ContentProvider的单元测试的使用
ContentProvider是android的四大组件之一，在编写代码的时候最好是加上单元测试，这样可以确定对数据的CRUD的正确。本篇文章主要介绍ContentProvider中两个主要辅助类的使用还有单元测试的在ContentProvider中的使用。
需要用到的两个辅助类：UriMatcher类和ContentUris类。
UriMatcher类：能够对输入的uri参数就行匹配，以确定对什么表执行什么样的操作。
ContentUris类：有些方法需要返回uri，运用此类可以方便的生成uri类。
对于单元测试，个人觉得非常有必要在今后写代码的时候使用，这样可以非常准确的确定代码的正确性。
使用单元测试的步骤：
1）加入instrumentation，这个部分的代码是固定，也可以完全在ADT提供的向导中导入。
<instrumentation android:name="android.test.InstrumentationTestRunner" android:targetPackage="com.example.android_contentprovider" > </instrumentation>
2）添加<uses-library>,这个部分的代码也是固定的写法。
<uses-library android:name="android.test.runner" />
好了，必备的知识已经讲完了，现在上代码：
1）生成一个SQLiteDatabase类，这个是必需的类MySQLiteOpenHelper类
package com.app.db;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class MySQLiteOpenHelper extends SQLiteOpenHelper {
private static String DB_NAME = "test.db3";
private static int VERSION = 1;
public MySQLiteOpenHelper(Context context) {
super(context, DB_NAME, null, VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
//建表语句
String create_student = "create table student(_id integer primary key autoincrement,name varchar(10),age integer,gender vachar(10))";
db.execSQL(create_student);
//千万不能执行这句
// db.close();
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
}
}
然后添加我们需要的MyContentProvider类：
package com.app.contentprovider;
import com.app.db.MySQLiteOpenHelper;
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.util.Log;
public class MyContentProvider extends ContentProvider {
MySQLiteOpenHelper helper = null;
private static UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);
// 匹配单条记录
private static final int student = 1;
// 匹配多条记录
private static final int students = 2;
static {
matcher.addURI("com.app.wx", "student/#", student);
matcher.addURI("com.app.wx", "student", students);
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
SQLiteDatabase db = helper.getWritableDatabase();
int action = matcher.match(uri);
switch (action) {
// 匹配单条记录
case student:
long id = ContentUris.parseId(uri);
//获取单条记录的id号
String delete_id = "_id=" + id;
if (selection != null) {
delete_id += delete_id + " and " + selection;
}
db.delete("student", delete_id, selectionArgs);
break;
// 匹配多条记录
case students:
db.delete("student", selection, selectionArgs);
break;
}
return 0;
}
//必需实现这个方法，这个方法与intent有关系，以后再讲
@Override
public String getType(Uri uri) {
int code = matcher.match(uri);
switch (code) {
case student:
return "vnd.android.cursor.item/student_item";
case students:
return "vnd.android.cursor.dir/students";
default:
return null;
}
}
@Override
public Uri insert(Uri uri, ContentValues values) {
SQLiteDatabase db = helper.getWritableDatabase();
int action = matcher.match(uri);
switch (action) {
case students:
long id1 = db.insert("student", "_id", values);
Log.i("--------", ContentUris.withAppendedId(uri, id1).toString());
return ContentUris.withAppendedId(uri, id1);
}
return null;
}
@Override
public boolean onCreate() {
helper = new MySQLiteOpenHelper(this.getContext());
return true;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String orderBy) {
SQLiteDatabase db = helper.getWritableDatabase();
Cursor cursor = null;
int action = matcher.match(uri);
switch (action) {
case students:
cursor = db.query("student", projection, selection, selectionArgs,
null, null, orderBy);
break;
}
System.out.println("-----------count:" + cursor.getCount());
return cursor;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] arg3) {
int count = -1;
SQLiteDatabase db = helper.getWritableDatabase();
int action = matcher.match(uri);
switch (action) {
case student:
// 以id来处理更新
long id = ContentUris.parseId(uri);
String id_selection = "_id=" + id;
if (selection != null && !selection.equals("")) {
id_selection = id_selection + " and " + values;
}
count = db.update("student", values, id_selection, arg3);
System.out.println("----------count:" + count);
break;
}
return count;
}
}
这个类很长，但是执行的方法都是比较常见的CURD的方法，重要的是UriMatcher和ContentUris类的使用。
接着执行单元测试类：Test
package com.app.contentprovider;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.test.AndroidTestCase;
import android.util.Log;
public class Test extends AndroidTestCase {
public void insert() {
ContentResolver resolver = this.getContext().getContentResolver();
String str = "content://com.app.wx/student";
ContentValues values = new ContentValues();
values.put("name", "wzq");
values.put("age", 18);
values.put("gender", "boy");
resolver.insert(Uri.parse(str), values);
}
public void update() {
ContentResolver resolver = this.getContext().getContentResolver();
String str = "content://com.app.wx/student/2";
ContentValues values = new ContentValues();
values.put("name", "哈哈");
resolver.update(Uri.parse(str), values, null, null);
}
public void query() {
ContentResolver resolver = this.getContext().getContentResolver();
String str = "content://com.app.wx/student";
Uri uri = Uri.parse(str);
Cursor cursor = resolver.query(uri, new String[] { "_id",
"name,age,gender" }, null, null, "_id desc");
Log.d("------count",cursor.getCount()+"");
}
public void delete() {
ContentResolver resolver = this.getContext().getContentResolver();
String str = "content://com.app.wx/student/2";
Uri uri = Uri.parse(str);
long id=resolver.delete(uri, null, null);
}
}
执行insert方法之后（执行了三次）：
执行了update方法之后：
执行了query方法之后：
执行了delete方法之后：
