一. 概述
此例子将文本文件存入data/data/files中，只有本程序能够读取。
二. 实现
1. 保存文件
/** * Save content to a file
* @param fileName the name of the file
* @param fileContent the content of the file
* @throws IOException
*/
public void save(String fileName, String fileContent) throws IOException {
FileOutputStream out = context.openFileOutput(fileName,
Context.MODE_APPEND);
out.write(fileContent.getBytes());
out.flush();
out.close();
}
2. 读取文件
/** * read the content in data/data/com.like.app/files
* @param fileName the name of the file
* @param fileContent the content of the file
* @return return the content of the file
* @throws IOException
*/
public String read(String fileName, String fileContent) throws IOException {
FileInputStream inputStream = context.openFileInput(fileName);
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while((len = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, len);
}
byte[] data = outputStream.toByteArray();
outputStream.close();
inputStream.close();
return new String(data);
}
3. 保存文件至SD卡
(1) 在操作SD卡之前，需要加入权限
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
(2) 方法实现
/** * save file to sdcard
* @param fileName the name of the file
* @param fileContent the content of the file
* @throws IOException
*/
public void saveToSdcard(String fileName, String fileContent) throws IOException {
//getExtrnalStorageDirectory() 获取sdcard路径
File file = new File(Environment.getExternalStorageDirectory(), fileName);
FileOutputStream outputStream = new FileOutputStream(file);
outputStream.write(fileContent.getBytes()); outputStream.close();
}
4. 从SD卡读取文件
/** * read content from sdcard
* @param fileName the name of the file
* @param fileContent the content of the file
* @return return the content of the file
* @throws IOException
*/
public String readFromSdcard(String fileName, String fileContent)
throws IOException {
FileInputStream inputStream = new FileInputStream(
new File(Environment.getExternalStorageDirectory(), fileName));
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0; while((len = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, len);
}
byte[] data = outputStream.toByteArray();
outputStream.close();
inputStream.close();
return new String(data);
}
