Sqldelight使用步骤

SQLDelight是Square提供的开源库，主要的作用结合AuToValue生成Java数据和数据库表创建的SQL语句。下边是sqldelight的官方介绍

SQLDelight generates Java models from your SQL CREATE TABLE statements. These models give you a typesafe API to read & write the rows of your tables. It helps you to keep your SQL statements together, organized, and easy to access from Java.

使用SQLDelight需要把SQL语句写到.sq的文件中，一般第一条语句为创建表结构。

1.引入工程中

buildscript {
  repositories {
    mavenCentral()
  }
  dependencies {
    classpath 'com.squareup.sqldelight:gradle-plugin:0.6.1'
  }
}

apply plugin: 'com.squareup.sqldelight'

2.如下边的SQL语句，创建一个User表结构

--user表
create table user(
    --id自增长
    _id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
    --名字
    name TEXT NOT NULL,
    --头像地址
    portrait TEXT ,
    --手机号
    phone TEXT
);
-- 查询使用到的语句，将会生成对应的方法.
selectAll:
SELECT *
FROM user;

insertRow:
INSERT INTO user(account, password,name,portrait,token,origin)
VALUES (?, ?, ?, ?,?,?);

3.通过这个sq文件将会生成一个User接口和一个内部类，进行数据库的操作。生成的文件存在app/build/generated/source/sqldelight中。

public interface UserModel {
  String TABLE_NAME = "user";

  String _ID = "_id";

  String NAME = "name";

  String PORTRAIT = "portrait";

  String PHONE = "phone";

  String CREATE_TABLE = ""
      + "create table user(\n"
      + "    --id自增长\n"
      + "    _id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,\n"
      + "    --名字\n"
      + "    name TEXT NOT NULL,\n"
      + "    --头像地址\n"
      + "    portrait TEXT ,\n"
      + "    --手机号\n"
      + "    phone TEXT\n"
      + ")";

  long _id();

  @NonNull
  String name();

  @Nullable
  String portrait();

  @Nullable
  String phone();

  interface Creator {
    T create(long _id, @NonNull String name, @Nullable String portrait, @Nullable String phone);
  }

  final class Mapper implements RowMapper {
    private final Factory userModelFactory;

    public Mapper(Factory userModelFactory) {
      this.userModelFactory = userModelFactory;
    }

    @Override
    public T map(@NonNull Cursor cursor) {
      return userModelFactory.creator.create(
          cursor.getLong(0),
          cursor.getString(1),
          cursor.isNull(2) ? null : cursor.getString(2),
          cursor.isNull(3) ? null : cursor.getString(3)
      );
    }
  }

  final class Marshal {
    protected final ContentValues contentValues = new ContentValues();

    Marshal(@Nullable UserModel copy) {
      if (copy != null) {
        this._id(copy._id());
        this.name(copy.name());
        this.portrait(copy.portrait());
        this.phone(copy.phone());
      }
    }

    public ContentValues asContentValues() {
      return contentValues;
    }

    public Marshal _id(long _id) {
      contentValues.put("_id", _id);
      return this;
    }

    public Marshal name(String name) {
      contentValues.put("name", name);
      return this;
    }

    public Marshal portrait(String portrait) {
      contentValues.put("portrait", portrait);
      return this;
    }

    public Marshal phone(String phone) {
      contentValues.put("phone", phone);
      return this;
    }
  }

  final class Factory {
    public final Creator creator;

    public Factory(Creator creator) {
      this.creator = creator;
    }

    /**
     * @deprecated Use compiled statements (https://github.com/square/sqldelight#compiled-statements)
     */
    @Deprecated
    public Marshal marshal() {
      return new Marshal(null);
    }

    /**
     * @deprecated Use compiled statements (https://github.com/square/sqldelight#compiled-statements)
     */
    @Deprecated
    public Marshal marshal(UserModel copy) {
      return new Marshal(copy);
    }

    public SqlDelightStatement selectUser() {
      return new SqlDelightStatement(""
          + "select * from user",
          new String[0], Collections.singleton("user"));
    }

