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HandSoft — Wed, 04 Jul 2007 14:17:00 GMT

instanceof 是Java的一个二元操作符,�?=, > , < 是同一�c�M��? �׃��它是由字母组成的,所以也是Java的保留关键字. 它的作用是测试它左边的对象是否是它右边的�cȝ��实例, �q�回boolean�c�d��的数据。例�Q?br>      String s = "I an an Object!";
      boolean isObject = s instanceOf Object;
我们声明了一个String对象引用, 指向一个String 对象, 然后用instanceof 来测试它所指向的对象是否是Object�cȝ��一个实�? 昄��, �q�是真的, 所以返回true,也就是isObject的��gؓTrue.
      instanceof有一些用�? 比如我们写了一个处理帐单的�pȝ��, 其中有这样三个类�Q?br>      public class Bill{//省略�l�节}
      public class PhoneBill extends Bill {//省略�l�节}
      public class GasBill extends Bill {//省略�l�节}
在处理程序里有一个方�? 接受一个Bill�c�d��的对�? 计算金额. 假设两种帐单计算�Ҏ��不同, 而传入的Bill对象可能是两�U�中的�Q何一�U? 所以要用instanceof来判断：
      public double calculate(Bill bill){
             if(bill instanceof PhoneBill){
                   //计算电话帐单
             }
             if(bill instanceof GasBill){
                  //计算煤气帐单
             }
             ...
      }
�q�样��可以用一个方法处理两�U�子�c?
然�? �q�种做法通常被认为是没有好好利用面向对象中的多态�? 其实上面的功能要求用�Ҏ��重蝲完全可以实现, �q�是面向对象�~�成应有的做�? 避免回到�l�构化编�E�模�? 只有提供两个名字和返回值都相同, 接受参数�c�d��不同的方法就可以�?
      public double calculate(PhoneBill bill){
           //计算电话帐单
      }
       public double calculate(GasBill bill){
          //计算燃气帐单
       }
所�? 使用instanceof在绝大多数情况下�q�不是推荐的做法, 应当好好利用多�?

HandSoft 2007-07-04 22:17 发表评论

PL/SQL �E�序包结构优化_1

HandSoft — Wed, 04 Jul 2007 09:16:00 GMT

PL/SQL�E�序包中�Q?br>�Ҏ��一�Q?br> 包头�Q?br> create or replace package XXXX_X_XXX_PKG is

                   PROCEDURE   A(errbuf           OUT VARCHAR2,
                            retcode                   OUT    VARCHAR2,
                            p_1                        IN    VARCHAR2,
                            p_2                        IN    NUMBER);

           end XXXX_X_XXX_PKG ;

注：包头中声明一个Procedure, 包体中声明一个主Procedure(例如: A),多个从Procedure(一般是些共用方�?(例如�Q�B), 注意包体中Procedure实现�ơ序�Q�应先声明B ,
在A�q�程里，可以调用B.

�Ҏ��?
      包头:
      create or replace package   XXXX_X_XXX_PKG    is

                   PROCEDURE    A(errbuf           OUT VARCHAR2,
                            retcode                   OUT    VARCHAR2,
                            p_1                        IN    VARCHAR2,
                            p_2                        IN    NUMBER);

                   PROCEDURE    B( retcode          OUT    VARCHAR2,
                            p_1                        IN    VARCHAR2,);

end XXXX_X_XXX_PKG ;
包体�?此时A可以直接引用B,不论实现�ơ序.

HandSoft 2007-07-04 17:16 发表评论

HandSoft — Fri, 29 Jun 2007 06:49:00 GMT

procedure

begin
BEGIN
    SELECT attribute5
           INTO l_list_name
    FROM   qp_list_headers_all
    WHERE list_header_id = p_list_header_id ;
exception
    when others then
      raise targetListNameError;
end;
exception

    WHEN targetListNameError THEN
      -- fnd_file.put_line(fnd_file.output , rpad(upload_list.item_number,20,' ')
      --                                      ||'Start date should later than the current latest effective start data of the target price list.');      --此信息输出到EBS�q�_��中View Output中。fnd_file.log: 输出到Log�?br>      dbms_output.put_line('Target List is Null!');            --注意: 此信息用于输出到PL/SQL Developer控制��C��?br>END;

