安卓SDK——Bmob云服务（便签案例）

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安卓SDK——Bmob云服务（登录注册）

https://blog.csdn.net/nishigesb123/article/details/89854563

---

这里完成一个便签案例

主要实现

• 添加便签
• 删除便签
• 修改便签内容
• 查询便签列表

---

新建一个实体类Note.class继承BmobObject （叫习惯了，话说这里应该叫“实体类”嘛？）

字段给一个context（内容）即可

package com.example.bombtest;

import cn.bmob.v3.BmobObject;

public class Note extends BmobObject {
    private String content;

    public String getContent() {
        return content;
    }

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

---

再建NoteListActivity作为启动界面

布局选择用一个ListView来显示

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".NoteListActivity">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/listView"
        >

    </ListView>
</android.support.constraint.ConstraintLayout>

NoteListActivity

package com.example.bombtest;

import android.content.Context;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

import cn.bmob.v3.Bmob;
import cn.bmob.v3.BmobQuery;
import cn.bmob.v3.exception.BmobException;
import cn.bmob.v3.listener.FindListener;
import cn.bmob.v3.listener.UpdateListener;

public class NoteListActivity extends AppCompatActivity {
    private ArrayList<Note> notes = new ArrayList<>();
    private ListView listView;
    NoteAdapter noteAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_note_list);
        Bmob.initialize(this, "0bc8b0a9e9aea4bb31f4be7fe9e9ec38");
        listView = findViewById(R.id.listView);

        //单击事件，点击修改
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                //列表项布局里的TextView
                TextView textView_content = view.findViewById(R.id.note_item);
                String content = textView_content.getText().toString();
                String objectid = (String) view.getTag();
                Intent intent = new Intent(NoteListActivity.this, NoteDetailActivity.class);
                intent.putExtra("content", content);
                intent.putExtra("objectid", objectid);
                startActivity(intent);
            }
        });

        //注册上下文菜单
        registerForContextMenu(listView);
    }

    @Override
    protected void onResume() {
        super.onResume();
        loadData();
    }

    //查询方法
    private void loadData() {
        BmobQuery<Note> query = new BmobQuery<>();
        //限定查询条数，不写默认10条?
        query.setLimit(50);
        //findObject是一个异步的过程
        query.findObjects(new FindListener<Note>() {
            @Override
            public void done(List<Note> list, BmobException e) {
                if (e == null) {
                    notes = (ArrayList<Note>) list;
                    noteAdapter = new NoteAdapter(NoteListActivity.this, notes);
                    listView.setAdapter(noteAdapter);
                }
            }
        });
    }

    static class NoteAdapter extends BaseAdapter {
        private Context context;
        private List<Note> list;

        public NoteAdapter(Context context, List<Note> list) {
            this.context = context;
            this.list = list;
        }

        @Override
        public int getCount() {
            return list.size();
        }

        @Override
        public Object getItem(int position) {
            return list.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null) {
                convertView = LayoutInflater.from(context).inflate(R.layout.layout_note_item, null);
            }
            Note note = list.get(position);
            TextView content = convertView.findViewById(R.id.note_item);
            //为了显示
            content.setText(note.getContent());
            //存储ID
            convertView.setTag(note.getObjectId());
            return convertView;
        }
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_note_list, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.add_note:
                //点击添加，跳转到添加界面
                Intent intent = new Intent(this, NoteNewActivity.class);
                startActivity(intent);
                break;
        }
        return true;
    }

    //创建上下文菜单
    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
        super.onCreateContextMenu(menu, v, menuInfo);
        //group id 自己的id 排序 文本内容
        menu.add(1, 100, 100, "删除");
    }

    //点击时候长按删除
    @Override
    public boolean onContextItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case 100:
                AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
                //targetView就是当前目标（当前点击的...)
                View view = info.targetView;
                String objectid = (String) view.getTag();
                Note note = new Note();
                note.setObjectId(objectid);
                note.delete(new UpdateListener() {
                    @Override
                    public void done(BmobException e) {
                        if (e == null) {
                            loadData();
                        }
                    }
                });
                break;
        }
        return super.onContextItemSelected(item);
    }

}

准备一个layout_note_item.xml作为列表项布局

<?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">
    <TextView
        android:id="@+id/note_item"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
</LinearLayout>

准备一个NoteDetailActivity作为修改界面

布局如下，只需要一个编辑框即可

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".NoteDetailActivity">

    <EditText
        android:id="@+id/edit_detail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toTopOf="parent"
         />
</android.support.constraint.ConstraintLayout>

NoteDetailActivity

package com.example.bombtest;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.KeyEvent;
import android.widget.EditText;

import cn.bmob.v3.exception.BmobException;
import cn.bmob.v3.listener.UpdateListener;

public class NoteDetailActivity extends AppCompatActivity {
    private EditText edit_detail;
    private String objectid;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_note_detail);
        edit_detail = findViewById(R.id.edit_detail);
        objectid = getIntent().getStringExtra("objectid");
        edit_detail.setText(getIntent().getStringExtra("content"));

    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            String content = edit_detail.getText().toString();
            if (!TextUtils.isEmpty(content)) {
                //如果内容不为空点返回进行保存操作
                Note note = new Note();
                note.setContent(content);
                note.update(objectid, new UpdateListener() {
                    @Override
                    public void done(BmobException e) {
                    }
                });
            }
        }
        return super.onKeyDown(keyCode, event);
    }
}

准备一个menu_note_list菜单文件，来作为APP的菜单，作为添加功能的入口。

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item android:id="@+id/add_note" android:title="添加"
        android:orderInCategory="100" app:showAsAction="always"/>
</menu>

同时准备一个NoteNewActivity实现新建便签，布局给一个Edittext即可

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".NoteNewActivity">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/edit_new"/>
</android.support.constraint.ConstraintLayout>

NoteNewActivity

package com.example.bombtest;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.KeyEvent;
import android.widget.EditText;

import cn.bmob.v3.exception.BmobException;
import cn.bmob.v3.listener.SaveListener;

public class NoteNewActivity extends AppCompatActivity {

    private EditText editText_content;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_note_new);
        editText_content = findViewById(R.id.edit_new);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            System.out.println("ADD界面返回键被按下");
            String content = editText_content.getText().toString();
            if (!TextUtils.isEmpty(content)) {
                Note note = new Note();
                note.setContent(content);
                note.save(new SaveListener<String>() {
                    @Override
                    public void done(String s, BmobException e) {

                    }
                });
            }
        }
        return super.onKeyDown(keyCode, event);
    }
}

---

效果测试

整体界面

点击添加

再点击返回保存（字有点小，可以考虑设置的大一点）

点击ListItem进入修改界面

修改内容并返回

可以看到控制台的数据也发生了变化

长按会出现删除

刷新控制台