Android ContentProvider完整案例

/**
 * 提供ContentProvider对外的各种常量，当外部数据需要访问的时候，就可以参考这些常量操作数据。
 * @author HB
 *
 */
public class ContentData {
    public static final String AUTHORITY = "hb.android.contentProvider";
    public static final String DATABASE_NAME = "teacher.db";
    //创建 数据库的时候，都必须加上版本信息；并且必须大于4
    public static final int DATABASE_VERSION = 4;
    public static final String USERS_TABLE_NAME = "teacher";
    
    public static final class UserTableData implements BaseColumns {
        public static final String TABLE_NAME = "teacher";
        //Uri，外部程序需要访问就是通过这个Uri访问的，这个Uri必须的唯一的。
        public static final Uri CONTENT_URI = Uri.parse("content://"+ AUTHORITY + "/teacher");
        // 数据集的MIME类型字符串则应该以vnd.android.cursor.dir/开头  
        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/hb.android.teachers";
        // 单一数据的MIME类型字符串应该以vnd.android.cursor.item/开头  
        public static final String CONTENT_TYPE_ITME = "vnd.android.cursor.item/hb.android.teacher";
        /* 自定义匹配码 */  
        public static final int TEACHERS = 1;  
        /* 自定义匹配码 */  
        public static final int TEACHER = 2;  
        
        public static final String TITLE = "title";
        public static final String NAME = "name";
        public static final String DATE_ADDED = "date_added";
        public static final String SEX = "SEX";
        public static final String DEFAULT_SORT_ORDER = "_id desc";
        
        public static final UriMatcher uriMatcher;  
        static {  
            // 常量UriMatcher.NO_MATCH表示不匹配任何路径的返回码  
            uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);  
            // 如果match()方法匹配content://hb.android.teacherProvider/teachern路径,返回匹配码为TEACHERS  
            uriMatcher.addURI(ContentData.AUTHORITY, "teacher", TEACHERS);  
            // 如果match()方法匹配content://hb.android.teacherProvider/teacher/230,路径，返回匹配码为TEACHER  
            uriMatcher.addURI(ContentData.AUTHORITY, "teacher/#", TEACHER);  
        }
    }
}

/**
 * 这个类继承SQLiteOpenHelper抽象类，用于创建数据库和表。创建数据库是调用它的父类构造方法创建。
 * @author HB
 */
public class DBOpenHelper extends SQLiteOpenHelper {

    // 在SQLiteOepnHelper的子类当中，必须有该构造函数，用来创建一个数据库；
    public DBOpenHelper(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 DBOpenHelper(Context context, String name) {
    // this(context, name, VERSION);
    // }

    public DBOpenHelper(Context context, String name, int version) {
        this(context, name, null, version);
    }
    
    /**
     * 只有当数据库执行创建 的时候，才会执行这个方法。如果更改表名，也不会创建，只有当创建数据库的时候，才会创建改表名之后 的数据表
     */
    @Override
    public void onCreate(SQLiteDatabase db) {
System.out.println("create table");
        db.execSQL("create table " + ContentData.UserTableData.TABLE_NAME
                + "(" + ContentData.UserTableData._ID
                + " INTEGER PRIMARY KEY autoincrement,"
                + ContentData.UserTableData.NAME + " varchar(20),"
                + ContentData.UserTableData.TITLE + " varchar(20),"
                + ContentData.UserTableData.DATE_ADDED + " long,"
                + ContentData.UserTableData.SEX + " boolean)" + ";");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

}

/**
 * 这个类给外部程序提供访问内部数据的一个接口
 * @author HB
 *
 */
public class TeacherContentProvider extends ContentProvider {
    
    private DBOpenHelper dbOpenHelper = null;  
    // UriMatcher类用来匹配Uri，使用match()方法匹配路径时返回匹配码  
      
