使用java获取歌曲的属性

今天使用java写了一个简单的android播放器，感觉还不错，就是向更加的完善一点上网搜索了一下获取音乐对象的属性，比如，作者，专辑，时间的大小。看到一个比较好的例子，贴出来给大家分享。

public class Mp3 {

 private SongInfo info = null;
 private RandomAccessFile ran = null;
 private File file = null;
 
 public Mp3() throws FileNotFoundException {
  file = new File("../MP3/music2/7 Years And 50 Days.mp3");
  ran = new RandomAccessFile(file, "r");
  System.out.println("文件装载完毕");

 }

 public static void main(String[] args) throws IOException {
  Mp3 read = new Mp3();
  byte[] buffer = new byte[128];

  read.ran.seek(read.ran.length() - 128);

  read.ran.read(buffer);
  SongInfo info = new SongInfo(buffer);
  System.out.println("name:" + info.getSongName() + " year:"
    + info.getYear() + " 歌手:" + info.getArtist() + " 专辑名:"
    + info.getAlbum() + " 备注:" + info.getComment());

 }

 
}

package Mp3;

public class SongInfo {

 private final String TAG = "TAG"; // 文件头1-3
 private String songName; // 歌曲名4-33
 private String artist; // 歌手名34-63
 private String album; // 专辑名61-93
 private String year; // 年94-97
 private String comment; // 备注98-125
 private byte r1, r2, r3; // 三个保留位126，127，128
 private boolean valid; // 是否合法
 public transient String fileName; // 此歌曲对应的文件名,没有封装

 public SongInfo(byte[] data) {
  if (data.length != 128) {
   throw new RuntimeException("数据长度不合法:" + data.length);
  }
  String tag = new String(data, 0, 3);
  // 只有前三个字节是TAG才处理后面的字节
  if (tag.equalsIgnoreCase("TAG")) {
   valid = true;
   songName = new String(data, 3, 30).trim();
   artist = new String(data, 33, 30).trim();
   album = new String(data, 63, 30).trim();
   year = new String(data, 93, 4).trim();
   comment = new String(data, 97, 28).trim();
   r1 = data[125];
   r2 = data[126];
   r3 = data[127];
  } else {
   valid = false;
  }
 }

 public SongInfo() {
 }

 /**
  * 返回是否合法
  *
  * @return 是否
  */
 public boolean isValid() {
  return valid;
 }

 /**
  * 得到此对象的128个字节的表示形式
  *
  * @return
  */
 public byte[] getBytes() {
  byte[] data = new byte[128];
  System.arraycopy(TAG.getBytes(), 0, data, 0, 3);
  byte[] temp = songName.getBytes();
  System.arraycopy(temp, 0, data, 3, temp.length > 30 ? 30 : temp.length);
  temp = artist.getBytes();
  System.arraycopy(temp, 0, data, 33, temp.length > 30 ? 30 : temp.length);
  temp = album.getBytes();
  System.arraycopy(temp, 0, data, 63, temp.length > 30 ? 30 : temp.length);
  temp = year.getBytes();
  System.arraycopy(temp, 0, data, 93, temp.length > 4 ? 4 : temp.length);
  temp = comment.getBytes();
  System.arraycopy(temp, 0, data, 97, temp.length > 28 ? 28 : temp.length);
  data[125] = r1;
  data[126] = r2;
  data[127] = r3;
  return data;
 }

 public String getArtist() {
  return artist;
 }

 public void setArtist(String authorName) {
  this.artist = authorName;
 }

 public String getComment() {
  return comment;
 }

 public void setComment(String comment) {
  this.comment = comment;
 }

 public byte getR1() {
  return r1;
 }

 public void setR1(byte r1) {
  this.r1 = r1;
 }

 public byte getR2() {
  return r2;
 }

 public void setR2(byte r2) {
  this.r2 = r2;
 }

 public byte getR3() {
  return r3;
 }

 public void setR3(byte r3) {
  this.r3 = r3;
 }

 public String getSongName() {
  return songName;
 }

 public void setSongName(String songName) {
  if (songName == null) {
   throw new NullPointerException("歌名不能是null!");
  }
  valid = true;
  this.songName = songName;
 }

 public String getAlbum() {
  return album;
 }

 public void setAlbum(String specialName) {
  this.album = specialName;
 }

 public String getYear() {
  return year;
 }

 public void setYear(String year) {
  this.year = year;
 }

}