Android简单使用SharedPreferences和 SQLite数据库实现数据存储

在安卓app中，我们希望之前设置的一些信息能够保存在手机中，这样下次打开app时就能直接显示我们上次保存的信息，此时使用SharedPreferences来存储key-value形式的数据，它是Android提供的一个轻量级的存储类，非常适合用来存储app的各项参数。

当我们需要处理大量数据时，如几百条几千条订单信息的增删改查，这时就需要一个稳健的数据库存储机制来提供支持，SQLite数据库就可以帮助我们完成这样的工作。SQLite是一款轻量级的嵌入式关系数据库，遵守ACID（原子性，一致性，隔离性，持久性）四要素。

SharedPreferences**实现的功能：

在登录页面输入用户名和密码（为节省时间未进行验证），使用SharedPreferences保存用户名和密码，并设置登录状态为1（已登录）
关闭应用后再次打开直接跳转到主页，并从SharedPreferences中获取用户名并显示
点击退出登录按钮，使用SharedPreferences修改登录状态为0（未登录），跳转到登录页面

SQLite数据库实现的功能：

在主页点击记账本按钮，跳转到账单页面，从SQLite数据库中获取数据并显示在ListView中
在账单页面点击记账按钮，跳转到添加账单页面，输入消费类别和消费金额，点击保存按钮将数据写入到SQLite数据库，并返回到账单页面
长按ListView中的子项弹出对话框提示是否删除该账单，点击确认后从SQLite数据库删除该账单（根据账单id），并刷新ListView显示

实现代码：

MySQLiteHelper.java：数据库操作辅助类SQLiteOpenHelper 负责SQLite数据库的创建和修改

package com.youngpain.alipay.util;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class MySQLiteHelper extends SQLiteOpenHelper {    private static final String DATABASE_NAME = "account.db";//数据库名称    private static final String TABLENAME = "account";//表名称    private static final int DATABASE_VERSION = 1;//数据库版本    //构造方法    public MySQLiteHelper(Context context) {        super(context, DATABASE_NAME, null, DATABASE_VERSION);    }    /**     * 重写onCreate()方法，调用execSQL()方法创建表     *     * @param db     */    @Override    public void onCreate(SQLiteDatabase db) {        String sql = "create table " + TABLENAME + "(id integer primary key autoincrement" +                ",name varchar(255),money integer)";        db.execSQL(sql);    }    /**     * 重写onUpgrade()方法，升级数据库     *     * @param db     * @param oldVersion     * @param newVersion     */    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {        String sql = "drop table if exists " + TABLENAME;        db.execSQL(sql);        this.onCreate(db);    }}

MainActivity.java：负责处理登录

package com.youngpain.alipay.activity;import android.app.Activity;import android.content.Intent;import android.content.SharedPreferences;import android.os.Bundle;import android.view.View;import android.view.Window;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;import com.youngpain.alipay.R;public class MainActivity extends Activity {    private EditText username;    private EditText password;    private Button loginButton;    private Button forgetButton;    //通过SharedPreferences写入登录信息    private SharedPreferences sharedPreferences;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //去除标题栏        requestWindowFeature(Window.FEATURE_NO_TITLE);        setContentView(R.layout.activity_main);        //初始化        init();        //读取loginInfo文件        SharedPreferences loginInfo = getSharedPreferences("loginInfo"                , Activity.MODE_PRIVATE);        //判断登录状态        if (loginInfo.getInt("login", 0) == 1) {            //已登录则跳转到个人信息页面，若已登录则用户名和密码已经存储到SharedPreferences中            Intent intent = new Intent(MainActivity.this, PersonInfoActivity.class);            startActivity(intent);        } else {            //如果当前未登录（退出登录），从SharedPreferences中获取用户名和密码，填入输入框            username.setText(loginInfo.getString("username", ""));            password.setText(loginInfo.getString("password", ""));        }        //测试        //forgetButton = findViewById(R.id.forget_pwd);        //forgetButton.setOnClickListener(new View.OnClickListener() {        //    @Override        //    public void onClick(View v) {        //        Toast.makeText(MainActivity.this, "通过setOnClickListener实现事件处理"        //                , Toast.LENGTH_LONG).show();        //    }        //});    }    /**     * 使用android:onClick="forgetPwd"实现事件处理     *     * @param view     */    public void forgetPwd(View view) {        Toast.makeText(MainActivity.this, "忘记密码", Toast.LENGTH_LONG).show();    }    /**     * 通过setOnClickListener实现事件处理     */    private void init() {        //获取控件        username = findViewById(R.id.login_et_user);        password = findViewById(R.id.login_et_password);        loginButton = findViewById(R.id.bt_login);        //绑定监听事件        loginButton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                String name = username.getText().toString().trim();                String pwd = password.getText().toString();                if ("".equals(name) || "".equals(pwd)) {                    Toast.makeText(MainActivity.this, "用户名或密码不能为空"                            , Toast.LENGTH_SHORT).show();                } else {                    Intent intent = new Intent(MainActivity.this                            , PersonInfoActivity.class);                    //使用Bundle传递数据                    //Bundle bundle = new Bundle();                    //bundle.putString("username", name);                    //intent.putExtras(bundle);                    //通过SharedPreferences保存信息，使用私有方式存储，不允许其他应用访问                    sharedPreferences = getSharedPreferences("loginInfo"                            , MODE_PRIVATE);                    //获取Editor添加数据                    SharedPreferences.Editor editor = sharedPreferences.edit();                    editor.putString("username", name);                    editor.putString("password", pwd);                    //1表示已登录，0表示未登录                    editor.putInt("login", 1);                    //提交修改                    editor.commit();                    //直接传递数据                    //intent.putExtra("username", name);                    //跳转到个人信息页面并退出当前页面                    startActivity(intent);                    finish();                }            }        });    }}

