Android简单SQLite数据库读写

Love The Way You Lie 2024-02-19 15:33 47阅读 0赞

MySQLiteOpenHelper.java：

import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;
    import android.support.annotation.Nullable;
    
    public class MySQLiteOpenHelper extends SQLiteOpenHelper {
    
        //数据库名称。
        public static final String DATABASE_NAME = "zhangphil.db";
    
        //数据库版本号。
        public static int DATABASE_VERSION = 1;
    
        private static MySQLiteOpenHelper helper;
    
        //表名。
        public static final String TABLE_NAME = "Student";
    
        public static final String STUDENT_ID = "id";
        public static final String STUDENT_NAME = "name";
        public static final String STUDENT_GENDER = "gender";
        public static final String STUDENT_AGE = "age";
    
        //创建数据库表的SQL语句。
        private String sql_create_table = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME + " (" + STUDENT_ID + " integer primary key autoincrement," + STUDENT_NAME + " varchar(60)," + STUDENT_GENDER + " varchar(1)," + STUDENT_AGE + " int)";
    
        public static MySQLiteOpenHelper getInstance(Context context) {
            if (helper == null) {
                helper = new MySQLiteOpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION);
            }
    
            return helper;
        }
    
        public MySQLiteOpenHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
            super(context, name, factory, version);
        }
    
        @Override
        public void onCreate(SQLiteDatabase db) {
            //创建数据库的表，如果不存在。
            db.execSQL(sql_create_table);
        }
    
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    
        }
    }

读写程序：

import android.content.ContentValues;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import android.os.Bundle;
    import android.support.v7.app.AppCompatActivity;
    
    import java.util.ArrayList;
    import java.util.List;
    
    /**
     * 本例数据样本容量很小，简单期间放到UI主线程中直接读写SQLite数据库。
     * 实际的开发中不允许这样在UI主线程读写SQLite数据库，应该把读写数据库操作的代码后台线程化。
     */
    public class MainActivity extends AppCompatActivity {
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
    
            SQLiteDatabase sqLiteDatabase = MySQLiteOpenHelper.getInstance(this).getWritableDatabase();
    
            ContentValues contentValues1 = getContentValues("zhang", "男", 18);
            ContentValues contentValues2 = getContentValues("phil", "男", 19);
    
            //往SQLite数据库中插入两条数据。
            sqLiteDatabase.insert(MySQLiteOpenHelper.TABLE_NAME, null, contentValues1);
            sqLiteDatabase.insert(MySQLiteOpenHelper.TABLE_NAME, null, contentValues2);
            sqLiteDatabase.close();
    
            //从SQLite数据库中读出数据。
            List<Student> students = query(MySQLiteOpenHelper.getInstance(this).getReadableDatabase());
            for (Student student : students) {
                System.out.println(student.id + "," + student.name + "," + student.gender + "," + student.age);
            }
        }
    
        private ContentValues getContentValues(String name, String gender, int age) {
            ContentValues contentValues = new ContentValues();
            contentValues.put(MySQLiteOpenHelper.STUDENT_NAME, name);
            contentValues.put(MySQLiteOpenHelper.STUDENT_GENDER, gender);
            contentValues.put(MySQLiteOpenHelper.STUDENT_AGE, age);
            return contentValues;
        }
    
        //查询SQLite数据库。读出所有数据内容。
        private List<Student> query(SQLiteDatabase db) {
            List<Student> students = null;
    
            Cursor cursor = db.rawQuery("SELECT * FROM " + MySQLiteOpenHelper.TABLE_NAME, null);
            if (cursor != null && cursor.getCount() > 0) {
    
                students = new ArrayList<>();
    
                while (cursor.moveToNext()) {
                    Student student = new Student();
    
                    student.id = cursor.getInt(cursor.getColumnIndex(MySQLiteOpenHelper.STUDENT_ID));
                    student.name = cursor.getString(cursor.getColumnIndex(MySQLiteOpenHelper.STUDENT_NAME));
                    student.gender = cursor.getString(cursor.getColumnIndex(MySQLiteOpenHelper.STUDENT_GENDER));
                    student.age = cursor.getInt(cursor.getColumnIndex(MySQLiteOpenHelper.STUDENT_AGE));
    
                    students.add(student);
                }
    
                cursor.close();
            }
    
            db.close();
    
            return students;
        }
    
        //数据容器，装载从数据库中读出的数据内容。
        private class Student {
            public int id;
            public String name;
            public String gender;
            public int age;
        }
    }