雲端記事本<三>：修改記事資料

此範例接續雲端記事本<二>來實作

將加入記事資料修改的功能，單擊項目將帶入編輯的畫面

新增一NoteActivity，用來編輯記事資料
activity佈局
> activity_note.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_note"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.pingtung.ccstudio.notepadcloud.NoteActivity"
    android:orientation="vertical">

    <EditText
        android:layout_width="match_parent"
        android:inputType="textMultiLine|textPersonName"
        android:text=""
        android:id="@+id/etTitle"
        android:layout_height="70dp"
        android:gravity="top|left"
        android:background="@drawable/rectangle"
        android:padding="5dp"
        android:hint="Title" />

    <EditText
        android:layout_width="match_parent"
        android:inputType="textMultiLine|textPersonName"
        android:text=""
        android:id="@+id/etContent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:scrollHorizontally="false"
        android:gravity="top|left"
        android:background="@drawable/rectangle"
        android:layout_marginTop="5dp"
        android:padding="5dp"
        android:hint="Content" />

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <Button
            android:text="取消"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btn_cancel"
            android:layout_weight="1" />

        <Button
            android:text="確定"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btn_ok"
            android:layout_weight="1" />
    </LinearLayout>
</LinearLayout>

> NoteActivity.java

package com.pingtung.ccstudio.notepadcloud;

import android.app.Activity;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class NoteActivity extends AppCompatActivity {
    //UI variables
    private Button btn_ok, btn_cancel;
    private EditText etTitle, etContent;

    //intent from caller
    private Intent intent;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_note);
        //find UId
        btn_ok = (Button)findViewById(R.id.btn_ok);
        btn_cancel = (Button)findViewById(R.id.btn_cancel);
        etTitle = (EditText)findViewById(R.id.etTitle);
        etContent = (EditText)findViewById(R.id.etContent);

        //intent from caller
        intent = getIntent();

        //若是EDIT_NOTE action，則顯示原本的title及content內容
        if(intent.getAction().equals("com.pingtung.ccstudio.notepadcloud.EDIT_NOTE")){
            String title,content;
            title = intent.getStringExtra("TITLE");
            content = intent.getStringExtra("CONTENT");
            etTitle.setText(title);
            etContent.setText(content);
        }

        View.OnClickListener onClickListener = new View.OnClickListener(){
            @Override
            public void onClick(View view) {
                if(view.getId()==R.id.btn_ok){
                    String title,content;
                    title = etTitle.getText().toString();
                    content = etContent.getText().toString();

                    if(title.equals("") || content.equals("")){
                        Toast.makeText(NoteActivity.this,"請輸入title及content",Toast.LENGTH_SHORT).show();
                        return;
                    }
                    intent.putExtra("TITLE",title);
                    intent.putExtra("CONTENT",content);
                    setResult(Activity.RESULT_OK, intent);
                }
                finish();
            }
        };

        btn_ok.setOnClickListener(onClickListener);
        btn_cancel.setOnClickListener(onClickListener);

    }
}

背景以圓角長方形填滿
> rectangle.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="#C5CAE9"/>
    <corners
        android:radius="15dp" />
</shape>

在manifest中加入開啟NoteActivity的actions(add及edit)
> AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.pingtung.ccstudio.notepadcloud">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".LoginActivity" />
        <activity android:name=".NoteActivity">
            <intent-filter>
                <!-- 新增用的名稱 -->
                <action android:name="com.pingtung.ccstudio.notepadcloud.ADD_NOTE" />
                <!-- 修改用的名稱 -->
                <action android:name="com.pingtung.ccstudio.notepadcloud.EDIT_NOTE" />
                <!-- 一定要加入，內容固定不變 -->
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>
    </application>

</manifest>

主畫面佈局刪除EditText，也使用NoteActivity記事新增
> activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.pingtung.ccstudio.notepadcloud.MainActivity">

