Android IPC机制之ContentProvider

ContentProvider：即内容提供者，用来管理数据，并对外暴露一个uri，外部可以通过uri和数据建立联系并获取或操作数据；

服务端：
1、首先创建一个数据库类，并创建一个表；
2、创建一个ContentProvider,用来操作这个数据库和表，实现增删改查和获取所有表里的数据信息；然后注册uri（对外暴露），其他客户端可以通过ContentResolver和对外暴露的uri使用ContentProvider来操作数据库并获取数据

客户端：
1、创建一个工具类，通过ContentResolver和服务端暴露的uri来和服务端建立联系，并通过服务端的ContentProvider来操作服务端的数据库并获取数据

 示例代码

服务端：

首先创建一个数据库

 1 package com.jiao.myaidl;
 2 
 3 import android.content.Context;
 4 import android.database.sqlite.SQLiteDatabase;
 5 import android.database.sqlite.SQLiteOpenHelper;
 6 
 7 /**
 8  * Created by jiaocg on 2016/3/12.
 9  * 数据库类
10  */
11 public class EmployeeDBHelper extends SQLiteOpenHelper {
12 
13     private final static String DB_NAME = "myDatabase.db";//数据库名字
14     private final static int DB_VERSION = 1;
15     public final static String EMPLOYEE_TABLE_NAME = "employee";
16     private String CREATE_BOOK_TABLE = "CREATE TABLE IF NOT EXISTS "
17             + EMPLOYEE_TABLE_NAME + " (id INTEGER PRIMARY KEY,"
18             + "workNum TEXT," + "name TEXT," + "department TEXT)";
19 
20     public EmployeeDBHelper(Context context) {
21         super(context, DB_NAME, null, DB_VERSION);
22 
23     }
24 
25     @Override
26     public void onCreate(SQLiteDatabase db) {
27 
28         db.execSQL(CREATE_BOOK_TABLE);
29     }
30 
31     @Override
32     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
33 
34     }
35 }

创建一个ContentProvider操作数据库

  1 package com.jiao.myaidl;
  2 
  3 import android.content.ContentProvider;
  4 import android.content.ContentValues;
  5 import android.content.UriMatcher;
  6 import android.database.Cursor;
  7 import android.database.sqlite.SQLiteDatabase;
  8 import android.net.Uri;
  9 import android.support.annotation.Nullable;
 10 
 11 /**
 12  * Created by jiaocg on 2016/3/12.
 13  */
 14 public class EmployeeProvider extends ContentProvider {
 15 
 16     private SQLiteDatabase mDb;
 17     private final static String AUTOORITY = "com.jiao.myaidl.employee.EmployeeProvider";
 18     private final static int EMPLOYEE_URI_CODE = 0;
 19     private static final UriMatcher sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
 20 
 21 
 22     //注册uri
 23     static {
 24         sUriMatcher.addURI(AUTOORITY, "employee", EMPLOYEE_URI_CODE);
 25     }
 26 
 27 
 28     @Override
 29     public boolean onCreate() {
 30 
 31         insertDataToDb();
 32         return true;
 33     }
 34 
 35 
 36     @Nullable
 37     void insertDataToDb() {
 38 
 39         mDb = new EmployeeDBHelper(getContext()).getWritableDatabase();
 40         mDb.execSQL("delete from " + EmployeeDBHelper.EMPLOYEE_TABLE_NAME);
 41         mDb.execSQL("insert into employee values(1,'1001','张三','销售部');");
 42         mDb.execSQL("insert into employee values(2,'1002','李四','人事部');");
 43         mDb.execSQL("insert into employee values(3,'1003','王五','研发部');");
 44         mDb.execSQL("insert into employee values(4,'1004','小明','研发部');");
 45         mDb.execSQL("insert into employee values(5,'1005','小强','销售部');");
 46     }
 47 
 48 
 49     public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
 50 
 51         String tableName = getTableName(uri);
 52 
 53         if (tableName == null) {
 54             throw new IllegalArgumentException("Unsupported URI: " + uri);
 55         }
 56         Cursor cursor = mDb.query(tableName, projection, selection, selectionArgs, null, null, sortOrder, null);
 57         return cursor;
 58     }
 59 
 60     @Nullable
 61     @Override
 62     public String getType(Uri uri) {
 63         return null;
 64     }
 65 
 66     @Nullable
 67     @Override
 68     public Uri insert(Uri uri, ContentValues values) {
 69         String table = getTableName(uri);
 70         if (table == null) {
 71             throw new IllegalArgumentException("Unsupported URI: " + uri);
 72         }
 73         mDb.insert(table, null, values);
 74         getContext().getContentResolver().notifyChange(uri, null);
 75         return uri;
 76     }
 77 
 78     @Override
 79     public int delete(Uri uri, String selection, String[] selectionArgs) {
 80         String table = getTableName(uri);
 81         if (table == null) {
 82             throw new IllegalArgumentException("Unsupported URI: " + uri);
 83         }
 84         int count = mDb.delete(table, selection, selectionArgs);
 85         if (count > 0) {
 86             getContext().getContentResolver().notifyChange(uri, null);
 87         }
 88         return count;
 89     }
 90 
 91     @Override
 92     public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
 93         String table = getTableName(uri);
 94         if (table == null) {
 95             throw new IllegalArgumentException("Unsupported URI: " + uri);
 96         }
 97         int row = mDb.update(table, values, selection, selectionArgs);
 98         if (row > 0) {
 99             getContext().getContentResolver().notifyChange(uri, null);
100         }
101         return row;
102     }
103 
104 
105     private String getTableName(Uri uri) {
106         String tableName = null;
107         if (sUriMatcher.match(uri) == EMPLOYEE_URI_CODE) {
108             tableName = EmployeeDBHelper.EMPLOYEE_TABLE_NAME;
109         }
110         return tableName;
111     }
112 }

