java JDBC连接数据库

JDBC（Java Data Base Connection） API由原SUN公司提供，

提供了Java应用程序与各种不同数据库交互的标准接口。

如：Connection（连接）接口、Statement接口

、PreparedStatement接口、ResultSet（结果集）接口等。

可以使用这些JDBC接口进行各类数据库操作。

JDBC链接数据库的基本操作

1、注册驱动（以MYSQL为例）

Class.forName("com.mysql.jdbc.Driver");

2、创建链接

String url = "jdbc:mysql://localhost:3306/student?useSSL=false";
String username = "root";
String password = "root";
conn = DriverManager.getConnection(url, username, password);

3、 创建执行对象

stmt = conn.createStatement();

4、 操作数据库

String sql = "select * from stuinfo";
rs = stmt.executeQuery(sql);

获取结果

while (rs.next()) {             System.out.println(rs.getString("StuName"));
}

6、关闭资源

try {
if (rs != null) {
rs.close();
}
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

执行对象解析时，



关于PreparedStatement 的用法：

String sql = "select * from stuinfo where stuid = ?";
pstmt = conn.prepareStatement(sql);
Scanner sc = new Scanner(System.in);
String stuid = sc.next();
pstmt.setString(1, stuid);
rs = pstmt.executeQuery();

下面的代码可用于jsp中的数据库连接时使用：

public class DButils {
private static final String URL = "jdbc:mysql://localhost:3306/pss?useSSL=false";
private static final String USER = "root";
private static final String PASSWORD = "123456yin";
private static final String DRIVER = "com.mysql.jdbc.Driver";

//静态块，用于注册数据库驱动
static {
try {
Class.forName(DRIVER);
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}

//数据库连接
public static Connection getConnection()
{
Connection conn = null;
try {
conn = DriverManager.getConnection(URL,USER,PASSWORD);
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
return conn;
}

//数据库关闭，用于需要获取结果时
public static void close(ResultSet rs,PreparedStatement state,Connection conn)
{
try {
if(rs != null)
rs.close();
if(state != null)
state.close();
if(conn != null)
conn.close();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}

}

//数据库关闭，用于不需要获取结果时
public static void close(PreparedStatement state,Connection conn)
{
try {
if(state != null)
state.close();
if(conn != null)
conn.close();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}

}
}

在数据库中的product表中按id查询并返回查询到的结果

public productinfo queryById(int proID)
{
productinfo pro = new productinfo();
Connection conn = DButils.getConnection();
PreparedStatement state = null;
ResultSet rs = null;
if(conn != null)
{
try {
String sql = "select * from product where prod_id = ?";
state = conn.prepareStatement(sql);
state.setInt(1, proID);
rs = state.executeQuery();
if(rs.next())
{
pro.setProd_id(rs.getInt("prod_id"));
pro.setProd_name(rs.getString("prod_name"));
pro.setProd_supplierid(rs.getInt("prod_supplierid"));
pro.setProd_inprice(rs.getDouble("prod_inprice"));
pro.setProd_outprice(rs.getDouble("prod_outprice"));
pro.setProd_wareid(rs.getInt("prod_wareid"));
pro.setProd_num(rs.getInt("prod_num"));
}

} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally{
DButils.close(rs,state, conn);
}
}
return pro;
}

删除数据库中的某一条信息

public int delete(int proID) {
// TODO Auto-generated method stub
productinfo pro = new productinfo();
Connection conn = DButils.getConnection();
PreparedStatement state = null;
ResultSet rs = null;
int flag = 0;
if(conn != null)
{
try {
String sql = "delete from product where prod_id = ?";
state = conn.prepareStatement(sql);
state.setInt(1, proID);
state.executeUpdate();
flag=1;
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally{
DButils.close(state, conn);
}
}
if(flag == 1)
return 1;
else
return 0;
}