Conver.java 
package com.ll19.flv;
 
public class Conver {
 
    public void run() {
        try {
            // 转换并截图
            String filePath = "D:\\video\\old\\test.avi";
            ConverVideo cv = new ConverVideo(filePath);
            cv.beginConver();
 
            // 仅截图
            // ProcessFlvImg pfi = new ProcessFlvImg();
            // pfi.processImg("D:\\video\\old\\test.avi");
 
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
 
    public static void main(String args[]) {
        Conver c = new Conver();
        c.run();
    }
}

ConverVideo.java
package com.ll19.flv;
 
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
import java.util.List;
 
public class ConverVideo {
 
    private Date dt;
    private long begintime;
    private String PATH;
    private String filerealname; // 文件名 不包括扩展名
    private String filename; // 包括扩展名
    private String videofolder = "D:\\video\\other\\"; // 别的格式视频的目录
    private String flvfolder = "D:\\video\\flv\\"; // flv视频的目录
    private String ffmpegpath = "D:\\video\\FFmpeg\\bin\\ffmpeg.exe"; // ffmpeg.exe的目录
    private String mencoderpath = "D:\\video\\mencoder\\"; // mencoder的目录
    private String videoRealPath = "D:\\video\\flv\\"; // 截图的视频目录;
    private String imageRealPath = "D:\\video\\img\\"; // 截图的存放目录
 
    public ConverVideo() {
    }
 
    public ConverVideo(String path) {
        PATH = path;
    }
 
    public String getPATH() {
        return PATH;
    }
 
    public void setPATH(String path) {
        PATH = path;
    }
 
    public boolean beginConver() {
        File fi = new File(PATH);
        filename = fi.getName();
        filerealname = filename.substring(0, filename.lastIndexOf("."))
                .toLowerCase();
        System.out.println("----接收到文件(" + PATH
                + ")需要转换-------------------------- ");
        if (!checkfile(PATH)) {
            System.out.println(PATH + "文件不存在" + " ");
            return false;
        }
        dt = new Date();
        begintime = dt.getTime();
        System.out
                .println("----开始转文件(" + PATH + ")-------------------------- ");
        if (process()) {
            Date dt2 = new Date();
            System.out.println("转换成功 ");
            long endtime = dt2.getTime();
            long timecha = (endtime - begintime);
            String totaltime = sumTime(timecha);
            System.out.println("共用了:" + totaltime + " ");
            if (processImg()) {
                System.out.println("截图成功了 ");
            } else {
                System.out.println("截图不成功了 ");
            }
            PATH = null;
            return true;
        } else {
            PATH = null;
            return false;
        }
    }
 
    public boolean processImg() {
 
        List commend = new java.util.ArrayList();
        commend.add(ffmpegpath);
        commend.add("-i");
        commend.add(videoRealPath + filerealname + ".flv");
        commend.add("-y");
        commend.add("-f");
        commend.add("image2");
        commend.add("-ss");
        commend.add("38");
        commend.add("-t");
        commend.add("0.001");
        commend.add("-s");
        commend.add("320x240");
        commend.add(imageRealPath + filerealname + ".jpg");
        try {
            ProcessBuilder builder = new ProcessBuilder();
            builder.command(commend);
            builder.start();
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }
 
    private boolean process() {
        int type = checkContentType();
        boolean status = false;
        if (type == 0) {
 
            // status = processFLV(PATH);// 直接将文件转为flv文件
            status = processFLV(PATH);
        } else if (type == 1) {
            String avifilepath = processAVI(type);
            if (avifilepath == null)
                return false;
            // avi文件没有得到
            else {
                System.out.println("kaishizhuang");
                status = processFLV(avifilepath);// 将avi转为flv
            }
        }
        return status;
    }
 
    private int checkContentType() {
        String type = PATH.substring(PATH.lastIndexOf(".") + 1, PATH.length())
                .toLowerCase();
        // ffmpeg能解析的格式：（asx，asf，mpg，wmv，3gp，mp4，mov，avi，flv等）
        if (type.equals("avi")) {
            return 0;
        } else if (type.equals("mpg")) {
            return 0;
        } else if (type.equals("wmv")) {
            return 0;
        } else if (type.equals("3gp")) {
            return 0;
        } else if (type.equals("mov")) {
            return 0;
        } else if (type.equals("mp4")) {
            return 0;
        } else if (type.equals("asf")) {
            return 0;
        } else if (type.equals("asx")) {
            return 0;
        } else if (type.equals("flv")) {
            return 0;
        }
        // 对ffmpeg无法解析的文件格式(wmv9，rm，rmvb等),
        // 可以先用别的工具（mencoder）转换为avi(ffmpeg能解析的)格式.
        else if (type.equals("wmv9")) {
            return 1;
        } else if (type.equals("rm")) {
            return 1;
        } else if (type.equals("rmvb")) {
            return 1;
        }
        return 9;
    }
 
    private boolean checkfile(String path) {
        File file = new File(path);
        if (!file.isFile()) {
            return false;
        } else {
            return true;
        }
    }
 