PersonInfoActivity.java：负责主页信息显示

package com.youngpain.alipay.activity;import android.app.Activity;import android.content.Intent;import android.content.SharedPreferences;import android.os.Bundle;import android.view.View;import android.view.Window;import android.widget.Button;import android.widget.TextView;import com.youngpain.alipay.R;public class PersonInfoActivity extends Activity {    private TextView username;    private TextView showName;    private TextView showPhone;    private TextView showEmail;    private Button editInfo;    private Button quitLogin;    private Button accountBtn;    //通过SharedPreferences获取登录信息    private SharedPreferences sharedPreferences;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //去除标题栏        requestWindowFeature(Window.FEATURE_NO_TITLE);        setContentView(R.layout.person_info);        //初始化        init();        //使用Bundle获取数据用户名并显示        //String name = getIntent().getExtras().getString("username");        //直接从Intent中获取用户名并显示        //String name = getIntent().getStringExtra("username");        //通过SharedPreferences获取保存的用户名        SharedPreferences loginInfo = getSharedPreferences("loginInfo"                , Activity.MODE_PRIVATE);        String name = loginInfo.getString("username", "admin");        username.setText("账号：" + name);    }    //重写onActivityResult方法获取上一个Activity传回来的数据    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        switch (resultCode) {            case 8:                String name = data.getStringExtra("name");                String phone = data.getStringExtra("phone");                String email = data.getStringExtra("email");                showName.setText(name);                showPhone.setText(phone);                showEmail.setText(email);                break;            default:                break;        }    }    //初始化    private void init() {        username = findViewById(R.id.username);        showName = findViewById(R.id.show_name);        showPhone = findViewById(R.id.show_phone);        showEmail = findViewById(R.id.show_email);        editInfo = findViewById(R.id.edit_person_info);        quitLogin = findViewById(R.id.quit_login);        accountBtn = findViewById(R.id.account_book);        editInfo.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                //获取EditPersonInfoActivity返回的数据                startActivityForResult(new Intent(PersonInfoActivity.this                        , EditPersonInfoActivity.class), 1);            }        });        quitLogin.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                //将SharedPreferences中的登录状态改为0（未登录）                sharedPreferences = getSharedPreferences("loginInfo"                        , MODE_PRIVATE);                SharedPreferences.Editor editor = sharedPreferences.edit();                editor.putInt("login", 0);                //提交修改                editor.commit();                //跳转到登录页面                Intent intent = new Intent(PersonInfoActivity.this                        , MainActivity.class);                startActivity(intent);                finish();            }        });        accountBtn.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                //跳转到账本页面                Intent intent = new Intent(PersonInfoActivity.this                        , AccountBookActivity.class);                startActivity(intent);            }        });    }}

EditPersonInfoActivity.java：负责修改个人信息

package com.youngpain.alipay.activity;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.view.Window;import android.widget.Button;import android.widget.EditText;import com.youngpain.alipay.R;public class EditPersonInfoActivity extends Activity {    private EditText editName;    private EditText editPhone;    private EditText editEmail;    private Button saveButton;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //去除标题栏        requestWindowFeature(Window.FEATURE_NO_TITLE);        setContentView(R.layout.edit_person_info);        //初始化        init();    }    //初始化    private void init() {        editName = findViewById(R.id.edit_name);        editPhone = findViewById(R.id.edit_phone);        editEmail = findViewById(R.id.edit_email);        saveButton = findViewById(R.id.save_person_info);        saveButton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                //获取输入信息                String name = editName.getText().toString().trim();                String phone = editPhone.getText().toString().trim();                String email = editEmail.getText().toString().trim();                Intent intent = new Intent();                intent.putExtra("name", name);                intent.putExtra("phone", phone);                intent.putExtra("email", email);                Activity activity = EditPersonInfoActivity.this;                //设置要返回的数据                activity.setResult(8, intent);                activity.finish();            }        });    }}

