使用SQLite将用户账号密码保存到本地

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//Db工具类package com.example.test;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class Db extends SQLiteOpenHelper {private static final String DBAdapter = null;public Db(Context context) {super(context, "NewDB", null, 1);}@Overridepublic void onCreate(SQLiteDatabase db) {                //创建user表db.execSQL("CREATE TABLE user(" + "_id integer primary key autoincrement,"+ "userid text not null," + "psw text not null )");}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {}}

package com.example.test;import android.app.Activity;import android.content.ContentValues;import android.content.Intent;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends Activity{private Button button = null;private EditText editText = null;public Db db = new Db(this);protected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);button = (Button)findViewById(R.id.button1);editText = (EditText)findViewById(R.id.editText1);                //向user表插入数据sqliteinsert();                //查询user表数据                sqlitequery();button.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {                                //单击按钮后将edittext置空editText.setText("");                                //删除user表数据sqlitedelete();//sqliteinsert();sqlitequery();}});}public void sqlitequery() {final SQLiteDatabase dbRead = db.getReadableDatabase();Cursor cursor = dbRead.query("user", null, null, null, null, null, null);while (cursor.moveToLast()) {String userid = cursor.getString(cursor.getColumnIndex("userid"));String psw = cursor.getString(cursor.getColumnIndex("psw"));                        //读出数据显示在edittext中editText.setText(userid+psw);break;}cursor.close();}public void sqliteinsert() {final SQLiteDatabase dbWrite = db.getReadableDatabase();String str_userid = "userid2";String str_psw = "psw";                //以键值对的形式存入数据ContentValues cv = new ContentValues();cv.put("userid", str_userid);cv.put("psw", str_psw);dbWrite.insert("user", null, cv);}public void sqlitedelete() {final SQLiteDatabase dbRead = db.getReadableDatabase();dbRead.delete("user", null, null);}}

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