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\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>