Android使用文件存储数据
Android上最基本的存储数据的方式即为使用文件存储数据,使用基本的Java的FileOutStream,BufferedWriter,FileInputStream和BufferedReader即可。
MainActivity.java
package org.elvalad.filepersistencetest; import android.app.Activity; import android.content.Context; import android.os.Bundle; import android.text.TextUtils; import android.view.Menu; import android.view.MenuItem; import android.widget.EditText; import android.widget.Toast; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; public class MainActivity extends Activity { private EditText edit; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); edit = (EditText) findViewById(R.id.edit); String inputText = load(); if (!TextUtils.isEmpty(inputText)) { edit.setText(inputText); edit.setSelection(inputText.length()); Toast.makeText(MainActivity.this, "Restoring successed", Toast.LENGTH_SHORT).show(); } } @Override protected void onDestroy() { super.onDestroy(); String inputText = edit.getText().toString(); save(inputText); } public void save(String inputText) { FileOutputStream out = null; BufferedWriter writer = null; try { out = openFileOutput("data", Context.MODE_APPEND); writer = new BufferedWriter(new OutputStreamWriter(out)); writer.write(inputText); } catch (IOException e) { e.printStackTrace(); } finally { try { if (writer != null) { writer.close(); } } catch (IOException e) { e.printStackTrace(); } } } public String load() { FileInputStream in = null; BufferedReader reader = null; StringBuilder content = new StringBuilder(); try { in = openFileInput("data"); reader = new BufferedReader(new InputStreamReader(in)); String line = ""; while ((line = reader.readLine()) != null) { content.append(line); } } catch (IOException e) { e.printStackTrace(); } finally { if (reader != null) { try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } } return content.toString(); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.menu_main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); //noinspection SimplifiableIfStatement if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } }
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" android:paddingBottom="@dimen/activity_vertical_margin" android:orientation="horizontal" tools:context=".MainActivity"> <EditText android:id="@+id/edit" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="Type something here"/> </LinearLayout>
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问道,修仙
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