概述
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;
}
}
最后
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