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[移动图书馆]在手持设备上一步一步实现Table(1)

王朝other·作者佚名  2006-12-27
窄屏简体版  字體: |||超大  

J2ME,J2EE,移动开发,移动企业开发,图书馆 在我开发移动图书馆过程中,由于要用到桌面程序中的表格UI,J2ME 高级界面API没有,就只好用低级API实现了,现在该Table的功能已经比较完善,我将通过几篇Blog,一步一步地把这个手持设备上使用的Table的源码共享给大家,希望对大家能有所用处。

我是借鉴Swing MVC的思想来实现这个Table组件的,包括一个TableModel接口和Table类。很明显,TableModel接口是Table数据模型,容纳Table要显示的数据,和与这些数据相关的getter方法供Table类使用。了解Swing Table的实现机制的朋友理解我的Table组件的思想应该没有任何问题,这里我也不想多做什么解释了,看代码吧,思想全都在里面。

下面代码一共有3个文件,一个主Midlet文件,推荐大家在NetBeans IDE中建工程,非常好用。

/*

* TableModel.java

*

* Created on 2006年7月2日, 下午3:53

*

* To change this template, choose Tools | Options and locate the template under

* the Source Creation and Management node. Right-click the template and choose

* Open. You can then make changes to the template in the Source Editor.

*/

package cn.edu.uestc.table;

/**

* <P>Returns the number of rows the model contains.

*/

public int getRowCount();

/**

* <P>Returns the text for the column header.

*/

public String getColumnHeaderText(int col);

/**

* <P>Returns whether column headers are displayed.

*/

public boolean hasColumnHeaders();

/**

* <P>Returns the value for the specified cell.

*/

public String getValueAt(int row,int col);

}

/*

* Table.java

*

* Created on 2006年7月2日, 下午3:55

*

* To change this template, choose Tools | Options and locate the template under

* the Source Creation and Management node. Right-click the template and choose

* Open. You can then make changes to the template in the Source Editor.

*/

package cn.edu.uestc.table;

import javax.microedition.lcdui.*;

/**

*

* @author pandaxiaoxi

*/

public class Table extends Canvas {

public static final int ORIENT_VERTICAL = 0;

public static final int ORIENT_HORIZONTAL = 1;

private TableModel model = null;

private Font font = Font.getDefaultFont();

private int columnWidth = 85;

private int orientation = ORIENT_VERTICAL; //每列竖直显示

private boolean separatorLines = true;

/**

* <P>Creates an instance with the associated model.

*/

public Table(TableModel model) {

if(null == model) {

throw new IllegalArgumentException("Cannot pass a null model to a table");

}

this.model = model;

}

public Table(){

}

public void setTableModel(TableModel model){

if(null == model) {

throw new IllegalArgumentException("Cannot pass a null model to a table");

}

this.model = model;

}

/**

* <P>Sets the column width

*/

public void setColumnWidth(int width) {

if(0 < width) {

columnWidth = width;

}

}

/**

* <P>Returns the column width.

*/

public int getColumnWidth() {

return columnWidth;

}

/**

* <P>Sets the table orientation.

*

* @param orient either <CODE>ORIENT_VERTICAL</CODE> or <CODE>ORIENT_HORIZONTAL</CODE>

*/

public void setOrientation(int orient) {

switch(orient) {

case ORIENT_VERTICAL:

case ORIENT_HORIZONTAL:

orientation = orient;

break;

default:

System.out.println("Invalid orientation!");

break;

}

}

/**

* <P>Returns the table orientation.

*/

public int getOrientation() {

return orientation;

}

/**

* <P>Toggles whether separator lines are used between rows and between columns.

*/

public void setSeparatorLines(boolean sep) {

separatorLines = sep;

}

/**

* <P>Returns whether separator lines are used.

*/

public boolean getSeparatorLines() {

return separatorLines;

}

public void paint(Graphics g) {

int width = getFullWidth(), height = getFullHeight();

// clear the background

g.setColor(255,255,255);

g.fillRect(0,0,width,height);

g.setColor(0,0,0);

// draw the border for the table

g.drawRect(0,0,width,height);

if(separatorLines) {

int vbars = 0;

int hbars = 0;

// determine how many vertical and horizontal bars to draw

switch(orientation) {

case ORIENT_VERTICAL:

vbars = model.getColumnCount();

hbars = model.getRowCount();

if(model.hasColumnHeaders()) hbars++;

break;

case ORIENT_HORIZONTAL:

vbars = model.getRowCount();

hbars = model.getColumnCount();

if(model.hasColumnHeaders()) vbars++;

break;

}

boolean flag = false;

