Android 开发笔记___SD卡基本操作

package com.example.alimjan.hello_world;

/**
 * Created by alimjan on 7/5/2017.
 */

        import android.annotation.TargetApi;
        import android.content.Context;
        import android.content.Intent;
        import android.os.Build;
        import android.os.Build.VERSION;
        import android.os.Bundle;
        import android.os.Environment;
        import android.support.v7.app.AppCompatActivity;
        import android.widget.TextView;

public class class__4_3_1 extends AppCompatActivity {

    private TextView tv_file_basic;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.code_4_3_1);
        tv_file_basic = (TextView) findViewById(R.id.tv_file_basic);
        getEnvironmentInfo();
    }

    @TargetApi(Build.VERSION_CODES.KITKAT)
    private void getEnvironmentInfo() {
        String desc = "系统环境（含SD卡）的信息如下：";
        desc = String.format("%s
　根目录路径：%s", desc,
                Environment.getRootDirectory().getAbsolutePath());
        desc = String.format("%s
　数据目录路径：%s", desc,
                Environment.getDataDirectory().getAbsolutePath());
        desc = String.format("%s
　下载缓存目录路径：%s", desc,
                Environment.getDownloadCacheDirectory().getAbsolutePath());
        desc = String.format("%s
　外部存储(即SD卡)目录路径：%s", desc,
                Environment.getExternalStorageDirectory().getAbsolutePath());
        desc = String.format("%s
　外部存储(即SD卡)状态：%s", desc,
                Environment.getExternalStorageState());
        desc = String.format("%s
　SD卡的相机目录路径：%s", desc,
                Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM));
        //DIRECTORY_DOCUMENTS是Android4.4.2（SDK19）及以上版本才有的常量
        //如果不做SDK版本判断，那么在低版本Android(例如4.2.2)上运行会报错
        //java.lang.NoSuchFieldError: android.os.Environment.DIRECTORY_DOCUMENTS
        if (VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            desc = String.format("%s
　SD卡的文档目录路径：%s", desc,
                    Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS));
        }
        desc = String.format("%s
　SD卡的下载目录路径：%s", desc,
                Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS));
        desc = String.format("%s
　SD卡的图片目录路径：%s", desc,
                Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES));
        desc = String.format("%s
　SD卡的视频目录路径：%s", desc,
                Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES));
        desc = String.format("%s
　SD卡的音乐目录路径：%s", desc,
                Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC));
        tv_file_basic.setText(desc);
    }

    public static void startHome(Context mcontext){
        Intent intent = new Intent(mcontext,class__4_3_1.class);
        mcontext.startActivity(intent);
    }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:focusable="true"
    android:focusableInTouchMode="true"
    android:orientation="vertical"
    android:padding="10dp" >

    <TextView
        android:id="@+id/tv_file_basic"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="@color/black"
        android:textSize="17sp" />

</LinearLayout>