这是一个BMP解码器的练习，实现8位，24位真彩的解码，放在这里做个记录。希望对各位有用：（分为四个文件，大家可以下载压缩文件，不需要Ctrl+A）
package text;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import javax.swing.JFrame;
public class BMPopener extends JFrame{
private Graphics g;
public MenuBar creatMenuBar(){
MenuBar mB = new MenuBar();
//定义一个菜单
Menu mn1 = new Menu("文件");
MenuItem mn1_I2 = new MenuItem("打开");
ButtonListener bL = new ButtonListener();
mn1_I2.addActionListener(bL);
mn1.add(mn1_I2);
mB.add(mn1);
return mB;
}
public void showUI(){
this.setTitle("BMP打开器");
this.setSize(1024,768);
FlowLayout fl = new FlowLayout();
this.setLayout(fl);
MenuBar mB = this.creatMenuBar();
this.setMenuBar(mB);
this.setResizable(false);
this.setDefaultCloseOperation(3);
this.getContentPane().setBackground(Color.WHITE);
this.setVisible(true);
g = this.getGraphics();
g.setFont(new Font("黑体",12,48));
g.setColor(Color.red);
g.drawString("欢迎使用", this.getHeight()/2-100,this.getWidth()/2);
}
public void paint(){
super.paint(g);
g.drawString("欢迎使用", this.getHeight()/2-100,this.getWidth()/2);
}
public static void main(String args[]){
BMPopener bOpPopener = new BMPopener();
bOpPopener.showUI();
}
}
package text;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import javax.swing.JFileChooser;
public class ButtonListener implements ActionListener{
JFileChooser fileChooser = new JFileChooser();
File file;
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
fileChooser.showOpenDialog(null);
file= fileChooser.getSelectedFile();
String path = file.getAbsolutePath();
System.out.print(path);
JiemaBMP jBmp = new JiemaBMP(path);
jBmp.showJiema();
}
}
package text;
import java.awt.Color;
import java.awt.Graphics;
import java.io.DataInputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.IOException;
import javax.swing.JFrame;
public class JiemaBMP extends JFrame{
private String pathString;
private Graphics g;
private UserColor[][] userColors;
private int unith = 23;
private UserColor[] userTiaoseban;
public JiemaBMP(String path) {
this.pathString =path;
}
public void showJiema() {
// TODO Auto-generated method stub
try{
FileInputStream fis = new FileInputStream(pathString);
DataInputStream dis = new DataInputStream(fis);
if(dis.read()!= 'B'){
throw new IOException("Not a .BMP file");
}
if(dis.read()!='M'){
throw new IOException("Not a .BMP file");
}
//得到总大小
int fileSize = readInt(dis);
System.out.println("文件大小："+fileSize);
System.out.println(readUsignedShort(dis));
System.out.println(readUsignedShort(dis));
//读取偏移量
int bitmapOffset = readInt(dis);
//读取当前结构体的大小
System.out.println("bitmapOffset="+bitmapOffset);
int bitmapInfoSize = readInt(dis);
System.out.println("bitmapInfoSize"+bitmapInfoSize);
//读取宽高
int width = readInt(dis);
int height = readInt(dis);
System.out.println("width:"+width+"height:"+height);
//读Plants总是1
System.out.println(readUsignedShort(dis));
//读位数
int bitCount = readUsignedShort(dis);
System.out.println("bitCount"+bitCount);
//读取压缩方式
int compressionType = readInt(dis);
System.out.println("CompressionType:"+compressionType);
//读取图片大小
int imageSize = readInt(dis);
//读分辨率
readInt(dis);
readInt(dis);
//读位图使用的颜色数
int colorsUsed = readInt(dis);
int colorsImportant = readInt(dis);
System.out.println("[colorused]= "+colorsUsed);
// Read the pixels from the stream based on the compression type
if(compressionType ==0){
if(bitCount == 24||bitCount == 4){
readRGB24(width, height, dis);
}
if(bitCount == 8||bitCount == 1){
readRGB8(width, height, dis);
}
// if(bitCount == 4){
