Code reuse in JDBC

When we connect to the database using JDBC, we use executeQuery (String SQL) to obtain a result set. When the database structure changes or other database table result sets are obtained, we need to re-traverse the ResultSet result set based on different data structures.
How can we establish a JDBC connection unrelated to the database structure? We can use the ResultSetMetaData () method to obtain the table structure. Then, use the Object [] array to traverse the result set. You can use the Iterator to obtain the expected results. The result can be retrieved by traversing the iterator.
The following is a method I wrote:
1 import java. math. BigDecimal;
2 import java. SQL. Connection;
3 import java. SQL. DriverManager;
4 import java. SQL. ResultSet;
5 import java. SQL. ResultSetMetaData;
6 import java. SQL. SQLException;
7 import java. SQL. Statement;
8 import java. util. ArrayList;
9 import java. util. Iterator;
10 import java. util. List;
11
12 public class newJdbc {
13 private String url = "jdbc: Oracle (large website database platform): thin: @ localhost: 1521: nitpro ";
14
15 private String dbUserName = "scott ";
16
17 private String dbUserPassword = "tiger ";
18
19 private Connection conn = null;
20
21 private Statement stmt = null;
22
23 private ResultSet rs = null;
24
25 public newJdbc (){
26 try {
27 Class. forName ("Oracle (large website database platform). jdbc. driver. Oracle (large website database platform) Driver ");
28} catch (ClassNotFoundException e ){
29 e. printStackTrace ();
30}
31}
32
33 public Connection getConnection (){
34 try {
35 conn = DriverManager. getConnection (url, dbUserName, dbUserPassword );
36} catch (SQLException e ){
37 e. printStackTrace ();
38}
39 return conn;
40}
41
42 public void close (ResultSet rs, Statement stmt, Connection conn ){
43 if (rs! = Null ){
44 try {
45 rs. close ();
46} catch (SQLException e ){
47 e. printStackTrace ();
48}
49}
50 if (stmt! = Null ){
51 try {
52 stmt. close ();
53} catch (SQLException e ){
54 e. printStackTrace ();
55}
56}
57 if (conn! = Null ){
58 try {
59 conn. close ();
60} catch (SQLException e ){
61 e. printStackTrace ();
62}
63}
64}
65
66 public List query (String SQL ){
67 List list = new ArrayList ();
68
69 conn = this. getConnection ();
70 try {
71 stmt = conn. createStatement ();
72 rs = stmt.exe cuteQuery (SQL );
73 // obtain the database table structure
74 ResultSetMetaData rsm = rs. getMetaData ();
75 // obtain the number of columns in the database
76 int col = rsm. getColumnCount ();
77 // generate an array of objects with col Length
78 Object [] obj = new Object [col];
79 // traverse the result set and save the result to the Object Array
80 while (rs. next ()){
81 for (int I = 0; I <col; I ++ ){
82 obj [I] = rs. getObject (I + 1 );
83}
84 list. add (obj );
85}
86} catch (SQLException e ){
87 e. printStackTrace ();
88} finally {
89 this. close (rs, stmt, conn );
90}
91 return list;
92}
93
94 public void update (String SQL ){
95 try {
96 conn = this. getConnection ();
97 stmt = conn. createStatement ();
98 stmt.exe cuteUpdate (SQL );
99} catch (SQLException e ){
100 & nbs