//如果在AndroidManifest.xml中<provider >不存在的话，在eclipse里面运行这个AP的时候，就会报错，

01-01 21:37:47.617: E/AndroidRuntime(3245): java.lang.RuntimeException: Unable to get provider com.contentp.test3.MyContentProvider: java.lang.ClassNotFoundException: com.contentp.test3.MyContentProvider

依此类推，我认为在AndroidManifest.xml中定义的组件也必须都存在，否则就会出错。

 

ContentObserver学习：

定义一个activity，监听/取消监听某Uri

package com.contentp.test3;import android.app.Activity;import android.content.ContentResolver;import android.net.Uri;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.provider.Settings;import android.util.Log;//用一个AP访问 系统中存在的联系人APpublic class ContentProviderTest3Activity extends Activity {    /** Called when the activity is first created. */    private ContentResolver cr;    private AirContentObserver aco;    private String TAG = "ContentProviderTest3Activity";    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        aco = new AirContentObserver(mHander);        regisContentObserver();    }    private void regisContentObserver(){        cr = getContentResolver();        Uri mUri = Settings.System.getUriFor(Settings.System.AIRPLANE_MODE_ON);        //注册ContentObserver，别忘了unregister.        cr.registerContentObserver(mUri, true, aco);    }    Handler mHander = new Handler(){        @Override        public void handleMessage(Message msg) {            // TODO Auto-generated method stub            super.handleMessage(msg);        }            };    //别忘了unregister.    @Override    protected void onDestroy() {        // TODO Auto-generated method stub        super.onDestroy();        cr.unregisterContentObserver(aco);        Log.v(TAG,"$$$$onDestroy--unregister");    }    }

 

定义ContentObserver的子类，override onChange()方法

package com.contentp.test3;import android.database.ContentObserver;import android.os.Handler;import android.util.Log;public class AirContentObserver extends ContentObserver{    private String TAG = "ContentProviderTest3Activity";    public AirContentObserver(Handler handler) {        super(handler);        // TODO Auto-generated constructor stub    }//所有ContentObserver子类都要override此onChange()方法。    @Override    public void onChange(boolean selfChange) {        // TODO Auto-generated method stub        super.onChange(selfChange);        Log.v(TAG,"$$$$$onchange");    }}

这样，当手机的飞行模式开启或关闭的时候，Uri就会发生变化，ContentObserver的子类的onChange()回调方法就会被调用，就会打出来onChange（）里面的log。

//

 

 

 

参考别人的：

 

 

package com.sql.test1; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteDatabase.CursorFactory; import android.database.sqlite.SQLiteOpenHelper; import android.util.Log; //SQLiteOpenHelper是一个abstract class public class MySqliteHelper extends SQLiteOpenHelper {
   public static final int VERSION=1; public static final String TABLE_NAME="srx0209"; public static final String ID="_id"; public static final String TEXT="text"; public static final String DATABASE_NAME="srx.db"; public MySqliteHelper(Context context){
   super(context, DATABASE_NAME, null, VERSION);     } //数据库第一次生成的时候会调用这个方法，一般我们在这个方法里面生成表     @Override public void onCreate(SQLiteDatabase db) {
   // TODO Auto-generated method stub //创建表     /*    String str_create=//"CREATE TABLE"+TABLE_NAME+"("+ID+"INTEGER PRIMARY KEY AUTOINCREMENT,"+TEXT+"text);";          "CREATE TABLE " + TABLE_NAME + "(" + ID           + " INTEGER PRIMARY KEY AUTOINCREMENT," + TEXT           + " text );";         db.execSQL(str_create);*/         Log.d("MySqliteHelper", "MySqliteHelper---onCreate--");     } //插入数据后，数据库立即更新。当数据库需要升级的时候，Android系统会自动（主动）调用此方法     @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
   // TODO Auto-generated method stub         Log.d("MySqliteHelper", "$$$$$$$call onUpgrade");     } }

 