// draw horizontal row with different color

for(int index = 0;index < hbars;index++) {

int y = index * getVerticalSpacing();

if(index == 0){

g.setColor(152, 152, 152);

g.fillRect(0,y, width-1,getVerticalSpacing());

continue;

}

if(flag){

g.setColor(215,215,215);

flag = false;

}else{

g.setColor(255,255,255);

flag = true;

}

g.fillRect(0,y, width-1,getVerticalSpacing());

}

g.setColor(70,95,182);

g.setColor(0,0,0);

// draw horizontal bars

for(int index = 0;index < hbars;index++) {

int y = index * getVerticalSpacing();

g.drawLine(0,y,width - 1,y);

}

// draw vertical bars

for(int index = 0;index < vbars;index++) {

//int x = index * getHorizontalSpacing();

int x = index * columnWidth;

g.drawLine(x,0,x,height - 1);

}

}

int rowOffset = 0; // used to flag whether headers are displayed

// if using column headers, let's show them first

if(model.hasColumnHeaders()) {

for(int col = 0;col < model.getColumnCount();col++) {

// the row should be -1 for this call

drawTableCell(g,0,col,model.getColumnHeaderText(col));

}

// set the row offset

rowOffset = 1;

}

// now draw each element of the table

for(int row = 0;row < model.getRowCount();row++) {

for(int col = 0;col < model.getColumnCount();col++) {

String value = model.getValueAt(row,col);

// now use the rowOffset to adjust if column headers were used

drawTableCell(g,row + rowOffset,col,value);

}

}

}

private void drawTableCell(Graphics g,int row,int col,String value) {

int valueSize = columnWidth - 4; // to make sure it fits in a column space

if(0 < valueSize) {

while(valueSize < font.stringWidth(value)) {

value = value.substring(0,value.length() - 1);

// if the string is now empty, just exit... we can't display it...

if(0 == value.length()) {

return;

}

}

int x = getXFor(row,col) + 1;

int y = getYFor(row,col) + 2;

g.drawString(value,x,y,Graphics.LEFT | Graphics.TOP);

}

}

private int getXFor(int row,int col) {

if(ORIENT_VERTICAL == orientation) {

return col * getHorizontalSpacing();

} else {

return row * getHorizontalSpacing();

}

}

private int getYFor(int row,int col) {

if(ORIENT_VERTICAL == orientation) {

return row * getVerticalSpacing();

} else {

return col * getVerticalSpacing();

}

}

private int getVerticalSpacing() {

return font.getHeight() + 3; // font height + 1 line above + 1 line below + 1 line for separator

}

private int getHorizontalSpacing() {

int rightBorder = getFullWidth() - 1;

if(ORIENT_VERTICAL == orientation) {

return rightBorder / model.getColumnCount();

} else {

return rightBorder / model.getRowCount();

}

}

// Scrollable interface

public int getFullWidth() {

int count = 0;

if(ORIENT_VERTICAL == orientation) {

count = model.getColumnCount();

} else {

count = model.getRowCount();

if(model.hasColumnHeaders()) count++;

}

return (count * columnWidth) + 1;

}

public int getFullHeight() {

int count = 0;

if(ORIENT_VERTICAL == orientation) {

count = model.getRowCount();

if(model.hasColumnHeaders()) count++;

} else {

count = model.getColumnCount();

}

return (getVerticalSpacing() * count) + 1;

}

public int getVerticalScrollAmount() {

return getVerticalSpacing();

}

public int getHorizontalScrollAmount() {

return getHorizontalSpacing();

}

public void render(Graphics g) {

paint(g);

}

}

/*

* TableDemo.java

*

* Created on 2006年7月2日, 下午3:59

*/

package cn.edu.uestc.table;

import javax.microedition.midlet.*;

import javax.microedition.lcdui.*;

/**

*

* @author pandaxiaoxi

* @version

*/

public class TableDemo extends MIDlet {

private Display display = null;

public void startApp() {

display = Display.getDisplay(this);

Table table = new Table(new TableModel(){

public int getColumnCount(){return 3;}

public int getRowCount(){return 5;}

public String getColumnHeaderText(int col){return Integer.toString(col)+"列";}

public boolean hasColumnHeaders(){return true;}

public String getValueAt(int row,int col){return Integer.toString(row)+"."+Integer.toString(col);}

});

display.setCurrent(table);

}

public void pauseApp() {

}

public void destroyApp(boolean unconditional) {

}

}

/**

*

* @author pandaxiaoxi

*/

public interface TableModel {

/**

* <P>Returns the number of columns the model contains.

*/

public int getColumnCount();

 
 
 
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