    /**
     * @deprecated Use {@link InsertUser}
     */
    @Deprecated
    public SqlDelightStatement insertUser(@NonNull String name, @Nullable String portrait,
        @Nullable String phone) {
      List args = new ArrayList();
      int currentIndex = 1;
      StringBuilder query = new StringBuilder();
      query.append("INSERT OR IGNORE INTO user (name,portrait,phone) values (");
      query.append('?').append(currentIndex++);
      args.add(name);
      query.append(",");
      if (portrait == null) {
        query.append("null");
      } else {
        query.append('?').append(currentIndex++);
        args.add(portrait);
      }
      query.append(",");
      if (phone == null) {
        query.append("null");
      } else {
        query.append('?').append(currentIndex++);
        args.add(phone);
      }
      query.append(")");
      return new SqlDelightStatement(query.toString(), args.toArray(new String[args.size()]), Collections.singleton("user"));
    }

    public Mapper selectUserMapper() {
      return new Mapper(this);
    }
  }

  final class InsertUser extends SqlDelightCompiledStatement.Insert {
    public InsertUser(SQLiteDatabase database) {
      super("user", database.compileStatement(""
              + "INSERT OR IGNORE INTO user (name,portrait,phone) values (?,?,?)"));
    }

    public void bind(@NonNull String name, @Nullable String portrait, @Nullable String phone) {
      program.bindString(1, name);
      if (portrait == null) {
        program.bindNull(2);
      } else {
        program.bindString(2, portrait);
      }
      if (phone == null) {
        program.bindNull(3);
      } else {
        program.bindString(3, phone);
      }
    }
  }
}

• Mapper主要用于把Cursor转为Java类型。
• Marshal的作用把Java类型转化为ContentValues后续插入数据库。
• Factory里面存在一个实现了Creator对象的属性，marshal方法返回Model的Marshal对象，通过asContentValues可以返回对应的contentValues。
• Creator接口定义了一个用于创建我们的数据类型。

4.使用AutoValue生成一个对应名为AutoValue_User的Java类型，i实现生成的UserModel接口，创建自己的FACTORY创建AutoValue_User类型实例。

@AutoValue
public abstract class User implements UserModel{
    //创建Factory类型
    public static final Factory FACTORY=new Factory<>(new Creator(){

        @Override
        public User create(long _id, @NonNull String name, @Nullable String portrait, @Nullable String phone) {
            //传入自动化生成的User实例
            return new AutoValue_User(_id,name,portrait,phone);
        }
    });
    //把Cursor对象转化为相应的实例对象
    public static final RowMapper SELECT_ALL_MAPPER=FACTORY.selectUserMapper();
}

5.创建数据库管理类,使用自动生成的创建表结构的语句。

public class SQLiteHelp extends SQLiteOpenHelper{
    //数据库名
    private static final String DBNAME = "test.db";
    //数据库版本号
    private static final int CURRENTVERSION = 1;
    //构造器，创建数据库
    public SQLiteHelp(Context context) {

        this(context, DBNAME, null, CURRENTVERSION);
    }
    public SQLiteHelp(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, DBNAME, factory, CURRENTVERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        //创建相应的数据库表
        sqLiteDatabase.execSQL(User.CREATE_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
}

6.进行数据操作

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //创建数据库对象
        SQLiteDatabase sqLiteHelp=new SQLiteHelp(this).getWritableDatabase();
        //使用InsertUser Factory类的insertUser已废弃
        User.InsertUser insertUser=new UserModel.InsertUser(sqLiteHelp);
        insertUser.bind("zyc","","1850*******");
        insertUser.program.executeInsert();
        getAllUsers(sqLiteHelp);
    }
    public List getAllUsers(SQLiteDatabase db) {
        List result = new ArrayList<>();
        //使用到对应的SQL语句
        Cursor cursor=db.rawQuery(User.FACTORY.selectUser().statement,User.FACTORY.selectUser().args);
        while (cursor.moveToNext()){
            //把Cursor转为Java类型
           result.add(User.SELECT_ALL_MAPPER.map(cursor));
        }
        return result;
    }
}