详解Java EE中SQL语句的自动构造方法
/**
* @version: 1.1
* @Time: 2008.03.02
*/
package com.river.page ;
import java.util.*;
import javax.servlet.http.HttpServletRequest;
public class PageUtil {
private HttpServletRequest request = null ;
public PageUtil(){
}
public void init(HttpServletRequest _request){
this.request = _request ;
}
public void clear(){
if(this.request != null){
this.request = null ;
}
}
public String get(String elementName){
if(request == null || request.getParameter(elementName) == null){
return "";
}else{
return request.getParameter(elementName);
}
}
public String get(HttpServletRequest _request,详解String elementName){
init(_request);
return get(elementName);
}
public String getSQL(HttpServletRequest _request){
init(_request);
return getSQL();
}
public String getSQL(){
String sqlstr = "";
String c_table = get("c_table");
String c_genre = get("c_genre");
String c_where = get("c_where");
if(c_genre == null || c_genre.equals("")){
return "the action is null/empty";
}
if(c_table == null || c_table.equals("")){
return "unknow table/empty" ;
}
if(c_genre.equalsIgnoreCase("INSERT")){
java.util.Enumeration arg_names = request.getParameterNames();
String colstr = "",valstr = "";
String arg_name,pre_name,end_name ;
while(arg_names.hasMoreElements()){
arg_name = String.valueOf(arg_names.nextElement());
if(arg_name.length() < 2){
continue;
}
pre_name = arg_name.substring(0,2);
end_name = arg_name.substring(2);
if(pre_name.equalsIgnoreCase("i_")){
colstr = colstr+","+end_name;
if(get(arg_name).equals("")){
valstr = valstr+",NULL";
}else{
valstr = valstr + "," + String.valueOf(get(arg_name));
}
}else if(pre_name.equalsIgnoreCase("s_")){
colstr = colstr+","+end_name;
if(get(arg_name).equals("")){
valstr = valstr+",NULL";
}else{
valstr = valstr+","+get(arg_name).replaceAll("","")+"";
}
}
}
if(!colstr.equals("")){
colstr = colstr.substring(1);
valstr = valstr.substring(1);
}
sqlstr = "INSERT INTO "+c_table+" ("+colstr+") VALUES ("+valstr+")";
return sqlstr;
}else if(c_genre.equalsIgnoreCase("UPDATE")){
java.util.Enumeration arg_names = request.getParameterNames();
String colstr = "";
String arg_name,pre_name,end_name ;
while(arg_names.hasMoreElements()){
arg_name = String.valueOf(arg_names.nextElement()).trim();
if(arg_name.length() < 2){
continue;
}
pre_name = arg_name.substring(0,2);
end_name = arg_name.substring(2);
if(pre_name.equalsIgnoreCase("i_")){
if(get(arg_name).equals("")){
colstr += ","+end_name+"=NULL";
}else{
colstr += ","+end_name+"="+get(arg_name);
}
}else if(pre_name.equalsIgnoreCase("s_")){
if(get(arg_name).equals("")){
colstr += ","+end_name+"="+get(arg_name);
}else{
colstr += ","+end_name+"="+get(arg_name).replaceAll("","")+"";
}
}
}
if(!colstr.equals("")){
colstr = colstr.substring(1);
}
sqlstr = "UPDATE "+c_table+" SET "+colstr;
if(!c_where.equals("")){
sqlstr += " WHERE "+c_where;
}
return sqlstr;
}else if(c_genre.equalsIgnoreCase("DELETE")){
sqlstr = "DELETE FROM "+c_table;
if(c_where != null && !c_where.equals("")){
sqlstr += " WHERE "+c_where;
}
}else{
com.river.debug.Debug.show("unknow action type : "+c_genre);
return null;
}
return sqlstr;
}
public String toString(){
return "version 1.0, date 2005.03.02, author river";
}
}
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