【Android 简单通信组件学习】ContentProvide 唯一与所有app交互的组件

首先我们了解
ContentProvider组件

它 实现系统数据访问

实现应用程序数据共享

补充一：

ContentProvider -数据提供者，

是Android四大组件之一，是程序之间数据共享的接口

Activity系统中对数据的访问限制是非常严格的，

不允许其他应用直接访问当前程序中存储在非SD卡中数据，

但是实际中我们经常会涉及到数据共享，

ContentProvider则是应用程序提供为外部访问的一个窗户，

为数据共享提供了统一的访问方法

补充二：



ContentProvide对数据进行封装，不用关心数据存储的细节。使用表的形式来组织数据

ContentProvider可以在不同的应用程序之间共享数据

Android为常见的一些数据提供了默认的ContentProvider（包括音频、视频、图片和通讯录等）

补充三：方法



1、ContentProvider类主要方法的作用：

public boolean onCreate()：

该方法在ContentProvider创建后就会被调用，Android开机后，ContentProvider在其它应用第一次访问它时才会被创建。

public Uri insert(Uri uri, ContentValues values)：

供外部ContentProvider添加数据。 public int delete(Uri uri, String selection, String[] selectionArgs)：

该方法用于供外部应用从ContentProvider删除数据。

public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs)：

该方法用于供外部应用更新ContentProvider中的数据。

public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)

用于供外部应用从ContentProvider中获取数据。 public String getType(Uri uri)：用于返回当前Url所代表数据的MIME类型。

如果操作的数据属于集合类型，那么MIME类型字符串应该以vnd.android.cursor.dir/开头



补充四：

1、ContentResolver操作ContentProvider中的数据

当外部应用需要对ContentProvider中的数据进行添加、删除、修改和查询操作时，可以使用ContentResolver 类来完成，要获取ContentResolver 对象，可以使用Activity提供的getContentResolver()方法

监听ContentProvider中数据的变化

如果ContentProvider的访问者需要知道ContentProvider中的数据发生变化，

可以在ContentProvider发生数据变化时调用getContentResolver().notifyChange(uri, null)

来通知注册在此URI上的访问者

例子：

QQ访问sd卡，读取图片，发送表情。

微信 访问通讯录，生成新的好友信息

代码效果：

一、添加学生：






查询学生：添加了几个，就能查询出几个






访问数据信息：

这里有2个，读取短信息的 eclipse从控制台输入信息试试，可以的

studio 的自行开第二个虚拟机发送短信








读取通讯录：抱歉啊，虚拟机没有安装输入法，不打中文了












虽然排序的不是很整齐，还有些疵瑕。

代码的组成：








公布代码：

一、MainActivity.java

package com.open_open.android_ch13contentprovide;

import android.app.Activity;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

import com.open_open.android_ch13contentprovide.utils.DbUtils;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
//添加学生
public void addStu(View view){
ContentValues values=new ContentValues();
values.put("sname","Toms"+Math.round(Math.random()*100));
values.put("sage",28);
values.put("ssex","男");
long id=new DbUtils(this).insert("stu",values);
Toast.makeText(this,"添加完毕,学生ID:"+id,5000).show();
}

public void findStu(View view){
Cursor cursor = new DbUtils(this).query("stu",null,null,null,null,null,null);
while (cursor.moveToNext()){
Toast.makeText(this,"姓名:"+cursor.getString(1),3000).show();
}
cursor.close();
}

public void doSystemData(View view){
Intent intent= new Intent(this,SmsActivity.class);
startActivity(intent);
}
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="添加学生"
android:textSize="28sp"
android:onClick="addStu"
/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="查询学生"
android:textSize="28sp"
android:onClick="findStu"
/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="访问系统数据"
android:textSize="28sp"
android:onClick="doSystemData"
/>
</LinearLayout>

二、SmsActivity.java

public class SmsActivity extends AppCompatActivity {
private EditText showMessage;
private ContentResolver resolver;

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

showMessage=(EditText)findViewById(R.id.showMessage);
resolver=getContentResolver();
}
//读取短信
public void readSms(View view){
Uri uri=Uri.parse("content://sms");
String[] selectItem={"address","date","read","body"};
Cursor cursor=resolver.query(uri,selectItem,null,null,null);
String[] cols=cursor.getColumnNames();
StringBuffer sb=new StringBuffer();
while (cursor.moveToNext()){
for (int i = 0; i <cols.length; i++) {
sb.append(cols[i]+"="+cursor.getString(i)+",");
}
sb.append("\n");
}
showMessage.setText(sb.toString());
cursor.close();
}
//读取通讯录
public void readTelephone(View view){
Uri uri= ContactsContract.Contacts.CONTENT_URI;
Uri uri2= ContactsContract.CommonDataKinds.Phone.CONTENT_URI;

