java中从main调用mysql连接的方法
我正在学习java,我添加了带有netbeans的mysql连接器,我正在尝试做一个示例应用程序来查询数据库,但是我不知道如何调用从主方法建立连接的方法 这是我的密码: MySqlJdbcTest.java:java中从main调用mysql连接的方法,java,mysql,Java,Mysql,我正在学习java,我添加了带有netbeans的mysql连接器,我正在尝试做一个示例应用程序来查询数据库,但是我不知道如何调用从主方法建立连接的方法 这是我的密码: MySqlJdbcTest.java: public class MySqlJdbcTest { public static void main(String[] args) { Connection conn = null; Statement stmt = null;
public class MySqlJdbcTest {
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
// new com.mysql.jdbc.Driver();
Class.forName("com.mysql.jdbc.Driver").newInstance();
//conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test?user=root&password=");
String connectionUrl = "jdbc:mysql://localhost:3306/test";
String connectionUser = "root";
String connectionPassword = "";
conn = DriverManager.getConnection(connectionUrl, connectionUser, connectionPassword);
stmt = conn.createStatement();
rs = stmt.executeQuery("SELECT * FROM java");
while (rs.next()) {
String id = rs.getString("id");
String firstName = rs.getString("name");
String lastName = rs.getString("number");
System.out.println("ID: " + id + ", First Name: " + firstName
+ ", Last Name: " + lastName);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try { if (rs != null) rs.close(); } catch (SQLException e) { e.printStackTrace(); }
try { if (stmt != null) stmt.close(); } catch (SQLException e) { e.printStackTrace(); }
try { if (conn != null) conn.close(); } catch (SQLException e) { e.printStackTrace(); }
}
}
}
下面是test.java文件:
public class Test {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
MySqlJdbcTest prueba = new MySqlJdbcTest();
prueba();
}
}
您有2个main(String[])
方法。Java要求您将其中一个作为应用程序的入口点
如果我们假定Test.main()
是应用程序的入口点,则可以调用另一个作为
public static void main(String[] args) {
MySqlJdbcTest.main(args);
}
这相当于调用一个静态
方法
但是,为了让事情更清楚,我建议您将MySqlJdbcTest.main()
方法重命名为其他方法,并可能删除static
修饰符和String[]
参数。结果会是这样的
public class MySqlJdbcTest {
public void executeSql() {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
// new com.mysql.jdbc.Driver();
Class.forName("com.mysql.jdbc.Driver").newInstance();
//conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test?user=root&password=");
String connectionUrl = "jdbc:mysql://localhost:3306/test";
String connectionUser = "root";
String connectionPassword = "";
conn = DriverManager.getConnection(connectionUrl, connectionUser, connectionPassword);
stmt = conn.createStatement();
rs = stmt.executeQuery("SELECT * FROM java");
while (rs.next()) {
String id = rs.getString("id");
String firstName = rs.getString("name");
String lastName = rs.getString("number");
System.out.println("ID: " + id + ", First Name: " + firstName
+ ", Last Name: " + lastName);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try { if (rs != null) rs.close(); } catch (SQLException e) { e.printStackTrace(); }
try { if (stmt != null) stmt.close(); } catch (SQLException e) { e.printStackTrace(); }
try { if (conn != null) conn.close(); } catch (SQLException e) { e.printStackTrace(); }
}
}
}
因为该方法现在是一个实例方法,所以需要一个类的实例来运行它
public class Test {
public static void main(String[] args) {
MySqlJdbcTest prueba = new MySqlJdbcTest();
prueba.executeSql();
}
}
考虑阅读将“main”方法重命名为其他方法,如“DoTest”,然后在Test.main中调用prueba.DoTest();