Android如何实现备忘录

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一、首先创建保存数据的表

Notedatabase,java

package com.example.biji_1;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class NoteDatabase extends SQLiteOpenHelper {    public static final String TABLE_NAME ="notes";    public static final String CONTENT ="content";    public static final String ID ="_id";    public static final String TIME ="time";    public static final String MODE ="mode";    public  NoteDatabase(Context context){        super(context,"notes",null,1);    }    @Override    public void onCreate(SQLiteDatabase db){        db.execSQL("CREATE TABLE " + TABLE_NAME + "(" + ID                + " INTEGER PRIMARY KEY AUTOINCREMENT, "                + CONTENT + " TEXT NOT NULL, "                + TIME + " TEXT NOT NULL, "                + MODE + " INTEGER DEFAULT 1)");    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion,int newVersion){    }}

二、主界面

MainAcitivity.java

public class MainActivity extends BaseActivity implements AdapterView.OnItemClickListener {    //test gittt    private NoteDatabase dbHelper;    private Context context = this;    final String TAG = "tag";    FloatingActionButton btn;    private ListView lv;    private NoteAdapter adapter;    private List noteList = new ArrayList();    private Toolbar myToolbar;    //弹出菜单    private PopupWindow popupWindow;    private PopupWindow popupCover;    private ViewGroup customView;    private ViewGroup coverView;    private LayoutInflater layoutInflater;    private RelativeLayout main;    private WindowManager wm;    private DisplayMetrics metrics;    private TextView setting_text;    private ImageView setting_image;    @Override    protected void onCreate(Bundle savedInstanceState){        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initPrefs();        btn = (FloatingActionButton) findViewById(R.id.fab);        lv = findViewById(R.id.lv);        myToolbar = findViewById(R.id.myToolbar);        adapter = new NoteAdapter(getApplicationContext(), noteList);        refreshListView();        lv.setAdapter(adapter);        setSupportActionBar(myToolbar);        getSupportActionBar().setHomeButtonEnabled(true);        getSupportActionBar().setDisplayHomeAsUpEnabled(true); //设置toolbar取代actionbar        initPopUpView();        myToolbar.setNavigationIcon(R.drawable.ic_baseline_menu_24);        myToolbar.setNavigationOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                Log.d(TAG, "onClick: shit");                showPopUpView();            }        });        lv.setOnItemClickListener(this);        btn.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                Intent intent = new Intent(MainActivity.this, EditActivity.class);                intent.putExtra("mode", 4);                startActivityForResult(intent, 0);            }        });    }    public void initPopUpView(){        layoutInflater = (LayoutInflater) MainActivity.this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);        customView = (ViewGroup) layoutInflater.inflate(R.layout.setting_layout, null);        coverView = (ViewGroup) layoutInflater.inflate(R.layout.setting_cover, null);        main = findViewById(R.id.main_layout);        wm = getWindowManager();        metrics = new DisplayMetrics();        wm.getDefaultDisplay().getMetrics(metrics);    }    public void showPopUpView(){        int width = metrics.widthPixels;        int height = metrics.heightPixels;        popupCover = new PopupWindow(coverView, width, height, false);        popupWindow = new PopupWindow(customView, (int) (width * 0.7), height, true);        popupWindow.setBackgroundDrawable(new ColorDrawable(Color.WHITE));        //在主界面加载成功之后 显示弹出        findViewById(R.id.main_layout).post(new Runnable() {            @Override            public void run() {                popupCover.showAtLocation(main, Gravity.NO_GRAVITY, 0, 0);                popupWindow.showAtLocation(main, Gravity.NO_GRAVITY, 0, 0);                setting_image = customView.findViewById(R.id.setting_settings_image);                setting_text = customView.findViewById(R.id.setting_settings_text);                setting_image.setOnClickListener(new View.OnClickListener() {                    @Override                    public void onClick(View v) {                        startActivity(new Intent(MainActivity.this, UserSettingsActivity.class));                    }                });                setting_text.setOnClickListener(new View.OnClickListener() {                    @Override                    public void onClick(View v) {                        startActivity(new Intent(MainActivity.this, UserSettingsActivity.class));                    }                });                coverView.setOnTouchListener(new View.OnTouchListener() {                    @Override                    public boolean onTouch(View v, MotionEvent event) {                        popupWindow.dismiss();                        return true;                    }                });                popupWindow.setOnDismissListener(new