Android 下的 SQLite 操作封装 —— DatabaseUtil
2024-08-23 22:39:36
看到别人写的代码不错，对自己目前的开发很有用，所以转载一下，希望也能帮助到其他人：
1.DatabaseUtil.java(封装的类)
package com.dbexample; import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log; public class DatabaseUtil{ private static final String TAG = "DatabaseUtil"; /**
* Database Name
*/
private static final String DATABASE_NAME = "student_database"; /**
* Database Version
*/
private static final int DATABASE_VERSION = 1; /**
* Table Name
*/
private static final String DATABASE_TABLE = "tb_student"; /**
* Table columns
*/
public static final String KEY_NAME = "name";
public static final String KEY_GRADE = "grade";
public static final String KEY_ROWID = "_id"; /**
* Database creation sql statement
*/
private static final String CREATE_STUDENT_TABLE =
"create table " + DATABASE_TABLE + " (" + KEY_ROWID + " integer primary key autoincrement, "
+ KEY_NAME +" text not null, " + KEY_GRADE + " text not null);"; /**
* Context
*/
private final Context mCtx; private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb; /**
* Inner private class. Database Helper class for creating and updating database.
*/
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
/**
* onCreate method is called for the 1st time when database doesn't exists.
*/
@Override
public void onCreate(SQLiteDatabase db) {
Log.i(TAG, "Creating DataBase: " + CREATE_STUDENT_TABLE);
db.execSQL(CREATE_STUDENT_TABLE);
}
/**
* onUpgrade method is called when database version changes.
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion);
}
} /**
* Constructor - takes the context to allow the database to be
* opened/created
*
* @param ctx the Context within which to work
*/
public DatabaseUtil(Context ctx) {
this.mCtx = ctx;
}
/**
* This method is used for creating/opening connection
* @return instance of DatabaseUtil
* @throws SQLException
*/
public DatabaseUtil open() throws SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
/**
* This method is used for closing the connection.
*/
public void close() {
mDbHelper.close();
} /**
* This method is used to create/insert new record Student record.
* @param name
* @param grade
* @return long
*/
public long createStudent(String name, String grade) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_NAME, name);
initialValues.put(KEY_GRADE, grade);
return mDb.insert(DATABASE_TABLE, null, initialValues);
}
/**
* This method will delete Student record.
* @param rowId
* @return boolean
*/
public boolean deleteStudent(long rowId) {
return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
} /**
* This method will return Cursor holding all the Student records.
* @return Cursor
*/
public Cursor fetchAllStudents() {
return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_NAME,
KEY_GRADE}, null, null, null, null, null);
} /**
* This method will return Cursor holding the specific Student record.
* @param id
* @return Cursor
* @throws SQLException
*/
public Cursor fetchStudent(long id) throws SQLException {
Cursor mCursor =
mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
KEY_NAME, KEY_GRADE}, KEY_ROWID + "=" + id, null,
null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
} /**
* This method will update Student record.
* @param id
* @param name
* @param standard
* @return boolean
*/
public boolean updateStudent(int id, String name, String standard) {
ContentValues args = new ContentValues();
args.put(KEY_NAME, name);
args.put(KEY_GRADE, standard);
return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + id, null) > 0;
}
}
2.代码使用方法
//插入
DatabaseUtil dbUtil = new DatabaseUtil(this);
dbUtil.open();
dbUtil.createStudent("Prashant Thakkar", "10th");
dbUtil.close(); //查询
DatabaseUtil dbUtil = new DatabaseUtil(this);
dbUtil.open();
Cursor cursor = dbUtil.fetchAllStudents();
if(cursor != null){
while(cursor.moveToNext()){
Log.i("Student", "Student Name: " + cursor.getString(1) +
" Grade " + cursor.getString(2));
}
}
dbUtil.close();
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