数据查询的方法

Util.java

import java.sql.*;

public class Util {
    private Connection conn;
    private Statement stm;
    private ResultSet rs;
    private String classname="com.mysql.jdbc.Driver";
    private String url="jdbc:mysql://localhost:3306/test";
    public Util(){
        try {
            Class.forName(classname);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    /*获取连接*/
    public Connection getConn() {
        try {
            conn=DriverManager.getConnection(url,"root","123456");
        } catch (SQLException e) {
            e.printStackTrace(System.err);
            conn=null;
        }
        return conn;
    }
    /*关闭连接*/
    public void closed(){
        
            try {
                if (rs!=null) {
                    rs.close();
                }
                if (stm!=null) {
                    stm.close();
                }
                if(conn!=null){
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
    }
    
    
    public void setConn(Connection conn) {
        this.conn = conn;
    }
    /*执行语句*/
    public Statement getStm() {
        
        try {
            conn=getConn();
            stm=conn.createStatement();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return stm;
    }
    public Statement getStmed(){
        
        try {
            conn=getConn();
            stm=conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return stm;
    }
    public ResultSet getAllRs(){
        String sql="select * from u";
        
        try {
            stm=getStmed();
            rs=stm.executeQuery(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
//  public static void main(String[] args) {
//      Util u = new Util();
//      ResultSet rr=u.getAllRs();
//      try {
//          while (rr.next()) {
//              System.out.println(rr.getString(1)+"\t"+rr.getString(2)+"\t"+rr.getString(3));
//          }
//      } catch (SQLException e) {
//          e.printStackTrace();
//      }
//  }
    
}

index.jsp

<body>
    <form action="result.jsp" method="post">
        <table>
            <tr align="center" valign="middle" bgcolor="#CCCCCC" height="22">
                <td>id</td>
                <td>name</td>
                <td>pwd</td>
            </tr>
            <%
                ResultSet rs = (ResultSet)session.getAttribute("resultset");
                rs.toString();
                while(rs.next()){
            %>
            <tr align="center" valign="middle" height="22">
            <td><%=rs.getString("id") %></td>
            <td><%=rs.getString("name") %></td>
            <td><%=rs.getString("pwd") %></td>
            </tr>
            <%} %>
            
            <tr>
                <td align="center" colspan="4">
                    <input type="submit" value="查询全部数据"/>
                </td>
            </tr>
        </table>
    </form>
    
    <table>
        <tr bgcolor="skyblue">
            <td align="center">生成的版权信息</td>
        </tr>
        <tr>
            <td>
                <jsp:useBean id="copyright" class="com.count.Copyright"></jsp:useBean>
                <jsp:getProperty property="copyrightStr" name="copyright"/>
            </td>
        </tr>
    </table>
</body>

result.jsp

<body>
    <jsp:useBean id="db" class="com.count.Util" scope="page"></jsp:useBean>
    <%
        ResultSet rs = db.getAllRs();
        session.setAttribute("resultset", rs);
        response.sendRedirect("index.jsp");
    %>
</body>

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数据查询的方法

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