Popup_Window.OnDismissListener() {                    @Override                    public void onDismiss() {                        popupCover.dismiss();                        Log.d(TAG, "onDismiss: test");                    }                });            }        });    }    public void initPrefs(){        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getBaseContext());        SharedPreferences.Editor editor = sharedPreferences.edit();        if (!sharedPreferences.contains("nightMode")) {            editor.putBoolean("nightMode", false);            editor.commit();        }    }    // 接受startActivityForResult的结果    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data){        int returnMode;        long note_Id;        returnMode = data.getExtras().getInt("mode", -1);        note_Id = data.getExtras().getLong("id", 0);        if (returnMode == 1) {  //update current note            String content = data.getExtras().getString("content");            String time = data.getExtras().getString("time");            int tag = data.getExtras().getInt("tag", 1);            Note newNote = new Note(content, time, tag);            newNote.setId(note_Id);            CRUD op = new CRUD(context);            op.open();            op.updateNote(newNote);            op.close();        } else if (returnMode == 0) {  // create new note            String content = data.getExtras().getString("content");            String time = data.getExtras().getString("time");            int tag = data.getExtras().getInt("tag", 1);            Note newNote = new Note(content, time, tag);            CRUD op = new CRUD(context);            op.open();            op.addNote(newNote);            op.close();        } else if (returnMode == 2) { // delete            Note curNote = new Note();            curNote.setId(note_Id);            CRUD op = new CRUD(context);            op.open();            op.removeNote(curNote);            op.close();        }        else{        }        refreshListView();        super.onActivityResult(requestCode, resultCode, data);    }  //判断笔记状态    @Override    public boolean onCreateOptionsMenu(Menu menu) {        getMenuInflater().inflate(R.menu.main_menu, menu);        //search setting        MenuItem mSearch = menu.findItem(R.id.action_search);        SearchView mSearchView = (SearchView) mSearch.getActionView();        mSearchView.setQueryHint("请输入搜索内容");        mSearchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {            @Override            public boolean onQueryTextSubmit(String query) {                return false;            }            @Override            public boolean onQueryTextChange(String newText) {                adapter.getFilter().filter(newText);                return false;            }        });        return super.onCreateOptionsMenu(menu);    }   //搜索    @Override    public boolean onOptionsItemSelected(MenuItem item){        switch (item.getItemId()){            case R.id.menu_clear:                new AlertDialog.Builder(MainActivity.this)                        .setMessage("删除全部吗？")                        .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {                            @Override                            public void onClick(DialogInterface dialog, int which) {                                dbHelper = new NoteDatabase(context);                                SQLiteDatabase db = dbHelper.getWritableDatabase();                                db.delete("notes", null, null);                                db.execSQL("update sqlite_sequence set seq=0 where name='notes'");                                refreshListView();                            }                        }).setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {                    @Override                    public void onClick(DialogInterface dialog, int which) {                        dialog.dismiss();                    }                }).create().show();                break;        }        return super.onOptionsItemSelected(item);    }  //主界面删除    public void refreshListView(){        CRUD op = new CRUD(context);        op.open();        // set adapter        if (noteList.size() > 0) noteList.clear();        noteList.addAll(op.getAllNotes());        op.close();        adapter.notifyDataSetChanged();    }  //刷新list    @Override    public void onItemClick(AdapterView parent, View view, int position, long id) {        switch (parent.getId()) {            case R.id.lv:                Note curNote = (Note) parent.getItemAtPosition(position);                Intent intent = new Intent(MainActivity.this, EditActivity.class);                intent.putExtra("content", curNote.getContent());                intent.putExtra("id", curNote.getId());                intent.putExtra("time", curNote.getTime());                intent.putExtra("mode", 3);     // MODE of 'click to edit'                intent.putExtra("tag", curNote.getTag());                startActivityForResult(intent, 1);      //collect data from edit                Log.d(TAG, "onItemClick: " + position);                break;        }    } //携带数据}