 

package com.sql.test1; import android.app.Activity; import android.content.ContentValues; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.os.Bundle; import android.widget.Button; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; public class SQLiteTest1Activity extends Activity {
   /** Called when the activity is first created. */ private static final String TAG = "SQLiteTest1Activity"; private Button btn_new_table; private Button btn_insert; private Button btn_delete_record; private Button btn_delete_table; private Button btn_modify; private Button btn_search; // 创建一个继承SQLiteOpenHelper的实例     private MySqliteHelper myOpenHelper; private SQLiteDatabase sqDatabase;     @Override public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);         setContentView(R.layout.main);         btn_new_table = (Button) findViewById(R.id.new_table);         btn_insert = (Button) findViewById(R.id.insert);         btn_delete_record = (Button) findViewById(R.id.delete_record);         btn_delete_table = (Button) findViewById(R.id.delete_table);         btn_modify = (Button) findViewById(R.id.modify);         btn_search = (Button) findViewById(R.id.search);         btn_new_table.setOnClickListener(myListener);         btn_insert.setOnClickListener(myListener);         btn_delete_record.setOnClickListener(myListener);         btn_delete_table.setOnClickListener(myListener);         btn_modify.setOnClickListener(myListener);         btn_search.setOnClickListener(myListener); // 初始化SQLiteOpenHelper的子类的实例，new MySqliteHelper 类实例对象的时候并没有创建数据库！         myOpenHelper = new MySqliteHelper(this); // myOpenHelper.getReadableDatabase();     }     OnClickListener myListener = new OnClickListener() {
   public void onClick(View v) {
   // getReadableDatabase：android // 会分析是否已经有了数据库，若没有会默认为我们创建一个数据库并且在系统路径data-data-包名下生成XX.db 文件!             sqDatabase = myOpenHelper.getReadableDatabase(); // TODO Auto-generated method stub             if (v.getId() == R.id.new_table) {
   //若MySqliteHelper已经创建了这个表，故此处按钮可不要，如果再点，会出错，提示表已经存在。                 String TABLE_NAME = "srx0209";                 String ID = "_id";                 String TEXT = "text"; //ID这一列type是integer，TEXT这一列type是text类型。                 String str_sql2 = "CREATE TABLE " + TABLE_NAME + "(" + ID                         + " INTEGER PRIMARY KEY AUTOINCREMENT," + TEXT                         + " text );";                 sqDatabase.execSQL(str_sql2);                 Log.d(TAG, "####new a table");             } else if (v.getId() == R.id.insert) {
                   ContentValues cv = new ContentValues(); //cv.put(MySqliteHelper.TEXT, "测试新的数据");                 cv.put(MySqliteHelper.TEXT, "testnewdata");                 sqDatabase.insert(MySqliteHelper.TABLE_NAME, null, cv);                 Log.d(TAG, "####insert");             } else if (v.getId() == R.id.delete_record) {
                   sqDatabase.delete(MySqliteHelper.TABLE_NAME, MySqliteHelper.ID + "=1", null);                 Log.d(TAG, "####delete_record");             } else if (v.getId() == R.id.delete_table) {
                   sqDatabase.execSQL("DROP TABLE srx0209");                 Log.d(TAG, "####delete_table");             } else if (v.getId() == R.id.modify) {
                   ContentValues cv = new ContentValues();                 cv.put(MySqliteHelper.TEXT, "修改后的数据");                 sqDatabase.update(MySqliteHelper.TABLE_NAME, cv,                         "_id " + "=" + Integer.toString(3), null);                 Log.d(TAG, "####modify");             } else if (v.getId() == R.id.search) {
                   Cursor cur = sqDatabase.rawQuery("SELECT * FROM "                         + MySqliteHelper.TABLE_NAME, null); if (cur != null) {
                       String temp = ""; int i = 0; while (cur.moveToNext()) {
   // 直到返回false说明表中到了数据末尾                         temp += cur.getString(0); // 参数0 指的是列的下标,这里的0指的是id列                         temp += cur.getString(1); // 这里的0相对于当前应该是咱们的text列了                         i++;                         temp += "  "; // 这里是我整理显示格式 ,呵呵~                         if (i % 3 == 0) // 这里是我整理显示格式 ,呵呵~                             temp += "\n";// 这里是我整理显示格式 ,呵呵~                         Log.d(TAG, "temp=="+temp);                     }                 }                 Log.d(TAG, "####search");             }         }     }; }