JDBC初探

Posted 2020-07-01 Jason杰

下载好JDBC之后，首先做的应该是查看它的文档

打开connector-j.html

 

 1 import java.sql.Connection;
 2 import java.sql.DriverManager;
 3 import java.sql.SQLException;
 4 
 5 // Notice, do not import com.mysql.jdbc.*
 6 // or you will have problems!
 7 
 8 public class LoadDriver {
 9     public static void main(String[] args) {
10         try {
11             // The newInstance() call is a work around for some
12             // broken Java implementations
13 
14             Class.forName("com.mysql.jdbc.Driver").newInstance();
15         } catch (Exception ex) {
16             // handle the error
17         }
18     }
19 }

这是注册MySQL Connector/J，之后

 1 import java.sql.Connection;
 2 import java.sql.DriverManager;
 3 import java.sql.SQLException;
 4 
 5 Connection conn = null;
 6 ...
 7 try {
 8     conn =
 9        DriverManager.getConnection("jdbc:mysql://localhost/test?" +
10                                    "user=minty&password=greatsqldb");
11 
12     // Do something with the Connection
13 
14    ...
15 } catch (SQLException ex) {
16     // handle any errors
17     System.out.println("SQLException: " + ex.getMessage());
18     System.out.println("SQLState: " + ex.getSQLState());
19     System.out.println("VendorError: " + ex.getErrorCode());
20 }

连接数据库，之后Using JDBC Statement Objects to Execute SQL

 1 import java.sql.Connection;
 2 import java.sql.DriverManager;
 3 import java.sql.SQLException;
 4 import java.sql.Statement;
 5 import java.sql.ResultSet;
 6 
 7 // assume that conn is an already created JDBC connection (see previous examples)
 8 
 9 Statement stmt = null;
10 ResultSet rs = null;
11 
12 try {
13     stmt = conn.createStatement();
14     rs = stmt.executeQuery("SELECT foo FROM bar");
15 
16     // or alternatively, if you don‘t know ahead of time that
17     // the query will be a SELECT...
18 
19     if (stmt.execute("SELECT foo FROM bar")) {
20         rs = stmt.getResultSet();
21     }
22 
23     // Now do something with the ResultSet ....
24 }
25 catch (SQLException ex){
26     // handle any errors
27     System.out.println("SQLException: " + ex.getMessage());
28     System.out.println("SQLState: " + ex.getSQLState());
29     System.out.println("VendorError: " + ex.getErrorCode());
30 }
31 finally {
32     // it is a good idea to release
33     // resources in a finally{} block
34     // in reverse-order of their creation
35     // if they are no-longer needed
36 
37     if (rs != null) {
38         try {
39             rs.close();
40         } catch (SQLException sqlEx) { } // ignore
41 
42         rs = null;
43     }
44 
45     if (stmt != null) {
46         try {
47             stmt.close();
48         } catch (SQLException sqlEx) { } // ignore
49 
50         stmt = null;
51     }
52 }

至此，就可以完成数据库的基本操作了