2.1 activity_main.xml

三、:EditActivity.java

package com.example.biji_1;import android.content.DialogInterface;import android.content.Intent;import android.os.Bundle;import android.util.Log;import android.view.KeyEvent;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.widget.EditText;import androidx.appcompat.app.AlertDialog;import androidx.appcompat.widget.Toolbar;import java.text.SimpleDateFormat;import java.util.Date;public class EditActivity extends BaseActivity {    EditText et;    private Toolbar myToolbar;    private String old_content = "";    private String old_time = "";    private int old_Tag = 1;    private long id = 0;    private int openMode = 0;    private int tag = 1;    public Intent intent = new Intent(); // message to be sent    private boolean tagChange = false;    private final String TAG = "tag";    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.edit_layout);        myToolbar = findViewById(R.id.myToolbar);        setSupportActionBar(myToolbar);        getSupportActionBar().setHomeButtonEnabled(true);        getSupportActionBar().setDisplayHomeAsUpEnabled(true); //设置toolbar取代actionbar        myToolbar.setNavigationOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                autoSetMessage();                setResult(RESULT_OK, intent);                finish();            }        });        myToolbar.setNavigationOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                autoSetMessage();                setResult(RESULT_OK, intent);                finish();            }        });        et = findViewById(R.id.et_1);        Intent getIntent = getIntent();        openMode = getIntent.getIntExtra("mode", 0);        if (openMode == 3) {//打开已存在的note            id = getIntent.getLongExtra("id", 0);            old_content = getIntent.getStringExtra("content");            old_time = getIntent.getStringExtra("time");            old_Tag = getIntent.getIntExtra("tag", 1);            et.setText(old_content);            et.setSelection(old_content.length());            Log.d("TAG","打开");        }    }    //渲染菜单栏    @Override    public boolean onCreateOptionsMenu(Menu menu_1) {        getMenuInflater().inflate(R.menu.edit_menu,menu_1);        return super.onCreateOptionsMenu(menu_1);    }    @Override    public boolean onOptionsItemSelected(MenuItem item){        switch (item.getItemId()){            case R.id.delete:                new AlertDialog.Builder(EditActivity.this)                        .setMessage("删除吗？")                        .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {                            @Override                            public void onClick(DialogInterface dialog, int which) {                                if (openMode == 4){ // new note                                    intent.putExtra("mode", -1);                                    setResult(RESULT_OK, intent);                                }                                else { // existing note                                    intent.putExtra("mode", 2);                                    intent.putExtra("id", id);                                    setResult(RESULT_OK, intent);                                }                                finish();                            }                        }).setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {                    @Override                    public void onClick(DialogInterface dialog, int which) {                        dialog.dismiss();                    }                }).create().show();                break;        }        return super.onOptionsItemSelected(item);    }    public boolean onKeyDown(int keyCode, KeyEvent event){        if (keyCode == KeyEvent.KEYCODE_HOME){            return true;        }        else if (keyCode == KeyEvent.KEYCODE_BACK){            autoSetMessage();            setResult(RESULT_OK, intent);            finish();            return true;        }        return super.onKeyDown(keyCode, event);    }    public void autoSetMessage(){        if(openMode == 4){            if(et.getText().toString().length() == 0){                intent.putExtra("mode", -1); //nothing new happens.            }            else{                intent.putExtra("mode", 0); // new one note;                intent.putExtra("content", et.getText().toString());                intent.putExtra("time", dateToStr());                intent.putExtra("tag", tag);            }        }        else {            if (et.getText().toString().equals(old_content) && !tagChange)                intent.putExtra("mode", -1); // edit nothing            else {                intent.putExtra("mode", 1); //edit the content                intent.putExtra("content", et.getText().toString());                intent.putExtra("time", dateToStr());                intent.putExtra("id", id);                intent.putExtra("tag", tag);            }        }    }    public String dateToStr(){        Date date = new Date();        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");        return simpleDateFormat.format(date);    }}

