Java JDBC连接三种数据库 - JAVA

ement stmt = null;
try
{
//得到连接
ct=DBUtil.getCon();
//ps=ct.prepareStatement(sqlstr);
stmt = ct.createStatement();
//创建结果集
rs = stmt.executeQuery(sqlstr);
//将结果集返回
return rs;
}
catch(SQLException e)
{
System.out.print("错误");
}
return null;
}
}

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
//主要用于完成对数据库的crud操作
public class SqlHelper
{
//定义需要的变量
private static Connection ct=null;//连接
private static ResultSet rs=null;//结果
private static PreparedStatement ps=null;

public ArrayList executeQuery(String sql,String []paras)
{
ArrayList al=new ArrayList();
try {
ct=DBUtil.getCon();
ps=ct.prepareStatement(sql);
//给sql问号赋值
for (int i = 0; i < paras.length; i++)
{
ps.setString(i+1, paras[i]);
}
rs=ps.executeQuery();
//非常有用的
ResultSetMetaData rsmd=rs.getMetaData();
//用法rs可以的到有多少列
int columnNum=rsmd.getColumnCount();
//循环从a1中取出数据封装到ArrayList中
while(rs.next())
{
Object []objects=new Object[columnNum];
for(int i=0;i {
objects[i]=rs.getObject(i+1); //返回对象数组
}
al.add(objects);
}
return al;
} catch (Exception e)
{
e.printStackTrace();
throw new RuntimeException(e.getMessage());
}finally
{
DBUtil.close(rs,ps,ct);
}

}
public ResultSet executeQuery(String sqlstr)
{
Statement stmt = null;
try
{
//得到连接
ct=DBUtil.getCon();
//ps=ct.prepareStatement(sqlstr);
stmt = ct.createStatement();
//创建结果集
rs = stmt.executeQuery(sqlstr);
//将结果集返回
return rs;
}
catch(SQLException e)
{
System.out.print("错误");
}
return null;
}
}

应用实例

[java]
public class Test
{
public static void main(String[] args)
{
SqlHelper sqlHelper=new SqlHelper();
String sql="select *from stu";
ArrayList al=sqlHelper.executeQuery(sql,null);
ArrayListstus=new ArrayList();
for(int i=0;i {
Object[] obj=(Object[])al.get(i);
Stu stu=new Stu();
stu.setId(Integer.parseInt(obj[0].toString()));
stu.setName(obj[1].toString());
stus.add(sight);
}

//从list中读
for(Stu s:stus){
System.out.println(s.getName());
}
}
}

public class Test
{
public static void main(String[] args)
{
SqlHelper sqlHelper=new SqlHelper();
String sql="select *from stu";
ArrayList al=sqlHelper.executeQuery(sql,null);
ArrayListstus=new ArrayList();
for(int i=0;i {
Object[] obj=(Object[])al.get(i);
Stu stu=new Stu();
stu.setId(Integer.parseInt(obj[0].toString()));
stu.setName(obj[1].toString());
stus.add(sight);
}

//从list中读
for(Stu s:stus){
System.out.println(s.getName());
}
}
}

Java JDBC连接三种数据库 (三)