详解Android数据存储―使用SQLite数据库

CREATE TABLE userInfo_brief (id INTEGER PRIMARY KEY AUTOINCREMENT,name TEXT,password TEXT);

  final static int VERSION=1;  final static String TABLENAME="userInfo_brief";  final static String ID="id";  final static String NAME="name";  final static String PASSWORD="password";  String sql="CREATE TABLE "+TABLENAME+"("+"ID"+" INTEGER PRIMARY KEY AUTOINCREMENT,"     +NAME+" TEXT,"// Attention:注意SQL语法，每个变量后需要有空格，否则不认识。    +PASSWORD+" TEXT,"    +AGE+" TEXT);";    db.execSQL(sql);

DROP TABLE userInfo_brief;

String sql="DROP TABLE "+TABLENAME+";";db.execSQL(sql);

SQliteDatabase.insert(String table,String nullColumnHack,ContentValues values)

ContentValues values=new ContentValues();//获取ContentValues对象，类似HashMAP      values.put(DatabaseHelper.NAME, name);//键值对形式保存数据      values.put(DatabaseHelper.PASSWORD, pass);      values.put(DatabaseHelper.AGE, age);      db.insert(DatabaseHelper.TABLENAME, null, values);

ContentValues values=new ContentValues();values.put(PASSWORD,"123456");//要更新的数据db.update(TABLENAME,values,NAME+"=?",new String[]{"bob"});

SQliteDatabase.delete(String table,String where-Clause,String[] WhereArgs)

db.delete(TABLENAME,NAME+"=?",new String[]{"bob"});

SQLiteQueryBuilder builder=new SQLiteQueryBuilder();//获得对象builder.setTables(TABLENAME_A,TABLENAME_B);//设置需要查询的表，可多个builder.appendWhere(TABLENAME_A+"."+NAME+"="TABLENAME_B+"."+NAME);//设置关联属性，表与属性间.隔开，属性以=连接cursor=builder.query(7个属性）;//7属性同单表查询

public class DatabaseHelper extends SQLiteOpenHelper {  final static String DATABASENAME="my_database.db";  final static int VERSION=1;  final static String TABLENAME="userInfo_detail";  final static String ID="id";  final static String NAME="name";  final static String PASSWORD="password";  final static String AGE="age";  public DatabaseHelper(Context context) {    super(context, DATABASENAME, null, VERSION);    // TODO 自动生成的构造函数存根  }  @Override  public void onCreate(SQLiteDatabase db) {    // TODO 自动生成的方法存根    String sql="CREATE TABLE "+TABLENAME+"("+"ID"+" INTEGER PRIMARY KEY AUTOINCREMENT,"    +NAME+" TEXT,"    +PASSWORD+" TEXT,"    +AGE+" TEXT);";    db.execSQL(sql);  }  @Override  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {    // TODO 自动生成的方法存根  }}

public class LoginActivity extends Activity {  private EditText username;   private EditText password;   private CheckBox autoLogin;   private SharedPreferences sharedPreferences;   private String message;   SQLiteDatabase db;  @Override   public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);    // MyApplication.getInstance().addActivity(this);     sharedPreferences = this.getSharedPreferences("userInfo",Context.MODE_WORLD_READABLE); //sharedPreferences实例化，用于记住登录状态，判断是否需要自动登录    if (sharedPreferences.getBoolean("AUTO_ISCHECK", false)) { //自动登录      Intent intent = new Intent();       intent.setClass(LoginActivity.this, MainActivity.class);       intent.putExtra("NAME", sharedPreferences.getString("userName", ""));      startActivity(intent);     } else {       setContentView(R.layout.login_main);       initView();      username = (EditText) findViewById(R.id.accountEdittext);      password = (EditText) findViewById(R.id.pwdEdittext);      Button btn_login=(Button) findViewById(R.id.login_in);     Button btn_register=(Button)findViewById(R.id.register);     btn_register.setOnClickListener(new OnClickListener() {//跳转注册界面      @Override      public void onClick(View v) {        // TODO 自动生成的方法存根        Intent intent=new Intent(LoginActivity.this, RegisterActivity.class);        startActivity(intent);      }    });     btn_login.setOnClickListener(new OnClickListener() { //判断登录       @Override       public void onClick(View v) {         // TODO Auto-generated method stub        userLogin();       }     });    }   }   /**    * 初始化视图控件    */   public void initView() {     Log.i(TAG, "初始化视图控件");     username = (EditText) findViewById(R.id.accountEdittext);     password = (EditText) findViewById(R.id.pwdEdittext);     autoLogin = (CheckBox) findViewById(R.id.checkBox1);     // 默认记住用户名     username.setText(sharedPreferences.getString("userName", ""));   }   /**    * 点击登录按钮时触发的方法    */   public void userLogin() {     //通过帮助类获得数据库对象    DatabaseHelper helper=new DatabaseHelper(getBaseContext());    db=helper.getReadableDatabase();    //得到用户输入信息    String usernameString = username.getText().toString();     String passwordString = password.getText().toString();     //根据用户名查询数据库信息    Cursor cursor=db.query(DatabaseHelper.TABLENAME, new String[]{DatabaseHelper.PASSWORD},        DatabaseHelper.NAME+"=?", new String[]{usernameString}, null, null, null);    //若没有查询到相关信息，不再继续操作    if(cursor.getCount()==0)    {      Toast.makeText(getBaseContext(), "用户名不存在", Toast.LENGTH_SHORT).show();      return;    }    //若用户名存在，则继续操作    cursor.moveToFirst(); //指向第一条记录    String password=cursor.getString(0);//取得密码    //判断密码，若一样则进行跳转    if(password.equals(passwordString)){      if(autoLogin.isChecked()){        Editor editor=sharedPreferences.edit();        editor.putString("userNAME", usernameString);        editor.putBoolean("AUTO_ISCHECK", true);        editor.commit();      }      Intent intent=new Intent(LoginActivity.this, MainActivity.class);      intent.putExtra("NAME",usernameString);      startActivity(intent);    }    else    {//     Editor editor = sharedPreferences.edit(); //      editor.putString("userName", usernameString); //      editor.commit();       Toast.makeText(getBaseContext(), "密码错误", Toast.LENGTH_SHORT).show();    }  } }