3.1 edit_layout.xml

四、对笔记进行增删查改

CRUD.java

package com.example.biji_1;import android.annotation.SuppressLint;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import java.util.ArrayList;import java.util.List;public class CRUD {    SQLiteOpenHelper dbHandler;    SQLiteDatabase db;    private static final String[] columns = {            NoteDatabase.ID,            NoteDatabase.CONTENT,            NoteDatabase.TIME,            NoteDatabase.MODE    };    public CRUD(Context context){        dbHandler = new NoteDatabase(context);    }    public void open(){        db = dbHandler.getWritableDatabase();    }    public void close(){        dbHandler.close();    }    //把note 加入到database里面    public Note addNote(Note note){        //add a note object to database        ContentValues contentValues = new ContentValues();        contentValues.put(NoteDatabase.CONTENT, note.getContent());        contentValues.put(NoteDatabase.TIME, note.getTime());        contentValues.put(NoteDatabase.MODE, note.getTag());        long insertId = db.insert(NoteDatabase.TABLE_NAME, null, contentValues);        note.setId(insertId);        return note;    }    public Note getNote(long id){        //get a note from database using cursor index        Cursor cursor = db.query(NoteDatabase.TABLE_NAME,columns,NoteDatabase.ID + "=?",                new String[]{String.valueOf(id)},null,null, null, null);        if (cursor != null) cursor.moveToFirst();        Note e = new Note(cursor.getString(1),cursor.getString(2), cursor.getInt(3));        return e;    }    @SuppressLint("Range")    public List getAllNotes(){        Cursor cursor = db.query(NoteDatabase.TABLE_NAME,columns,null,null,null, null, null);        List notes = new ArrayList<>();        if(cursor.getCount() > 0){            while(cursor.moveToNext()){                Note note = new Note();                note.setId(cursor.getLong(cursor.getColumnIndex(NoteDatabase.ID)));                note.setContent(cursor.getString(cursor.getColumnIndex(NoteDatabase.CONTENT)));                note.setTime(cursor.getString(cursor.getColumnIndex(NoteDatabase.TIME)));                note.setTag(cursor.getInt(cursor.getColumnIndex(NoteDatabase.MODE)));                notes.add(note);            }        }        return notes;    } //查找笔记    public int updateNote(Note note) {        //update the info of an existing note        ContentValues values = new ContentValues();        values.put(NoteDatabase.CONTENT, note.getContent());        values.put(NoteDatabase.TIME, note.getTime());        values.put(NoteDatabase.MODE, note.getTag());        // updating row        return db.update(NoteDatabase.TABLE_NAME, values,                NoteDatabase.ID + "=?",new String[] { String.valueOf(note.getId())});    } //更新笔记    public void removeNote(Note note) {        //remove a note according to ID value        db.delete(NoteDatabase.TABLE_NAME, NoteDatabase.ID + "=" + note.getId(), null);    }  //删除笔记}

4.1 note_layout.xml

五、演示效果

5.1 登录界面

哈哈界面随自己走各位别喷

5.2笔记界面

之前自己写的

5.3 增加记录

5.4删除记录

在主界面那个删除是删除全部会提示你 然后你点击进去之后还有一个删除那条记录的删除键 这里就不做演示了

5.5 查找记录

哈哈
##5.6 改记录

改之前

改之后可以看到时间变化

其它效果靠这样演示不出来，源码在下面可以自取

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