参考：contentprovider的学习实例总结  http://www.cnblogs.com/chenglong/articles/1892029.html
Android学习十九：ContentProvider初步  http://blog.sina.com.cn/s/blog_5688414b0100xagp.html
android 自定义 Content Provider示例  http://byandby.iteye.com/blog/837466

实例源码下载：http://download.csdn.net/detail/yang_hui1986527/4430639

Profile.java

package com.snowdream.contentprovider;

import android.net.Uri;

public class Profile {
	
	/**
	 * 表格名称
	 */
	public static final String TABLE_NAME = "profile";
	
	/**
	 * 列表一，_ID，自动增加
	 */
	public static final String COLUMN_ID = "_id";
	
	/**
	 * 列表二，名称
	 */
	public static final String COLUMN_NAME = "name";
     
     
    public static final String AUTOHORITY = "com.snowdream.provider";
    public static final int ITEM = 1;
    public static final int ITEM_ID = 2;
     
    public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.snowdream.profile";
    public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/vnd.snowdream.profile";
     
    public static final Uri CONTENT_URI = Uri.parse("content://" + AUTOHORITY + "/profile");
}

package com.snowdream.contentprovider;

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

public class DBHelper extends SQLiteOpenHelper {

	/**
	 * 数据库名称
	 */
	private static final String DATABASE_NAME = "test.db";  
	
	/**
	 * 数据库版本
	 */
	private static final int DATABASE_VERSION = 1;  

	public DBHelper(Context context) {
		super(context, DATABASE_NAME, null, DATABASE_VERSION);
	}

	@Override
	public void onCreate(SQLiteDatabase db)  throws SQLException {
		//创建表格
		db.execSQL("CREATE TABLE IF NOT EXISTS "+ Profile.TABLE_NAME + "("+ Profile.COLUMN_ID +" INTEGER PRIMARY KEY AUTOINCREMENT," + Profile.COLUMN_NAME +" VARCHAR NOT NULL);");
	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)  throws SQLException {
		//删除并创建表格
		db.execSQL("DROP TABLE IF EXISTS "+ Profile.TABLE_NAME+";");
		onCreate(db);
	}
}

package com.snowdream.contentprovider;

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;

public class MyProvider extends ContentProvider {

	DBHelper mDbHelper = null;
	SQLiteDatabase db = null;

	private static final UriMatcher mMatcher;
	static{
		mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
		mMatcher.addURI(Profile.AUTOHORITY,Profile.TABLE_NAME, Profile.ITEM);
		mMatcher.addURI(Profile.AUTOHORITY, Profile.TABLE_NAME+"/#", Profile.ITEM_ID);
	}

	@Override
	public int delete(Uri uri, String selection, String[] selectionArgs) {
		// TODO Auto-generated method stub
		return 0;
	}

	@Override
	public String getType(Uri uri) {
		switch (mMatcher.match(uri)) {
		case Profile.ITEM:
			return Profile.CONTENT_TYPE;
		case Profile.ITEM_ID:
			return Profile.CONTENT_ITEM_TYPE;
		default:
			throw new IllegalArgumentException("Unknown URI"+uri);
		}
	}

	@Override
	public Uri insert(Uri uri, ContentValues values) {
		// TODO Auto-generated method stub
		long rowId;
		if(mMatcher.match(uri)!=Profile.ITEM){
			throw new IllegalArgumentException("Unknown URI"+uri);
		}
		rowId = db.insert(Profile.TABLE_NAME,null,values);
		if(rowId>0){
			Uri noteUri=ContentUris.withAppendedId(Profile.CONTENT_URI, rowId);
			getContext().getContentResolver().notifyChange(noteUri, null);
			return noteUri;
		}

		throw new SQLException("Failed to insert row into " + uri);
	}

	@Override
	public boolean onCreate() {
		// TODO Auto-generated method stub
		mDbHelper = new DBHelper(getContext());

		db = mDbHelper.getReadableDatabase();

		return true;
	}

	@Override
	public Cursor query(Uri uri, String[] projection, String selection,
			String[] selectionArgs, String sortOrder) {
		// TODO Auto-generated method stub
		Cursor c = null;
		switch (mMatcher.match(uri)) {
		case Profile.ITEM:
			c =  db.query(Profile.TABLE_NAME, projection, selection, selectionArgs, null, null, sortOrder);
			break;
		case Profile.ITEM_ID:
			c = db.query(Profile.TABLE_NAME, projection,Profile.COLUMN_ID + "="+uri.getLastPathSegment(), selectionArgs, null, null, sortOrder);
			break;
		default:
			throw new IllegalArgumentException("Unknown URI"+uri);
		}

		c.setNotificationUri(getContext().getContentResolver(), uri);
		return c;
	}

	@Override
	public int update(Uri uri, ContentValues values, String selection,
			String[] selectionArgs) {
		// TODO Auto-generated method stub
		return 0;
	}

}

package com.snowdream.contentprovider;

import com.snowdream.contentprovider.R;

import android.app.ListActivity;
import android.content.ContentResolver;
import android.content.ContentUris;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.os.Bundle;
import android.view.Menu;
import android.widget.SimpleCursorAdapter;


public class MainActivity extends ListActivity {
	private SimpleCursorAdapter adapter= null;
	private Cursor mCursor = null;
	private ContentResolver mContentResolver = null;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		initData();
		initAdapter();
	}

	public void initData(){
		mContentResolver = getContentResolver();

		//填充数据
		for (int i = 0; i < 100; i++) {
			ContentValues values = new ContentValues();
			values.put(Profile.COLUMN_NAME, "张三"+i);
			mContentResolver.insert(Profile.CONTENT_URI, values);
		}
	}


	public void initAdapter(){
		//查询表格，并获得Cursor
		//查询全部数据
		mCursor = mContentResolver.query(Profile.CONTENT_URI, new String[]{Profile.COLUMN_ID,Profile.COLUMN_NAME}, null, null, null);

