jsp教程调用java类并查询sql数据库教程

package bean;

import java.sql.*;

public class MyDb_Page{

private Statement stmt;

private Connection conn=null;

private ResultSet rs=null;

private String navi;

public void connection(String db_name,String user,String pwd) throws Exception{

Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");

String url="jdbc:mysql教程://www.update8.com:3306/" + db_name;

conn=DriverManager.getConnection(url,user,pwd);

stmt=conn.createStatement();

}

public ResultSet query(String sql) throws Exception{

rs=stmt.executeQuery(sql);

return rs;

}

public ResultSet query(String query,int size,int page) throws Exception{

int page_count; //总页数

int result_count; //总记录数

int begin; //当前页第一条记录索引号

String sql=query;

int i=query.indexOf("from");

String sql2=query.substring(i);

rs=query("select count(*) " + sql2);

rs.next();

result_count=rs.getInt(1);

page_count=(result_count + size - 1)/size;

begin=(page-1)*size;

String s=" limit " + begin + "," +size;

sql=sql + s;

rs=query(sql);

//设置导航栏

String back="没有了";

String pre="没有了";

if(page>1) back="<a href=?page=" + String.valueOf(page-1) + ">上一页</a>";

if(page<page_count) pre="<a href=?page=" + String.valueOf(page+1) + ">下一页</a>";

navi=back + " " + pre;

return rs;

}

public String getNavi(){

return navi;

}

public int update(String sql) throws Exception{

int n=0;

n=stmt.executeUpdate(sql);

return n;

}

public boolean delete(String sql) throws Exception{

boolean flag=false;

flag=stmt.execute(sql);

return flag;

}

}

%>

<jsp:useBean id="www.update8.com" class="bean.MyDb_Page" scope="page"/>

<%

String sql="select * from student";

ResultSet rs=db.query(sql);

while(rs.next()){

out.println(rs.getString(10);

}

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