AccountBookActivity.java：负责账单显示

package com.youngpain.alipay.activity;import android.app.Activity;import android.app.AlertDialog;import android.content.DialogInterface;import android.content.Intent;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.View;import android.view.Window;import android.widget.AdapterView;import android.widget.Button;import android.widget.ListView;import android.widget.SimpleAdapter;import android.widget.Toast;import com.youngpain.alipay.R;import com.youngpain.alipay.util.MySQLiteHelper;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;public class AccountBookActivity extends Activity {    private ListView accountListView;    private Button accountBtn;    private MySQLiteHelper sqLiteHelper;    private SimpleAdapter simpleAdapter;    private List> accounts;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //去除标题栏        requestWindowFeature(Window.FEATURE_NO_TITLE);        setContentView(R.layout.account_book);        //初始化        init();        //从数据库获取账单信息并显示        sqLiteHelper = new MySQLiteHelper(AccountBookActivity.this);        SQLiteDatabase database = sqLiteHelper.getReadableDatabase();        //表名，列名，查询条件（可包含?），查询参数（替代?），分组字段，分组条件，排序字段        Cursor cursor = database.query("account", null, null                , null, null, null, null);        //将查询到的数据封装到List方便ListView使用        accounts = new ArrayList<>();        while (cursor.moveToNext()) {            Map map = new HashMap<>();            Integer id = cursor.getInt(cursor.getColumnIndex("id"));            String name = cursor.getString(cursor.getColumnIndex("name"));            Double money = cursor.getDouble(cursor.getColumnIndex("money"));            map.put("id", id);            map.put("name", name);            map.put("money", money);            accounts.add(map);        }        //关闭数据库        database.close();        //创建Adapter        simpleAdapter = new SimpleAdapter(this, accounts, R.layout.account_book_item                , new String[]{"name", "money"}, new int[]{R.id.type, R.id.money});        //绑定Adapter        accountListView.setAdapter(simpleAdapter);    }    //初始化    private void init() {        accountListView = findViewById(R.id.account_listview);        accountBtn = findViewById(R.id.add_account);        accountBtn.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                //点击记账按钮跳转到添加账单页面                Intent intent = new Intent(AccountBookActivity.this                        , AddAccountBookActivity.class);                startActivity(intent);            }        });        accountListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {            @Override            public boolean onItemLongClick(AdapterView<?> parent, View view, final int position                    , final long id) {                //创建对话框                new AlertDialog.Builder(AccountBookActivity.this).setTitle("删除账单")                        .setIcon(R.drawable.dialog).setMessage("确定要删除该账单？")                        .setPositiveButton("确定", new DialogInterface.OnClickListener() {                            @Override                            public void onClick(DialogInterface dialog, int which) {                                //获取要删除数据的id                                String id = String.valueOf(accounts.get(position).get("id"));                                //从数据库删除数据                                SQLiteDatabase database = sqLiteHelper.getWritableDatabase();                                database.delete("account", "id=?"                                        , new String[]{id});                                //关闭数据库                                database.close();                                //从List中删除数据并刷新ListView显示                                accounts.remove(position);                                simpleAdapter.notifyDataSetChanged();                                accountListView.invalidate();                            }                        })                        .setNegativeButton("取消", null).create().show();                return false;            }        });    }}

AddAccountBookActivity.java：负责添加账单

package com.youngpain.alipay.activity;import android.app.Activity;import android.content.ContentValues;import android.content.Intent;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.View;import android.view.Window;import android.widget.Button;import android.widget.EditText;import com.youngpain.alipay.R;import com.youngpain.alipay.util.MySQLiteHelper;public class AddAccountBookActivity extends Activity {    private EditText editAccountType;    private EditText editAccountMoney;    private Button saveAccountBook;    private MySQLiteHelper sqLiteHelper;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //去除标题栏        requestWindowFeature(Window.FEATURE_NO_TITLE);        setContentView(R.layout.add_account_book);        //初始化        init();    }    //初始化    private void init() {        editAccountType = findViewById(R.id.edit_account_type);        editAccountMoney = findViewById(R.id.edit_account_money);        saveAccountBook = findViewById(R.id.save_account_book);        saveAccountBook.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                //通过SQLiteOpenHelper调用getWritableDatabase()方法获取SQLiteDatabase，其提供了数据操作方法                sqLiteHelper = new MySQLiteHelper(AddAccountBookActivity.this);                SQLiteDatabase database = sqLiteHelper.getWritableDatabase();                //获取消费类型和金额                String name = editAccountType.getText().toString();                double money = Double.valueOf(editAccountMoney.getText().toString());                //使用封装数据                ContentValues values = new ContentValues();                values.put("name", name);                values.put("money", money);                //插入数据                database.insert("account", null, values);                //关闭数据库                database.close();                //跳转到账单页面                Intent intent = new Intent(AddAccountBookActivity.this                        , AccountBookActivity.class);                startActivity(intent);            }        });    }}

SharedPreferences**实现的功能：

SQLite数据库实现的功能：

实现代码：

运行结果：

源码：下载

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