用CREATE TABLE语句生成Java模型

时间：2016-05-23 10:07 来源：互联网作者：源码搜藏收藏

SQLDelight从SQL生成Java模型 CREATE TABLE 语句。这些模型给你一个类型安全的API来读写你的表中的行。它可以帮助你保持你的SQL语句共同组织，并容易从Java访问。例要使用SQLDelight，把你的SQL语句在 .sq 文件，就像在src / main / sqldelight / COM /

SQLDelight从SQL生成Java模型CREATE TABLE语句。这些模型给你一个类型安全的API来读写你的表中的行。它可以帮助你保持你的SQL语句共同组织，并容易从Java访问。

例

要使用SQLDelight，把你的SQL语句在.sq文件，就像 在src / main / sqldelight / COM /例子/ HockeyPlayer.sq。通常情况下，第一条语句创建一个表。

CREATE TABLE hockey_player (
  _id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
  number INTEGER NOT NULL,
  name TEXT NOT NULL
);

-进一步SQL语句由标识符进行。这将被用于命名恒定 -在生成的Java代码。

select_by_name:
SELECT *
FROM hockey_player
WHERE name = ;

从这个SQLDelight会生成一个HockeyPlayerModel嵌套类的Java接口读取（映射器）和写作（元帅）表。

package com.example;

import android.content.ContentValues;
import android.database.Cursor;
import java.lang.String;

public interface HockeyPlayerModel {
  String TABLE_NAME = "hockey_player";

  String _ID = "_id";

  String NUMBER = "number";

  String NAME = "name";

  String CREATE_TABLE = ""
      + "CREATE TABLE hockey_player (\n"
      + "  _id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,\n"
      + "  number INTEGER NOT NULL,\n"
      + "  name TEXT NOT NULL\n"
      + ")";

  String SELECT_BY_NAME = ""
      + "SELECT *\n"
      + "FROM hockey_player\n"
      + "WHERE name = ";

  long _id();

  long number();

  String name();

  final class Mapper<T extends HockeyPlayerModel> {
    private final Creator<T> creator;

    protected Mapper(Creator<T> creator) {
      this.creator = creator;
    }

    public T map(Cursor cursor) {
      return creator.create(
          cursor.getLong(cursor.getColumnIndex(_ID)),
          cursor.getLong(cursor.getColumnIndex(NUMBER)),
          cursor.getString(cursor.getColumnIndex(NAME))
      );
    }

    public interface Creator<R extends HockeyPlayerModel> {
      R create(long _id, long number, String name);
    }
  }

  class HockeyPlayerMarshal<T extends HockeyPlayerMarshal<T>> {
    protected ContentValues contentValues = new ContentValues();

    public HockeyPlayerMarshal() {
    }

    public final ContentValues asContentValues() {
      return contentValues;
    }

    public T _id(long _id) {
      contentValues.put(_ID, _id);
      return (T) this;
    }

    public T number(long number) {
      contentValues.put(NUMBER, number);
      return (T) this;
    }

    public T name(String name) {
      contentValues.put(NAME, name);
      return (T) this;
    }
  }
}

AutoValue

使用谷歌的AutoValue可以最低限度地使模型/元帅/映射器的实现：

@AutoValue
public abstract class HockeyPlayer implements HockeyPlayerModel {
  public static final Mapper<HockeyPlayer> MAPPER = new Mapper<>(new Mapper.Creator() {
    @Override public HockeyPlayer create(long _id, long number, String name) {
      return new AutoValue_HockeyPlayer(_id, age, number, gender);
    }
  }

  public static final class Marshal extends HockeyPlayerMarshal<Marshal> { }
}

如果您还使用Retrolambda匿名类可以通过方法引用来代替：

@AutoValue
public abstract class HockeyPlayer implements HockeyPlayerModel {
  public static final Mapper<HockeyPlayer> MAPPER = new Mapper<>(AutoValue_HockeyPlayer::new);

  public static final class Marshal extends HockeyPlayerMarshal<Marshal> { }
}

消费代码

使用生成的常量引用表名和SQL语句。

public void insert(SqliteDatabase db, long _id, long number, String name) {
  db.insert(HockeyPlayer.TABLE_NAME, null, new HockeyPlayer.Marshal()
    ._id(_id)
    .number(number)
    .name(name)
    .asContentValues());
}

public List<HockeyPlayer> alecs(SQLiteDatabase db) {
  List<HockeyPlayer> result = new ArrayList<>();
  try (Cursor cursor = db.rawQuery(HockeyPlayer.SELECT_BY_NAME, new String[] { "Alec" })) {
    while (cursor.moveToNext()) {
      result.add(HockeyPlayer.MAPPER.map(cursor));
    }
  }
  return result;
}