		//查询部分数据
		//String selection = Profile.COLUMN_ID + " LIKE '%1'";
		//mCursor = mContentResolver.query(Profile.CONTENT_URI, new String[]{Profile.COLUMN_ID,Profile.COLUMN_NAME}, selection, null, null);


		//查询一个数据
		//Uri uri = ContentUris.withAppendedId(Profile.CONTENT_URI, 50);
		//mCursor = mContentResolver.query(uri, new String[]{Profile.COLUMN_ID,Profile.COLUMN_NAME}, null, null, null);

		startManagingCursor(mCursor);

		//设置adapter
		adapter = new SimpleCursorAdapter(this, android.R.layout.simple_list_item_2, mCursor, new String[]{Profile.COLUMN_ID,Profile.COLUMN_NAME}, new int[]{android.R.id.text1,android.R.id.text2});
		setListAdapter(adapter);
	}


	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		getMenuInflater().inflate(R.menu.activity_main, menu);
		return true;
	}


}

当我们渲染一个完全封闭的物体的时候，多边形的背面都是隐藏的，我们无法看见。但是如果这个物体有一些空洞，那么一些背面就可以被看见了。然而因为这些多边形的法向量的方向在这个时候不是正确的，所以会渲染出错误的结果。为了合理的渲染这些背面，我们必须反转法向量，然后基于这些反转的法向量来计算光照。

下图显示了一个采用Phong光照模型绘制茶壶使用双面渲染与否的结果对比：

图一 使用双面渲染与不使用的效果对比

一、固定管线OpenGL实现双面渲染

在固定管线中，我们需要用一个函数来启用双面光照：

glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE);

这样，OpenGL将会反转表面的法线的方向，表示背面多边形的法线。

实例：

void GLWidget::initLight()
{
	GLfloat light_ambient[]={0.7,0.8,0.9,1.0};   
	GLfloat light_diffuse[]={1.0,1.0,1.0,1.0};   
	GLfloat light_specular[]={1.0,1.0,1.0,1.0};   
	GLfloat light_position[]={2.0,2.0,2.0,0.0};
	GLfloat mat_diffuse[]={0.8,0.8,0.8,1.0}; 

	glLightfv(GL_LIGHT0,GL_AMBIENT,light_ambient);   
	glLightfv(GL_LIGHT0,GL_DIFFUSE,light_diffuse);   
	glLightfv(GL_LIGHT0,GL_SPECULAR,light_specular);   
	glLightfv(GL_LIGHT0,GL_POSITION,light_position); 

	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);
	glEnable(GL_AUTO_NORMAL);
	glEnable(GL_NORMALIZE);
	//glEnable(GL_CULL_FACE);
	//启用双面光照
	glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE);
	glMaterialfv(GL_FRONT_AND_BACK,GL_DIFFUSE,mat_diffuse);  
}

二、可编程管线OpenGL实现双面渲染

假设我们的光照（采用Phong光照模型）计算是基于顶点的。在顶点着色器中，我们需要为每个顶点分别计算两次：front face和back face。两次计算采用的法向量不同。

#version 400

layout (location = 0) in vec3 VertexPosition;
layout (location = 1) in vec3 VertexNormal;

out vec3 FrontColor;
out vec3 BackColor;

struct LightInfo{
	vec4 Position;
	vec3 La;
	vec3 Ld;
	vec3 Ls;
};
uniform LightInfo Light;

struct MaterialInfo{
	vec3 Ka;
	vec3 Kd;
	vec3 Ks;
	float Shininess;
};
uniform MaterialInfo Material;

uniform mat4 ModelViewMatrix;
uniform mat3 NormalMatrix;
uniform mat4 ProjectionMatrix;
uniform mat4 MVP;

//转化到视空间
void getEyeSpace(out vec3 tnorm,out vec4 eyeCoords)
{
	//convert normal and position to eye coords
	tnorm = normalize(NormalMatrix * VertexNormal);
	eyeCoords = ModelViewMatrix * vec4(VertexPosition,1.0);
}

//计算Phong光照模型
vec3 phongModel(vec4 eyeCoords,vec3 tnorm)
{
	vec3 s = normalize(vec3(Light.Position - eyeCoords));
	vec3 v = normalize(-eyeCoords.xyz);
	vec3 r = reflect(-s,tnorm);

	vec3 ambient = Light.La * Material.Ka;

	float sDotN = max(dot(s,tnorm),0.0);
	vec3 diffuse = Light.Ld * Material.Kd * sDotN;

	vec3 specular = vec3(0.0);
	if(sDotN > 0)
		specular = Light.Ls * Material.Ks * 
					pow(max(dot(r,v),0.0),Material.Shininess);

	return (ambient + diffuse + specular);
}

void main()
{
	vec3 tnorm;
	vec4 eyeCoords;
	getEyeSpace(tnorm,eyeCoords);
	FrontColor = phongModel(eyeCoords,tnorm);
	BackColor = phongModel(eyeCoords,-tnorm);

	gl_Position = MVP * vec4(VertexPosition,1.0);
}

gl_FrontFacing是GLSL内置的关键字，它代表图元是面向光源还是背向光源。

片断着色器 twosided.frag：

#version 400

in vec3 FrontColor;
in vec3 BackColor;

layout (location = 0) out vec4 FragColor;

void main()
{
	if(gl_FrontFacing)
	{
		FragColor = vec4(FrontColor,1.0);
	}
	else
	{
		FragColor = vec4(BackColor,1.0);
	}
}