Android开发学习---如何写数据到外部存储设备(sd卡),Environment.getExternalStorageDirectory,怎么获取sd卡的大小?

本文主要介绍如何写数据到sd卡,这里主要到的技术是Environment中的方法.

1.

package com.amos.datasave;

import java.io.File;
import java.io.FileOutputStream;

import android.annotation.SuppressLint;
import android.content.Context;
import android.os.Environment;
import android.util.Log;
import android.widget.Toast;

@SuppressLint("WorldWriteableFiles")
public class savePasswordService {
private Context context;

private String tag = "savePasswordService";

public savePasswordService(Context context) {
this.context = context;
}

public void savePasswordToFile(String name, String password) {
// 这里设置文件的权限
String content = name + ":" + password;
Log.d(tag, "设置文件的读写权限");
try {
FileOutputStream fileOutput = context.openFileOutput("LoginTestConfig.txt", Context.MODE_WORLD_READABLE | Context.MODE_WORLD_WRITEABLE);
fileOutput.write(content.getBytes());
fileOutput.flush();
fileOutput.close();
} catch (Exception e) {
Log.d(tag, "设置文件的读写权限失败!");
e.printStackTrace();
}
}
//写数据到sdcard
public void savePasswordToSDCard(String name, String password) {
// android 2.1 /sdcard/xx.txt
// android 2.2 /mnt/sdcard/xx.txt
// self_define /excard/xx.txt

//        File externalStorageDirectory = Environment.getExternalStorageDirectory();
//        String path = externalStorageDirectory.getPath();
//        System.out.println("path:" + path);

// 要存储的内容
String content = name + ":" + password;

Log.d(tag, "检验sdcard是否可用?");
//判断sdcard是否存在?
if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
Log.d(tag, "sdcard不可用!");
Toast.makeText(context, "没有找到SDCard!", Toast.LENGTH_LONG);
return ;
};

try {
// File file = new File("/sdcard/qqpassword.txt");
// File file = new File(path + "/qqpassword2.txt");
File file = new File(Environment.getExternalStorageDirectory(), "/qqpassword2.txt");
FileOutputStream fos = new FileOutputStream(file);
fos.write(content.getBytes());
fos.flush();
fos.close();
} catch (Exception e) {
e.printStackTrace();
}

}

}

View Code
如何获取sdcard的大小?

StatFs statFs = new StatFs(Environment.getExternalStorageDirectory().getPath());
long blockSize = statFs.getBlockSize();
long blockCount = statFs.getBlockCount();
long sdCardSize = blockSize*blockCount;
Log.d(tag,""+sdCardSize );

这里使用的是Environment中的方法获取到sdcard的路径,然后将其路径通过StatFs类,该类主要获取指定文件路径下的文件信息(filesystem info).

获取其块大小,块数量.