数据持久化之文件存储

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<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"

    tools:context="${relativePackage}.${activityClass}"

    android:orientation="vertical" >

    <EditText

        android:id="@+id/edit"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:hint="Type   something here" />

    <Button

        android:id="@+id/save_data"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="Save   data"/>

    <Button

        android:id="@+id/restore_data"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="Restore   data"/>

</LinearLayout>

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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;

import android.app.Activity;

import android.content.Context;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

import android.widget.Toast;

public class MainActivity   extends Activity   {

    private EditText edit;

    private Button saveData, restoreData;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        edit   = (EditText) findViewById(R.id.edit);

        saveData   = (Button) findViewById(R.id.save_data);

        restoreData   = (Button) findViewById(R.id.restore_data);

        String   inputText = load();

        if (!TextUtils.isEmpty(inputText)) {

            edit.setText(inputText);

            edit.setSelection(inputText.length());

            Toast.makeText(this,   "Restoring Succeeded", Toast.LENGTH_SHORT).show();

        }

        saveData.setOnClickListener(new OnClickListener() {

            @Override

            public void onClick(View v) {

                //   TODO Auto-generated method stub

                SharedPreferences.Editor   editor = getSharedPreferences("data", MODE_PRIVATE).edit();

                editor.putString("name",   "Tom");

                editor.putInt("age",   23);

                editor.putBoolean("married",   false);

                editor.commit();

            }

        });

        restoreData.setOnClickListener(new OnClickListener() {

            @Override

            public void onClick(View v) {

                //   TODO Auto-generated method stub

                SharedPreferences   pref = getSharedPreferences("data", MODE_PRIVATE);

                String   name = pref.getString("name", "");

                int age = pref.getInt("age", 0);

                boolean married = pref.getBoolean("married",   false);

                Toast.makeText(MainActivity.this,   "name=" + name + ",age=" + age + ",married=" + married, Toast.LENGTH_SHORT).show();

            }

        });

    }

    @Override

    protected void onDestroy() {

        //   TODO Auto-generated method stub

        super.onDestroy();

        String   inputText = edit.getText().toString();

        save(inputText);

    }

    public void save(String inputText) {

        FileOutputStream   fileOutputStream = null;

        BufferedWriter   bufferedWriter = null;

        try {

            fileOutputStream   = openFileOutput("data", Context.MODE_PRIVATE);

            bufferedWriter   = new BufferedWriter(new OutputStreamWriter(fileOutputStream));

            bufferedWriter.write(inputText);

        }   catch (FileNotFoundException   e) {

            //   TODO Auto-generated catch block

            e.printStackTrace();

        }   catch (IOException   e) {

            //   TODO Auto-generated catch block

            e.printStackTrace();

        }   finally {

            try {

                if (bufferedWriter != null) {

                    bufferedWriter.close();

                }

            }   catch (IOException   e) {

                //   TODO Auto-generated catch block

                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 (FileNotFoundException   e) {

            //   TODO Auto-generated catch block

            e.printStackTrace();

        }   catch (IOException   e) {

            //   TODO Auto-generated catch block

            e.printStackTrace();

        }   finally {

            if (reader != null) {

                try {

                    reader.close();

                }   catch (IOException   e) {

                    //   TODO Auto-generated catch block

                    e.printStackTrace();

                }

            }

        }

        return content.toString();

    }

}