Android应用中内嵌SQLite数据库的基本 *** 作指南

概述一、首先写一个类继承SQLiteOpenHelper类重写他的方法指定db的名称、版本，重写oncreat和onUpgrade方法，写SQL语句创建表

一、首先写一个类继承sqliteOpenHelper类

重写他的方法指定db的名称、版本，重写oncreat和onUpgrade方法，写SQL语句创建表

public class MysqLiteOpenhelper extends sqliteOpenHelper {  private static String name = "person.db";  private static int version = 1;  public MysqLiteOpenhelper(Context context){    super(context,name,null,version);    }  /*   *数据库第一次被创建时调用的方法   *db是被创建的数据库   */  @OverrIDe  public voID onCreate(sqliteDatabase db) {    db.execsql("create table person(ID integer primary key autoincrement,name varchar(20),number varchar(20) )");  }  /*当数据库版本更新时调用此方法*/  @OverrIDepublic voID onUpgrade(sqliteDatabase db,int oldVersion,int newVersion) {  }

二、创建一个DAO类对外提供增删改查接口
其中执行增删改查的方法可以用SQL语句也可以使用系统给出的API,下面的代码中把两种方法都写了出来

public class Persondao {  private MysqLiteOpenhelper helper;  public Persondao(){  }  public Persondao(Context context){    helper = new MysqLiteOpenhelper(context);  }  public voID add(String name,String number){    sqliteDatabase db = helper.getWritableDatabase();    db.execsql("insert into person (name,number)values(?,?)",new Object[]{name,number});    /*ContentValues values = new ContentValues();    values.put("number",number);    values.put("name",name);    long ID = db.insert("Person",values);*/    db.close();  }  public boolean find(String name){    sqliteDatabase db = helper.getWritableDatabase();    //Cursor cursor = db.rawquery("select *from person where name=?",new String[]{name});    Cursor cursor = db.query("person","name=?",new String[]{name},null);    boolean result =cursor.movetoNext();    cursor.close();    db.close();    return result;      }  public int update(String name,String newnumber){    sqliteDatabase db = helper.getWritableDatabase();    //db.execsql("update person set number=? where name=?",new Object[]{newnumber,name});    ContentValues values = new ContentValues();    values.put("number",newnumber);    int number = db.update("person",values,new String[]{newnumber});    db.close();    return number;  }  public int delet(String name){    sqliteDatabase db = helper.getWritableDatabase();    //db.execsql("delete from person where name=?",new String[]{name});    int number = db.delete("person",new String[]{name});    db.close();      return number;  }  public List<Person> findAll(){    List<Person> persons = new ArrayList<Person>();    sqliteDatabase db = helper.getWritableDatabase();    //Cursor cursor = db.rawquery("select *from person",null);    Cursor cursor = db.query("person",new String[]{"ID","name","number"},null);    while (cursor.movetoNext()) {      int ID = cursor.getInt(cursor.getColumnIndex("ID"));      String name = cursor.getString(cursor.getColumnIndex("name"));      String number = cursor.getString(cursor.getColumnIndex("number"));      Person p = new Person();      persons.add(p);    }    db.close();    cursor.close();    return persons;   }}

三、增删改查 *** 作

import androID.content.ContentValues;import androID.content.Context;import androID.database.Cursor;import androID.database.sqlite.sqliteDatabase;import androID.database.sqlite.sqliteOpenHelper; public class TodoDB extends sqliteOpenHelper {  private final static String DATABASE_name = "todo_db";  private final static int DATABASE_VERSION = 1;  private final static String table_name = "todo_table";  public final static String FIELD_ID = "_ID";  public final static String FIELD_TEXT = "todo_text";   public TodoDB(Context context) {    super(context,DATABASE_name,DATABASE_VERSION);  }   @OverrIDe  public voID onCreate(sqliteDatabase db) {    /* 建立table */    String sql = "CREATE table " + table_name + " (" + FIELD_ID        + " INTEGER primary key autoincrement," + " " + FIELD_TEXT        + " text)";    db.execsql(sql);  }   @OverrIDe  public voID onUpgrade(sqliteDatabase db,int newVersion) {    String sql = "DROP table IF EXISTS " + table_name;    db.execsql(sql);    onCreate(db);  }   public Cursor select() {    sqliteDatabase db = this.getReadableDatabase();    Cursor cursor = db        .query(table_name,null);    return cursor;  }   public long insert(String text) {    sqliteDatabase db = this.getWritableDatabase();    /* 将新增的值放入ContentValues */    ContentValues cv = new ContentValues();    cv.put(FIELD_TEXT,text);    long row = db.insert(table_name,cv);    return row;  }   public voID delete(int ID) {    sqliteDatabase db = this.getWritableDatabase();    String where = FIELD_ID + " = ?";    String[] whereValue = { Integer.toString(ID) };    db.delete(table_name,where,whereValue);  }   public voID update(int ID,String text) {    sqliteDatabase db = this.getWritableDatabase();    String where = FIELD_ID + " = ?";    String[] whereValue = { Integer.toString(ID) };    /* 将修改的值放入ContentValues */    ContentValues cv = new ContentValues();    cv.put(FIELD_TEXT,text);    db.update(table_name,cv,whereValue);  }}

四、写一个JavaBean设置他的get、set方法

public class Person {   private int ID;  private String name;  private String number;  public Person(){  }  public Person(int ID,String name,String number) {    this.ID = ID;    this.name = name;    this.number = number;  }  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 String getNumber() {    return number;  }  public voID setNumber(String number) {    this.number = number;  }}

五、mainactivity中使用它

private sqliteOpenHelper helper;Persondao dao = new Persondao();helper = new MysqLiteOpenhelper(this);helper.getWritableDatabase();    sqliteDatabase db = helper.getWritableDatabase();

六、关于数据库的事务处理
androID开发中数据库的 *** 作非常慢，将所有 *** 作打包成一个事务能够大大的提高处理速度，其中最重要的是保证了数据的一致性，让事务中的所有 *** 作都能成功执行，或者失败，或者这所有 *** 作都回滚。

sqliteDatabase db = helper.getWritableDatabase();db.beginTransaction();try{ //在这里执行多个数据库 *** 作，执行过程中可能会抛出异常 db.execsql("update person set number=? where name=?",new Object[]{"1",jacky}); db.execsql("update person set number=? where name=?",new Object[]{"2","sunny"}); db.setTransactionSuccessful();}catch{ //捕获异常 throw e；}finally{  //所有 *** 作完成结束一个事务  db.endTransaction();  db.close;}

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