01_19_ContentProvider初步

01_19_ContentProvider初步（插入数据成功、但查询失败，得进一步调试）


最重要的是在AndroidMainfest.xml中注册provider

<provider android:name="mars.cp.FirstContentProvider"
                  android:authorities="mars.cp.FirstContentProvider"/>

具体如下：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android=""
      package="mars.cp"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".CPActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <provider android:name="mars.cp.FirstContentProvider"
                  android:authorities="mars.cp.FirstContentProvider"/>
    </application>
    <uses-sdk android:minSdkVersion="4" />
</manifest>

//CPActivity.java
package mars.cp;

import mars.cp.FirstProviderMetaData.UserTableMetaData;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class CPActivity extends Activity {
    /** Called when the activity is first created. */
    private Button insertButton = null;
    private Button queryButton = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        queryButton = (Button) findViewById(R.id.query);
        queryButton.setOnClickListener(new QueryListener());
        insertButton = (Button) findViewById(R.id.insert);
        insertButton.setOnClickListener(new InsertListener());
    //    System.out.println(getContentResolver().getType(FirstProviderMetaData.UserTableMetaData.CONTENT_URI));
    }

    class InsertListener implements OnClickListener {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            ContentValues values = new ContentValues(); //USER_NAME = "name"
            values.put(FirstProviderMetaData.UserTableMetaData.USER_NAME,
                    "zhangsan");
            Uri uri = getContentResolver()
                    .insert(            //CONTENT_URI = Uri.parse("content://" + AUTHORIY + "/users");
                            FirstProviderMetaData.UserTableMetaData.CONTENT_URI,
                            values);
            System.out.println("uri--->" + uri.toString());
        }

    }

    class QueryListener implements OnClickListener {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Cursor c = getContentResolver().query( //这里有问题
                    FirstProviderMetaData.UserTableMetaData.CONTENT_URI, null,
                    null, null, null);
            //query(Uri uri, String[] projection, String selection, String[] selectionArgs,String sortOrder)
            while(c.moveToNext()){
                System.out.println(c.getString(c.getColumnIndex(UserTableMetaData.USER_NAME)));
            }
        }

    }
}

//FirstContentProvider.java
package mars.cp;

import java.util.HashMap;

import mars.cp.FirstProviderMetaData.UserTableMetaData;
import mars.sqlite3.db.DatabaseHelper;
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.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.text.TextUtils;

public class FirstContentProvider extends ContentProvider {

    public static final UriMatcher uriMatcher;
    public static final int INCOMING_USER_COLLECTION = 1;
    public static final int INCOMING_USER_SINGLE = 2;
    private DatabaseHelper dh;
    static {
        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        uriMatcher.addURI(FirstProviderMetaData.AUTHORIY, "/users",
                INCOMING_USER_COLLECTION);
        uriMatcher.addURI(FirstProviderMetaData.AUTHORIY, "/users/#",
                INCOMING_USER_SINGLE);
    }

    public static HashMap<String,String> userProjectionMap;
    static
    {
        userProjectionMap = new HashMap<String,String>();
        userProjectionMap.put(UserTableMetaData._ID,UserTableMetaData._ID);
        userProjectionMap.put(UserTableMetaData.USER_NAME, UserTableMetaData.USER_NAME);
    }
    @Override
    public int delete(Uri arg0, String arg1, String[] arg2) {
        // TODO Auto-generated method stub
        System.out.println("delete");
        return 0;
    }

    //根据传入的URI，返回该URI所表示的数据类型
    @Override
    public String getType(Uri uri) {
        // TODO Auto-generated method stub
        System.out.println("getType");
        switch(uriMatcher.match(uri)){
        case INCOMING_USER_COLLECTION:
            return UserTableMetaData.CONTENT_TYPE;
        case INCOMING_USER_SINGLE:
            return UserTableMetaData.CONTENT_TYPE_ITEM;
        default:
            throw new IllegalArgumentException("Unknown URI" + uri);
        }
    }

    /**
     * 该函数的返回值是一个Uri，这个Uri表示的是刚刚使用这个函数所插入的数据
     * content://mars.cp.FirstContentProvider/users/1
     */
    @Override
    public Uri insert(Uri uri, ContentValues values) {
        System.out.println("insert");
        SQLiteDatabase db = dh.getWritableDatabase();
        long rowId = db.insert(UserTableMetaData.TABLE_NAME, null, values);//TABLE_NAME = "users";
        if(rowId > 0){
            Uri insertedUserUri = ContentUris.withAppendedId(UserTableMetaData.CONTENT_URI, rowId);
            //通知监听器，数据已经改变
            getContext().getContentResolver().notifyChange(insertedUserUri, null);
            return insertedUserUri;
        }
        throw new SQLException("Failed to insert row into" + uri);
    }

