LWUIT 上使用List实现表格

本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！

      最近越来越多人用LWUIT，问得问题也越来越多了。最近超级多人问的是，如何使用List实现表格。以前我用Grid实现了表格(http://blog.csdn.net/hellogv/archive/2009/01/12/3759984.aspx ),现在就来说说如何使用List是一个表格。

      先来对比一下Grid表格与List表格：

Grid表格                                List表格

  

Grid表格与List表格所消耗的资源差不多，List所使用的结构和控件(都是Label)略多，但是Grid使用的是Button(衍生于Label,但是多很多方法和属性)，所以两者的运行速度都差不多，至于用哪个，就看你喜欢了。

本文的源代码可以到这里下载：http://download.csdn.net/source/1792549

本文关键的两个文件是：Cls_CellList. java 和ListDemo.java, Cls_CellList. java 封装了本文所用的List,而 ListDemo.java则是演示使用，代码简单易明，一般人也能看懂，呵呵呵。

Cls_CellList. java主要使用了ListCellRenderer这个东西，源代码如下：

package com.sun.lwuit.uidemo; import com.sun.lwuit.Component; import com.sun.lwuit.Container; import com.sun.lwuit.Label; import com.sun.lwuit.List; import com.sun.lwuit.events.ActionListener; import com.sun.lwuit.layouts.BorderLayout; import com.sun.lwuit.layouts.BoxLayout; import com.sun.lwuit.list.ListCellRenderer; import com.sun.lwuit.plaf.Border; public class Cls_CellList { static public List createList(CellList[] celllist,int stringWidth,ActionListener lAListner) { List list = new List(celllist); list.getStyle().setBgTransparency(0); //开始显示List list.setListCellRenderer(new CellRenderer(celllist[0].getColumm().length,stringWidth)); //添加消息处理 list.addActionListener(lAListner); return list; } static public class CellRenderer extends Container implements ListCellRenderer { //初始化显示Columm每个字段的Label private Label[] lbColumm ; private Label focus = new Label(""); public CellRenderer(int size,final int stringWidth) { lbColumm = new Label[size]; setLayout(new BorderLayout()); Container cnt = new Container(new BoxLayout(BoxLayout.X_AXIS)); for(int i=0;i<lbColumm.length;i++)//定义显示Columm每个字段的Label { lbColumm[i]=new Label(){ //很多人都问怎么setWidth平时没什么用，这是因为setWidth必须在重载的时候使用，LWUIT奇怪的地方之一！ public void setWidth(int arg0) { super.setWidth(stringWidth); } }; lbColumm[i].getStyle().setFgColor(getStyle().getFgSelectionColor());//设置为最亮的颜色 lbColumm[i].getStyle().setBgTransparency(0);//设置背景为透明，不然会遮挡focus影响外观 cnt.addComponent(lbColumm[i]); } addComponent(BorderLayout.CENTER, cnt); focus.getStyle().setBgTransparency(255); focus.getStyle().setBorder(Border.createRoundBorder(10, 10)); } public Component getListCellRendererComponent(List list, Object value, int index, boolean isSelected) { CellList cellList = (CellList) value; for(int i=0;i<lbColumm.length;i++) { lbColumm[i].setText(cellList.getColumm()[i]); } return this; } public Component getListFocusComponent(List list) { //Columm栏不具备选中事件 if(list.getSelectedIndex()>0) return focus; return null; } } static public class CellList { //保存该列的所有字段 private String[] lstColumm; public CellList(String[] columm) { //复制数组 lstColumm=new String[columm.length]; System.arraycopy(columm, 0, lstColumm, 0, lstColumm.length); } //返回该列 public String[] getColumm(){ return lstColumm; } } }

ListDemo.java源代码如下：

/* * Copyright ?2008 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. * */ package com.sun.lwuit.uidemo; import com.sun.lwuit.Command; import com.sun.lwuit.Font; import com.sun.lwuit.Form; import com.sun.lwuit.List; import com.sun.lwuit.events.ActionEvent; import com.sun.lwuit.events.ActionListener; import com.sun.lwuit.layouts.BorderLayout; public class ListDemo implements ActionListener { public Form form = new Form("ListDemo"); private Command backCommand = new Command("Back", 1); private String[][] myList = { {" 标题1 "," 标题2 "," 标题3 "," 标题4 "},//表格每个字段的显示长度由标题栏的最长一项决定 {"aaaaa","bbbbb","ccccc","ddddd"}, {"11111","222222","33333","444444"}, {"aaaaa","bbbbb","ccccc","ddddd"}, {"11111","222222","33333","444444"}, {"aaaaa","bbbbb","ccccc","ddddd"}, {"11111","222222","33333","444444"}, {"aaaaa","bbbbb","ccccc","ddddd"}, {"11111","222222","33333","444444"} }; ListDemo(){ form.setLayout(new BorderLayout()); form.addCommand(backCommand); form.setScrollable(true); //定义列表的列数 Cls_CellList.CellList[] cellArray = new Cls_CellList.CellList[myList.length]; for (int i = 0; i < cellArray.length; i++) { cellArray[i] = new Cls_CellList.CellList(myList[i]); } //取得Columm的标题栏中长度最大的一项 int stringWidth=0; for(int i=0;i<myList[0].length;i++) { int size=Font.getDefaultFont().stringWidth(myList[0][i])+8;//给最长的字段留点空余 if(stringWidth<size) stringWidth=size; } //构造list并且显示 form.addComponent(BorderLayout.CENTER,Cls_CellList.createList(cellArray,stringWidth,new ListActionListener())); form.setCommandListener(this); } public void actionPerformed(ActionEvent arg0) { Command command=arg0.getCommand(); if(command==backCommand) UIDemoMIDlet.backToMainMenu(); } //按下列表触发的事件 private class ListActionListener implements ActionListener { public void actionPerformed(ActionEvent evt) { int selectIndex=((List)evt.getSource()).getSelectedIndex(); String str=""; for(int i=0;i<myList[selectIndex].length;i++) str=str+myList[selectIndex][i]+"_"; form.setTitle(str); } } }