> list = new ArrayList>();
//静态代码块，在程序编译的时候执行
static {
//创建Properties对象
Properties properties = new Properties();
//获取文件输入流
InputStream is = JDBCUtil_cj.class.getClassLoader().getResourceAsStream("jdbc.properties");
try {
//加载输入流
properties.load(is);
is.close();
//加载mysql驱动
Class.forName(properties.getProperty("driver"));
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
//关闭资源
public static void closeRes(Connection conn,PreparedStatement ps,ResultSet rs) {
try {
if(rs != null){
rs.close();
}
if(ps != null){
ps.close();
}
if(conn != null){
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
//获取连接
public static Connection getConnection(){
Connection conn = null;
Properties properties = new Properties();
InputStream is = JDBCUtil_cj.class.getClassLoader().getResourceAsStream("jdbc.properties");
try {
properties.load(is);
is.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
conn = DriverManager.getConnection(
properties.getProperty("url"),
properties.getProperty("username"),
properties.getProperty("password"));
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
public static void main(String[] args) {
Connection connection = getConnection();
String sql = "select * from dept where deptno = ?";
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt(1,10);
resultSet = preparedStatement.executeQuery();
ResultSetMetaData md = resultSet.getMetaData(); //获得结果集结构信息,元数据
int columnCount = md.getColumnCount(); //获得列数
while (resultSet.next()) {
MaprowData = new HashMap();
for (int i = 1; i <= columnCount; i++) {
rowData.put(md.getColumnName(i), resultSet.getObject(i));
}
JDBCUtil_cj cj = new JDBCUtil_cj();
cj.list.add(rowData);
for (Map.Entryentry : rowData.entrySet()) {
System.out.println(entry.getKey()+"==="+entry.getValue());
}
System.out.println(rowData);
System.out.println(cj.list);
}
} catch (SQLException e) {
e.printStackTrace();
}
JDBCUtil_cj.closeRes(connection,preparedStatement,resultSet);
}
}
)
