jdbc链接数据库

public class connectFactory {
private static String name="";
private static String user="";
private static String password="";
private static String url="";
static Connection conn=null;

static{
name="oracle.jdbc.driver.OracleDriver";
user="HQ133";
password="HQ133";
url="jdbc:oracle:thin:@localhost:1521:XE";
}

public static Connection getConnection(){
if(conn==null){

try {
Class.forName(name);
conn=DriverManager.getConnection(url, user, password);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
return conn;
}
public static void main(String []args){
Connection conn = connectFactory.getConnection();
if(conn==null){
System.out.println("--null--");
}else{
System.out.println("--not null--");
}

}
}

public class userDao {
public int yanZheng(String name,String password){
Connection conn=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
int count=0;
conn=connectFactory.getConnection();
if(conn==null){
System.out.println("ddddddd");
}
String sql="SELECT count(*) FROM users where name=? and password=?";

try {
pstmt=conn.prepareStatement(sql);
pstmt.setString(1,name);
pstmt.setString(2, password);
rs=pstmt.executeQuery();
if(rs.next()){
count=rs.getInt(1);
}

} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
if(rs!=null){
try {
rs.close();
} catch (SQLException e) {
count=0;
}
}

if(pstmt!=null){

try {
pstmt.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
}
return count;

}

public List select(){
Connection conn=null;
PreparedStatement pstmt=null;
ResultSet rs=null;

List<Student> list=new ArrayList<Student>();
conn=connectFactory.getConnection();
String sql="SELECT * FROM info";
try {
pstmt=conn.prepareStatement(sql);
rs=pstmt.executeQuery();
while(rs.next()){
Student stu=new Student();
stu.setId(rs.getInt(1));
stu.setName(rs.getString(2));
stu.setAge(rs.getInt(3));
stu.setSex(rs.getString(4));
list.add(stu);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
try {
rs.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
return list;
}
public int delete(int id){
Connection conn=null;
PreparedStatement pstmt=null;
int count=0;
conn=connectFactory.getConnection();
String sql="DELETE FROM INFO WHERE id=?";
try {
pstmt=conn.prepareStatement(sql);
pstmt.setInt(1,id);
count=pstmt.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
if(pstmt!=null){
try {
pstmt.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
return count;

}
public int update(int id,String name,int age,String sex){
Connection conn=null;
PreparedStatement pstmt=null;
int count=0;
conn=connectFactory.getConnection();
String sql="UPDATE info set name=?,age=?,sex=? WHERE id=?";
try {
pstmt=conn.prepareStatement(sql);
pstmt.setString(1, name);
pstmt.setInt(2, age);
pstmt.setString(3, sex);
pstmt.setInt(4, id);
count=pstmt.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
if(pstmt!=null){
try {
pstmt.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
return count;
}
}