HandSoft 2007-06-29 14:49 发表评论

java复制对象属性org.apache.commons.beanutils.BeanUtils...用法感悟

HandSoft — Wed, 11 Apr 2007 02:40:00 GMT

在Strut�?实现table中复制一行的功能
line[j]是要复制的一�?Action中可以获取到要复制的行的ID.
因�ؓline[j]中有很多属�?要是一个一个的属性去get,然后set的话,代码量会
很大,而且会出现很多冗余代码�?br>�q�是我要复制出来的一�?br>if (j == rowId && !line[j].getNewRecord()) {
     rowList.add(line[j]);
     //��这一行全部复�?br>    }
现在要��得其中的某几个属性复制出来�ؓ�I?br>则需要一个一个的set,get.
if (j == rowId && !line[j].getNewRecord()) {
    CreateDeliveryLineRow cdlr = new CreateDeliveryLineRow  ();
    if(line[j].getMfgLot() != null){
         cdlr.setMfgLot = null;
   }
。。。。。�?br>     rowList.add(cdlr);
     //��这一行全部复�?br>    }

以下是比较好的解��x��?
利用apache的common�c�M��的BeanUtils来实现对象属性的复制
if (j == rowId && !line[j].getNewRecord()) {


      CreateDeliveryLineRow row = new CreateDeliveryLineRow();
      BeanUtils.copyProperties(row,line[j]);　　　//复制出对象line[j],��其属性赋予row
       row.setQuantity(null);                                     //在row中轻杄��实现�Ҏ��几个属性的控制
      row.setMfgLot(null);
      row.setMiniQuantity(null);
      row.setBoxQuantity(null);
      rowList.add(row);
      //rowList.add(cdr);
    }
===================================================
CreateDeliveryForm getForm = (CreateDeliveryForm) form;
。。。。。�?br>CreateDeliveryLineRow[] line = getForm.getLine();
if (line != null && line instanceof CreateDeliveryLineRow[]) {
   int size = line.length;

   for (int j = 0; j < size; j++) {
    if (!line[j].getNewRecord() && !line[j+1].getNewRecord()) {
     if (line[j].getBoxQuantity() == 0L) {
      line[j].setBoxQuantity(null);
     }
     if (line[j].getMiniQuantity() == 0L) {
      line[j].setMiniQuantity(null);
     }
     if (line[j].getQuantity() == 0D) {
      line[j].setQuantity(null);
     }
     rowList.add(line[j]);
    }
    if (j == rowId && !line[j].getNewRecord()) {


      CreateDeliveryLineRow row = new CreateDeliveryLineRow();
      BeanUtils.copyProperties(row,line[j]);
      row.setQuantity(null);
      row.setMfgLot(null);
      row.setMiniQuantity(null);
      row.setBoxQuantity(null);
       rowList.add(row);
      //rowList.add(cdr);
    }

}
}

。。。。。�?br>request.setAttribute("results", rowList);

HandSoft 2007-04-11 10:40 发表评论

Dwr---example

HandSoft — Sun, 21 Jan 2007 15:35:00 GMT

1. 在web.xml文�g中注册dwr

    dwr-invoker
    DWR Servlet
    Direct Web Remoter Servlet
    uk.ltd.getahead.dwr.DWRServlet

        debug
        true


    dwr-invoker
    /dwr/*

    search.jsp

2.dwr.xml










3.DB
CREATE TABLE APARTMENTS (id INTEGER, bedrooms INTEGER, bathrooms INTEGER, price INTEGER, address VARCHAR, city VARCHAR, province VARCHAR);
INSERT INTO APARTMENTS VALUES (16001, 1, 1, 850, '123 King St. East', 'Toronto', 'ON');
INSERT INTO APARTMENTS VALUES (16002, 2, 1, 1000, '1023 Yonge Ave.', 'Toronto', 'ON');
INSERT INTO APARTMENTS VALUES (16003, 2, 2, 1050, '27 Winchester St.', 'Toronto', 'ON');
4.Apertment.java
普通的javabean
5.DBUtils.java
   数据库链接类
   public class DBUtils {

/*
* Creates the sample data (table and records).
*/
public static void setupDatabase(BufferedReader reader) {
  Connection c = null;
  Statement stmt = null;
  try {
   c = openConnection();
   stmt = c.createStatement();
   // reads the file with the SQL statements
   String line;
   while ((line = reader.readLine()) != null) {
    stmt.execute(line);
   }
   stmt.close();
   c.close();
  } catch (IOException e) {
   e.printStackTrace();
  } catch (SQLException e) {
   e.printStackTrace();
  } finally {
   try {
    stmt.close();
    c.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }
}

