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\n　根目录路径：%s", desc,

                 Environment.getRootDirectory().getAbsolutePath());

         desc = String.format("%s\n　数据目录路径：%s", desc,

                 Environment.getDataDirectory().getAbsolutePath());

         desc = String.format("%s\n　下载缓存目录路径：%s", desc,

                 Environment.getDownloadCacheDirectory().getAbsolutePath());

         desc = String.format("%s\n　外部存储(即SD卡)目录路径：%s", desc,

                 Environment.getExternalStorageDirectory().getAbsolutePath());

         desc = String.format("%s\n　外部存储(即SD卡)状态：%s", desc,

                 Environment.getExternalStorageState());

         desc = String.format("%s\n　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\n　SD卡的文档目录路径：%s", desc,

                     Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS));

         }

         desc = String.format("%s\n　SD卡的下载目录路径：%s", desc,

                 Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS));

         desc = String.format("%s\n　SD卡的图片目录路径：%s", desc,

                 Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES));

         desc = String.format("%s\n　SD卡的视频目录路径：%s", desc,

                 Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES));

         desc = String.format("%s\n　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>