清单文件中注册ContentProvider

　

1  <provider
2             android:name="com.jiao.myaidl.EmployeeProvider"
3             android:authorities="com.jiao.myaidl.employee.EmployeeProvider"
4             android:exported="true" />

 

客户端：

创建一个工具类，通过服务端暴露的uri和服务端的数据库建立联系

 1 package com.jiao.myaidl;
 2 
 3 import android.content.ContentResolver;
 4 import android.content.ContentValues;
 5 import android.content.Context;
 6 import android.database.Cursor;
 7 import android.net.Uri;
 8 import android.util.Log;
 9 import com.jiao.myaidl.entity.Employee;
10 import java.util.ArrayList;
11 import java.util.List;
12 
13 /**
14  * Created by jiaocg on 2016/3/12.
15  */
16 public class HandleProvider {
17 
18     private static Context mContext;
19     private static HandleProvider mInstance;
20     private static Uri mEmployeeUri;
21     private static final String EMPLOYEE_CONTENT_URI = "content://com.jiao.myaidl.employee.EmployeeProvider/employee";
22 
23     private HandleProvider(Context context) {
24         this.mContext = context;
25         mEmployeeUri = Uri.parse(EMPLOYEE_CONTENT_URI);
26     }
27 
28 
29     //单例
30     public static HandleProvider getmInstance(Context context) {
31         if (mInstance == null) {
32             synchronized (HandleProvider.class) {
33                 if (mInstance == null) {
34                     mInstance = new HandleProvider(context);
35                 }
36             }
37         }
38 
39         return mInstance;
40     }
41 
42 
43     public void delete() {
44         ContentResolver contentResolver = mContext.getContentResolver();
45         String where = "id=?";
46         String[] where_args = {"7"};//满足条件的 值集合
47         contentResolver.delete(mEmployeeUri, where, where_args);
48     }
49 
50 
51     public void update() {
52         ContentResolver contentResolver = mContext.getContentResolver();
53         ContentValues values = new ContentValues();
54         values.put("name", "梁山伯");
55         String where = "id=?";
56         String[] where_args = {"1"};
57         contentResolver.update(mEmployeeUri, values, where, where_args);
58     }
59 
60     public void create() {
61         ContentValues values = new ContentValues();
62         values.put("id", 7);
63         values.put("workNum", "1006");
64         values.put("name", "张三丰");
65         values.put("department", "研发部");
66         mContext.getContentResolver().insert(mEmployeeUri, values);
67     }
68 
69 
70     public List<String> query() {
71         List<String> list = new ArrayList<>();
72         Cursor cursor = mContext.getContentResolver().query(mEmployeeUri, new String[]{"id", "workNum", "name", "department"}, null, null, null);
73 
74         while (cursor.moveToNext()) {
75             Employee employee = new Employee();
76             employee.setId(cursor.getInt(0));
77             employee.setWorkNum(cursor.getString(1));
78             employee.setName(cursor.getString(2));
79             employee.setDepartment(cursor.getString(3));
80             String str = employee.toString();
81             list.add(str);
82             Log.d("mainActivity", "query employee:" + str);
83         }
84         cursor.close();
85         return list;
86     }
87 }

