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

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;
@Override
protected 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 autoincrement
db.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" >

<ListView
android: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;
@Override
protected 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
@Override
public boolean onContextItemSelected(MenuItem item) {
AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
//info.id得到listview中选择的条目绑定的id
String 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(){
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
String 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SimpleCursorAdapter
SimpleCursorAdapter 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();
}
}
@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" >

<ListView
android:id="@+id/show"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</ListView>

</LinearLayout>

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>
<TextView
android:layout_width="100dip"
android:layout_height="wrap_content"
android:text="音乐名"
android:textSize="30px"
android:textColor="#ffffff" />
<EditText
android:id="@+id/musicN"
android:layout_width="100dip"
android:layout_height="wrap_content" />
</TableRow>
<TableRow>
<TextView
android:layout_width="100dip"
android:layout_height="wrap_content"
android:text="歌手"
android:textSize="30px"
android:textColor="#ffffff" />
<EditText
android:id="@+id/singerN"
android:layout_width="100dip"
android:layout_height="wrap_content" />
</TableRow>
</TableLayout>