Beispielanalyse für den ContentProvider des Android-Inhaltsanbieters

Das Beispiel in diesem Artikel beschreibt die Verwendung des Android-Inhaltsanbieters ContentProvider. Teilen Sie es wie folgt mit allen als Referenz:

PersonContentProvider-Inhaltsanbieterklasse

package com.ljq.db;
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;
/**
 * 内容提供者
 * 
 * 作用：统一数据访问方式，方便外部调用
 * 
 * @author jiqinlin
 * 
 */
public class PersonContentProvider extends ContentProvider {
  // 数据集的MIME类型字符串则应该以vnd.android.cursor.dir/开头
  public static final String PERSONS_TYPE = "vnd.android.cursor.dir/person";
  // 单一数据的MIME类型字符串应该以vnd.android.cursor.item/开头
  public static final String PERSONS_ITEM_TYPE = "vnd.android.cursor.item/person";
  public static final String AUTHORITY = "com.ljq.provider.personprovider";// 主机名
  /* 自定义匹配码 */
  public static final int PERSONS = 1;
  /* 自定义匹配码 */
  public static final int PERSON = 2;
  public static final Uri PERSONS_URI = Uri.parse("content://" + AUTHORITY + "/person");
  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;
  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://com.ljq.provider.personprovider/person路径，返回匹配码为PERSONS
    uriMatcher.addURI(AUTHORITY, "person", PERSONS);
    // 如果match()方法匹配content://com.ljq.provider.personprovider/person/230路径，返回匹配码为PERSON
    uriMatcher.addURI(AUTHORITY, "person/#", PERSON);
  }
  @Override
  public boolean onCreate() {
    dbOpenHelper = new DBOpenHelper(this.getContext());
    return true;
  }
  @Override
  public Uri insert(Uri uri, ContentValues values){
    SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
    long id = 0;
    switch (uriMatcher.match(uri)) {
    case PERSONS:
      id = db.insert("person", "name", 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 PERSON:
      id = db.insert("person", "name", 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 PERSONS:
      count = db.delete("person", selection, selectionArgs);
      break;
    case PERSON:
      // 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;// 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("person", 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 PERSONS:
      count = db.update("person", values, selection, selectionArgs);
      break;
    case PERSON:
      // 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("person", 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 PERSONS:
      return PERSONS_TYPE;
    case PERSON:
      return PERSONS_ITEM_TYPE;
    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 PERSONS:
      return db.query("person", projection, selection, selectionArgs, null, null, sortOrder);
    case PERSON:
      // 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
      return db.query("person", projection, where, selectionArgs, null, null, sortOrder);
    default:
      throw new IllegalArgumentException("Unknown URI " + uri);
    }
  }
}

Dateiliste

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.ljq.sql" android:versionCode="1"
  android:versionName="1.0">
  <application android:icon="@drawable/icon"
    android:label="@string/app_name">
    <uses-library android:name="android.test.runner" />
    <activity android:name=".SqlActivity"
      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="com.ljq.db.PersonContentProvider"
       android:authorities="com.ljq.provider.personprovider" />
  </application>
  <uses-sdk android:minSdkVersion="7" />
  <instrumentation
    android:name="android.test.InstrumentationTestRunner"
    android:targetPackage="com.ljq.sql" android:label="Tests for My App" />
</manifest>

PersonContentProviderTest-Inhaltsanbieter-Testklasse

package com.ljq.test;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.test.AndroidTestCase;
import android.util.Log;
/**
 * 外部访问内容提供者
 * 
 * @author jiqinlin
 *
 */
public class PersonContentProviderTest extends AndroidTestCase{
  private static final String TAG = "PersonContentProviderTest";
  public void testSave() throws Throwable{
    ContentResolver contentResolver = this.getContext().getContentResolver();
    Uri insertUri = Uri.parse("content://com.ljq.provider.personprovider/person");
    ContentValues values = new ContentValues();
    values.put("name", "ljq");
    values.put("phone", "1350000009");
    Uri uri = contentResolver.insert(insertUri, values);
    Log.i(TAG, uri.toString());
  }
  public void testUpdate() throws Throwable{
    ContentResolver contentResolver = this.getContext().getContentResolver();
    Uri updateUri = Uri.parse("content://com.ljq.provider.personprovider/person/1");
    ContentValues values = new ContentValues();
    values.put("name", "linjiqin");
    contentResolver.update(updateUri, values, null, null);
  }
  public void testFind() throws Throwable{
    ContentResolver contentResolver = this.getContext().getContentResolver();
    //Uri uri = Uri.parse("content://com.ljq.provider.personprovider/person");
    Uri uri = Uri.parse("content://com.ljq.provider.personprovider/person");
    Cursor cursor = contentResolver.query(uri, null, null, null, "id asc");
    while(cursor.moveToNext()){
      int personid = cursor.getInt(cursor.getColumnIndex("id"));
      String name = cursor.getString(cursor.getColumnIndex("name"));
      String phone = cursor.getString(cursor.getColumnIndex("phone"));
      Log.i(TAG, "personid="+ personid + ",name="+ name+ ",phone="+ phone);
    }
    cursor.close();
  }
  public void testDelete() throws Throwable{
    ContentResolver contentResolver = this.getContext().getContentResolver();
    Uri uri = Uri.parse("content://com.ljq.provider.personprovider/person/1");
    contentResolver.delete(uri, null, null);
  }
}

Ich hoffe, dass dieser Artikel für alle hilfreich ist, die sich mit der Android-Programmierung befassen.

Weitere verwandte Artikel zur Analyse von ContentProvider-Nutzungsbeispielen für Android-Inhaltsanbieter finden Sie auf der chinesischen PHP-Website!