从list取值

主要是实现功能：在jsp页面输入SQL语句，下面显示结果。基本思路：SQL语句存入hashmap，然后hashmap存入list，从list怎么取hashmap？从hashmap怎么取结果？用jsp取，相关代码：

public static List executeQueryStringList(String sql) {    

     if (sql == null || sql.trim().equals("")) {
            log.info("参数sql不能为空，必须是select语句。");    
            throw new NullPointerException("sql参数不能为空字符串或者null。");    
     }    
     Connection conn = null;    
     PreparedStatement pst = null;    
     ResultSet rst = null;    
     List l = new ArrayList();    
     try {    
            conn = DbConnection.getConn(); // 打开链接    
            pst = conn.prepareStatement(sql);// 开始执行sql    

           ResultSetMetaData rsmd = pst.getMetaData();
           int columnCount = rsmd.getColumnCount();

           // 获取所有的列数；    
           String[] columnStr = new String[columnCount];    
           for (int i = 1; i <= columnCount; i++) {    
               columnStr[i - 1] = rsmd.getColumnName(i).toLowerCase();

               // 都转换为小写    
           }    
           rst = pst.executeQuery();    

           while (rst.next()) {    
                String[] tempObject = new String[columnCount];    
                for (int i = 0; i < columnCount; i++) {    
                     tempObject[i] = rst.getObject(columnStr[i]) == null ? ""    
: rst.getObject(columnStr[i]).toString();

                     // 如果key和value任意一个为null，均会抛出异常    
                }    
                l.add(tempObject);    
           }    
           if (l.size() < 1)    
           l = null;    
     } catch (SQLException e) {    
            log.error(sql + "语句查询出错！", e);    
            return null;    
     } finally {    
            closeAll(rst, pst, conn);    
     }    
     return l;    
}    

 

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不知道你是不是这个意思：

public class Test {    

        public static Map<String,User> searchAllUser(String sql){    
                Map<String,User> users = new HashMap<String,User>();    
                User user = new User();    
                /**    
                 * 这里你可以这样写    
                 * List<User> users = new ArrayList<User>();    
                 * rst = pst.executeQuery();    
                 * while(rst.next()){    
                 * User user = new User();    
                 * user.setName(rst.getString("userName"));    
                 * users.put(user);    
                 * }    
                 * return users;    
                 *    
                 */    
                users.put("user",user);    
                return users;    
        }    
        
        public static List<User> getAllUser(){    
                Map<String,User> users = searchAllUser("select * from user");    
                List<User> allUsers = new ArrayList<User>();    
                for(int i = 0 ; i < users.size() ; i ++){    
                        allUsers.add(users.get(i));    
                }    
                return allUsers;    
        }    
        
        public static void main(String[] args) {    
                //在这里取List中的值    
                List<User> users = getAllUser();    
                for(User user : users){    
                        System.out.println(user.getName());    
                }    
        }    
}    

class User{    
        private String name;    

        public String getName() {    
                return name;    
        }    

        public void setName(String name) {    
                this.name = name;    
        }    
        
}    

这样就可以取到Map中的值：
for(Map.Entry<String, User> map : users.entrySet()){
            String key = map.getKey();//当前Map中的Key
            User value = map.getValue();//当前Map中的value
}