Android 文件存储－－内部存储的例子

Question

1）新建Android 项目，项目名称：DemoInternalStorage
2) 在继承于Activity的类中编写相应代码，代码如下所示：

1. /*
   
2. * Copyright (C) Mesada Technologies Co., Ltd. 2005-2010.
   
3. * All rights reserved.
   
4. *
   
5. * This software is the confidential and proprietary information
   
6. * of Mesada Technologies Co., Ltd. ("Confidential Information").
   
7. * You shall not disclose such Confidential Information and shall
   
8. * use it only in accordance with the terms of the license agreement
   
9. * you entered into with Mesada.
   
10. */
    
11. package com.mesada.demo;
    
12. 
    
13. import java.io.ByteArrayOutputStream;
    
14. import java.io.FileInputStream;
    
15. import java.io.FileOutputStream;
    
16. import java.io.IOException;
    
17. 
    
18. import android.app.Activity;
    
19. import android.content.Context;
    
20. import android.os.Bundle;
    
21. import android.text.Editable;
    
22. import android.text.TextWatcher;
    
23. import android.util.Log;
    
24. import android.view.View;
    
25. import android.view.View.OnClickListener;
    
26. import android.widget.Button;
    
27. import android.widget.EditText;
    
28. import android.widget.Toast;
    
29. 
    
30. /**
    
31. * This is a demo about file storage.
    
32. *
    
33. * @author Xiaolong Long
    
34. * @date 2010-12-30
    
35. * @version 1.0
    
36. */
    
37. public class MainActivity extends Activity implements OnClickListener {
    
38. private static final String TAG = "MainActivity";
    
39. private static final boolean mIsPrintInfo = true;
    
40. 
    
41. private static final String FILENAME = "temp.txt";
    
42. 
    
43. EditText mMsgView;
    
44. Button mSave;
    
45. Button mPrint;
    
46. Button mCancel;
    
47. 
    
48. boolean mIsLegal = false;
    
49. 
    
50. @Override
    
51. protected void onCreate(Bundle savedInstanceState) {
    
52. if (mIsPrintInfo)
    
53. Log.i(TAG, "onCreate()...");
    
54. 
    
55. super.onCreate(savedInstanceState);
    
56. setContentView(R.layout.main);
    
57. setupControlers();
    
58. 
    
59. mSave.setEnabled(false);
    
60. MsgTextWater msgTextWater = new MsgTextWater();
    
61. mMsgView.addTextChangedListener(msgTextWater);
    
62. 
    
63. mSave.setOnClickListener(this);
    
64. mPrint.setOnClickListener(this);
    
65. mCancel.setOnClickListener(this);
    
66. }
    
67. 
    
68. /**
    
69. *
    
70. * Find the views that were identified by the id attributes from the XML.
    
71. *
    
72. * @param
    
73. * @return
    
74. * @date 2010-12-30
    
75. * @author Xiaolong Long
    
76. */
    
77. private void setupControlers() {
    
78. if (mIsPrintInfo)
    
79. Log.i(TAG, "setupControlers()...");
    
80. 
    
81. mMsgView = (EditText) findViewById(R.id.msg);
    
82. mSave = (Button) findViewById(R.id.saveMsg);
    
83. mPrint = (Button) findViewById(R.id.printMsg);
    
84. mCancel = (Button) findViewById(R.id.cancel);
    
85. }
    
86. 
    
87. 
    
88. /**
    
89. *
    
90. * Find the views that were identified by the id attributes from the XML.
    
91. *
    
92. * @param
    
93. * @return
    
94. * @date 2010-12-30
    
95. * @author Xiaolong Long
    
96. */
    
97. private void setupControlers() {
    
98. if (mIsPrintInfo)
    
99. Log.i(TAG, "setupControlers()...");
    
100. 
     
101. mMsgView = (EditText) findViewById(R.id.msg);
     
102. mSave = (Button) findViewById(R.id.saveMsg);
     
103. mPrint = (Button) findViewById(R.id.printMsg);
     
104. mCancel = (Button) findViewById(R.id.cancel);
     
105. }
     
106. 
     
107. public void onClick(View v) {
     
108. if (mIsPrintInfo)
     
109. Log.i(TAG, "onClick()...");
     
110. 
     
111. // Returns this view's identifier.
     
112. int id = v.getId();
     
113. switch (id) {
     
114. case R.id.saveMsg:
     
115. try {
     
116. saveMsg();
     
117. Toast.makeText(MainActivity.this, R.string.success_write,
     
118. Toast.LENGTH_SHORT).show();
     
119. mMsgView.setText("");
     
120. } catch (IOException e) {
     
121. Log.e(TAG,
     
122. "failed to save the content to the file which called temp.txt",
     
123. e);
     
124. Toast.makeText(MainActivity.this, R.string.failed_write,
     
125. Toast.LENGTH_SHORT).show();
     
126. }
     
127. break;
     
128. case R.id.printMsg:
     
129. try {
     
130. mMsgView.requestFocus();
     
131. mMsgView.setText(getMsg());
     
132. } catch (IOException e) {
     
133. Log.e(TAG,
     
134. "failed to read a file from internal storage which called temp.txt",
     
135. e);
     
136. Toast.makeText(MainActivity.this, R.string.failed_read,
     
137. Toast.LENGTH_SHORT).show();
     
138. }
     
139. break;
     
140. case R.id.cancel:
     
141. finish();
     
142. break;
     
143. default:
     
144. break;
     
145. }
     
146. }
     
147. /**
     
148. *
     
149. * To create and write a file to the internal storage.
     