      
    /**
     * 是一个回调函数，在ContentProvider创建的时候，就会运行,第二个参数为指定数据库名称，如果不指定，就会找不到数据库；
     * 如果数据库存在的情况下是不会再创建一个数据库的。（当然首次调用 在这里也不会生成数据库必须调用SQLiteDatabase的 getWritableDatabase,getReadableDatabase两个方法中的一个才会创建数据库）
     */
    @Override  
    public boolean onCreate() { 
        //这里会调用 DBOpenHelper的构造函数创建一个数据库；
        dbOpenHelper = new DBOpenHelper(this.getContext(), ContentData.DATABASE_NAME, ContentData.DATABASE_VERSION);
        return true;  
    }  
    /**
     * 当执行这个方法的时候，如果没有数据库，他会创建，同时也会创建表，但是如果没有表，下面在执行insert的时候就会出错
     * 这里的插入数据也完全可以用sql语句书写，然后调用 db.execSQL(sql)执行。
     */
    @Override  
    public Uri insert(Uri uri, ContentValues values){  
        //获得一个可写的数据库引用，如果数据库不存在，则根据onCreate的方法里创建；
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();  
        long id = 0;  
        
        switch (uriMatcher.match(uri)) {  
        case TEACHERS:  
            id = db.insert("teacher", null, values);    // 返回的是记录的行号，主键为int，实际上就是主键值  
            return ContentUris.withAppendedId(uri, id);  
        case TEACHER:  
            id = db.insert("teacher", null, values); 
            String path = uri.toString();  
            return Uri.parse(path.substring(0, path.lastIndexOf("/"))+id); // 替换掉id  
        default:  
            throw new IllegalArgumentException("Unknown URI " + uri);  
        }
    }  
      
    @Override  
    public int delete(Uri uri, String selection, String[] selectionArgs) {  
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();  
        int count = 0;  
        switch (uriMatcher.match(uri)) {  
        case TEACHERS:  
            count = db.delete("teacher", selection, selectionArgs);  
            break;  
        case TEACHER:  
            // 下面的方法用于从URI中解析出id，对这样的路径content://hb.android.teacherProvider/teacher/10  
            // 进行解析，返回值为10  
            long personid = ContentUris.parseId(uri);  
            String where = "_ID=" + personid;    // 删除指定id的记录  
            where += !TextUtils.isEmpty(selection) ? " and (" + selection + ")" : "";    // 把其它条件附加上  
            count = db.delete("teacher", where, selectionArgs);  
            break;  
        default:  
            throw new IllegalArgumentException("Unknown URI " + uri);  
        }  
        db.close();  
        return count;  
    }  
  
    @Override  
    public int update(Uri uri, ContentValues values, String selection,  
            String[] selectionArgs) {  
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();  
        int count = 0;  
        switch (uriMatcher.match(uri)) {  
        case TEACHERS:  
            count = db.update("teacher", values, selection, selectionArgs);  
            break;  
        case TEACHER:  
            // 下面的方法用于从URI中解析出id，对这样的路径content://com.ljq.provider.personprovider/person/10  
            // 进行解析，返回值为10  
            long personid = ContentUris.parseId(uri);  
            String where = "_ID=" + personid;// 获取指定id的记录  
            where += !TextUtils.isEmpty(selection) ? " and (" + selection + ")" : "";// 把其它条件附加上  
            count = db.update("teacher", values, where, selectionArgs);  
            break;  
        default:  
            throw new IllegalArgumentException("Unknown URI " + uri);  
        }  
        db.close();  
        return count;  
    }  
      
    @Override  
    public String getType(Uri uri) {  
        switch (uriMatcher.match(uri)) {  
        case TEACHERS:  
            return CONTENT_TYPE;  
        case TEACHER:  
            return CONTENT_TYPE_ITME;  
        default:  
            throw new IllegalArgumentException("Unknown URI " + uri);  
        }  
    }  
  
