Android四大组件应用系列——使用ContentProvider实现跨进程通讯
| 一、问题描述 |
如何在Android中实现不同应用之间的通讯（既跨进程进行调用）？Android提供了多种实现方式，使我们可以实现跨进程访问Activity、通过ContentProvider跨进程访问其他应用的数据、通过Broadcast可以向android系统中所有应用程序发送广播、使用AIDL实现跨进程的Service。下面我们就使用ContentProvider实现跨进程访问数据，并可对数据进行增、删、改、查
| 二、应用实现 |
使用ContentProvider实现数据共享，主要是共享应用的Sqlite数据库，再一个应用中（本例的shareinfo）提供数据源（Sqlite数据库）并创建ContentProvider组件， ContentProvider组件主要对外（其他应用）提供访问数据的接口（Uri信息），其他应用（本例的other）通过这个接口（Uri信息）实现跨进程的方法调用
如图所示：
本例涉及两个应用shareinfo和other
| 三、shareinfo应用的核心 |
作为数据的提供者首先是开发对外可访问的数据库（Sqlite）
涉及两个组件DbOpenHelper和SQLiteHelper
代码如下：
public class DbOpenHelper extends SQLiteOpenHelper { public DbOpenHelper(Context context) { super(context, "jereh.db", null, 4); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL("create table person(personid integer primary key " + " autoincrement,name varchar(20),phone varchar(12) null)"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){ db.execSQL("drop table person"); onCreate(db); } } public class SQLiteHelper { private Context context; private DbOpenHelper helper = null; public SQLiteHelper(Context context){ helper = new DbOpenHelper(context); } public void save(Person person){//增 SQLiteDatabase db = helper.getWritableDatabase(); db.execSQL("insert into person(name,phone) values(?,?)",new Object[]{person.getName(),person.getPhone()}); db.close(); } public void delete(int personid){//删 SQLiteDatabase db = helper.getWritableDatabase(); db.execSQL("delete from person where personid=?", new Integer[]{personid}); db.close(); } public void update(Person person){//改 SQLiteDatabase db = helper.getWritableDatabase(); db.execSQL("update person set name=?,phone=? where personid=?", new Object[]{person.getName(),person.getPhone(),person.getPersonid()}); db.close(); } public Person find(int personid){//查 SQLiteDatabase db = helper.getReadableDatabase(); //Cursor cursor = db.rawQuery("select * from person where personid=?", new String[]{personid+""}); Cursor cursor=db.rawQuery("select * from person",null); if(cursor.moveToFirst()){ int id = cursor.getInt(cursor.getColumnIndex("personid")); String name = cursor.getString(cursor.getColumnIndex("name")); String phone = cursor.getString(cursor.getColumnIndex("phone")); return new Person(personid, name, phone); } cursor.close(); return null; } }
然后编写ContentProvider组件代码如下：
package com.jereh; public class PersonProvider extends ContentProvider { private DbOpenHelper openHelper; private static final UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH); private static final int PERSONS = 1; private static final int PERSON = 2; static{ MATCHER.addURI("com.jereh.providers.personprovider", "person", PERSONS); //* 根据pesonid来删除记录 MATCHER.addURI("com.jereh.providers.personprovider", "person/#", PERSON); } @Override public boolean onCreate() { openHelper = new DbOpenHelper(this.getContext()); return false; } @Override public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { SQLiteDatabase sqLiteDatabase = openHelper.getReadableDatabase(); switch (MATCHER.match(uri)) { case 1: return sqLiteDatabase.query("person", projection, selection, selectionArgs, null, null, sortOrder); case 2: long rowid = ContentUris.parseId(uri); String where = "personid="+rowid; if(selection != null && "".equals(selection.trim())){ where = selection+"and"+where; } return sqLiteDatabase.query("person", projection, where, selectionArgs, null, null, sortOrder); } return null; } @Override public String getType(Uri uri) { switch (MATCHER.match(uri)) { case 1: return "vnd.android.cursor.dir/person"; case 2: return "vnd.android.cursor.item/person"; } return null; } @Override public Uri insert(Uri