本文主要是介绍ContentProvider demo，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
1、DataBaseTest/app/src/main/AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="example.com.databasetest"> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <provider android:authorities="example.com.databasetest" android:name=".TeacherContentProvider" android:grantUriPermissions="true"/> </application> </manifest>
2、布局文件：DataBaseTest/app/src/main/res/layout/activity_main.xml
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="example.com.databasetest.MainActivity"> <Button android:text="insert" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="13dp" android:id="@+id/insert" android:onClick="iinsertTeacher" android:layout_alignParentTop="true" android:layout_alignParentStart="true" /> <Button android:text="querys" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_below="@+id/query" android:layout_alignParentStart="true" android:id="@+id/querys" android:onClick="querysTeacher" /> <Button android:text="query" android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/query" android:onClick="queryTeacher" android:layout_below="@+id/insert" android:layout_alignParentStart="true" /> <Button android:text="update" android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/update" android:layout_below="@+id/querys" android:layout_alignParentStart="true" android:onClick="updateTeacher" /> <Button android:text="delete" android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/delete" android:onClick="deleteTeacher" android:layout_below="@+id/update" android:layout_alignParentStart="true" /> </RelativeLayout>
3、显示页面：DataBaseTest/app/src/main/java/example/com/databasetest/MainActivity.java
package example.com.databasetest;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.util.Log; import android.view.View;import java.util.Date;public class MainActivity extends Activity { Uri uri = Uri.parse("content://example.com.databasetest/teacher");@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);} public void iinsertTeacher(View v) { ContentResolver cr = getContentResolver();ContentValues cv = new ContentValues();cv.put("title", "jiaoshou");cv.put("name", "jiaoshi");cv.put("sex", true);Log.e("myy","iinsertTeacher(View v)");Uri uri2 = cr.insert(uri, cv);System.out.println(uri2.toString());} public void querysTeacher(View v) { 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();} public void queryTeacher(View v) { 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) { return;} int name = c.getColumnIndex("name");System.out.println(c.getString(name));c.close();} public void updateTeacher(View v) { 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);} public void deleteTeacher(View v) { ContentResolver cr = getContentResolver();cr.delete(uri, "_ID=?", new String[]{"2"});} }
4、创建常量：DataBaseTest/app/src/main/java/example/com/databasetest/ContentData.java
package example.com.databasetest;import android.content.UriMatcher; import android.net.Uri; import android.provider.BaseColumns;/** * Created by myy on 18-7-2. */ public class ContentData { public static final String AUTHORITY = "example.com.databasetest";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/example.com.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/example.com.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);} } }
5、创建数据库：DataBaseTest/app/src/main/java/example/com/databasetest/DBOpenHelper.java
package example.com.databasetest;import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import android.database.sqlite.SQLiteDatabase.CursorFactory; import android.util.Log;/** * Created by myy on 18-7-2. */ 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) { Log.e("myy","DBOpenHelper--->Create database" );db.execSQL("CREATE TABLE IF NOT EXISTS " + 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) { } }
6、重写privoder：DataBaseTest/app/src/main/java/example/com/databasetest/TeacherContentProvider.java
package example.com.databasetest;import android.content.ContentProvider; import android.content.ContentUris; import android.content.ContentValues; import android.content.UriMatcher; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.net.Uri; import android.text.TextUtils; import android.util.Log;import static example.com.databasetest.ContentData.UserTableData.TEACHER; import static example.com.databasetest.ContentData.UserTableData.TEACHERS; import static example.com.databasetest.ContentData.UserTableData.CONTENT_TYPE; import static example.com.databasetest.ContentData.UserTableData.CONTENT_TYPE_ITME;/** * Created by myy on 18-7-2. */ 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 private static final UriMatcher uriMatcher=new UriMatcher(UriMatcher.NO_MATCH);/** * 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() { Log.e("myy","TeacherContentProvider--->Create database" );//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){ Log.e("myy","TeacherContentProvider---insert(),uriMatcher.match(uri):" + uriMatcher.match(uri) );//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:Log.e("myy","TeacherContentProvider---insert(),throw new IllegalArgumentException(\"Unknown URI \" + uri)" );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);} } }还未调通，待debug。
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