    <TextView
        android:text="LoginUser:"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:id="@+id/textView6"
        android:textSize="18sp"
        android:textColor="@android:color/black" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="UserName"
        android:id="@+id/tvUser"
        android:textSize="18sp"
        android:layout_marginLeft="17dp"
        android:layout_marginStart="17dp"
        android:layout_alignParentBottom="true"
        android:layout_toRightOf="@+id/textView6"
        android:layout_toEndOf="@+id/textView6"
        android:textColor="@android:color/holo_red_light" />

    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:id="@+id/listView"
        android:dividerHeight="2dp"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_above="@+id/textView6" />

</RelativeLayout>

主畫面控制加入修改記事程式碼，並將新增的功能改為啟動NoteActivity
> MainActivity.java

package com.pingtung.ccstudio.notepadcloud;

import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MainActivity extends AppCompatActivity {
    //UI variables
    private TextView tvUser;
    private ListView listView;
    //private EditText etTitle, etContent;

    //餵給listView的相關變數
    private ItemPlusAdapter itemPlusAdapter;
    private List<ItemPlus> itemPlusList;

    //Firebase instance variables
    private FirebaseAuth auth;
    private FirebaseUser user;
    private FirebaseDatabase firebaseDatabase;
    private DatabaseReference mRef;

    //start activity requestCode
    private final static int REQUEST_ADD = 0;
    private final static int REQUEST_EDIT = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //local variable
        String userUid="";

        //find UId
        tvUser = (TextView)findViewById(R.id.tvUser);
        listView = (ListView)findViewById(R.id.listView);
        //etTitle = (EditText)findViewById(R.id.etTitle);
        //etContent = (EditText)findViewById(R.id.etContent);

        //取得auth實體(只有一個實體app內皆能共用)
        auth = FirebaseAuth.getInstance();
        user = auth.getCurrentUser();

        //若無登入帳戶，則getCurrentUser()傳回null
        //開啟LoginActivity
        if(user==null){
            startActivity(new Intent(this,LoginActivity.class));
            finish();
        }else{
            tvUser.setText(user.getEmail());
            userUid = user.getUid();
        }

        //實體化餵給listView的相關變數: arrayList, adapter
        itemPlusList = new ArrayList<>();
        itemPlusAdapter = new ItemPlusAdapter(MainActivity.this,R.layout.single_line,itemPlusList);
        listView.setAdapter(itemPlusAdapter);

        //取得firebase根目錄下"/users/$uid"的reference
        //不同登入的使用者有不同的Uid，無法存取其他人的資料
        firebaseDatabase = FirebaseDatabase.getInstance();
        mRef = firebaseDatabase.getReference("users/"+userUid);

        //對使用者根目錄(/users/$uid)註冊一子目錄變更監聽器
        ChildEventListener childEventListener = new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                String key = dataSnapshot.getKey();
                Log.d("android","onChildAdded: "+ key);
                Item item = dataSnapshot.getValue(Item.class);
                ItemPlus itemPlus = new ItemPlus(item, key);
                itemPlusList.add(itemPlus);
            }

            //子目錄下若有資料異動(value)會被呼叫
            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {
                Item item = dataSnapshot.getValue(Item.class);
                String key = dataSnapshot.getKey();
                Log.d("android","onChildChanged: "+ key);

                ItemPlus tmp;
                for(int i=0;i<itemPlusList.size();i++){
                    tmp = itemPlusList.get(i);
                    if(tmp.getKey().equals(key)){
                        itemPlusList.set(i,new ItemPlus(item,key));
                        break;
                    }
                }
            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {
                String key = dataSnapshot.getKey();
                Log.d("android", "onChildRemoved: " + key);

                ItemPlus tmp=null;
                for(ItemPlus ip:itemPlusList){
                    if(ip.getKey().equals(key)){
                        tmp = ip;
                        break;
                    }
                }
                if(itemPlusList.contains(tmp))
                    itemPlusList.remove(tmp);
            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        };
        mRef.addChildEventListener(childEventListener);

