主要程式碼：
SharedPreferences sharedPreferences = getSharedPreferences(String name, int mode);
String name:是你要儲存在手機內的檔案名稱。
Int mode:是你儲存的方式，通常都是使用MODE_PRIVATE(除了你這個app其他app不能使用)
各種MODE
Sr.No
|
Mode & description
|
1
|
MODE_APPEND
This will
append the new preferences with the already existing preferences
|
2
|
MODE_ENABLE_WRITE_AHEAD_LOGGING
Database
open flag. When it is set , it would enable write ahead logging by default
|
3
|
MODE_MULTI_PROCESS
This method
will check for modification of preferences even if the sharedpreference
instance has already been loaded
|
4
|
MODE_PRIVATE
By setting
this mode, the file can only be accessed using calling application
|
5
|
MODE_WORLD_READABLE
This mode
allow other application to read the preferences
|
6
|
MODE_WORLD_WRITEABLE
This mode
allow other application to write the preferences
|
儲存方式：
SharedPreferences sharedPreferences = getSharedPreferences(data, MODE_PRIVATE);
假設你在EditText內打了一串東西想之後打開app之後還留存。
sharedPreferences.edit()
.putString(“I_WANT_TO_SAVE_EDIT”, OneEdit.getText().toString())
.apply();
呼叫sharedPreferences在後面加一個
eidt() （英文大補帖： edit 編輯 ）
仔使用putstring 加入你要處存的東西
apply 使它生效（英文大補帖： apply 始生效 ）
這就存起來了。
它會存在叫“I_WANT_TO_SAVE_EDIT”的檔案內。
讀取方式：
OneEdit.setText(sharedPreferences.getString(“I_WANT_TO_SAVE_EDIT”, ""));
同場加映
固定Switch開關的問題。
當我讓SWITCH開關成開啟狀態，當下次開啟APP時，要如何保持在開啟狀態呢？
當然是先在xml 內畫一個
switchButton
activity_main.xml
<Switch
android:id="@+id/switch_button"
android:layout_marginTop="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal" />
MainActivity.java
先設定元件
private Switch switch_buton;
指定給xml
switch_buton = (Switch) findViewById(R.id.switch_button);
設定SwitchButton的點擊方式
switch_buton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (switch_buton.isChecked()) {
//如果SwitchButton開啟 do something
//儲存
sharedPreferences.edit().putBoolean(switchField, true).apply();
Log.d(handle, "onClick isChecked switchField= is Open");
} else {
//如果SwitchButton關閉 do something
//儲存
sharedPreferences.edit().putBoolean(switchField, false).apply();
Log.d(handle, "onClick isClosed switchField= is Closed");
}
}
});
然後再OnCreate的地方丟入，這行是指你開啟APP時，讀取你存在sharedPreferences內的SWITCH 狀態。
switch_buton.setChecked(sharedPreferences.getBoolean(switchField, false));
這樣SwitchButton就可以正常開關囉！
完整程式碼：
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.chat.a015865.sharedpreferences.MainActivity">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="1" />
<EditText
android:id="@+id/oneField"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="2" />
<EditText
android:id="@+id/twoField"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="3" />
<EditText
android:id="@+id/threeField"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Switch
android:id="@+id/switch_button"
android:layout_marginTop="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal" />
<Button
android:id="@+id/close_button"
android:text="關閉app"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
MainActivity.java
public class MainActivity extends AppCompatActivity {
private static final String handle = MainActivity.class.getSimpleName();
private EditText OneEdit, TWO, THREE;
private Context context;
private Button close_Button;
private Activity activity;
private SharedPreferences sharedPreferences;
private static final String data = "DATA";
private static final String helloField = "ONE_STATE";
private static final String twoField = "TWO_STATE";
private static final String threeField = "THREE_SATE";
private static final String switchField = "SWITCH_STATE";
private Switch switch_buton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context = this;
activity = this;
initView();
initSet();
readData();//讀取
}
private void initView() {
close_Button = (Button) findViewById(R.id.close_button);
sharedPreferences = getSharedPreferences(data, MODE_PRIVATE);
switch_buton = (Switch) findViewById(R.id.switch_button);
OneEdit = (EditText) findViewById(R.id.oneField);
TWO = (EditText) findViewById(R.id.twoField);
THREE = (EditText) findViewById(R.id.threeField);
}
private void initSet() {
switch_buton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (switch_buton.isChecked()) {
//如果SwitchButton開啟 do something
//儲存
sharedPreferences.edit().putBoolean(switchField, true).apply();
Log.d(handle, "onClick isChecked switchField= is Open");
} else {
//如果SwitchButton關閉 do something
//儲存
sharedPreferences.edit().putBoolean(switchField, false).apply();
Log.d(handle, "onClick isClosed switchField= is Closed");
}
}
});
close_Button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
finish();
}
});
}
public void readData() {//讀取
switch_buton.setChecked(sharedPreferences.getBoolean(switchField, false));
OneEdit.setText(sharedPreferences.getString(helloField, ""));
TWO.setText(sharedPreferences.getString(twoField, ""));
THREE.setText(sharedPreferences.getString(threeField, ""));
}
public void saveData() {//儲存
sharedPreferences.edit()
.putString(helloField, OneEdit.getText().toString())
.putString(twoField, TWO.getText().toString())
.putString(threeField, THREE.getText().toString())
.apply();
}
@Override
protected void onPause() {
super.onPause();
Log.d(handle, "onPause()");
saveData();
}
@Override
protected void onStop() {
super.onStop();
Log.d(handle, "onStop()");
saveData();
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(handle, "onDestroy()");
saveData();
}
}
Demo下載：
https://drive.google.com/open?id=0Byk75IYx-dKXMDZZcHFHY3U4SXc
有問題請發問囉！