uri, ContentValues values) { SQLiteDatabase sqLiteDatabase = openHelper.getWritableDatabase(); switch (MATCHER.match(uri)) { case 1: long rowid = sqLiteDatabase.insert("person", "name", values); return ContentUris.withAppendedId(uri, rowid); default: break; } return null; } //* 删除特定personid行的记录 @Override public int delete(Uri uri, String selection, String[] selectionArgs) { SQLiteDatabase sqLiteDatabase = openHelper.getWritableDatabase(); switch (MATCHER.match(uri)) { case 1: return sqLiteDatabase.delete("person", selection, selectionArgs); case 2: long rowid = ContentUris.parseId(uri); String where = "personid="+rowid; if(selection != null && "".equals(selection.trim())){ where = selection+"and"+where; } return sqLiteDatabase.delete("person", where, selectionArgs); } return 0; } @Override public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { SQLiteDatabase sqLiteDatabase = openHelper.getWritableDatabase(); switch (MATCHER.match(uri)) { case 1: return sqLiteDatabase.update("person", values, selection, selectionArgs); case 2: long rowid = ContentUris.parseId(uri); String where = "personid="+rowid; if(selection != null && "".equals(selection.trim())){ where = selection+"and"+where; } return sqLiteDatabase.update("person", values, where, selectionArgs); } return 0; } }
在AndroidManifest.xml中注册provider
<provider android:name="com.jereh.PersonProvider" android:authorities="com.jereh.providers.personprovider">
shareinfo应用编写完成
| 四、编写other应用 |
接下来编写other应用，在这个应用中访问shareinfo中数据，我们使用Android JUnit进行测试，开发单元测试组件如下：
public class AccessProvider extends AndroidTestCase { public void testInsert(){ Uri uri = Uri.parse("content://com.jereh.providers.personprovider/person"); ContentResolver resolver = this.getContext().getContentResolver(); ContentValues values = new ContentValues(); values.put("name", "xiaoli"); values.put("phone", "333333"); resolver.insert(uri, values); } public void testDelete(){ Uri uri = Uri.parse("content://com.jereh.providers.personprovider/person/2"); ContentResolver resolver = this.getContext().getContentResolver(); resolver.delete(uri, null, null); } public void testUpdate(){ Uri uri = Uri.parse("content://com.jereh.providers.personprovider/person/3"); ContentResolver resolver = this.getContext().getContentResolver(); ContentValues values = new ContentValues(); values.put("name", "ljb"); values.put("phone", "00000000"); resolver.update(uri, values, null, null); } public void testQuery(){ Uri uri = Uri.parse("content://com.jereh.providers.personprovider/person"); ContentResolver resolver = this.getContext().getContentResolver(); Cursor cursor = resolver.query(uri, new String[]{"name","phone"}, null, null, null); while(cursor.moveToNext()){ String name = cursor.getString(cursor.getColumnIndex("name")); String phone = cursor.getString(cursor.getColumnIndex("phone")); System.out.println("name="+name+" "+"phone="+phone); } } }
执行单元测试，测试结果如图所示：
所有方法均通过了测试，实现了在一个应用（other）中访问另一个应用（shareinfo）中的数据
AndroidManifest.xml配置：
<application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name="com.jereh.other.MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <uses-library android:name="android.test.runner" /> </application> <instrumentation android:name="android.test.InstrumentationTestRunner" android:targetPackage="com.jereh" android:label="My Test"> </instrumentation>
作者：杰瑞教育
出处：http://www.cnblogs.com/jerehedu/
版权声明：本文版权归烟台杰瑞教育科技有限公司和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
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出处：http://www.cnblogs.com/jerehedu/
版权声明：本文版权归烟台杰瑞教育科技有限公司和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
技术咨询：