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：

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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。

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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>