101、使用ContentProvider在应用间传递数据

【ContentWriter】

package com.jikexueyuan.contentwriter;

import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;

public class Myprovider extends ContentProvider {
    public static final Uri URI = Uri.parse("content://com.jikexueyuan.cp");
    SQLiteDatabase database;

    @Override
    public int delete(Uri arg0, String arg1, String[] arg2) {
        return 0;
    }

    @Override
    public String getType(Uri arg0) {
        return null;
    }

    @Override
    public Uri insert(Uri arg0, ContentValues arg1) {
        database.insert("tab", "_id", arg1);
//        database.close();
        return null;
    }

    @Override
    public boolean onCreate() {
        database = getContext().openOrCreateDatabase("mycp.db3", Context.MODE_PRIVATE, null);
        database.execSQL("create table tab(_id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL)");
        
        return true;
    }

    @Override
    public Cursor query(Uri arg0, String[] arg1, String arg2, String[] arg3,
            String arg4) {
        Cursor cursor = database.query("tab", null, null, null, null, null, null);
        return cursor;
    }

    @Override
    public int update(Uri arg0, ContentValues arg1, String arg2, String[] arg3) {
        return 0;
    }

}

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        findViewById(R.id.button1).setOnClickListener(new View.OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                write();
            }
        });
    }
    
    public void write() {
        ContentValues values;
        values = new ContentValues();
        values.put("name", "Java");
        getContentResolver().insert(Myprovider.URI, values);
        
        values = new ContentValues();
        values.put("name", "Swift");
        getContentResolver().insert(Myprovider.URI, values);
        
        values = new ContentValues();
        values.put("name", "Python");
        getContentResolver().insert(Myprovider.URI, values);
        
        values = new ContentValues();
        values.put("name", "C#");
        getContentResolver().insert(Myprovider.URI, values);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.jikexueyuan.contentwriter"
    android:versionCode="1"
    android:versionName="1.0" >
    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="19" />
    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.jikexueyuan.contentwriter.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>
        <provider android:name="Myprovider" android:exported="true" 
            android:authorities="com.jikexueyuan.cp" />
    </application>

</manifest>

【ContentReader】

public class MainActivity extends Activity {  
    Uri URI = Uri.parse("content://com.jikexueyuan.cp");

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        Cursor cursor = getContentResolver().query(URI, null, null, null, null);
        cursor.moveToFirst();
        for (int i = 0; i < cursor.getCount(); i++) {
            String value = cursor.getString(cursor.getColumnIndex("name"));
            Toast.makeText(getApplicationContext(), value, Toast.LENGTH_SHORT).show();
            cursor.moveToNext();
        }
    }
}