    // 对ffmpeg无法解析的文件格式(wmv9，rm，rmvb等), 可以先用别的工具（mencoder）转换为avi(ffmpeg能解析的)格式.
    private String processAVI(int type) {
        List commend = new java.util.ArrayList();
        commend.add(mencoderpath);
        commend.add(PATH);
        commend.add("-oac");
        commend.add("mp3lame");
        commend.add("-lameopts");
        commend.add("preset=64");
        commend.add("-ovc");
        commend.add("xvid");
        commend.add("-xvidencopts");
        commend.add("bitrate=600");
        commend.add("-of");
        commend.add("avi");
        commend.add("-o");
        commend.add(videofolder + filerealname + ".avi");
        // 命令类型：mencoder 1.rmvb -oac mp3lame -lameopts preset=64 -ovc xvid
        // -xvidencopts bitrate=600 -of avi -o rmvb.avi
        try {
            ProcessBuilder builder = new ProcessBuilder();
            builder.command(commend);
            Process p = builder.start();
 
            doWaitFor(p);
            return videofolder + filerealname + ".avi";
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
 
    // ffmpeg能解析的格式：（asx，asf，mpg，wmv，3gp，mp4，mov，avi，flv等）
    private boolean processFLV(String oldfilepath) {
 
        if (!checkfile(PATH)) {
            System.out.println(oldfilepath + " is not file");
            return false;
        }
 
        List commend = new java.util.ArrayList();
        commend.add(ffmpegpath);
        commend.add("-i");
        commend.add(oldfilepath);
        commend.add("-ab");
        commend.add("64");
        commend.add("-acodec");
        commend.add("mp3");
        commend.add("-ac");
        commend.add("2");
        commend.add("-ar");
        commend.add("22050");
        commend.add("-b");
        commend.add("230");
        commend.add("-r");
        commend.add("24");
        commend.add("-y");
        commend.add(flvfolder + filerealname + ".flv");
        try {
            ProcessBuilder builder = new ProcessBuilder();
            String cmd = commend.toString();
            builder.command(commend);
            Process p = builder.start();
            doWaitFor(p);
            p.destroy();
            deleteFile(oldfilepath);
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }
 
    public int doWaitFor(Process p) {
        InputStream in = null;
        InputStream err = null;
        int exitValue = -1; // returned to caller when p is finished
        try {
            System.out.println("comeing");
            in = p.getInputStream();
            err = p.getErrorStream();
            boolean finished = false; // Set to true when p is finished
 
            while (!finished) {
                try {
                    while (in.available() > 0) {
                        Character c = new Character((char) in.read());
                        System.out.print(c);
                    }
                    while (err.available() > 0) {
                        Character c = new Character((char) err.read());
                        System.out.print(c);
                    }
 
                    exitValue = p.exitValue();
                    finished = true;
 
                } catch (IllegalThreadStateException e) {
                    Thread.currentThread().sleep(500);
                }
            }
        } catch (Exception e) {
            System.err.println("doWaitFor();: unexpected exception - "
                    + e.getMessage());
        } finally {
            try {
                if (in != null) {
                    in.close();
                }
 
            } catch (IOException e) {
                System.out.println(e.getMessage());
            }
            if (err != null) {
                try {
                    err.close();
                } catch (IOException e) {
                    System.out.println(e.getMessage());
                }
            }
        }
        return exitValue;
    }
 
    public void deleteFile(String filepath) {
        File file = new File(filepath);
        if (PATH.equals(filepath)) {
            if (file.delete()) {
                System.out.println("文件" + filepath + "已删除");
            }
        } else {
            if (file.delete()) {
                System.out.println("文件" + filepath + "已删除 ");
            }
            File filedelete2 = new File(PATH);
            if (filedelete2.delete()) {
                System.out.println("文件" + PATH + "已删除");
            }
        }
    }
 
    public String sumTime(long ms) {
        int ss = 1000;
        long mi = ss * 60;
        long hh = mi * 60;
        long dd = hh * 24;
 
        long day = ms / dd;
        long hour = (ms - day * dd) / hh;
        long minute = (ms - day * dd - hour * hh) / mi;
        long second = (ms - day * dd - hour * hh - minute * mi) / ss;
        long milliSecond = ms - day * dd - hour * hh - minute * mi - second
                * ss;
 
        String strDay = day < 10 ? "0" + day + "天" : "" + day + "天";
        String strHour = hour < 10 ? "0" + hour + "小时" : "" + hour + "小时";
        String strMinute = minute < 10 ? "0" + minute + "分" : "" + minute + "分";
        String strSecond = second < 10 ? "0" + second + "秒" : "" + second + "秒";
        String strMilliSecond = milliSecond < 10 ? "0" + milliSecond : ""
                + milliSecond;
        strMilliSecond = milliSecond < 100 ? "0" + strMilliSecond + "毫秒" : ""
                + strMilliSecond + " 毫秒";
        return strDay + " " + strHour + ":" + strMinute + ":" + strSecond + " "
                + strMilliSecond;
 
    }
}

[b]ProcessFlvImg.java[/b]

package com.ll19.flv;
 
import java.io.File;
import java.util.List;
 
public class ProcessFlvImg {
 
    public String ffmpegpath = "D:\\video\\FFmpeg\\bin\\ffmpeg.exe"; // ffmpeg.exe的目录
 
    public boolean processImg(String path) {
 
        File fi = new File(path);
 
        List commend = new java.util.ArrayList();
        commend.add(ffmpegpath);
        commend.add("-i");
        commend.add(path);
        commend.add("-y");
        commend.add("-f");
        commend.add("image2");
        commend.add("-ss");
        commend.add("38");
        commend.add("-t");
        commend.add("0.001");
        commend.add("-s");
        commend.add("320x240");
        commend.add(fi.getPath() + ".jpg");
 
        try {
            ProcessBuilder builder = new ProcessBuilder();
            builder.command(commend);
            builder.start();
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }
 
}