- 文件存儲
activity_mian.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<EditText
android:id="@+id/edit"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Type something here"/>
</LinearLayout>
修改MainActivity
package com.syc.androidlearning;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.os.Bundle;
import android.text.TextUtils;
import android.widget.EditText;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
public class MainActivity extends AppCompatActivity {
private EditText editText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = findViewById(R.id.edit);
String inputText = load();
if (!TextUtils.isEmpty(inputText)){
editText.setText(inputText);
Toast.makeText(this,"restoring succeed",Toast.LENGTH_SHORT).show();
}
}
private 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 (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null){
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return content.toString();
}
@Override
protected void onDestroy() {
super.onDestroy();
String input = editText.getText().toString();
save(input);
}
public void save(String input) {
FileOutputStream outputStream = null;
BufferedWriter writer = null;
try {
outputStream = openFileOutput("data", Context.MODE_PRIVATE);
writer = new BufferedWriter(new OutputStreamWriter(outputStream));
writer.write(input);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) {
try {
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
- SharedPreference存儲
SharedPreference使用鍵值對存儲數據,他比文件存儲更加簡單。
修改activity_mian.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/save"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="save"/>
<Button
android:id="@+id/restore"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="restore data"/>
</LinearLayout>
修改ActivityMain文件
package com.syc.androidlearning;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button saveData = findViewById(R.id.save);
Button restoreData = findViewById(R.id.restore);
saveData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SharedPreferences.Editor editor = getSharedPreferences("data", MODE_PRIVATE).edit();
editor.putString("name", "SYC");
editor.putInt("age", 24);
editor.apply();
}
});
restoreData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SharedPreferences preferences = getSharedPreferences("data", MODE_PRIVATE);
String name = preferences.getString("name", "");
int age = preferences.getInt("age", 0);
Log.d("MainActivity", "name is " + name + "age is " + age);
}
});
}
}