java连接数据库的例子

ConnectionManager.java
import java.sql.*;
public class ConnectionManager {
private static final String DRIVER_CLASS="com.microsoft.sqlserver.jdbc.SQLServerDriver";
private static final String DATABASE_URL="jdbc:sqlserver://localhost:1433;DatabaseName=student";
private static final String DATABASE_USER="xz";
private static final String DATABASE_PASSWORD="test";
private ConnectionManager()
{}
/**
* 返回连接
* @return Connection
* @throws DBAccessException
*/
public static Connection getConnection()
{
Connection dbConnection=null;
try {
Class.forName(DRIVER_CLASS);
dbConnection=DriverManager.getConnection(DATABASE_URL,DATABASE_USER,DATABASE_PASSWORD);
} catch (ClassNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return dbConnection;
}
/**
* 关闭连接
* @param conn
* Connection
*/
public static void closeConnection(Connection conn)
{
try{
if(conn!=null && !conn.isClosed())
{
conn.close();
conn=null;
}
}catch(Exception ex)
{
System.out.println(ex.getMessage());
}
}
/**
* 关闭结果集
* @param rs
* ResultSet
*/
public static void closeResultSet(ResultSet rs)
{
try{
if(rs!=null)
{
rs.close();
rs=null;
}
}catch(Exception ex)
{
System.out.println(ex.getMessage());
}
}
/**
* 关闭SQL预处理语句
* @param pstmt
* PreparedStatement
*/
public static void closePreparedStatement(PreparedStatement pstmt)
{
try{
if(pstmt!=null)
{
pstmt.close();
pstmt=null;
}
}catch(Exception ex)
{
System.out.println(ex.getMessage());
}
}
/**
* 关闭SQL语句
* @param stmt
* Statement
*/
public static void closeStatement(Statement stmt)
{
try{
if(stmt!=null)
{
stmt.close();
stmt=null;
}
}catch(Exception ex)
{
System.out.println(ex.getMessage());
}
}
public static void main(String[]args)
{

try {
Connection con=ConnectionManager.getConnection();
if(!con.isClosed())
System.out.println("数据库连接成功。。。。。");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
User.javapublic class User {
private String username;
private String userpass;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getUserpass() {
return userpass;
}
public void setUserpass(String userpass) {
this.userpass = userpass;
}
}
UserDAO.javaimport java.util.*;
import java.sql.*;
public class UserDAO {
public List<User> getAllUser()
{
Connection conn=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
List<User> userList=new ArrayList<User>();
String sql="select UserName,UserPas from Users";

try {
conn=ConnectionManager.getConnection();
pstmt=conn.prepareStatement(sql);
rs=pstmt.executeQuery();
while(rs.next())
{
User u=new User();
u.setUsername(rs.getString("UserName"));
u.setUserpass(rs.getString("UserPas"));
userList.add(u);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally
{
ConnectionManager.closeConnection(conn);
ConnectionManager.closePreparedStatement(pstmt);
ConnectionManager.closeResultSet(rs);
}
return userList;
}
}

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