// readRGB4(width, height, dis);
// }
// if(bitCount == 1){
// readRGB1(width, height, dis);
// }
}
}catch(Exception e){
}
}
public void readRGB1(int width,int height,DataInputStream dis) throws IOException{
}
public void readRGB4(int width,int height,DataInputStream dis) throws IOException{
}
public void readRGB8(int width,int height,DataInputStream dis)throws IOException{
this.setTitle(pathString);
//设置一个大小
this.setSize(width,height+unith);
this.setResizable(false);
this.setVisible(true);
g = this.getGraphics();
userTiaoseban = new UserColor[256];
userColors = new UserColor[width][height];
for(int i = 0;i<256;i++){
int blue = dis.read();
int green = dis.read();
int red = dis.read();
dis.read();
userTiaoseban[i] = new UserColor(red, green, blue);
System.out.println("加了="+i);
}
//System.out.println(userTiaoseban[217].red+userTiaoseban[217].green);
//按行读取如果H,W为正则到这来
for(int h = height-1;h>=0;h--){
for(int w = 0;w<width;w++){
// Read in the red, green, and blue components
int num = dis.read();
userColors[w][h] = userTiaoseban[num];
if((userColors[w][h].red!=255)||(userColors[w][h].green!=255)||(userColors[w][h].blue!= 255)){
g.setColor(new Color(userColors[w][h].red,userColors[w][h].green,userColors[w][h].blue));
g.fillOval(w, h+unith, 1, 1);
}
}
}
}
public void readRGB24(int width,int height,DataInputStream dis)throws IOException{
this.setTitle(pathString);
//设置一个大小
this.setSize(width,height+unith);
this.setResizable(false);
this.setVisible(true);
g = this.getGraphics();
userColors = new UserColor[width][height];
//System.out.println(userTiaoseban[217].red+userTiaoseban[217].green);
//按行读取如果H,W为正则到这来
for(int h = height-1;h>=0;h--){
for(int w = 0;w<width;w++){
// Read in the red, green, and blue components
int blue = dis.read();
int green = dis.read();
int red = dis.read();
userColors[w][h] = new UserColor(red, green, blue);
if((userColors[w][h].red!=255)||(userColors[w][h].green!=255)||(userColors[w][h].blue!= 255)){
g.setColor(new Color(userColors[w][h].red,userColors[w][h].green,userColors[w][h].blue));
g.fillOval(w, h+unith, 1, 1);
}
}
}
}
//构造一个整数的方法
public final int readInt(DataInputStream dis) throws IOException{
int ch1 = dis.read();
int ch2 = dis.read();
int ch3 = dis.read();
int ch4 = dis.read();
if((ch1|ch2|ch3|ch4)<0)
throw new IOException();
return ((ch4<<24)+(ch3<<16)+(ch2<<8)+(ch1<<0));
}
//构造一个读2个字节整数的方法
public final int readUsignedShort(DataInputStream dis) throws IOException{
int ch1 = dis.read();
int ch2 = dis.read();
if((ch1|ch2)<0)
throw new EOFException();
return(ch2<<8)+(ch1<<0);
}
public final int disHH(int num){
return (num&8)>>3;
}
public final int disHL(int num){
return (num&4)>>2;
}
public final int disLH(int num){
return (num&2)>>1;
}
public final int disLL(int num){
return (num&1);
}
/*
* 定义一个将高位输出的方法(针对RGB4)
*/
public final int disH(int num){
return num>>4;
}
/*
* 定义一个将低位输出的方法(针对RGB4)
*/
public final int disL(int num){
int num1 = 15;
return num&num1;
}
//重写重绘方法
public void paint(Graphics g){
super.paint(g);
for(int h = userColors[0].length-1;h>=0;h--){
for(int w=0;w<userColors.length;w++){
if((userColors[w][h].red!=255)||(userColors[w][h].green!=255)||userColors[w][h].blue!=255){
g.setColor(new Color(userColors[w][h].red,userColors[w][h].green,userColors[w][h].blue));
g.fillOval(w, h+unith, 1, 1);
}
}
}
}
}
package text;
publicclass UserColor {
publicintred;
publicintgreen;
publicintblue;
public UserColor(int red,int green,int blue){
this.red = red;
this.green = green;
this.blue = blue;
}
}