如何获取sdcard的总容量

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >
    <Button
        android:id="@+id/bt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="获取容量"/>
    <TextView
        android:layout_marginTop="20dp"
        android:layout_below="@id/bt"
        android:textSize="20sp"
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

</RelativeLayout>

MainActivity.java

package com.example.sdcard;

import java.io.File;

import android.os.Bundle;
import android.os.Environment;
import android.os.StatFs;
import android.app.Activity;
import android.text.format.Formatter;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;

public class MainActivity extends Activity implements OnClickListener{

    private TextView tv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv = (TextView) findViewById(R.id.tv);
        findViewById(R.id.bt).setOnClickListener(this);
    }
    @Override
    public void onClick(View v) {
        File file=Environment.getExternalStorageDirectory();
        //sdcard的描述
        StatFs fs=new StatFs(file.getAbsolutePath());
        int blockCount=fs.getBlockCount();
        long blockSize=fs.getBlockSize();
        int availableBlocks=fs.getAvailableBlocks();
        //总容量
        long sdcardsize=blockSize*blockCount;
        //格式化
        String sdcardsizeStr=Formatter.formatFileSize(this, sdcardsize);
        tv.setText("sdcard的总容量:"+sdcardsizeStr);
    }
}