    @Override  
    public Cursor query(Uri uri, String[] projection, String selection,  
            String[] selectionArgs, String sortOrder) {  
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();  
        switch (uriMatcher.match(uri)) {  
        case TEACHERS:  
            return db.query("teacher", projection, selection, selectionArgs, null, null, sortOrder);  
        case TEACHER:  
            // 进行解析，返回值为10  
            long personid = ContentUris.parseId(uri);  
            String where = "_ID=" + personid;// 获取指定id的记录  
            where += !TextUtils.isEmpty(selection) ? " and (" + selection + ")" : "";// 把其它条件附加上  
            return db.query("teacher", projection, where, selectionArgs, null, null, sortOrder);  
        default:  
            throw new IllegalArgumentException("Unknown URI " + uri);  
        }  
    }  
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="hb.android.contentProvider"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />


    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".TeacherActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
<span style="white-space:pre">        </span><provider android:name=".TeacherContentProvider"
<span style="white-space:pre">            </span>android:authorities="hb.android.contentProvider" />
    </application>
</manifest>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<Button 
    android:id="@+id/insert"
    android:text="@string/insert"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>
<Button 
    android:id="@+id/query"
    android:text="@string/query"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>
<Button 
    android:id="@+id/querys"
    android:text="@string/querys"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>
<Button 
    android:id="@+id/update"
    android:text="@string/update"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>
<Button 
    android:id="@+id/delete"
    android:text="@string/delete"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>
</LinearLayout>

package hb.android.contentProvider;

import java.util.Date;

import android.app.Activity;
import android.content.ContentResolver;
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;

/**
 * 这个类用来测试ContentProvider是否可用。通过 给定的uri访问，数据库；
 * 
 * @author HB
 * 
 */
public class TeacherActivity extends Activity {
    Button insert;
    Button query;
    Button update;
    Button delete;
    Button querys;
    Uri uri = Uri.parse("content://hb.android.contentProvider/teacher");

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        insert = (Button) findViewById(R.id.insert);
        query = (Button) findViewById(R.id.query);
        update = (Button) findViewById(R.id.update);
        delete = (Button) findViewById(R.id.delete);
        querys = (Button) findViewById(R.id.querys);
        // 绑定监听器的两种方法一；
        insert.setOnClickListener(new InsertListener());
        query.setOnClickListener(new QueryListener());
        // 方法二
        update.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                // TODO Auto-generated method stub
                ContentResolver cr = getContentResolver();
                ContentValues cv = new ContentValues();
                cv.put("name", "huangbiao");
                cv.put("date_added", (new Date()).toString());
                int uri2 = cr.update(uri, cv, "_ID=?", new String[]{"3"});
System.out.println("updated"+":"+uri2);
            }
        });

        delete.setOnClickListener(new OnClickListener() {
            
            public void onClick(View v) {
                ContentResolver cr = getContentResolver();
                cr.delete(uri, "_ID=?", new String[]{"2"});
            }
        });

        querys.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                // TODO Auto-generated method stub
                ContentResolver cr = getContentResolver();
                // 查找id为1的数据
                Cursor c = cr.query(uri, null, null,null, null);
                System.out.println(c.getCount());
                c.close();
            }
        });
    }

    class InsertListener implements OnClickListener {

        public void onClick(View v) {
            // TODO Auto-generated method stub
            ContentResolver cr = getContentResolver();

            ContentValues cv = new ContentValues();
            cv.put("title", "jiaoshou");
            cv.put("name", "jiaoshi");
            cv.put("sex", true);
            Uri uri2 = cr.insert(uri, cv);
            System.out.println(uri2.toString());
        }

    }

    class QueryListener implements OnClickListener {

        public void onClick(View v) {
            // TODO Auto-generated method stub
            ContentResolver cr = getContentResolver();
            // 查找id为1的数据
            Cursor c = cr.query(uri, null, "_ID=?", new String[] { "1" }, null);
            //这里必须要调用 c.moveToFirst将游标移动到第一条数据,不然会出现index -1 requested , with a size of 1错误；cr.query返回的是一个结果集。
            if (c.moveToFirst() == false) {
                // 为空的Cursor
                return;
            }
            int name = c.getColumnIndex("name");
            System.out.println(c.getString(name));
            c.close();
        }
    }
}