Mysql公司幫我們寫好了Mysql Driver的類, 方便我們寫Java程序的時候調用類來執行數據庫的相關操作,如果想要連接數據庫,我們按一下步驟執行就可以了。
1. 導入mysql-connector-java-3.1.13-bin.jar(如果沒有,CSDN上下載一個)。
2. 安裝mysql,創建一個用戶(默認用戶名爲root,密碼123456), 在上面創建一個數據庫(假設爲homework1), 在上面創建一個表(假設爲account).
3. 然後在Java程序中寫入相應的代碼如下, 即可。
import java.sql.DriverManager;
import java.sql.SQLException;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Driver;
import com.mysql.jdbc.ResultSet;
import com.mysql.jdbc.Statement;
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
try {
//註冊驅動
DriverManager.registerDriver(new Driver());
//建立連接
Connection conn = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/homework1","root","123456");
//創建語句
Statement st = (Statement) conn.createStatement();
//執行查詢
ResultSet rSet = (ResultSet) st.executeQuery("select * from account");
//拿到結果集處理
while(rSet.next()){
System.out.println(rSet.getObject(1) + " | " + rSet.getObject(2));
}
//釋放資源
rSet.close();
st.close();
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
總結:
1.註冊驅動的方式有三種
DriverManager.registerDriver(new Driver());
System.setProperty("jdbc.drivers","com.mysql.jdbc.Driver");
Class.forName("com.mysql.jdbc.Driver");
2. 連接時的url的含義
協議:子協議:子名稱//主機名:端口號/數據庫名, 屬性名 ,屬性值
"jdbc:mysql//localhost:3306/homewoke1" ,"root","123456";
3. 提供標準模板
static void template() throws Exception{
String url = "jdbc:mysql://localhost:3306/homework1";
String username = "root";
String password = "123456";
Connection conn = null;
Statement stat = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = (Connection) DriverManager.getConnection(url,username,password);
stat = (Statement) conn.createStatement();
rs = (ResultSet) stat.executeQuery("Select * from account");
//處理結果
} finally{
try {
if(rs != null)
rs.close();
} finally{
try {
if(stat != null)
stat.close();
} finally{
if(conn != null)
conn.close();
}
}
}
}
4. 更進一步的 封裝成一個類
import java.sql.DriverManager;
import java.sql.SQLException;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.ResultSet;
import com.mysql.jdbc.Statement;
/**
* 封裝一個類 來實現具體的JDBC的操作,簡潔化代碼
* @author Neuclil
*
*/
public class JdbcUtil {
private static String url = "jdbc:mysql://localhost:3306/homework1";
private static String username = "root";
private static String password = "123456";
private JdbcUtil(){
}
static{
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
throw new ExceptionInInitializerError(e);
}
}
public static Connection getConnection() throws SQLException{
return (Connection) DriverManager.getConnection(url,username,password);
}
public static void free(ResultSet rs, Statement stat, Connection conn){
try {
if(rs != null)
rs.close();
}catch (Exception e) {
e.printStackTrace();
} finally{
try {
if(stat != null)
stat.close();
}catch (Exception e) {
e.printStackTrace();
} finally{
if(conn != null)
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}