Cursor cursor=resolver.query(uri,new String[]{"_id","display_name"},null,null,null);
String[] cols=cursor.getColumnNames();
StringBuffer sb=new StringBuffer();
while (cursor.moveToNext()){
for (int i = 0; i <cols.length ; i++) {
sb.append(cols[i]+"="+cursor.getString(i)+",");
Cursor c2=resolver.query(uri2,new  String[]{"data1"},"_id="
+cursor.getInt(0),null,null);
String[] col2=c2.getColumnNames();
while (c2.moveToNext()){
for (int j = 0; j <col2.length ; j++) {
sb.append(col2[j]+"="+c2.getString(j)+",");
}
}
}
sb.append("\n");
}
showMessage.setText(sb.toString());
cursor.close();
}
}




package com.open_open.android_ch13contentprovide;

import android.content.ContentResolver;
import android.database.Cursor;
import android.net.Uri;
import android.provider.ContactsContract;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;



public class SmsActivity extends AppCompatActivity {
private EditText showMessage;
private ContentResolver resolver;

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

showMessage=(EditText)findViewById(R.id.showMessage);
resolver=getContentResolver();
}
//读取短信
public void readSms(View view){
Uri uri=Uri.parse("content://sms");
String[] selectItem={"address","date","read","body"};
Cursor cursor=resolver.query(uri,selectItem,null,null,null);
String[] cols=cursor.getColumnNames();
StringBuffer sb=new StringBuffer();
while (cursor.moveToNext()){
for (int i = 0; i <cols.length; i++) {
sb.append(cols[i]+"="+cursor.getString(i)+",");
}
sb.append("\n");
}
showMessage.setText(sb.toString());
cursor.close();
}
//读取通讯录
public void readTelephone(View view){
Uri uri= ContactsContract.Contacts.CONTENT_URI;
Uri uri2= ContactsContract.CommonDataKinds.Phone.CONTENT_URI;

Cursor cursor=resolver.query(uri,new String[]{"_id","display_name"},null,null,null);
String[] cols=cursor.getColumnNames();
StringBuffer sb=new StringBuffer();
while (cursor.moveToNext()){
for (int i = 0; i <cols.length ; i++) {
sb.append(cols[i]+"="+cursor.getString(i)+",");
Cursor c2=resolver.query(uri2,new  String[]{"data1"},"_id="
+cursor.getInt(0),null,null);
String[] col2=c2.getColumnNames();
while (c2.moveToNext()){
for (int j = 0; j <col2.length ; j++) {
sb.append(col2[j]+"="+c2.getString(j)+",");
}
}
}
sb.append("\n");
}
showMessage.setText(sb.toString());
cursor.close();
}
}




activity_sms.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<EditText
android:id="@+id/showMessage"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="textMultiLine"
android:text="暂时没有数据显示"
/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="读取短信息"
android:onClick="readSms"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="读取通讯录"
android:onClick="readTelephone"/>

</LinearLayout>


三、provider 包：MyProvider.java

package com.open_open.android_ch13contentprovide.provider;

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.net.Uri;

import com.open_open.android_ch13contentprovide.utils.DbUtils;

/**
* Created by Administrator on 2016/12/15.
*/
public class MyProvider extends ContentProvider{
//定义几个常量用来充当URI标示值
private static final int STUS=1;
private static final int STU=2;

//构建URI匹配对象
private static UriMatcher matcher=new UriMatcher
(UriMatcher.NO_MATCH);
//构建匹配项,/#：ID为#
static{
matcher.addURI("com.open_open.android_ch13contentprovide", "stu", STUS);
matcher.addURI("com.open_open.android_ch13contentprovide", "stu/#", STU);
}

private DbUtils dbUtils;
//初始化工作
@Override
public boolean onCreate() {
//获取操作数据库的工具类
dbUtils=new DbUtils(this.getContext());
return false;
}

//公共的查询接口
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
String  sortOrder) {
switch (matcher.match(uri)) {
case STUS:
return dbUtils.query("stu", projection, selection, selectionArgs, null, null, sortOrder);
case STU:
long id= ContentUris.parseId(uri);//从URI取出要查询数据的ID

String where="_id="+id;
if(selection!=null){
//查询有条件where=selection+" and "+where;
}
return dbUtils.query("stu", projection, where, selectionArgs, null, null, sortOrder);
default:
break;
}
return null;
}

@Override
public String getType(Uri uri) {
switch (matcher.match(uri)) {
case STUS:
return "vnd.android.cursor.dir/stu";  //dir:目录列表
case STU:
return
"vnd.android.cursor.item/stu"; //item:一个项目
default:
break;
}
return null;
}

@Override
public Uri insert(Uri uri, ContentValues values) {
if(matcher.match(uri)==STUS){
long id=dbUtils.insert("stu", values);
//在uri后面追加一个ID部分
return ContentUris.withAppendedId(uri, id);
}
return null;
}