    //是一个回调方法，所以说在ContentProvider创建的时候执行
    @Override
    public boolean onCreate() {
        //打开数据库
        dh = new DatabaseHelper(getContext(),FirstProviderMetaData.DATABASE_NAME);//DATABASE_NAME = "FirstProvider.db";
        System.out.println("onCreate");
        return true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
            String sortOrder) {
        SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
        switch(uriMatcher.match(uri)){
        case INCOMING_USER_COLLECTION:
            qb.setTables(UserTableMetaData.TABLE_NAME);
            qb.setProjectionMap(userProjectionMap);
            break;
        case INCOMING_USER_SINGLE:
            qb.setTables(UserTableMetaData.TABLE_NAME); //TABLE_NAME = "users"
            qb.setProjectionMap(userProjectionMap);
            qb.appendWhere(UserTableMetaData._ID + "=" + uri.getPathSegments().get(1));
            break;
        }
        String orderBy;
        if(TextUtils.isEmpty(sortOrder)){
            orderBy = UserTableMetaData.DEFAULT_SORT_ORDER; //String DEFAULT_SORT_ORDER = "_id desc";
        }
        else{
            orderBy = sortOrder;
        }
        SQLiteDatabase db = dh.getWritableDatabase();
        //Cursor c = qb.query(db, projectionIn, selection, selectionArgs, groupBy, having, sortOrder)
        Cursor c = qb.query(db, projection, selection, selectionArgs, null, null, orderBy);//这里有问题

        c.setNotificationUri(getContext().getContentResolver(), uri);
        System.out.println("query");
        return c;
    }
    //12-25 04:08:43.103: E/AndroidRuntime(487):     at mars.cp.FirstContentProvider.query(FirstContentProvider.java:111)
    //12-25 04:08:43.103: E/AndroidRuntime(487): java.lang.IllegalStateException: Invalid tables
    //12-25 04:08:43.103: E/AndroidRuntime(487):     at mars.cp.CPActivity$QueryListener.onClick(CPActivity.java:51)

    @Override
    public int update(Uri arg0, ContentValues arg1, String arg2, String[] arg3) {
        // TODO Auto-generated method stub
        System.out.println("update");
        return 0;
    }

}

//FirstProviderMetaData.java
package mars.cp;

import android.net.Uri;
import android.provider.BaseColumns;

public class FirstProviderMetaData {
    public static final String AUTHORIY = "mars.cp.FirstContentProvider";
    //数据库名称
    public static final String DATABASE_NAME = "FirstProvider.db";
    //数据库的版本
    public static final int DATABASE_VERSION = 1;
    //表名
    public static final String USERS_TABLE_NAME = "users";

    public static final class UserTableMetaData implements BaseColumns{
        //表名
        public static final String TABLE_NAME = "users";
        //访问该ContentProvider的URI
        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORIY + "/users");
        //该ContentProvider所返回的数据类型的定义
        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.firstprovider.user";
        public static final String CONTENT_TYPE_ITEM = "vnd.android.cursor.item/vnd.firstprovider.user";
        //列名
        public static final String USER_NAME = "name";
        //默认的排序方法
        public static final String DEFAULT_SORT_ORDER = "_id desc";
    }
}

//DatabaseHelper.java
package mars.sqlite3.db;

import mars.cp.FirstProviderMetaData;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;

//DatabaseHelper作为一个访问SQLite的助手类，提供两个方面的功能，
//第一，getReadableDatabase(),getWritableDatabase()可以获得SQLiteDatabse对象，通过该对象可以对数据库进行操作
//第二，提供了onCreate()和onUpgrade()两个回调函数，允许我们在创建和升级数据库时，进行自己的操作

public class DatabaseHelper extends SQLiteOpenHelper {

    private static final int VERSION = 1;

    // 在SQLiteOepnHelper的子类当中，必须有该构造函数
    public DatabaseHelper(Context context, String name, CursorFactory factory,
            int version) {
        // 必须通过super调用父类当中的构造函数
        super(context, name, factory, version);
        // TODO Auto-generated constructor stub
    }

    public DatabaseHelper(Context context, String name) {
        this(context, name, VERSION);
    }

    public DatabaseHelper(Context context, String name, int version) {
        this(context, name, null, version);
    }

    // 该函数是在第一次创建数据库的时候执行,实际上是在第一次得到SQLiteDatabse对象的时候，才会调用这个方法
    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        System.out.println("create a Database");
        // execSQL函数用于执行SQL语句
        db.execSQL("create table " + FirstProviderMetaData.USERS_TABLE_NAME
                + "(" + FirstProviderMetaData.UserTableMetaData._ID
                + " INTEGER PRIMARY KEY AUTOINCREMENT,"
                + FirstProviderMetaData.UserTableMetaData.USER_NAME
                + " varchar(20));");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub
        System.out.println("update a Database");
    }

}