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Android学习--------实现增删改查数据库操作以及实现相似微信好友对话管理操作...

编程日记 2023/09/16 23:55:33

近期的一个实验用到东西挺多，特地总结一下。

要求功能：

1、第一个页面加入歌曲名和歌手，跳到第二个页面列表显示全部记录。使用sqlite数据库

2、对于第二个页面显示的信息能够进行删除和改动操作，并自己主动刷新

最后我做的效果：

长按列表项弹出单个管理的菜单，像微信好友对话管理一样。

删除时能够直接删除这一条并在列表中直接显示。更新时弹出对话框更新内容提交后在列表中又一次显示。

做此例遇到的困难：

1、菜单获取上下文

2、获取对话框中的内容

3、对话框button加入监听事件-----注意包不要导错：import android.content.DialogInterface.OnClickListener;

主要代码例如以下：

第一个页面：

package com.example.musiclist;import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;public class MainActivity extends Activity {SQLiteDatabase db;String music;String singer;Button add;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);db = SQLiteDatabase.openOrCreateDatabase(this.getFilesDir().toString()+"/music.db3", null);add = (Button)findViewById(R.id.add);add.setOnClickListener(new OnClickListener(){Cursor cursor = null;public void onClick(View sourse){music = ((EditText)findViewById(R.id.music)).getText().toString();singer = ((EditText)findViewById(R.id.singer)).getText().toString();try{insertData(db,music,singer);}catch(SQLiteException se){//primary key autoincrementdb.execSQL("create table musiclist(_id integer primary key autoincrement," +"music varchar(30) ,"+"singer varchar(30))");insertData(db,music,singer);}finally{//cursor.close();Intent intentSec = new Intent(MainActivity.this,SecondActivity.class);startActivity(intentSec);}}});}private void insertData(SQLiteDatabase db,String name,String weibo){//运行插入语句db.execSQL("insert into musiclist values(null,?,?

)",new String[]{music,singer}); } public void onDestroy(){ super.onDestroy(); if(db!=null&&db.isOpen()){ db.close(); } } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } }

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical" ><ListViewandroid:id="@+id/show"android:layout_width="fill_parent"android:layout_height="wrap_content" ></ListView></LinearLayout>

第二个页面:

package com.example.musiclist;import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.support.v4.widget.SimpleCursorAdapter;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnCreateContextMenuListener;
import android.widget.AdapterView.AdapterContextMenuInfo;
import android.widget.CursorAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TableLayout;public class SecondActivity extends Activity {SQLiteDatabase db;ListView show;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_second);show = (ListView)findViewById(R.id.show);db = SQLiteDatabase.openOrCreateDatabase(this.getFilesDir().toString()+"/music.db3", null);//显示列表showlist();// 加入长按点击弹出选择菜单show.setOnCreateContextMenuListener(new OnCreateContextMenuListener() {public void onCreateContextMenu(ContextMenu menu, View v,ContextMenuInfo menuInfo) {menu.setHeaderTitle("选择操作");menu.add(0, 0, 0, "更新该条");menu.add(0, 1, 0, "删除该条");}});}//给菜单项加入事件@Overridepublic boolean onContextItemSelected(MenuItem item) {AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();//info.id得到listview中选择的条目绑定的idString id = String.valueOf(info.id);switch (item.getItemId()) {case 0:updateDialog(id);return true;case 1://System.out.println("删除"+info.id);deleteData(db,id);showlist();return true;default:return super.onContextItemSelected(item);}}//更新对话框private void updateDialog(final String id){final TableLayout updatemsg = (TableLayout)getLayoutInflater().inflate(R.layout.updatemsg, null);new AlertDialog.Builder(this).setTitle("更新该条信息").setView(updatemsg).setPositiveButton("更新",new OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which) {// TODO Auto-generated method stubString musicN = ((EditText)updatemsg.findViewById(R.id.musicN)).getText().toString();String singerN = ((EditText)updatemsg.findViewById(R.id.singerN)).getText().toString();updateData(db,id,musicN,singerN);showlist();}}).setNegativeButton("取消", new OnClickListener(){public void onClick(DialogInterface dialog,int which){}}).create().show();}private void updateData(SQLiteDatabase db,String id,String musicN,String singerN){db.execSQL("update musiclist set music='"+musicN+"',singer='"+singerN+"' where _id=?",new String[]{id});}//删除列表项private void deleteData(SQLiteDatabase db,String id){db.execSQL("delete from musiclist where _id=?",new String[]{id});}//显示列表项private void showlist(){Cursor cursor = null;try{cursor = db.rawQuery("select * from musiclist", null);inflateList(cursor);}catch(SQLiteException se){db.execSQL("create table musiclist(_id integer primary key autoincrement," +"music varchar(30) ,"+"singer varchar(30))");//查询cursor = db.rawQuery("select * from musiclist", null);inflateList(cursor);}finally{//cursor.close();}}private void inflateList(Cursor cursor){//填充SimpleCursorAdapterSimpleCursorAdapter adapter = new SimpleCursorAdapter(SecondActivity.this,R.layout.line,cursor,new String[]{"_id","music","singer"},new int[]{R.id.idS,R.id.musicS,R.id.singerS},CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);show.setAdapter(adapter);}public void onDestroy(){super.onDestroy();if(db!=null&&db.isOpen()){db.close();}}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}
}

列表 line.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:orientation="horizontal"> <TextView android:id="@+id/idS" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text=" " /> <TextView android:id="@+id/musicS" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text=" " /> <TextView android:id="@+id/singerS" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text=" " /> </LinearLayout>

对话框：updatemsg.xml

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent" ><TableRow><TextViewandroid:layout_width="100dip"android:layout_height="wrap_content"android:text="音乐名"android:textSize="30px"android:textColor="#ffffff" /><EditTextandroid:id="@+id/musicN"android:layout_width="100dip"android:layout_height="wrap_content" /></TableRow><TableRow><TextViewandroid:layout_width="100dip"android:layout_height="wrap_content"android:text="歌手"android:textSize="30px"android:textColor="#ffffff" /><EditTextandroid:id="@+id/singerN"android:layout_width="100dip"android:layout_height="wrap_content" /></TableRow>
</TableLayout>

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