java实现数据库的数据写入到txt的方法

package datatest;import java.io.BufferedOutputStream;import java.io.IOException;import java.io.UnsupportedEncodingException;import java.net.URLEncoder;import java.sql.ResultSet;import java.sql.SQLException;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import bean.ConnDB;public class export extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response)   throws ServletException, IOException {  //设置编码  response.setCharacterEncoding("UTF-8");  //连接数据库  ConnDB conn = new ConnDB();  ServletOutputStream outputstream = null;  BufferedOutputStream buffoutputstream = null;   String txt_name = "导出的txt文件名.txt";//导出的txt文件名  try {   response.reset();// 清空输出流   response.setContentType("text/plain;charset=utf-8");   //设置txt文件名称编码，防止中文乱码   response.setHeader("Content-disposition", "attachment; filename="+URLEncoder.encode(txt_name, "UTF-8"));  StringBuffer write = new StringBuffer();   outputstream=response.getOutputStream();   buffoutputstream = new BufferedOutputStream(outputstream);  //根据id查询数据库   int id=Integer.parseInt(request.getParameter("id"));   String sql = "select a.id,name,account,password ";   sql+="from test_rank a ";   sql+="left join test_join b on b.id=a.id where a.id="+id;   ResultSet rs = conn.doQuery(sql);   String content="";   try {    while(rs.next())    {     //把数据库中读取的数据写入     content=rs.getString("name")+"\r\n";//在txt中换行为\t\n     write.append(content);     content=rs.getString("account")+"\r\n";     write.append(content);     break;    }   } catch (SQLException e) {    // TODO Auto-generated catch block    e.printStackTrace();   }   //write.append(content);   //设置编码 防止中文乱码   String str = new String(write.toString().getBytes(),"gbk");   buffoutputstream.write(str.toString().getBytes("gbk"));   buffoutputstream.flush();  } catch (IOException e) {   // TODO Auto-generated catch block   e.printStackTrace();  }  finally {   if (outputstream != null)    try {     outputstream.close();    } catch (IOException e) {     // TODO Auto-generated catch block     e.printStackTrace();    }   if (buffoutputstream != null)    try {     buffoutputstream.close();    } catch (IOException e) {     // TODO Auto-generated catch block     e.printStackTrace();    }  } } public void doPost(HttpServletRequest request, HttpServletResponse response)   throws ServletException, IOException {  this.doGet(request, response); }}