Android存储-文件存储

文件存储一般可以存较大的东西，如文本，图片或者音频视频

Talk is cheap ,show you the code

public class MainActivity extends ActionBarActivity {

	// 写出文件名
	private EditText filenameText;
	// 写出文件内容
	private EditText filecontentText;
	// 读取文件内容
	private TextView showContent;

	private Server server;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		filenameText = (EditText) findViewById(R.id.fileName);
		filecontentText = (EditText) findViewById(R.id.fileContent);
		showContent = (TextView) findViewById(R.id.content);
		server = new Server();

		// 保存到非SD卡
		findViewById(R.id.writeLocBtn).setOnClickListener(
				new OnClickListener() {

					@Override
					public void onClick(View arg0) {

						String fileName = filenameText.getText().toString();
						String fileContent = filecontentText.getText()
								.toString();
						try {
							server.writeToLoc(fileName, fileContent);
						} catch (Exception e) {
							// TODO Auto-generated catch block
							e.printStackTrace();
						}
					}
				});

		// 保存到SD卡
		findViewById(R.id.writeSDBtn).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {

				String fileName = filenameText.getText().toString();
				String fileContent = filecontentText.getText().toString();
				try {
					if (Environment.getExternalStorageState().equals(
							Environment.MEDIA_MOUNTED)) {
						server.writeToSD(fileName, fileContent);
					} else {
						Toast.makeText(getApplicationContext(),
								R.string.SDfail, 1).show();
					}
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		});

		// 读本地非SD卡文件
		findViewById(R.id.readLocBtn).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {
				String fileName = filenameText.getText().toString();
				try {
					showContent.setText(server.readLoc(fileName));
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}

			}
		});

		// 读SD卡文件
		findViewById(R.id.readSDBtn).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {
				String fileName = filenameText.getText().toString();
				try {
					showContent.setText(server.readSD(fileName));
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}

			}
		});

		// 删除本机非SD卡文件
		findViewById(R.id.delLocBtn).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {
				String fileName = filenameText.getText().toString();
				server.delLocFile(fileName);
			}
		});

		// 删除SD文件
		findViewById(R.id.delSDBtn).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {
				String fileName = filenameText.getText().toString();
				server.delSDFile(fileName);
			}
		});
	}

	private class Server {
		// 往本机非SD卡存储
		// 文件an路径为data/data/"packagename"/filename
		void writeToLoc(String filename, String filecontent) throws Exception {

			/*
			 * 存储分为很多模式 MODE_PRIVATE：只能本应用读取，写入的时候为覆盖
			 * MODE_APPEND:只能本应用读取，写入时为追加，如没有该文件创建新文件
			 * MODE_WORLD_WRITEABLE:其它应用可写入 MODE_WORLD_READABLE：其它应用可读取
			 * MODE_WORLD_WRITEABLE + MODE_WORLD_READABLE：写 + 读
			 */

			FileOutputStream outStream = MainActivity.this.openFileOutput(
					filename, Context.MODE_PRIVATE);
			outStream.write(filecontent.getBytes());
			outStream.close();
		}

		// 往本机SD卡存储
		void writeToSD(String filename, String filecontent) throws Exception {
			// 获得SD卡对应的存储目录
			File file = new File(Environment.getExternalStorageDirectory()
					.getCanonicalPath(), filename);
			FileOutputStream outStream = new FileOutputStream(file);
			outStream.write(filecontent.getBytes());
			outStream.close();
		}

		// 读取非SD卡中文件
		String readLoc(String filename) throws Exception {

			// 判断是否存在该文件
			File file = new File(MainActivity.this.getFilesDir().getPath(),
					filename);
			if (file.exists() && file.isFile()) {
				FileInputStream inStream = MainActivity.this
						.openFileInput(filename);

				BufferedReader br = new BufferedReader(new InputStreamReader(
						inStream));
				StringBuilder sb = new StringBuilder("");
				String line = null;
				// 循环读取文件内容
				while ((line = br.readLine()) != null) {
					sb.append(line);
				}
				br.close();
				return sb.toString();
			} else {
				Toast.makeText(getApplicationContext(), R.string.non_existent,
						1).show();
				return null;
			}
		}

		// 读取SD卡中文件
		String readSD(String filename) throws Exception {

			// 先判断SD卡是否存在,并且是否具有读写权限
			File file = new File(Environment.getExternalStorageDirectory(),
					filename);
			if (!Environment.getExternalStorageState().equals(
					Environment.MEDIA_MOUNTED)) {
				Toast.makeText(getApplicationContext(), R.string.SDfail, 1)
						.show();
				return null;

				// 再判断是否存在该文件
			} else if (file.exists() && file.isFile()) {
				FileInputStream inStream = new FileInputStream(Environment
						.getExternalStorageDirectory().getCanonicalPath()
						+ "//" + filename);

				BufferedReader br = new BufferedReader(new InputStreamReader(
						inStream));
				StringBuilder sb = new StringBuilder("");
				String line = null;
				// 循环读取文件内容
				while ((line = br.readLine()) != null) {
					sb.append(line);
				}
				br.close();
				return sb.toString();
			} else {
				Toast.makeText(getApplicationContext(), R.string.non_existent,
						1).show();
				return null;
			}

		}

		// 删除本机非SD卡中的文件
		void delLocFile(String filename) {

			// MainActivity.this.getFilesDir().getPath() 获取data下files路径
			File file = new File(MainActivity.this.getFilesDir().getPath(),
					filename);
			if (file.exists() && file.isFile()) {
				file.delete();
			} else {
				Toast.makeText(getApplicationContext(), R.string.non_existent,
						1).show();
			}
		}

		// 删除SD卡中的文件
		void delSDFile(String filename) {

			// Environment.getExternalStorageDirectory().getPath() 获取SD卡路径
			File file = new File(Environment.getExternalStorageDirectory()
					.getPath(), filename);
			if (file.exists() && file.isFile()) {
				file.delete();
			} else {
				Toast.makeText(getApplicationContext(), R.string.non_existent,
						1).show();
			}
		}
	}

}

    <!-- 在SDCard中创建与删除文件权限 -->
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
    <!-- 往SDCard写入数据权限 -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <EditText
        android:id="@+id/fileName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="text" />

    <EditText
        android:id="@+id/fileContent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="text" />

    <TextView
        android:id="@+id/content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Button
        android:id="@+id/writeLocBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/saveLocBtn" />

    <Button
        android:id="@+id/writeSDBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/saveSDBtn" />

    <Button
        android:id="@+id/readLocBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/readLocBtn" />
    
    <Button
        android:id="@+id/readSDBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/readSDBtn" />

    <Button
        android:id="@+id/delLocBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/delLocBtn" />
    
    <Button
        android:id="@+id/delSDBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/delSDBtn" />