Android 备忘录的实现流程详解

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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<note> notelist = new arraylist<note>();
    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 popupwindow.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

<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <androidx.appcompat.widget.toolbar
        android:id="@+id/mytoolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionbarsize"
        android:elevation="4dp"
        app:titletextcolor="#ffebcd"
        app:popuptheme="@style/themeoverlay.appcompat.light"
        />
    <edittext
        android:id="@+id/et_1"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:gravity="top"
        />

</linearlayout>

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<note> getallnotes(){
        cursor cursor = db.query(notedatabase.table_name,columns,null,null,null, null, null);

        list<note> 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

<?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:paddingleft="10dp"
    android:paddingright="10dp"
    android:paddingtop="5dp"
    android:paddingbottom="12dp"
    android:orientation="vertical"
    android:background="@drawable/note_shape">


    <textview
        android:id="@+id/tv_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="content"
        android:textsize="20dp"
        android:textcolor="	#00f5ff"
        android:singleline="true"
        />

    <textview
        android:id="@+id/tv_time"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="time"
        android:textsize="16dp"
        android:textcolor="	#00f5ff"/>


</linearlayout>

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

5.6源码

上面给的代码不全 https://github.com/xiekangssq/local.git

总结

有写的各位看起来不适应的可以 评论指导

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