SD卡操作【安卓8】

 1 private TextView tv;    
 2 private Button bt1;
 3 private Button bt2;     
 4 private EditText et;
 5 
 6 protected void onCreate(Bundle savedInstanceState) {
 7         super.onCreate(savedInstanceState);
 8         setContentView(R.layout.xml文件);
 9         et = (EditText) findViewById(R.id.sdET);
10         tv = (TextView) findViewById(R.id.sdTV);
11         bt1 = (Button) findViewById(R.id.sdBT01);
12         bt2 = (Button) findViewById(R.id.sdBT02);
13         bt1.setOnClickListener(this);
14         bt2.setOnClickListener(this);
15     }
16 
17 public void onClick(View v) {
18         if (!Environment.getExternalStorageState().equals(
19                 Environment.MEDIA_MOUNTED)) {// 判断SD卡是否存在
20             Toast.makeText(Sd0.this, "SD卡不存在", 3000).show();
21             return;
22         }
23         switch (v.getId()) {
24         case R.id.sdBT01:
25             // 创建文件夹对象
26             File dir = new File(Environment.getExternalStorageDirectory(),"test");
27             if (!dir.exists()) { // 如果目录不存在，就创建
28                 dir.mkdir();
29             }
30             File file = new File(dir, "test.txt"); // 创建文件
31             PrintWriter pw;
32             try {
33                 pw = new PrintWriter(file);
34                 pw.println(et.getText().toString());
35                 pw.close();
36                 Toast.makeText(Sd0.this, "保存成功", 3000).show();
37             } catch (FileNotFoundException e) {
38                 e.printStackTrace();
39             }
40             break;
41         case R.id.sdBT02:
42             File f = new File(Environment.getExternalStorageDirectory()+
43                     "/test/test.txt");// 创建文件夹对象
44             BufferedReader br;
45             try {
46                 br = new BufferedReader(new InputStreamReader(new FileInputStream(f)));
47                 String str = null;
48                 while ((str = br.readLine()) != null) {
49                     tv.append(str);
50                 }
51             } catch (FileNotFoundException e) {
52                 e.printStackTrace();
53             } catch (IOException e) {
54                 e.printStackTrace();
55             }
56             break;
57         }
58 }