150. *
     
151. * @param
     
152. * @return
     
153. * @date 2010-12-30
     
154. * @author Xiaolong Long
     
155. */
     
156. private void saveMsg() throws IOException {
     
157. String msg = String.valueOf(mMsgView.getText());
     
158. FileOutputStream fos = openFileOutput(FILENAME, Context.MODE_APPEND);
     
159. // To create and write a private file to the internal storage:
     
160. fos.write(msg.getBytes("utf-8"));
     
161. fos.flush();
     
162. fos.close();
     
163. }
     
164. 
     
165. /**
     
166. * To read a file from internal storage.
     
167. *
     
168. * @param
     
169. * @return
     
170. * @date 2010-12-30
     
171. * @author Xiaolong Long
     
172. */
     
173. private String getMsg() throws IOException {
     
174. FileInputStream fis = openFileInput(FILENAME);
     
175. int length = FILENAME.length();
     
176. byte[] buffer = new byte[length];
     
177. 
     
178. ByteArrayOutputStream bos = new ByteArrayOutputStream();
     
179. int count = 0;
     
180. while ((count = fis.read(buffer)) != -1) {
     
181. bos.write(buffer, 0, count);
     
182. }
     
183. fis.close();
     
184. bos.close();
     
185. return bos.toString();
     
186. }
     
187. class MsgTextWater implements TextWatcher {
     
188. 
     
189. public void afterTextChanged(Editable s) {
     
190. 
     
191. }
     
192. 
     
193. public void beforeTextChanged(CharSequence s, int start, int count,
     
194. int after) {
     
195. }
     
196. 
     
197. public void onTextChanged(CharSequence s, int start, int before,
     
198. int count) {
     
199. mIsLegal = validate(s);
     
200. if (mIsLegal) {
     
201. mSave.setEnabled(true);
     
202. return;
     
203. }
     
204. mSave.setEnabled(false);
     
205. }
     
206. 
     
207. /**
     
208. *
     
209. * To check the view if legal.
     
210. *
     
211. * @param
     
212. * @return
     
213. * @date 2010-12-30
     
214. * @author Xiaolong Long
     
215. */
     
216. private boolean validate(CharSequence s) {
     
217. String ss = s.toString();
     
218. if (!"".equals(ss)) {
     
219. return true;
     
220. }
     
221. return false;
     
222. }
     
223. }
     
224. }
     
225. 3）main.xml 文件如下所示：
     
226. <?xml version="1.0" encoding="utf-8"?>
     
227. <LinearLayout
     
228. xmlns:android="http://schemas.android.com/apk/res/android"
     
229. android:orientation="vertical"
     
230. android:layout_width="fill_parent"
     
231. android:layout_height="fill_parent">
     
232. <TextView
     
233. android:layout_width="fill_parent"
     
234. android:layout_height="wrap_content"
     
235. android:text="@string/enter_msg" />
     
236. <EditText
     
237. android:id="@+id/msg"
     
238. android:layout_width="fill_parent"
     
239. android:layout_height="wrap_content"></EditText>
     
240. <LinearLayout
     
241. android:layout_width="fill_parent"
     
242. android:layout_height="wrap_content"
     
243. android:orientation="horizontal"
     
244. android:gravity="right">
     
245. <Button
     
246. android:id="@+id/saveMsg"
     
247. android:text="@string/savemsg"
     
248. android:layout_width="180px"
     
249. android:layout_height="wrap_content"></Button>
     
250. <Button
     
251. android:id="@+id/printMsg"
     
252. android:text="@string/printmsg"
     
253. android:layout_width="145px"
     
254. android:layout_height="wrap_content"></Button>
     
255. <Button
     
256. android:id="@+id/cancel"
     
257. android:text="@string/cancel"
     
258. android:layout_width="145px"
     
259. android:layout_height="wrap_content"></Button>
     
260. </LinearLayout>
     
261. </LinearLayout>
     
262. 
     
263. 4）AndroidMainfest.xml 文件如下所示：
     
264. <?xml version="1.0" encoding="utf-8"?>
     
265. <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     
266.       package="com.mesada.demo"
     
267.       android:versionCode="1"
     
268.       android:versionName="1.0">
     
269.     <application android:icon="@drawable/icon" android:label="@string/app_name">
     
270.         <activity android:name=".MainActivity"
     
271.                   android:label="@string/app_name">
     
272.             <intent-filter>
     
273.                 <action android:name="android.intent.action.MAIN" />
     
274.                 <category android:name="android.intent.category.LAUNCHER" />
     
275.             </intent-filter>
     
276.         </activity>
     
277. 
     
278.     </application>
     
279.     <uses-sdk android:minSdkVersion="8" />
     
280. 
     
281. </manifest>

复制代码5）完成，顺便上传截图：

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2011-03-21 20:18 上传