sqlqueryaction.java

教师管理系统是在学校局域网架设的B/S结构的办公平台。系统有四个模块：系统设置

import java.io.*;
import javax.servlet.*;
import java.sql.*;

import Base.Action.*;
import Base.DataBean.*;
/**
 * 用于查询的模块 modular
 * 
 */
public class SqlQueryAction extends Action
{ 
        DefaultDataBean m_dBean = null;
        //交易处理的入口函数，
        //参数：  DefaultDataBean类的实例
        //返回值：0 - 出错，错误原因放在key: Action.perform.errReason, value:为String类
        //                  错误代码放在key: Action.perform.errCode,   value:为Integer类
        //        1 - 成功，可以继续执行后一个交易
        public int perform(DefaultDataBean dBean)  throws IOException, ServletException
        {
             int iPos[],iOccur=0;
              
             try{   
                 String strActionName = dBean.getAttributeStr(m_servlet.ACTION_NAME_PREFIX);
                 if(strActionName == null) strActionName = new String("");
                 m_dBean = dBean;
        	 String paraName = m_servlet.ACTION_PARA_PREFIX + "sql";
        	 String paraSqlStr = dBean.getAttributeStr(paraName);
        	 if( paraSqlStr==null || paraSqlStr.length() == 0 )
        	 {
        	 	setError(1000,"no sql string found");
        	 	return 0;
        	 }
        	// m_servlet.log(2,"para Sql String :[" +  paraSqlStr+"]");
        	 
        	 //find how many ? characters in  paraSqlStr
        	 for( int i=0; i < paraSqlStr.length(); i++)
        	 {
        	 	i = paraSqlStr.indexOf('?',i);
        	 	if( i == -1 ) break;
        	 	iOccur ++;
        	 }
        	 
        	 //find Sql paras in  xml
        	 String[] sqlParaValue = new String[iOccur];
        	 for( int i=0; i< iOccur; i++)
        	 {
        	 	paraName = m_servlet.ACTION_PARA_PREFIX + i;
        	 	String name = dBean.getAttributeStr(paraName);
        	 	sqlParaValue[i] = dBean.getAttributeStr(name);
        	 	
        	 	m_servlet.log(2,"name:"+paraName+" val:"+sqlParaValue[i]+" i:"+ i);
        	 }
        	 if( iOccur > 0 )
        	 {
        	 	int iRet = 0;
        	 	StringBuffer strBuf = new StringBuffer(paraSqlStr); 
        	 	for( int i=0; i< iOccur; i++)
        	        {
        	        	iRet = strBuf.toString().indexOf('?',iRet);
        	        	strBuf = strBuf.replace(iRet,iRet+1,sqlParaValue[i]);
        	        	iRet += sqlParaValue[i].length();
        	        }
        	        paraSqlStr = strBuf.toString();
        	 }
        	 
        	 m_servlet.log(2,"  Sql :[" +  paraSqlStr+"]");
        	 Statement stmt = (Statement)dBean.getAttribute("Action.perform.Statement");
        	 if(stmt == null ) { setError(1000,"数据库连接失败 (no Statement object)"); return 0; }
        	 Query(dBean,stmt,paraSqlStr,strActionName);
             }catch(Exception e){
   	         setError( 1000 , e.getMessage() );
   	      m_servlet.log("SqlQueryAction:",e);
        	 return 0;
   	     }
   	     
             return 1;
        }
        void Query(DefaultDataBean dBean,Statement stmt,String Sql,String strActionName) throws Exception
        {
           ResultSet rs=null; 
        	rs = stmt.executeQuery(Sql); 
        	ResultSetMetaData rsma= rs.getMetaData();
                String prefixStr = 
                               strActionName.length() == 0 ? strActionName : strActionName + ".";
                 int iRow = 0;
        	 while (rs.next())
                 {
                    for(int i=0;i<rsma.getColumnCount();i++)
                    {
                    	String colname = rsma.getColumnLabel(i+1);
                    	String coldata = rs.getString(i+1);
                    	if(coldata == null) coldata = new String("");
                        dBean.putAttribute(prefixStr + colname,coldata,iRow);
                        if(iRow==0) m_servlet.log(2,"  col name:" +  prefixStr + colname);
                    }
                    iRow++;
                  }
                //纪录符合纪录的个数
                dBean.setCount(strActionName,iRow);  
                m_servlet.log(2,"  "+iRow+" rows were found");
                if(rs!=null) rs.close();
                return;
        }
        void setError(int errCode ,String errReason)
        {
             if(m_dBean != null)
             {
             	if(errReason == null) { errReason = new String(""); errCode = 101; }
             	m_dBean.putAttribute("Action.perform.errReason",errReason );
             	m_dBean.putAttribute("Action.perform.errCode",new Integer(errCode) );
             	m_servlet.log(2,"Action report error: " + errReason); 
             }
             return;
        }
 
    
}