/*
* Opens a database connection.
*/
public static Connection openConnection() throws SQLException {
  Connection c = DriverManager.getConnection("jdbc:hsqldb:mem:dwr-sample", "sa", "");
  return c;
}

}

6.ContextListener.java
   实现了ServletContextListerer接口的类
   public class ContextListener implements javax.servlet.ServletContextListener {

/**
* This method is invoked when the Web Application has been removed and is
* no longer able to accept requests.
* @param event
*/
public void contextDestroyed(ServletContextEvent event) {
}

/**
* This method is invoked when the Web Application is ready to service requests.
* @param event
*/
public void contextInitialized(ServletContextEvent event) {
  try {
   // load the driver
   Class.forName("org.hsqldb.jdbcDriver");
   // create the table and add sample data
   InputStreamReader in = new InputStreamReader(getClass().getClassLoader().getResourceAsStream("db.sql"));
   BufferedReader reader = new BufferedReader(in);
   DBUtils.setupDatabase(reader);
  } catch (ClassNotFoundException e) {
   e.printStackTrace();
  }

}

}
7.ApartmentDAO.java
   业务逻辑�?br />   public class ApartmentDAO {

/**
* Returns the available apartments based on the search criteria.
* @param bedrooms minimum number of bedrooms
* @param bathrooms minimum number of bathrooms
* @param price maximum price to be paid
* @return
*/
public Collection findApartments(int bedrooms, int bathrooms, int price) {
  Collection list = new Vector();
  String sql = "select * from APARTMENTS" +
    createSearchWhereClause(bedrooms, bathrooms, price) +
    "order by bedrooms, bathrooms, price";

  // define db variables
  Connection c = null;
  Statement stmt = null;
  try {
   c = DBUtils.openConnection();
   stmt = c.createStatement();
   // just run the sql statement
   ResultSet rs = stmt.executeQuery(sql);
   while(rs.next()) {
    Apartment apartment = this.getApartment(rs);
    list.add(apartment);
   }
  } catch (SQLException e) {
   e.printStackTrace();
  } finally {
   try {
    stmt.close();
    c.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }

  return list;
}

/**
* Returns the number of available apartments based on the search criteria.
* @param bedrooms minimum number of bedrooms
* @param bathrooms minimum number of bathrooms
* @param price maximum price to be paid
* @return
*/
public int countApartments(int bedrooms, int bathrooms, int price) {
  String sql = "select count(*) as total from APARTMENTS" + createSearchWhereClause(bedrooms, bathrooms, price);
  int numberApartments = -1;
  // define db variables
  Connection c = null;
  Statement stmt = null;
  try {
   c = DBUtils.openConnection();
   stmt = c.createStatement();
   // just run the sql statement
   ResultSet rs = stmt.executeQuery(sql);
   if (rs.next()) {
    numberApartments = rs.getInt("total");
   }
  } catch (SQLException e) {
   e.printStackTrace();
  } finally {
   try {
    stmt.close();
    c.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }

  return numberApartments;
}

/**
* Creates a Unit object from the database.
* @param rs
* @return
* @throws SQLException
*/
private Apartment getApartment(ResultSet rs) throws SQLException {
  Apartment ap = new Apartment();
  ap.setId(rs.getInt("id"));
  ap.setAddress(rs.getString("address"));
  ap.setBedrooms(rs.getInt("bedrooms"));
  ap.setBathrooms(rs.getInt("bathrooms"));
  ap.setPrice(rs.getInt("price"));
  ap.setCity(rs.getString("city"));
  ap.setProvince(rs.getString("province"));
  return ap;
}

/**
* Creates the where clause for the search SQL statement.
* @param bedrooms
* @param bathrooms
* @param price
* @return
*/
private String createSearchWhereClause(int bedrooms, int bathrooms, int price) {
  String where = " where bedrooms >= " + bedrooms +
    " and bathrooms >= " + bathrooms +
    " and price < " + price;
  return where;
}

}
8. search.jsp

DWR Example

Find an apartment to rent

City	Toronto
Beds
Baths
Price
Available apartments:

Results

Id	Address	Beds	Baths	Price

�׃��目需�?需在我们现有的struts、hibernate工程上集成ajax功能.��目�l�决定��用Dwr.
刚开始研�I�Dwr.觉得真的很不�? 只需很少量的代码,��p��在现有的工程上集成ajax技�? 期待Dwr有更辉煌的明天！
喜欢Dwr技术的IT界朋友可以与本�h联系�Q�望提出好的意见与徏�?

HandSoft 2007-01-21 23:35 发表评论