1.新建一個SqlDBHelper類繼承SQLiteOpenHelper用來創建數據庫
public class SqlDBHelper extends SQLiteOpenHelper {
// 數據庫名字
private static String name = "lsqTest.db";
// 版本
private static int version = 1;
//表名
public static final String TABLE_NAME_USER = "User";
public static final String TABLE_NAME_ORDE = "Order";
/**
* 建數據庫
*/
public SqlDBHelper(Context context) {
super(context, name, null, version);
}
/**
* 建表
*/
@Override
public void onCreate(SQLiteDatabase db) {
//Id integer primary autoincrement key id設置爲主鍵 自增長
String sql_user = "create table if not exists " + TABLE_NAME_USER + " (Id integer primary autoincrement key, Name text, Age integer)";
db.execSQL(sql_user);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
//根據version的改變升級數據庫
}
}
2.創建一個實體類UserBean
public class UserBean {
private int id;
private String name;
private int age;
public UserBean() {
}
public UserBean(int id, String name, int age) {
this.id = id;
this.name = name;
this.age = age;
}
public UserBean(String name, int age) {
this.age = age;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
3.創建一個管理類UserDao，這裏就用來操作數據庫（增刪改查）
public class UserDao {
private static final String TAG = "UserDao";
// 列定義
private final String[] USER_COLUMNS = new String[]{"Id", "Name", "Age"};
private Context context;
private SqlDBHelper sqlDBHelper;
public UserDao(Context context) {
this.context = context;
sqlDBHelper = new SqlDBHelper(context);
}
/**
* 判斷表中是否有數據
*/
public boolean isDataExist() {
int count = 0;
SQLiteDatabase db = null;
Cursor cursor = null;
try {
db = sqlDBHelper.getWritableDatabase();
// select count(Id) from Orders
cursor = db.query(SqlDBHelper.TABLE_NAME_USER, new String[]{"COUNT(Id)"}, null, null, null, null, null);
db.setTransactionSuccessful();
if (cursor.moveToFirst()) {
count = cursor.getInt(0);
}
if (count > 0) return true;
} catch (Exception e) {
Log.e(TAG, "", e);
} finally {
if (cursor != null) {
cursor.close();
}
if (db != null) {
db.endTransaction();
db.close();
}
}
return false;
}
/**
* 初始化數據
*/
public void initTable() {
SQLiteDatabase db = null;
try {
db = sqlDBHelper.getWritableDatabase();
db.beginTransaction();
db.execSQL("insert into " + SqlDBHelper.TABLE_NAME_USER + " (Name, Age) values ( 'Lsq', 20)");
db.setTransactionSuccessful();
} catch (Exception e) {
Log.e(TAG, "", e);
} finally {
if (db != null) {
db.endTransaction();
db.close();
}
}
}
/**
* 添加用戶數據
*/
public boolean addUser(UserBean userBean) {
SQLiteDatabase db = null;
try {
db = sqlDBHelper.getWritableDatabase();
db.beginTransaction();
ContentValues contentValues = new ContentValues();
contentValues.put("Name", userBean.getName());
contentValues.put("Age", userBean.getAge());
db.insertOrThrow(SqlDBHelper.TABLE_NAME_USER, null, contentValues);
return true;
} catch (SQLiteConstraintException e) {
Toast.makeText(context, "主鍵重複", Toast.LENGTH_SHORT).show();
} catch (Exception e) {
Log.e(TAG, "", e);
} finally {
if (db != null) {
db.endTransaction();
db.close();
}
}
return false;
}
/**
* 刪除用戶數據
* 根據id刪除
*/
public boolean deleteUser(int id) {
SQLiteDatabase db = null;
try {
db = sqlDBHelper.getWritableDatabase();
db.beginTransaction();
db.delete(SqlDBHelper.TABLE_NAME_USER, "Id = ?", new String[]{String.valueOf(id)});
} catch (Exception e) {
Log.e(TAG, "", e);
} finally {
if (db != null) {
db.endTransaction();
db.close();
}
}
return false;
}
/**
* 改變用戶的數據
*/
public boolean changeUser(UserBean userBean) {
SQLiteDatabase db = null;
try {
db = sqlDBHelper.getWritableDatabase();
db.beginTransaction();
ContentValues contentValues = new ContentValues();
contentValues.put("Name", userBean.getName());
contentValues.put("Age", userBean.getAge());
db.update(SqlDBHelper.TABLE_NAME_USER, contentValues, "id=?", new String[]{String.valueOf(userBean.getId())});
return true;
} catch (Exception e) {
Log.e(TAG, "", e);
} finally {
if (db != null) {
db.endTransaction();
db.close();
}
}
return false;
}
/**
* 根據id查找用戶的數據
*/
public UserBean SearchUser(int id) {
SQLiteDatabase db = null;
Cursor cursor = null;
try {
db = sqlDBHelper.getReadableDatabase();
db.beginTransaction();
cursor = db.query(SqlDBHelper.TABLE_NAME_USER, new String[]{"id"}, "id=?", new String[]{String.valueOf(id)}, null, null, null);
db.setTransactionSuccessful();
if (cursor.getCount() > 0) {
UserBean userBean = parseUser(cursor);
return userBean;
}
} catch (Exception e) {
Log.e(TAG, "", e);
} finally {
if (cursor != null) {
cursor.close();
}
if (db != null) {
db.endTransaction();
db.close();
}
}
return null;
}
/**
* 查找所有用戶數據
*/
public List<UserBean> searchAllUser() {
SQLiteDatabase db = null;
Cursor cursor = null;
try {
db = sqlDBHelper.getReadableDatabase();
db.beginTransaction();
cursor = db.query(SqlDBHelper.TABLE_NAME_USER, USER_COLUMNS, "id=?", null, null, null, null);
db.setTransactionSuccessful();
if (cursor.getCount() > 0) {
List<UserBean> list = new ArrayList<>();
while (cursor.moveToNext()) {
list.add(parseUser(cursor));
}
return list;
}
} catch (Exception e) {
} finally {
if (cursor != null) {
cursor.close();
}
if (db != null) {
db.endTransaction();
db.close();
}
}
return null;
}
/**
* 將查找到的數據轉換成Order類
*/
private UserBean parseUser(Cursor cursor) {
UserBean userBean = new UserBean();
userBean.setId(cursor.getInt(cursor.getColumnIndex("Id")));
userBean.setName(cursor.getString(cursor.getColumnIndex("Name")));
userBean.setAge(cursor.getInt(cursor.getColumnIndex("Age")));
return userBean;
}
//更多操作
}
4.在需要用的地方
private UserDao userDao;
userDao = new UserDao(this);
然後使用ordersDao進行操作就好