我創(chuàng)建了一個方法 ( getData()) 來從數(shù)據(jù)庫接收數(shù)據(jù)，這似乎有效。我想要的是只使用 1 個參數(shù)，所以該方法應該以className.getData("SELECT * FROM myTable"). 我怎樣才能做到這一點？public List<String> getData(String sql, Map column) { this.driver(); try { Connection conn = DriverManager.getConnection(this.url); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery(sql); List<String> result = new ArrayList<>(); if (column.containsKey("string")) { for (Object i : column.values()) { while (rs.next()) { result.add(rs.getString(String.valueOf(i))); } } return result; } } catch (SQLException e) { e.printStackTrace(); } return null;}private void driver() { // Ensure we have mariadb Driver in classpath try { Class.forName("org.mariadb.jdbc.Driver"); } catch (ClassNotFoundException e) { e.printStackTrace(); }}
2 回答
慕妹3146593
TA貢獻1820條經(jīng)驗 獲得超9個贊
當然，您不需要將列名作為參數(shù)傳遞。JDBC 允許您從元數(shù)據(jù)中獲取列名。就像下面一樣
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
Integer colunNum = rsmd.getColumnCount();
for(int i =0; i < columnNum; i ++){
String colmnName = rsmd.getColumnName(i);
....
}
歸功于：從 java.sql.ResultSet 中檢索列名
婷婷同學_
TA貢獻1844條經(jīng)驗 獲得超8個贊
在類實例化中調(diào)用驅(qū)動方法。
static {
// Ensure we have mariadb Driver in classpath
try {
Class.forName("org.mariadb.jdbc.Driver");
}
catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
你也應該關(guān)閉你的資源。您可以使用try-with-resources來做到這一點。
public List<String> getData(String sql, Map column) {
try (
Connection conn = DriverManager.getConnection(this.url);
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql);
){
List<String> result = new ArrayList<>();
if (column.containsKey("string")) {
for (Object i : column.values()) {
while (rs.next()) {
result.add(rs.getString(String.valueOf(i)));
}
}
return result;
}
}
catch (SQLException e) {
e.printStackTrace();
}
return null;
}
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