主代码，获取和使用服务端的数据

 1 package com.jiao.myaidl;
 2 
 3 import android.os.Bundle;
 4 import android.support.v7.app.AppCompatActivity;
 5 import android.view.View;
 6 import android.widget.Button;
 7 
 8 import com.jiao.myaidl.client.R;
 9 
10 import java.util.List;
11 
12 public class EmployeeActivity extends AppCompatActivity implements View.OnClickListener {
13 
14     @Override
15     protected void onCreate(Bundle savedInstanceState) {
16         super.onCreate(savedInstanceState);
17         setContentView(R.layout.activity_employee);
18 
19         initView();
20     }
21 
22     private void initView() {
23 
24         Button insert_button = (Button) findViewById(R.id.insert_button);
25         Button delete_button = (Button) findViewById(R.id.delete_button);
26         Button update_button = (Button) findViewById(R.id.update_button);
27         Button query_button = (Button) findViewById(R.id.query_button);
28         Button clear_button = (Button) findViewById(R.id.clear_button);
29         insert_button.setOnClickListener(this);
30         delete_button.setOnClickListener(this);
31         update_button.setOnClickListener(this);
32         query_button.setOnClickListener(this);
33         clear_button.setOnClickListener(this);
34     }
35 
36     @Override
37     public void onClick(View v) {
38         switch (v.getId()) {
39             case R.id.insert_button://插入
40 
41                 HandleProvider.getmInstance(this).create();
42 
43                 break;
44 
45             case R.id.delete_button:
46                 HandleProvider.getmInstance(this).delete();
47                 break;
48 
49             case R.id.update_button:
50                 HandleProvider.getmInstance(this).update();
51                 break;
52             case R.id.query_button:
53                 List<String> list = HandleProvider.getmInstance(this).query();
54                 for (int i = 0; i < list.size(); i++) {
55                     System.out.println(list.get(i));
56 
57                 }
58                 break;
59             case R.id.clear_button:
60 
61                 break;
62         }
63 
64     }
65 }

布局代码：

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     xmlns:tools="http://schemas.android.com/tools"
 4     android:layout_width="match_parent"
 5     android:layout_height="match_parent"
 6     android:orientation="vertical"
 7     android:paddingBottom="@dimen/activity_vertical_margin"
 8     android:paddingLeft="@dimen/activity_horizontal_margin"
 9     android:paddingRight="@dimen/activity_horizontal_margin"
10     android:paddingTop="@dimen/activity_vertical_margin"
11     tools:context="com.example.ljd.client.MainActivity">
12 
13     <LinearLayout
14         android:layout_width="match_parent"
15         android:layout_height="wrap_content"
16         android:orientation="horizontal">
17 
18         <Button
19             android:id="@+id/insert_button"
20             android:layout_width="match_parent"
21             android:layout_height="match_parent"
22             android:layout_weight="1"
23             android:text="插入" />
24 
25         <Button
26             android:id="@+id/delete_button"
27             android:layout_width="match_parent"
28             android:layout_height="match_parent"
29             android:layout_weight="1"
30             android:text="删除" />
31     </LinearLayout>
32 
33     <LinearLayout
34         android:layout_width="match_parent"
35         android:layout_height="wrap_content"
36         android:orientation="horizontal">
37 
38         <Button
39             android:id="@+id/update_button"
40             android:layout_width="match_parent"
41             android:layout_height="wrap_content"
42             android:layout_weight="1"
43             android:text="更新" />
44 
45         <Button
46             android:id="@+id/query_button"
47             android:layout_width="match_parent"
48             android:layout_height="wrap_content"
49             android:layout_weight="1"
50             android:text="查询" />
51     </LinearLayout>
52 
53 </LinearLayout>

 

posted @ 2016-03-14 10:47  Android、Boy  阅读(236)  评论(0)  编辑  收藏  举报