public class RegisterActivity extends Activity {  String name;  String pass;  String age;  SQLiteDatabase db;  @Override  protected void onCreate(Bundle savedInstanceState) {    // TODO 自动生成的方法存根    super.onCreate(savedInstanceState);    setContentView(R.layout.register);    final EditText et_userName=(EditText)findViewById(R.id.editText_1);    final EditText et_password=(EditText)findViewById(R.id.editText_2);    final EditText et_age=(EditText)findViewById(R.id.editText_3);    Button btn_confirm=(Button)findViewById(R.id.register_confirm);    btn_confirm.setOnClickListener(new OnClickListener() {      @Override      public void onClick(View v) {        // TODO 自动生成的方法存根        name=et_userName.getText().toString();        pass=et_password.getText().toString();        age=et_age.getText().toString();        //得到数据库对象        DatabaseHelper helper=new DatabaseHelper(getBaseContext());        db=helper.getWritableDatabase();        //判断用户名是否已存在        Cursor cursor=db.query(DatabaseHelper.TABLENAME, new String[]{DatabaseHelper.NAME},            DatabaseHelper.NAME+"=?", new String[]{name}, null, null, null);        //若查询目标已存在        if(cursor.getCount()>0){          Toast.makeText(getBaseContext(), "用户名已存在", Toast.LENGTH_SHORT).show();          return;        }      //若不存在，则插入数据      ContentValues values=new ContentValues();      values.put(DatabaseHelper.NAME, name);      values.put(DatabaseHelper.PASSWORD, pass);      values.put(DatabaseHelper.AGE, age);      db.insert(DatabaseHelper.TABLENAME, null, values);      //进行跳转      Intent intent=new Intent(RegisterActivity.this, MainActivity.class);      intent.putExtra("NAME", name);      startActivity(intent);      }    });  }}

public class MainActivity extends Activity {  String name;  String pass;  String age;   private Button logout;   SQLiteDatabase db;   private SharedPreferences sharedPreferences;    protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);  //  MyApplication.getInstance().addActivity(this);     setContentView(R.layout.main_activity);    logout=(Button) findViewById(R.id.logout);    doQuery();//进行查询    doShow();//进行显示    logout.setOnClickListener(new OnClickListener() {      @Override      public void onClick(View v) {        // TODO 自动生成的方法存根        removeSharedPreference();       Intent intent=new Intent();       intent.setClass(MainActivity.this, LoginActivity.class);       startActivity(intent);      }    });  }  private void doQuery() {    // TODO 自动生成的方法存根    name=getIntent().getExtras().getString("NAME");    DatabaseHelper helper=new DatabaseHelper(getBaseContext());    db=helper.getReadableDatabase();    //准备查询de属性    String[] columns=new String[]{DatabaseHelper.PASSWORD,DatabaseHelper.AGE};    Cursor cursor=db.query(DatabaseHelper.TABLENAME, columns, DatabaseHelper.NAME+"=?",         new String[]{name}, null, null, null);    cursor.moveToFirst();    while(!cursor.isAfterLast()){//判断是否是最后一条记录      pass=cursor.getString(0);       age=cursor.getString(1);      cursor.moveToNext();    }  }  private void doShow() {    // TODO 自动生成的方法存根    TextView tv_show=(TextView)findViewById(R.id.show1);    tv_show.setText("用户信息如下：/n"+"账户："+name+"/n密码"+pass+"/n年龄"+age);  }  public void removeSharedPreference() {    sharedPreferences = getSharedPreferences("userInfo", Context.MODE_PRIVATE);    Editor editor = sharedPreferences.edit();    //editor.remove("userName");    editor.remove("AUTO_ISCHECK");    editor.commit();// 提交修改    }}