JDBC

最新推荐文章于 2025-09-06 09:33:29 发布

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最新推荐文章于 2025-09-06 09:33:29 发布

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CC 4.0 BY-SA版权

文章标签：数据库

原文链接：http://www.cnblogs.com/bluewhy/p/4950285.html

本文提供了一个使用JDBC连接MySQL数据库并查询用户ID是否存在的一段示例代码。通过设置数据库驱动、URL、用户名及密码等参数，利用PreparedStatement执行SQL语句，实现对用户ID的计数查询。

JDBC代码

private static final long serialVersionUID = 1L;

public static final String DBDRIVER="com.mysql.jdbc.Driver";//org.gjt.mm.mysql.Driver

public static final String DBURL="jdbc:mysql://localhost:3306/test";

public static final String DBUSER="root";

public static final String DBPASS="";

request.setCharacterEncoding("GBK");

response.setContentType("text/html");
        Connection connection=null;
        PreparedStatement preparedStatement=null;
        ResultSet rSet=null;
        PrintWriter out=response.getWriter();
        String userid=request.getParameter("userid");
        try {
            Class.forName(DBDRIVER);
            connection=DriverManager.getConnection(DBURL,DBUSER,DBPASS);
            String sql="select count(userid) from user where userid=?";
            preparedStatement=connection.prepareStatement(sql);
            preparedStatement.setString(1, userid);
            rSet=preparedStatement.executeQuery();
            if(rSet.next()){
                if(rSet.getInt(1)>0)
                    out.print("true");
                else out.print("false");
                out.close();
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        finally{
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }