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Java实现的图像查看器完整实例

2019年07月22日  | 移动技术网IT编程  | 我要评论

本文实例讲述了java实现的图像查看器。分享给大家供大家参考。具体如下：

1. mycanvas.java：

package pictureviewer;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
public class mycanvas extends canvas implements componentlistener{
  private bufferedimage bi;
  private image im;
  private int image_width;
  private int image_height;
  public void setimage(bufferedimage bi){
    this.bi = bi;
    this.zoom();
  }
  public void paint(graphics g){
    g.drawimage(im,(this.getwidth()-image_width)/2,(this.getheight()-image_height)/2,this);
  }
  public void componentresized(componentevent e){
    if(bi != null){
      system.out.println("resize!!");
      this.zoom();
      this.repaint();
    }
  }
  public void componentmoved(componentevent e){}
  public void componentshown(componentevent e){}
  public void componenthidden(componentevent e){}
  public void zoom(){
    if(bi == null)
      return;
    int screen_width = this.getwidth();
    int screen_height = this.getheight();
    double screen_proportion = 1.0 * screen_height / screen_width;
    system.out.println("screen: w "+screen_width+" ,h "+screen_height+" ,p0 "+screen_proportion);
    image_width = bi.getwidth(this);
    image_height = bi.getheight(this);
    double image_proportion = 1.0 * image_height / image_width;
    system.out.println("image: w "+image_width+" ,h "+image_height+" ,p1 "+image_proportion);
    if(image_proportion > screen_proportion){
      image_height = screen_height;
      image_width = (int)(image_height / image_proportion);  
      system.out.println(" p1>p0 w= "+image_width);
    }else{
      image_width = screen_width;
      image_height = (int)(image_width * image_proportion);  
      system.out.println(" p0>p1 h= "+image_height);
    }
    im = bi.getscaledinstance(image_width,image_height,image.scale_smooth);
  }
}

2. myfilter.java：

package pictureviewer;
import java.io.file;
import java.io.filenamefilter;
public class myfilter implements filenamefilter{
  private string[] extension;  
  public myfilter(){
    extension = new string[]{".jpg", ".jpg", ".gif", ".gif", ".png", ".png", ".jpeg", ".jpeg"}; 
  }
  public myfilter(string[] extension){
    this.extension = extension; 
  }
  public boolean accept(file dir,string name){
    for(string s : extension){
      if(name.endswith(s)){
        return true;
      }
    }  
    return false; 
  }  
}

3. pictureviewer.java：

package pictureviewer;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
public class pictureviewer implements actionlistener{
  private frame frame;
  private mycanvas mc ;
  private string fpath;
  private string fname;
  private file[] files;
  private int findex ;
  private filedialog fd_load; 
  private myfilter filter;
  private button previous ;
  private button next ;
  public static void main( string args[]) throws exception {
    new pictureviewer().init();
  }
  public void init(){
    frame = new frame("pictureviewer");
    panel pb = new panel();
    button select = new button("选择图片");
    previous = new button("上一张");
    next = new button("下一张");
    select.addactionlistener(this);
    previous.addactionlistener(this);
    next.addactionlistener(this);
    pb.add(select);
    pb.add(previous);
    pb.add(next); 
    mc = new mycanvas();
    mc.setbackground(new color(200,210,230));
    mc.addcomponentlistener(mc);
    frame.add(pb,"north");
    frame.add(mc,"center");
    frame.setsize(360,360);
    frame.setlocation(400,200);
    frame.addwindowlistener(new windowadapter(){
      public void windowclosing(windowevent e){
        system.exit(0); 
      }  
    }); 
    frame.setvisible(true); 
    this.validatebutton();
    filter = new myfilter();
    fd_load = new filedialog(frame,"打开文件",filedialog.load);
    fd_load.setfilenamefilter(filter);
  }
  public void actionperformed(actionevent e){
    string command = e.getactioncommand();
    if(command.equals("选择图片")){
      fd_load.setvisible(true);
      fpath = fd_load.getdirectory();
      fname = fd_load.getfile();
      if((fpath != null) && (fname != null)){
        this.display(new file(fpath + fname)); 
        files = new file(fpath).listfiles(filter);
        this.setindex();
      }
    }else if(command.equals("上一张")){
      findex--;
      if(findex<0)
        findex = 0;
      this.display(files[findex]);
    }else if(command.equals("下一张")){
      findex++;
      if(findex >= files.length)
        findex = files.length-1;
      this.display(files[findex]);
    }
    this.validatebutton();
  }  
  public void display(file f){
    try{
      bufferedimage bi = imageio.read(f);
      mc.setimage(bi);
      frame.settitle("pictureviewer - [" + f.getname() + "]");
    }catch(exception e){
      e.printstacktrace();
    }
    mc.repaint();
  }
  public void setindex(){
    file current = new file(fpath + fname); 
    if(files != null){
      for(int i=0;i<files.length;i++){
        if(current.equals(files[i])){
          findex = i; 
        }
      }
    }
  }
  public void validatebutton(){
    previous.setenabled((files!=null) && (findex > 0));
    next.setenabled((files!=null) && (findex<(files.length-1))); 
  }
}

希望本文所述对大家的java程序设计有所帮助。

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