每天进步一点-----数据存储

SharedPreferences：

package com.example.sharedpreferencestest;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {
    
    private Button saveData;
    
    private Button restoreData;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        saveData = (Button) findViewById(R.id.save_data);
        restoreData = (Button) findViewById(R.id.restore_data);
        saveData.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();
                editor.putString("name", "Tom");
                editor.putInt("age", 28);
                editor.putBoolean("married", false);
                editor.commit();
            }
        });
        restoreData.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                SharedPreferences pref = getSharedPreferences("data", MODE_PRIVATE);
                String name = pref.getString("name", "");
                int age = pref.getInt("age", 0);
                boolean married = pref.getBoolean("married", false);
                Log.d("MainActivity", "name is " + name);
                Log.d("MainActivity", "age is " + age);
                Log.d("MainActivity", "married is " + married);
            }
        });
    }

}

 

File文件存储

package com.example.filepersistencetest;

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;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.text.TextUtils;
import android.widget.EditText;
import android.widget.Toast;

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(this, "Restoring succeeded", 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_PRIVATE);
            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();
    }

}

 

DataBase数据库存储

package com.example.databasetest;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;

public class MyDatabaseHelper extends SQLiteOpenHelper {

    public static final String CREATE_BOOK = "create table Book ("
            + "id integer primary key autoincrement, " 
            + "author text, "
            + "price real, " 
            + "pages integer, " 
            + "name text)";
    
    public static final String CREATE_CATEGORY = "create table Category ("
            + "id integer primary key autoincrement, "
            + "category_name text, "
            + "category_code integer)";

    private Context mContext;

    public MyDatabaseHelper(Context context, String name,
            CursorFactory factory, int version) {
        super(context, name, factory, version);
        mContext = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_BOOK);
        db.execSQL(CREATE_CATEGORY);
        Toast.makeText(mContext, "Create succeeded", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("drop table if exists Book");
        db.execSQL("drop table if exists Category");
        onCreate(db);
    }

}

 

package com.example.databasetest;

import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {

    private MyDatabaseHelper dbHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        dbHelper = new MyDatabaseHelper(this, "BookStore.db", null, 2);
        Button createDatabase = (Button) findViewById(R.id.create_database);
        createDatabase.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                dbHelper.getWritableDatabase();
            }
        });
        Button addData = (Button) findViewById(R.id.add_data);
        addData.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                ContentValues values = new ContentValues();
                values.put("name", "The Da Vinci Code");
                values.put("author", "Dan Brown");
                values.put("pages", 454);
                values.put("price", 16.96);
                db.insert("Book", null, values);
                values.clear();
                values.put("name", "The Lost Symbol");
                values.put("author", "Dan Brown");
                values.put("pages", 510);
                values.put("price", 19.95);
                db.insert("Book", null, values);
            }
        });
        Button updateData = (Button) findViewById(R.id.update_data);
        updateData.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                ContentValues values = new ContentValues();
                values.put("price", 10.99);
                db.update("Book", values, "name = ?",
                        new String[] { "The Da Vinci Code" });
            }
        });
        Button deleteButton = (Button) findViewById(R.id.delete_data);
        deleteButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                db.delete("Book", "pages > ?", new String[] { "500" });
            }
        });
        Button queryButton = (Button) findViewById(R.id.query_data);
        queryButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                Cursor cursor = db.query("Book", null, null, null, null, null,
                        null);
                if (cursor.moveToFirst()) {
                    do {
                        String name = cursor.getString(cursor
                                .getColumnIndex("name"));
                        String author = cursor.getString(cursor
                                .getColumnIndex("author"));
                        int pages = cursor.getInt(cursor
                                .getColumnIndex("pages"));
                        double price = cursor.getDouble(cursor
                                .getColumnIndex("price"));
                        Log.d("MainActivity", "book name is " + name);
                        Log.d("MainActivity", "book author is " + author);
                        Log.d("MainActivity", "book pages is " + pages);
                        Log.d("MainActivity", "book price is " + price);
                    } while (cursor.moveToNext());
                }
                cursor.close();
            }
        });
        Button replaceData = (Button) findViewById(R.id.replace_data);
        replaceData.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                db.beginTransaction();
                try {
                    db.delete("Book", null, null);
//                    if (true) {
//                        throw new NullPointerException();
//                    }
                    ContentValues values = new ContentValues();
                    values.put("name", "Game of Thrones");
                    values.put("author", "George Martin");
                    values.put("pages", 720);
                    values.put("price", 20.85);
                    db.insert("Book", null, values);
                    db.setTransactionSuccessful();
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    db.endTransaction();
                }
            }
        });
    }

}