根据文件的类型，调用系统内对应的activity打开相应的文件
private void openFile(File file)
{
Intent intent = new Intent();
//设置这个intent的activity的运行跳转方式：将Activity放到一个新的Task中
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
//设置intent Action 属性
//ACTION_VIEW：用于显示用户的数据。比较通用，会根据用户的数据类型打开相应的Activity
intent.setAction(android.content.Intent.ACTION_VIEW);
//设置当前文件的Uri和文件类型，以方便条用系统内的相应activity
intent.setDataAndType(Uri.fromFile(file), getMIMEType(file));
startActivity(intent);
}
//获取文件类型
private String getMIMEType(File file)
{
String type = "";
String fileName = file.getName();
//取出文件后缀名并转成小写
String fileEnds = fileName.substring(fileName.lastIndexOf(".")+1,fileName.length()).toLowerCase();
//音频文件
if(fileEnds.equals("m4a")||fileEnds.equals("mp3")||fileEnds.equals("mid")||fileEnds.equals("xmf")||fileEnds.equals("ogg")||fileEnds.equals("wav"))
{
type = "audio/*";// 系统将列出所有可能打开音频文件的程序选择器
}
else if(fileEnds.equals("3gp")||fileEnds.equals("mp4"))
{//视频文件，此处不全，可以根据下面的媒体类型表自行扩充
type = "video/*";// 系统将列出所有可能打开视频文件的程序选择器
}
else if(fileEnds.equals("jpg")||fileEnds.equals("gif")||fileEnds.equals("png")||fileEnds.equals("jpeg")||fileEnds.equals("bmp"))
{//图像文件
type = "image/*";// 系统将列出所有可能打开图片文件的程序选择器
}
else
{
type = "*/*"; // 系统将列出所有可能打开该文件的程序选择器
}
return type;
}
MIME类型:Multipurpose Internet Mail Extensions:互联网媒体类型
内容类型（Content-Type），这个头部领域用于指定消息的类型。一般以下面的形式出现。
Content-Type: [type]/[subtype]; parameter
type有下面的形式。
- Text：用于标准化地表示的文本信息，文本消息可以是多种字符集和或者多种格式的；
- Multipart：用于连接消息体的多个部分构成一个消息，这些部分可以是不同类型的数据；
- Application：用于传输应用程序数据或者二进制数据；
- Message：用于包装一个E-mail消息；
- Image：用于传输静态图片数据；
- Audio：用于传输音频或者音声数据；
- Video：用于传输动态影像数据，可以是与音频编辑在一起的视频数据格式。
subtype用于指定type的详细形式。content-type/subtype配对的集合和与此相关的参数，将随着时间而增长。
private final String[][] MIME_MapTable={
//{后缀名，MIME类型}
{".3gp", "video/3gpp"},
{".apk", "application/vnd.android.package-archive"},
{".asf", "video/x-ms-asf"},
{".avi", "video/x-msvideo"},
{".bin", "application/octet-stream"},
{".bmp", "image/bmp"},
{".c", "text/plain"},
{".class", "application/octet-stream"},
{".conf", "text/plain"},
{".cpp", "text/plain"},
{".doc", "application/msword"},
{".docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document"},
{".xls", "application/vnd.ms-excel"},
{".xlsx", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"},
{".exe", "application/octet-stream"},
{".gif", "image/gif"},
{".gtar", "application/x-gtar"},
{".gz", "application/x-gzip"},
{".h", "text/plain"},
{".htm", "text/html"},
{".html", "text/html"},
{".jar", "application/java-archive"},
{".java", "text/plain"},
{".jpeg", "image/jpeg"},
{".jpg", "image/jpeg"},
{".js", "application/x-javascript"},
{".log", "text/plain"},
{".m3u", "audio/x-mpegurl"},
{".m4a", "audio/mp4a-latm"},
{".m4b", "audio/mp4a-latm"},
{".m4p", "audio/mp4a-latm"},
{".m4u", "video/vnd.mpegurl"},
{".m4v", "video/x-m4v"},
{".mov", "video/quicktime"},
{".mp2", "audio/x-mpeg"},
{".mp3", "audio/x-mpeg"},
{".mp4", "video/mp4"},
{".mpc", "application/vnd.mpohun.certificate"},
{".mpe", "video/mpeg"},
{".mpeg", "video/mpeg"},
{".mpg", "video/mpeg"},
{".mpg4", "video/mp4"},
{".mpga", "audio/mpeg"},
{".msg", "application/vnd.ms-outlook"},
{".ogg", "audio/ogg"},
{".pdf", "application/pdf"},
{".png", "image/png"},
{".pps", "application/vnd.ms-powerpoint"},
{".ppt", "application/vnd.ms-powerpoint"},
{".pptx", "application/vnd.openxmlformats-officedocument.presentationml.presentation"},
{".prop", "text/plain"},
{".rc", "text/plain"},
{".rmvb", "audio/x-pn-realaudio"},
{".rtf", "application/rtf"},
{".sh", "text/plain"},
{".tar", "application/x-tar"},
{".tgz", "application/x-compressed"},
{".txt", "text/plain"},
{".wav", "audio/x-wav"},
{".wma", "audio/x-ms-wma"},
{".wmv", "audio/x-ms-wmv"},
{".wps", "application/vnd.ms-works"},
{".xml", "text/plain"},
{".z", "application/x-compress"},
{".zip", "application/x-zip-compressed"},
{"", "*/*"}
};