类型

SQLDelight列定义是相同的常规SQLite的列定义，但支持一个额外的列约束其指定生成的接口列的Java类型。SQLDelight原生支持，同样类型的 光标和ContentValues 期望：

CREATE TABLE some_types {
  some_long INTEGER,           -- Stored as INTEGER in db, retrieved as Long
  some_double REAL,            -- Stored as REAL in db, retrieved as Double
  some_string TEXT,            -- Stored as TEXT in db, retrieved as String
  some_blob BLOB,              -- Stored as BLOB in db, retrieved as byte[]
  some_int INTEGER AS Integer, -- Stored as INTEGER in db, retrieved as Integer
  some_short INTEGER AS Short, -- Stored as INTEGER in db, retrieved as Short
  some_float REAL AS Float     -- Stored as REAL in db, retrieved as Float
}

布尔值

SQLDelight支持布尔列，将它们存储在数据库中的整数。由于它们作为整数实现时，它们可以给INT列约束：

CREATE TABLE hockey_player (
  injured INTEGER AS Boolean DEFAULT 0
)

自定义类

如果您想获取自定义类型的列，您可以指定Java类型为字符串的sqlite：

CREATE TABLE hockey_player (
  birth_date INTEGER AS 'java.util.Calendar' NOT NULL
)

但是，创建一个元帅或映射器将要求您提供ColumnAdapter它知道如何将映射光标到你的类型和元帅你的类型变成ContentValues ：

public class HockeyPlayer implements HockeyPlayerModel {
  private static final ColumnAdapter<Calendar> CALENDAR_ADAPTER = new ColumnAdapter<>() {
    @Override public Calendar map(Cursor cursor, int columnIndex) {
      Calendar calendar = Calendar.getInstance();
      calendar.setTimeInMillis(cursor.getLong(columnIndex));
      return calendar;
    }

    @Override public void marshal(ContentValues contentValues, String key, Calendar value) {
      contentValues.put(key, value.getTimeInMillis());
    }
  }

  public static final Mapper<HockeyPlayer> MAPPER = new Mapper<>(new Mapper.Creator<>() { },
    CALENDAR_ADAPTER);

  public static final class Marshal extends HockeyPlayerMarshal<Marshal> {
    public Marshal() {
      super(CALENDAR_ADAPTER);
    }
  }
}

枚举

作为一种方便SQLDelight运行包括ColumnAdapter用于存储枚举为文本。

CREATE TABLE hockey_player (
  position TEXT AS 'com.example.hockey.HockeyPlayer.Position'
)

public class HockeyPlayer implements HockeyPlayerModel {
  public enum Position {
    CENTER, LEFT_WING, RIGHT_WING, DEFENSE, GOALIE
  }

  private static final ColumnAdapter<Position> POSITION_ADAPTER = EnumColumnAdapter.create(Position.class);

  public static final Mapper<HockeyPlayer> MAPPER = new Mapper<>(new Mapper.Creator<>() { },
    POSITION_ADAPTER);

  public static final class Marshal extends HockeyPlayerMarshal<Marshal> {
    public Marshal() {
      super(POSITION_ADAPTER);
    }
  }
}

SQL语句的参数

SQL查询也可以包含参数以同样的方式SqliteDatabase作用：

select_by_position:
SELECT *
FROM hockey_player
WHERE position = ;

Cursor centers = db.rawQuery(HockeyPlayer.SELECT_BY_POSITION, new String[] { Center.name() });

的IntelliJ插件

该插件的IntelliJ提供语言级特性为.sq文件，包括：

语法高亮
重构/查找用法
代码自动完成
生成模式编辑后的文件

下载

对于摇篮插件：

buildscript {
  repositories {
    mavenCentral()
  }
  dependencies {
    classpath 'com.squareup.sqldelight:gradle-plugin:0.3.2'
  }
}

apply plugin: 'com.squareup.sqldelight'

该插件的IntelliJ可以从Android的工作室通过导航安装
>首选项- - Android电子工作室>插件- >浏览资料库- >搜索SQLDelight

的开发版本（包括IDE插件ZIP）快照是可 Sonatype的的快照库。