        //註冊使用者根目錄監聽器
        //只要子目錄值一有變更，便會收到通知
        //通知adapter資料有變更，刷新listView顯示
        ValueEventListener valueEventListener = new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                Log.d("android","onDataChange");
                itemPlusAdapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        };
        mRef.addValueEventListener(valueEventListener);

        //註冊listView長按事件
        //詢問是否刪除
        listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> adapterView, View view, int position, long l) {
                final ItemPlus itemPlus = itemPlusList.get(position);

                AlertDialog.Builder ab = new AlertDialog.Builder(MainActivity.this);

                ab.setTitle(itemPlus.getTitle())
                        .setMessage("是否刪除此筆紀錄?")
                        .setIcon(R.mipmap.ic_launcher)
                        .setCancelable(true);
                ab.setPositiveButton("確定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        mRef.child(itemPlus.getKey()).removeValue();
                    }
                });
                ab.setNegativeButton("取消", null);
                ab.show();

                return true;
            }
        });

        //註冊listView單擊事件
        //修改note內容
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
                final ItemPlus itemPlus = itemPlusList.get(position);

                Intent intent = new Intent();
                intent.setAction("com.pingtung.ccstudio.notepadcloud.EDIT_NOTE");
                intent.putExtra("TITLE",itemPlus.getTitle());
                intent.putExtra("CONTENT",itemPlus.getContent());
                intent.putExtra("KEY",itemPlus.getKey());
                startActivityForResult(intent,REQUEST_EDIT);
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main,menu);

        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch(item.getItemId()){
            case R.id.add:
                Intent intent = new Intent();
                intent.setAction("com.pingtung.ccstudio.notepadcloud.ADD_NOTE");
                startActivityForResult(intent,REQUEST_ADD);
                /*
                String title = etTitle.getText().toString();
                String content = etContent.getText().toString();

                if(title.equals("") || content.equals("")){
                    Toast.makeText(MainActivity.this,"請輸入title及content",Toast.LENGTH_SHORT).show();
                }else{
                    //使用push()讓系統自動產生key值
                    //key值依timestamp產生，不會重複且不斷向上遞增
                    mRef.push().setValue(new Item(title,content));
                    etTitle.setText("");
                    etContent.setText("");
                }
                */
                break;
            case R.id.logout:
                //將auth登出
                auth.signOut();
                startActivity(new Intent(this,LoginActivity.class));
                finish();
                break;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if(RESULT_OK==resultCode){
            String title, content;
            title = data.getStringExtra("TITLE");
            content = data.getStringExtra("CONTENT");

            if(REQUEST_ADD==requestCode){
                mRef.push().setValue(new Item(title,content));
            }else if(REQUEST_EDIT==requestCode){
                String key;
                Map<String,Object> map = new HashMap<>();

                key = data.getStringExtra("KEY");
                //這邊和setValue比較不同，需將item轉成map的格式
                //才能使用updateChildren
                map.put(key, new Item(title,content).toMap());
                mRef.updateChildren(map);

            }
        }
    }
}

這邊有一點要特別注意，修改記事時使用到的updateChildren(Map<String, Object> update)

這邊Object必需是一個Map物件()

故在Item class中加入一轉換map物件的函式

> Item.java

package com.pingtung.ccstudio.notepadcloud;

import java.util.HashMap;
import java.util.Map;

/**
 * Created by crowd_000 on 10/6/2016.
 */

public class Item {
    private String title;
    private String content;

    public Item(){
    }

    public Item(String title, String content) {
        this.title = title;
        this.content = content;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public Map<String, Object> toMap() {
        HashMap<String, Object> result = new HashMap<>();
        result.put("title", title);
        result.put("content", content);

        return result;
    }

}

這樣子就完成整個記事本的基本功能了

> 完整程式碼(Github)