Android + SQLite 开发（一）基础

一、创建数据库配置文件

新建一个类继承接口类SQLiteOpenHelper，并实现其中的onCreate与onUpgrade方法
注意：
1、execSQL一次只能执行一种sql语句，不支持多表创建和插入等操作，建议将数据库创建语句分开写入，如下
2、数据库存在时不会执行，如果需修改数据库，建议清除手机端应用数据再重新打开应用，会重新运行onCreate；或者使用sql语句进行修改

public class SqlLite extends SQLiteOpenHelper {private static final String db_name = \"SQLite_db.db\";//数据文件的名字private static int NUMBER = 1;//当前数据库版本，用于升级private static final String table_name = \"students\";//表名private static String sql = null;//sql语句public SqlLite(@Nullable Context context) {super(context, db_name, null, NUMBER);}/***当数据库第一次创建时调用onCreate方法，并执行其中的sql语句*注意：数据库存在时不会执行，如果需修改数据库，建议清除手机端应用数据再重新打开应用，会重新运行onCreate；或者使用sql语句进行修改*/@Overridepublic void onCreate(SQLiteDatabase db) {//创建表sql = 	\"CREATE TABLE ClassList ( \\n\" +\"CLid   INTEGER    PRIMARY KEY ,\\n\" +\"classname  VARCHAR(50) NOT NULL ,\\n\" +\"weeksum VARCHAR(50) NOT NULL ,\\n\" +\"classroom VARCHAR(50) NOT NULL ,\\n\" +\"DayTime VARCHAR(50) NOT NULL\\n\" +\");\";db.execSQL(sql);sql = 	\"CREATE TABLE Curriculum ( \\n\"+\"DTid   INTEGER    PRIMARY KEY ,\\n\"+\"WeekTime1 INT,);\";db.execSQL(sql);sql = 	\"insert into ClassList(CLid,classname,weeksum,classroom,DayTime)\\n\"+\"values(1,\'专业英语\',\'1-12\',\'多媒体101\',\'8:00-9:40\')\";db.execSQL(sql);}/*** 当数据库进行升级是调用，这里通过NUMBER值来进行判断，数据库是否升级* 可不写*/@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {}}

二、创建javabean文件，用于保存数据库数据

例：

public class ClassList {private int CLid;private String ClassCame;private String WeekSum;private String ClassRoom;private String DayTime;public ClassList() {}public ClassList(int CLid, String classCame, String weekSum, String classRoom, String dayTime) {this.CLid = CLid;ClassCame = classCame;WeekSum = weekSum;ClassRoom = classRoom;DayTime = dayTime;}public int getCLid() {return CLid;}public void setCLid(int CLid) {this.CLid = CLid;}public String getClassCame() {return ClassCame;}public void setClassCame(String classCame) {ClassCame = classCame;}public String getWeekSum() {return WeekSum;}public void setWeekSum(String weekSum) {WeekSum = weekSum;}public String getClassRoom() {return ClassRoom;}public void setClassRoom(String classRoom) {ClassRoom = classRoom;}public String getDayTime() {return DayTime;}public void setDayTime(String dayTime) {DayTime = dayTime;}@Overridepublic String toString() {return \"ClassList{\" +\"CLid=\" + CLid +\", ClassCame=\'\" + ClassCame + \'\\\'\' +\", WeekSum=\'\" + WeekSum + \'\\\'\' +\", ClassRoom=\'\" + ClassRoom + \'\\\'\' +\", DayTime=\'\" + DayTime + \'\\\'\' +\'}\';}}

三、创建DAO类进行数据库操作

SQLiteDatabase的execSQL方法可执行任意SQL语句，包括带占位符的SQL语句。但由于该方法没有返回值，因此一般用于执行DDL(data definition language)语句或DML(data manipulation language)语句；如果需要执行査询语句，则可调用SQLiteDatabase的rawQuery(String sql, String[] selectionArgs)方法

例：增删改查：

public class tab_service {private static final String TAG = \"tab_service\";private SqlLite sqllite = null;//数据库对象private static SQLiteDatabase db = null; //数据库类private static String sql = null;public tab_service(Context context) {this.sqllite = new SqlLite(context);//获得数据库操作实例}//查询所有数据public List<ClassList> selectClassList(){List<ClassList> ClassList=new ArrayList<ClassList>();db=sqllite.getReadableDatabase();sql=\"select * from ClassList \";Cursor cur = db.rawQuery(sql, null);while (cur.moveToNext()) {int CLid = cur.getInt(cur.getColumnIndex(\"CLid\"));String classname = cur.getString(cur.getColumnIndex(\"classname\"));String WeekSum = cur.getString(cur.getColumnIndex(\"weeksum\"));String classroom = cur.getString(cur.getColumnIndex(\"classroom\"));String DayTime = cur.getString(cur.getColumnIndex(\"DayTime\"));ClassList stu = new ClassList(CLid,classname,WeekSum,classroom,DayTime);ClassList.add(stu);}cur.close();db.close();return ClassList;}}

四、在Activity调用

例：
使用了工厂方法创建DAO对象

public class ServiceFactory {public static tab_service Service(Context context){return new tab_service(context);}}

在activity中获取数据

List <ClassList> classList=ServiceFactory.Service(getApplicationContext()).selectClassList();Iterator<ClassList> iterator = classList.iterator();while(iterator.hasNext()){ClassList cl=iterator.next();Log.d(TAG, \"onCreate: ClassList:\"+cl.toString());}