1.FileFilter

package test;import java.io.File;import java.io.FileFilter;public class FileFilterTest implements FileFilter {            private String extension;        public FileFilterTest(String extension) {        this.extension = extension;    }    /**     *      */    @Override    public boolean accept(File pathname) {                    if(pathname.isDirectory()){            return false;        }                String name = pathname.getName();        int num = name.lastIndexOf(".");        if(num == -1){            return false;        }        if(name.length()-1 == num){            return false;        } else {                    return extension.equals(name.substring(num+1));        }    }            public static void main(String[] args) {                File path = new File("E:\\书籍\\java 编程");        //获得过滤对象        FileFilterTest ft = new FileFilterTest("pdf");                File[] files = path.listFiles(ft);                for (int i = 0; i < files.length; i++) {            System.out.println(files[i].getAbsolutePath());        }             }}

2.FilenameFilter

package test;import java.io.File;import java.io.FilenameFilter;public class FileNameFilterTest implements FilenameFilter {        //判断图片是否格式是否是 gif    private boolean isGif(String fileName){        if(fileName.toLowerCase().endsWith(".gif")){            return true;        } else {            return false;        }            }    //判断图片是否格式是否是 jpg    private boolean isJpg(String fileName){        if(fileName.toLowerCase().endsWith(".jpg")){            return true;        } else {            return false;        }            }    //判断图片是否格式是否是 png    private boolean isPng(String fileName){        if(fileName.toLowerCase().endsWith(".png")){            return true;        } else {            return false;        }            }            @Override    public boolean accept(File dir, String name) {        return (isGif(name)||isJpg(name)||isPng(name));    }        public static void main(String[] args) {        File path = new File("C:\\img");        //获得过滤对象        FileNameFilterTest ft = new FileNameFilterTest();                File[] f = path.listFiles(ft);                for (int i = 0; i < f.length; i++) {            File file = f[i];                        System.out.println(file.getAbsolutePath());                    }    }}