Android开发之通过游标适配器读取数据(源代码分享)

   依照惯例我们先来看下谷歌官方文档对游标适配器的介绍,该适配器可以将数据库的数据暴露给ListView,将数据显示在LIstView空间上。特别注意的一点是,官方文档上写道游标必须包含一个列命名为“_id”,否则这个类将不会工作。此外,使用与这个类MergeCursor不会工作如果合并后的游标有重叠的的“_id”列中的值。 通过对官网文档的解读,我们就可以知道通过游标适配器访问数据库库的表单的数据,一定要创建一列名为"_id",否则就会报错。现在lets,go!

MainAcitivity的代码

package com.example.f13_cursor02;

import com.example.f13_cursor.dao.DBManager;

import android.os.Bundle;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.support.v4.widget.SimpleCursorAdapter;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;

public class MainActivity extends Activity {
	private Button button;
	private ListView listView;
	private SimpleCursorAdapter adapter;//生命一个游标适配器
	private DBManager dbManager;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		dbManager = new DBManager(this);
		listView = (ListView) this.findViewById(R.id.listView1);
		button = (Button) this.findViewById(R.id.button1);
		Cursor cursor = dbManager.query("person", null, null, null, null, null,
				null, null);
		adapter = new SimpleCursorAdapter(this, R.layout.item, cursor,
				new String[] { "name", "address" }, new int[] { R.id.textView1,
						R.id.textView2 });
		listView.setAdapter(adapter);
		button.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
              ContentValues contentValues=new ContentValues();
              contentValues.put("name", "jack");
              contentValues.put("address", "hangzhou");
              dbManager.insert("person", null, contentValues);
			}
			
		});
		adapter.notifyDataSetChanged();
	}

	@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;
	}

}

MyOpenHelper类的代码,该类继承SQLiteOpenHelper,用于创建数据库。

package com.example.f13_cursor.dao;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

public class MyOpenHelper extends SQLiteOpenHelper {
	private static final int DATABASE_VERSION = 1;
	private static final String PERSON_TABLE_NAME = "person";

	public MyOpenHelper(Context context) {
		super(context, PERSON_TABLE_NAME, null, DATABASE_VERSION);
		// TODO Auto-generated constructor stub
	}

	@Override
	public void onCreate(SQLiteDatabase db) {
		// TODO Auto-generated method stub
		db.execSQL("create table "
				+ PERSON_TABLE_NAME
				+ "(_id integer primary key autoincrement,name varchar(64),address varchar(64))");

	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		// TODO Auto-generated method stub

	}

}
DBManager类,用于对数据库进行增删改查

package com.example.f13_cursor.dao;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

public class DBManager {
	private MyOpenHelper helper;
	private SQLiteDatabase database;

	public DBManager(Context context) {
		// TODO Auto-generated constructor stub
		helper = new MyOpenHelper(context);
		database = helper.getWritableDatabase();
	}

	public boolean insert(String table, String nullColumnHack,
			ContentValues values) {
		boolean flag = false;
		long count = database.insert(table, nullColumnHack, values);
		flag = count > 0 ? true : false;
		return flag;
	}

	public Cursor query(String table, String[] columns, String selection,
			String[] selectionArgs, String groupBy, String having,
			String orderBy, String limit) {
		Cursor cursor = null;
		cursor = database.query(table, columns, selection, selectionArgs,
				groupBy, having, orderBy);
		return cursor;

	}

	public void conn() {
		if (database != null) {
			database.close();
		}
	}
}


Android开发之通过游标适配器读取数据(源代码分享),布布扣,bubuko.com

Android开发之通过游标适配器读取数据(源代码分享)

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