException e) { e.printStackTrace(); } finally { try { closeAll(rs, psmt, conn); } catch (SQLException e) { e.printStackTrace(); } } } /** * 根据表的名字来获得表的信息 * @param tableName */ public static void getTableInfoByTableName(String tableName) { Connection conn = getConnection(); PreparedStatement psmt = null; ResultSet rs = null; String sql = "select * from " + tableName; try { psmt = conn.prepareStatement(sql); rs = psmt.executeQuery(); while(rs.next()) { ResultSetMetaData resultSetMetaData = rs.getMetaData(); for(int i = 1; i<= resultSetMetaData.getColumnCount(); i++) { if(i < resultSetMetaData.getColumnCount()) { System.out.print(rs.getObject(resultSetMetaData.getColumnName(i)) + ", "); } else { System.out.print(rs.getObject(resultSetMetaData.getColumnName(i))); } } System.out.println(); } } catch (SQLException e) { e.printStackTrace(); } finally { try { closeAll(rs, psmt, conn); } catch (SQLException e) { e.printStackTrace(); } } } } |
2：构造一个操作数据库的BaseDao类
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public class BaseDao { /** * 根据一些参数来保存相应的对象 * @param sql 要执行的sql语句 * @param params 为sql语句中相应的参数赋值 * @return */ protected boolean saveOrUpdate(String sql, Object[] params) { Connection conn = null; PreparedStatement psmt = null; boolean flag = false; conn = DBUtil.getConnection(); if(conn != null) { try { psmt = conn.prepareStatement(sql); for(int i = 1; i <= params.length; i++) { psmt.setObject(i, params[i-1]); } if(psmt.executeUpdate() > 0) { flag = true; } } catch (SQLException e) { e.printStackTrace(); } finally { try { DBUtil.closeAll(null, psmt, conn); } catch (SQLException e) { e.printStackTrace(); } } } return flag; } /** * 根据一定的参数获得某个具体的对象 * @param sql 要执行的sql语句 * @param params 为sql语句中相应的参数赋值 * @return */ public Object queryForObject(String sql, Object[] params, RowMapForObject rowMapForObject) { Connection conn = null; PreparedStatement psmt = null; conn = DBUtil.getConnection(); Object obj = null; ResultSet rs = null; if(conn != null) { try { psmt = conn.prepareStatement(sql); if(params != null && params.length > 0) { for(int i = 1; i <= params.length; i++) { psmt.setObject(i, params[i - 1]); } } rs = psmt.executeQuery(); obj = rowMapForObject.rowMapForObject(rs); } catch (SQLException e) { e.printStackTrace(); } finally { try { DBUtil.closeAll(null, psmt, conn); } catch (SQLException e) { e.printStackTrace(); } } } return obj; } /** * 根据相应的参数获得查询的结果集 * @param sql * @param params * @return */ public List queryForList(String sql, Object[] params, RowMapForList rowMapForList) { Connection conn = null; PreparedStatement psmt = null; conn = DBUtil.getConnection(); List list = null; ResultSet rs = null; if(conn != null) { try { psmt = conn.prepareStatement(sql); if(params != null && params.length > 0) { for(int i = 1; i <= params.length; i++) { psmt.setObject(i, params[i - 1]); } } rs = psmt.executeQuery(sql); list = new ArrayList(); list = rowMapForList.rowMapForList(rs); } catch (SQLException e) { e.printStackTrace(); } finally { try { DBUtil.closeAll(null, psmt, conn); } catch (SQLException e) { e.printStackTrace(); } } } return list; } } |
3：新建一个StudentDao类，该类继承自BaseDao，实现对Student的管理
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public class StudentDao extends BaseDao { /** * 保存一个Student的信息 */ public boolean saveStudent(Student student) { String sql = "insert into t_student(name, age) values(?, ?)"; Object[] params = new Object[]{student.getName(), student.getAge()}; return super.saveOrUpdate(sql, params); } /** * 根据id获得一个Student的信息 * @param id * @return */ public Student getStudentById(long id) { String sql = "select * from t_student where id=?"; Object[] params = new Object[]{id}; return (Student)super.queryForObject(sql, params, new RowMapForObject() { public Object rowMapForObject(ResultSet rs) { Student student = null; try { if(rs != null && rs.next()) { student = new Student(); student.setAge(rs.getInt(Student.AGE)); student.setId(rs.getLong(Student.ID)); student.setName(rs.getString(Student.NAME)); } } catch (SQLException e) { e.printStackTrace(); } return student; } }); } /** * 获得所有Student的信息 * @return */ public List getStudentAll() { String sql = "select * from t_student"; List list = super.queryForList(sql, null, new RowMapForList() { @Override public List rowMapForList(ResultSet rs) { List list = null; try { if(rs != null) { list = new ArrayList(); while(rs.next()) { Student student = new Student(); student.setId(rs.getLong("id")); student.setAge(rs.getInt("age")); student.setName(rs.getString("name")); list.add(student); } } } catch(SQLException e) { e.printStackTrace(); } return list; } }); return list; } } |
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原文链接：http://blog.csdn.net/woshisap/article/details/7192822
