开个新坑,此专栏将分享一些简单的小型APP
效果介绍
使用安卓内置数据库实现数据存储,使用AlertDialog实现弹窗效果,主要功能实现为通过ui触发事件,设置监听器监听特定事件,并进相应的处理操作,主要操作为数据库操作,增删改查。
AS中我们创建的内容
下面我们逐个编写这些java类和xml文件的代码
MainActivity
package com.example.app1;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.database.Cursor;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
public class MainActivity extends AppCompatActivity {
Database phoneDatabase;
SimpleCursorAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.my_main);
phoneDatabase=new Database(this);
phoneDatabase.open();
ListView lv=findViewById(R.id.listview);
Cursor c = phoneDatabase.query();
adapter=new SimpleCursorAdapter(this,R.layout.row_view,
c,new String[]{Database.KEY_NAME,Database.KEY_PHONE},
new int[]{R.id.row_view_tv_name,R.id.row_view_tv_phone});
lv.setAdapter(adapter);
Button bt_insert=findViewById(R.id.bt_insert);
Button bt_reset=findViewById(R.id.bt_reset);
bt_insert.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
addData();
}
});
bt_reset.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
phoneDatabase.reset();
updateListView();
}
});
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Database.PhoneCursor c = phoneDatabase.queryById(position+1);
c.moveToFirst();
Data pd;
if (c.getPhone().equals("待完成")){
pd = new Data(c.getName(), "已完成");
}else {
pd = new Data(c.getName(), "待完成");
}
c.close();
phoneDatabase.update(pd,position+1);
updateListView();
}
});
registerForContextMenu(lv);
}
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
getMenuInflater().inflate(R.menu.ctx_menu,menu);
}
@Override
public boolean onContextItemSelected(@NonNull MenuItem item) {
AdapterView.AdapterContextMenuInfo menuInfo = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
long id = menuInfo.id;
switch (item.getItemId()){
case R.id.ctx_mod:
modifyData(id);
break;
case R.id.ctx_del:
deleteData(id);
break;
}
return super.onContextItemSelected(item);
}
public void addData(){
DataDialog DataDialog = new DataDialog(this,"创建新目标");
DataDialog.showDialog(new Data("", ""), new DataDialog.OnDialogSubmitListener() {
@Override
public void onSubmit(Data pd) {
phoneDatabase.insert(pd);
updateListView();
}
});
}
public void deleteData(long id){
phoneDatabase.delete(id);
updateListView();
}
public void modifyData(final long id){
Database.PhoneCursor c = phoneDatabase.queryById(id);
c.moveToFirst();
Data phoneData = new Data(c.getName(), c.getPhone());
c.close();
DataDialog phoneDataDialog = new DataDialog(this,"目标任务" + id);
phoneDataDialog.showDialog(phoneData, new DataDialog.OnDialogSubmitListener() {
@Override
public void onSubmit(Data pd) {
phoneDatabase.update(pd,id);
updateListView();
}
});
}
private void updateListView() {
adapter.getCursor().requery();
}
@Override
protected void onDestroy() {
super.onDestroy();
phoneDatabase.close();
}
}
DataDialog
package com.example.app1;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.EditText;
public class DataDialog {
private Context context;
private String title;
public DataDialog(Context context, String title) {
this.context = context;
this.title = title;
}
public interface OnDialogSubmitListener {
public void onSubmit(Data pd);
}
public void showDialog(final Data pd, final OnDialogSubmitListener l){
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setTitle(title);
View v = LayoutInflater.from(context).inflate(R.layout.dialog_view, null, false);
final EditText name = v.findViewById(R.id.dialog_view_name);
name.setText(pd.getName());
builder.setView(v);
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if(l !=null){
pd.setName(name.getText().toString());
pd.setPhone("待完成");
l.onSubmit(pd);
}
}
});
builder.setNegativeButton("Cancel",null);
builder.create().show();
}
}
Database
package com.example.app1;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.CursorWrapper;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class Database {
private static final String DB_NAME = "phone_database.db";
private static final String TABLE_NAME = "contact";
public static final String KEY_NAME = "name";
public static final String KEY_PHONE = "phone";
private Context context;
private int version = 1;
private DatabaseHelper databaseHelper;
private SQLiteDatabase db;
public Database(Context context) {
this.context = context;
databaseHelper = new DatabaseHelper();
}
public void open() {
if (db == null || !db.isOpen()) {
db = databaseHelper.getWritableDatabase();
}
}
public void close() {
if (db != null && db.isOpen()) {
db.close();
}
}
public ContentValues getContentValues(Data pd) {
ContentValues cv = new ContentValues();
cv.put(KEY_NAME, pd.getName());
cv.put(KEY_PHONE, pd.getPhone());
return cv;
}
public long insert(Data pd) {
return db.insert(TABLE_NAME, null, getContentValues(pd));
}
public int delete(long id) {
return db.delete(TABLE_NAME, "_id=" + id, null);
}
public int update(Data pd, long id) {
return db.update(TABLE_NAME, getContentValues(pd), "_id=" + id, null);
}
public void reset() {
databaseHelper.resetData(db);
}
public Cursor query() {
String sql = String.format("select * from %s", TABLE_NAME);
return db.rawQuery(sql, null);
}
public Cursor fuzzyQuery(String keyword) {
String sql = String.format("select * from %s where %s like ? or %s like ?", TABLE_NAME, KEY_NAME, KEY_PHONE);
return db.rawQuery(sql, new String[]{"%" + keyword + "%", "%" + keyword + "%"});
}
public PhoneCursor queryById(long id) {
String sql = String.format("select * from %s where _id=%d", TABLE_NAME, id);
Cursor cursor = db.rawQuery(sql,null);
return new PhoneCursor(cursor);
}
class DatabaseHelper extends SQLiteOpenHelper {
public DatabaseHelper() {
super(context, DB_NAME, null, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql = String.format("create table if not exists %s " +
"(_id integer primary key autoincrement,%s text,%s text)", TABLE_NAME ,KEY_NAME, KEY_PHONE);
db.execSQL(sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
resetData(db);
}
public void resetData(SQLiteDatabase db) {
String sql = String.format("drop table if exists %s", TABLE_NAME);
db.execSQL(sql);
onCreate(db);
}
}
class PhoneCursor extends CursorWrapper {
private Cursor cursor;
public PhoneCursor(Cursor cursor) {
super(cursor);
this.cursor = cursor;
}
public String getName() {
return cursor.getString(cursor.getColumnIndex(KEY_NAME));
}
public String getPhone() {
return cursor.getString(cursor.getColumnIndex(KEY_PHONE));
}
}
}
Data
package com.example.app1;
public class Data {
private String name;
private String phone;
public Data(String name, String phone) {
this.name = name;
this.phone = phone;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
}
dialog_view.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<EditText
android:id="@+id/dialog_view_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="任务目标"
android:inputType="textPersonName"
android:text="" />
</LinearLayout>
my_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="好好学习。" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/bt_insert"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="创建目标" />
<Button
android:id="@+id/bt_reset"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="重置" />
</LinearLayout>
<ListView
android:id="@+id/listview"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
row_view.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingTop="5dp" android:paddingBottom="5dp" android:paddingLeft="4dp">
<TextView
android:id="@+id/row_view_tv_name"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="目标任务" />
<TextView
android:id="@+id/row_view_tv_phone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="15dp"
android:text="待完成" />
</LinearLayout>
ctx_menu.xml
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:id="@+id/ctx_mod"
android:title="更改" />
<item
android:id="@+id/ctx_del"
android:title="删除" />
</menu>