@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
switch (matcher.match(uri)) {
case STUS:
int c=dbUtils.delete("stu", selection, selectionArgs);
return c;

case STU:
long id=ContentUris.parseId(uri);
String where="_id="+id;
if(selection!=null){
where=selection+" and "+where;
}
int c2=dbUtils.delete("stu", where, selectionArgs);
return c2;
default:
break;
}
return 0;
}

@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
switch (matcher.match(uri)) {
case STUS:
long i=dbUtils.update("stu", values, selection, selectionArgs);
return (int)i;
case STU:
long id=ContentUris.parseId(uri);
String where="_id="+id;
if(selection!=null){
where=selection+" and "+where;
}
long i2=dbUtils.update("stu", values, where, selectionArgs);
return (int)i2;
default:
break;
}
return 0;
}

}


四、utils 包 ：

DbHelper.java

package com.open_open.android_ch13contentprovide.utils;

import android.content.Context;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

/**
* Created by Administrator on 2016/12/15.
*/
public class DbHelper extends SQLiteOpenHelper{

public DbHelper(Context context) {
super(context, "mydb.db", null, 1);
}

@Override
public void onCreate(SQLiteDatabase db) {
//建表：注意：_id 中不能大写！否则无法识别
String sql="create table if not exists stu(" +
"_id integer primary key," +
"sname text," +
"sage integer," +
"ssex text" +
")";
db.execSQL(sql);
//插入第一条数据
sql="insert into stu(sname,sage,ssex) values('xiaoming',23,'男')";
//插入第二条数据
db.execSQL(sql);
sql="insert into stu(sname,sage,ssex) values('Lucy',23,'女')";
db.execSQL(sql);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
String sql="drop table stu";
db.execSQL(sql);
onCreate(db);
}

}


DbUtils.java （sql添加，更新，删除，查询的方法）

package com.open_open.android_ch13contentprovide.utils;

import android.content.Context;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

/**
* Created by Administrator on 2016/12/15.
*/
public class DbUtils {
private Context ctx;
private SQLiteDatabase sdb;

public DbUtils(Context ctx){
this.ctx=ctx;
sdb=new DbHelper(ctx).getReadableDatabase();
}
//插入
public long insert(String tableName,ContentValues values){
long id=sdb.insert(tableName,null,values);
return id;
}
//更新
public long update(String table,ContentValues values,String wherClause
,String[] whereArgs){
long id=sdb.update(table,values,wherClause,whereArgs);
return id;
}
//删除
public int delete(String table,String whereClause,String[] whereArgs){
int count=sdb.delete(table,whereClause,whereArgs);
return count;
}
//查询
public Cursor query(String table,String[] columns,String selection,String[]
selectionArgs,String groupBy,String having,String orderBy){
Cursor cursor=sdb.query(table,columns,selection,selectionArgs,groupBy,having,orderBy);
return cursor;
}

}


其他：AndroidMainfest.xml

<!-- 权限开启！ -->

<uses-permission android:name="android.permission.WRITE_SMS"/>

<uses-permission android:name="android.permission.READ_SMS"/>

<uses-permission android:name="android.permission.READ_CONTACTS"/>


public class SmsActivity extends AppCompatActivity {
private EditText showMessage;
private ContentResolver resolver;

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

showMessage=(EditText)findViewById(R.id.showMessage);
resolver=getContentResolver();
}
//读取短信
public void readSms(View view){
Uri uri=Uri.parse("content://sms");
String[] selectItem={"address","date","read","body"};
Cursor cursor=resolver.query(uri,selectItem,null,null,null);
String[] cols=cursor.getColumnNames();
StringBuffer sb=new StringBuffer();
while (cursor.moveToNext()){
for (int i = 0; i <cols.length; i++) {
sb.append(cols[i]+"="+cursor.getString(i)+",");
}
sb.append("\n");
}
showMessage.setText(sb.toString());
cursor.close();
}
//读取通讯录
public void readTelephone(View view){
Uri uri= ContactsContract.Contacts.CONTENT_URI;
Uri uri2= ContactsContract.CommonDataKinds.Phone.CONTENT_URI;

Cursor cursor=resolver.query(uri,new String[]{"_id","display_name"},null,null,null);
String[] cols=cursor.getColumnNames();
StringBuffer sb=new StringBuffer();
while (cursor.moveToNext()){
for (int i = 0; i <cols.length ; i++) {
sb.append(cols[i]+"="+cursor.getString(i)+",");
Cursor c2=resolver.query(uri2,new  String[]{"data1"},"_id="
+cursor.getInt(0),null,null);
String[] col2=c2.getColumnNames();
while (c2.moveToNext()){
for (int j = 0; j <col2.length ; j++) {
sb.append(col2[j]+"="+c2.getString(j)+",");
}
}
}
sb.append("\n");
}
showMessage.setText(sb.toString());
cursor.close();
}
}