我希望在Android 工作室中的多个活动之间共享代码。我用Google搜索了一下，但似乎只能找到如何在项目之间共享代码，或者如何在活动之间共享数据。
我想这样做的原因是我有几个try {} catch块，如果有错误，我想将这些数据保存在sqlite数据库中。我可以在每个活动中放置相同的函数并调用它，但这看起来效率非常低，当我需要稍微修改它如何插入数据等时会很痛苦。
我将传递两个参数，activity名称和错误，并期待成功/失败标志。
非常感谢任何想法！
答案 0 :(得分：3)
在包名称中创建一个Common类，如下所示：
public class Common {
private static Dialog dialog = null;
/*
* A Common function to display toast.
* */
public static Void displayToast(Context context, String strToast) {
Toast.makeText(context, strToast, Toast.LENGTH_SHORT).show();
return null;
}
/*
* A Common function to display Log.
* */
public static Void displayLog(String strTitle, String strText) {
Log.d(strTitle, strText);
return null;
}
/*
* A Common function to check internet connection.
* */
public static boolean isOnline(Context c) {
try {
ConnectivityManager cm = (ConnectivityManager) c.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
if (netInfo != null && netInfo.isConnectedOrConnecting()) {
return true;
}
return false;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
/*
* A common function to check length for input.
* */
public static boolean isValidLength(String fName) {
if (fName.trim().length() > 0) {
return true;
}
return false;
}
/*
* A common function to validate Email id.
* */
public static boolean isValidEmail(String email) {
String EMAIL_PATTERN = "^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@"
+ "[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";
Pattern pattern = Pattern.compile(EMAIL_PATTERN);
Matcher matcher = pattern.matcher(email);
return matcher.matches();
}
现在，在以下任何活动中访问这些功能：
Common.displayToast(MainActivity.this, "Message");
if (Common.isOnline(MainActivity.this)) {
//your code
} else {
//your code
}
调用必要的函数。
答案 1 :(得分：0)
您可以创建class BaseActivity extends Activity
{
}
class your Actvity extends BaseActivity
{}
并使用此基类扩展所有活动。
喜欢：
MPMusicPlayerController将您的所有代码写入基本活动并相应地用于每个活动。
答案 2 :(得分：0)
你需要定义一个名为 DatabaseHandler 的扩展 SQLiteOpenHelper （在其中添加 public 访问规范的函数），同时放入所有数据库相关功能。之后，您需要在要调用其功能的活动中初始化其对象并调用所需的函数。如果您在应用程序中使用了很多 DatabaseHandler 类，也可以使用单例设计模式。
<强>数据库处理器
package package_name;
import java.util.ArrayList;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import <packagename>.Profile;
public class DatabaseHandler extends SQLiteOpenHelper {
private Context context = null;
//private SQLiteDatabase mWDB, mRDB;
private static final String TAG = DatabaseHandler.class.getSimpleName();
/** Database Version <br/> Should change if any changes in DB for higher verion*/
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "db_name";
// Table Names
public static final String TABLE_PROFILE = "TABLE_PROFILE";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
this.context = context;
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
try {
enableForeignKeysConstraint(db);
db.execSQL("CREATE TABLE IF NOT EXISTS " + TABLE_PROFILE
+ " (user_id TEXT, email TEXT, name TEXT, address TEXT, address_x TEXT, address_y TEXT,"
+ " image_src TEXT, dob datetime, gender TEXT, profession TEXT, dateCreated datetime,"
+ " dateModified datetime);");
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop table if necessary, here
onCreate(db);
}
@Override
public void onConfigure(SQLiteDatabase db) {
super.onConfigure(db);
enableForeignKeysConstraint(db);
}
/**
* We need to enable foreign keys before executing any query creating a table, also on database
* configuration changes. For it, this method helps.
* @param db SQLiteDatabase
*/
public void enableForeignKeysConstraint(SQLiteDatabase db) {
if (!db.isReadOnly()) {
// Enable foreign key constraints
db.execSQL("PRAGMA foreign_keys=ON;");
}
}
////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////// INSERT DATA ////////////////////////////////////////
/**
* Inserts a profile record into database.
* @param profile
* @param dateCreated
*/
private void insertProfile(Profile profile, String dateCreated) {
SQLiteDatabase db = null;
try {
db = this.getWritableDatabase();
Log.i(TAG, "insertProfile(): Query is processing ...");
ContentValues values = new ContentValues();
values.put("user_id", profile.getUserId());
values.put("name", profile.getName());
values.put("email", profile.getEmail());
long id = db.insert(TABLE_PROFILE, null, values);
if (id != -1)
Log.i(TAG, "insertProfile(): Inserted successfully");
else
Log.i(TAG, "insertProfile(): Insertion failed");
}
catch(Exception e) {
e.printStackTrace();
}
if(db != null)
db.close();
}
////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////// SELECT DATA ////////////////////////////////////////
/**
* To get profile against user id stored into local database.
* @param userId
* @return Profile - An object if exists otherwise null.
*/
public Profile getProfile(String userId) {
Profile profile = null;
String query = "SELECT * FROM "+TABLE_PROFILE+ " WHERE user_id = "+userId+";";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(query, null);
Log.i(TAG, "getProfile():" + query);
if (cursor.moveToFirst()) {
do {
profile = new Profile();
profile.setUserId(cursor.getString(0));
profile.setEmail(cursor.getString(1));
profile.setName(cursor.getString(2));
} while (cursor.moveToNext());
}
cursor.close();
db.close();
return profile;
}
////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////// DELETE DATA ////////////////////////////////////////
/**
* Deletes the favorite place record against userId.
* @param place_id
*/
public void deleteProfile(String userId) {
SQLiteDatabase db = this.getWritableDatabase();
int deleteCount = db.delete(TABLE_PROFILE, "user_id=" + userId, null);
if(deleteCount > 0)
Log.i(TAG, "deleteProfile(): Deleted profile with id = " + userId);
}
////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////// UPDATE DATA ////////////////////////////////////////
private void updateProfile(Profile profile) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("name", profile.getName());
db.update(TABLE_PROFILE, values, "user_id = '"+profile.getUserId()+"'", null);
Log.i(TAG,"updateProfile(): Updated profile for userId="+profile.getUserId());
}
}
配置文件
public class Profile {
private String userId;
private String name;
private String email;
public Profile() {
userId = "";
name = "";
email = "";
}
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
}