学步园

android  未提供获取外置SD储存卡的相应函数或方法，但我们可以自己写一个。当前只能用Environment.getExternalStorageDirectory()获取内置的SD卡路径，因为不同机型的系统SD卡的路径不相同，但是我们仍然可以有方法去获得外置SD卡的路径，  内置和外置SD卡的信息存在system/etc/vold.fstab 里面，我们可以从这里获得外置SD卡的路径，  这里面的内容就算在设备非ROOT的情况下也是可读的，所以这个方法值得一试：

本人写好了一个类，可供直接使用或参考：

Dev_MountInfo.class

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;

import com.snuabar.getmounteddevices.Dev_MountInfo.DevInfo;

import android.os.Environment;

public class Dev_MountInfo implements IDev {
	/**
	 * ***
	 */
	public final String HEAD = "dev_mount";
	public final String LABEL = "<label>";
	public final String MOUNT_POINT = "<mount_point>";
	public final String PATH = "<part>";
	public final String SYSFS_PATH = "<sysfs_path1...>";

	/**
	 * Label for the volume
	 */
	private final int NLABEL = 1;
	/**
	 * Partition
	 */
	private final int NPATH = 2;
	/**
	 * Where the volume will be mounted
	 */
	private final int NMOUNT_POINT = 3;
	private final int NSYSFS_PATH = 4;

	private final int DEV_INTERNAL = 0;
	private final int DEV_EXTERNAL = 1;

	private ArrayList<String> cache = new ArrayList<String>();

	private static Dev_MountInfo dev;
	private DevInfo info;

	private final File VOLD_FSTAB = new File(Environment.getRootDirectory()
			.getAbsoluteFile()
			+ File.separator
			+ "etc"
			+ File.separator
			+ "vold.fstab");

	public static Dev_MountInfo getInstance() {
		if (null == dev)
			dev = new Dev_MountInfo();
		return dev;
	}

	private DevInfo getInfo(final int device) {
		// for(String str:cache)
		// System.out.println(str);

		if (null == info)
			info = new DevInfo();

		try {
			initVoldFstabToCache();
		} catch (IOException e) {
			e.printStackTrace();
		}

		if (device >= cache.size())
			return null;
		String[] sinfo = cache.get(device).split(" ");

		info.setLabel(sinfo[NLABEL]);
		info.setMount_point(sinfo[NMOUNT_POINT]);
		info.setPath(sinfo[NPATH]);
		info.setSysfs_path(sinfo[NSYSFS_PATH]);

		return info;
	}

	/**
	 * init the words into the cache array
	 * @throws IOException
	 */
	private void initVoldFstabToCache() throws IOException {
		cache.clear();
		BufferedReader br = new BufferedReader(new FileReader(VOLD_FSTAB));
		String tmp = null;
		while ((tmp = br.readLine()) != null) {
			// the words startsWith "dev_mount" are the SD info
			if (tmp.startsWith(HEAD)) {
				cache.add(tmp);
			}
		}
		br.close();
		cache.trimToSize();
	}

	public class DevInfo {
		private String label, mount_point, path, sysfs_path;

		/**
		 * return the label name of the SD card
		 * @return
		 */
		public String getLabel() {
			return label;
		}

		private void setLabel(String label) {
			this.label = label;
		}

		/**
		 * the mount point of the SD card
		 * @return
		 */
		public String getMount_point() {
			return mount_point;
		}

		private void setMount_point(String mount_point) {
			this.mount_point = mount_point;
		}

		/**
		 * SD mount path
		 * @return
		 */
		public String getPath() {
			return path;
		}

		private void setPath(String path) {
			this.path = path;
		}

		/**
		 * "unknow"
		 * @return
		 */
		public String getSysfs_path() {
			return sysfs_path;
		}

		private void setSysfs_path(String sysfs_path) {
			this.sysfs_path = sysfs_path;
		}

	}

	@Override
	public DevInfo getInternalInfo() {
		return getInfo(DEV_INTERNAL);
	}

	@Override
	public DevInfo getExternalInfo() {
		return getInfo(DEV_EXTERNAL);
	}
}

interface IDev {
	DevInfo getInternalInfo();

	DevInfo getExternalInfo();
}

使用方法：

Dev_MountInfo dev = Dev_MountInfo.getInstance();
DevInfo info = dev.getInternalInfo();//Internal SD Card Informations
info = dev.getExternalInfo();//External SD Card Informations

//   Methods:
info.getLabel(); // SD 卡的名称
info.getMount_point();//SD 卡挂载点
info.getPath(); //SD 卡路径
info.getSysfs_path(); // ....没弄清楚什么意思

不能保证所有版本系统和机型都适合，暂时只用LG P990 2.3.7  和华硕 平板 4.0.3进行过测试，都可以成功获取外置SD卡路径，  若此方法在你的机型或系统中无法获取相应路径，请回复，good luck!

有另一种方法可以得到外置SD卡路径：

System.getenv(); // 返回的是一个map
Map<String, String> map = System.getenv();

//遍历出来可以看到最后一项是外置SD卡路径

Set<String> set = map.keySet();
    	Iterator<String> key = set.iterator();
    	while(key.hasNext())
    		Log.d("123", key.next());
    	
    	Collection<String> col = map.values();
    	Iterator<String> val = col.iterator();
    	while(val.hasNext())
    		Log.d("123", val.next());

//不同的机型获得的会有所不同，先试试！！