JDBC study notes --ResultSetMetaData

1.why:

If only one result set, but do not know how many columns in the result set, the column names are what.

1) It should be used when writing generic query methods.

public <T> T get(Class<T> clazz, String sql, Object ... args){

}

2.what: Object describing the ResultSet.

3.how:

. ① ResultSetMetaData object obtained: calling the getMetaData the ResultSet () method 
ResultMetaData rsmd = resultSet.getMetaData (); 
which has useful method ②.ResultsetMetaData: 
    > the getColumnCount int (): The results which set includes a column 
    > String getColumnLabel (int column) : Gets the designated column aliases, indexes start at 1 

// get the result set aliases for each column

for (int I = 0; I <rsmd.getColumnCount (); I ++) { 
    String columnLabel rsmd.getColumnLabel = (I + 1); 
} 

// sample code on the ResultSetMetaData 
// 1 was ResultSetMetaData object. 
ResultSetMetaData rsmd = Result. the getMetaData (); 

the while (ResultSet.next ()) { 
　　. 2 // print column name of each column 
　　for (int I = 0; I <rsmd.getColumnCount (); I ++) { 
　　　　String columnLabel rsmd.getColumnLabel = (I + 1); // Get the specified column aliases 
　　　　System.out.println (columnLabel); // Print alias
　　　　Object columnValue = resultSet.getObject (columnLabel); # the alias obtain the corresponding data in the database
　　　　
　　　　values.put (columnLabel, columnValue ); 
　　} 
}