Android SqlLite的简单实用

我就是我 2022-06-07 13:16 209阅读 0赞

## 1.先写一个MySqlHelper类,用于创建数据库 ##

public class MySqlHelper extends SQLiteOpenHelper{
        public MySqlHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
            super(context, name, factory, version);
        }
    
        @Override
        public void onCreate(SQLiteDatabase db) {
            String sql = "create table if not exists user(_id Integer primary key autoincrement ,uname varchar(20),upass varchar(20))";
            db.execSQL(sql);
        }
    
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    
        }
    }

## 2.写个Dialog的页面布局zhuce\_item.xml ##

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical" android:layout_width="match_parent"
        android:layout_height="match_parent">
    
        <EditText
            android:id="@+id/zhucename"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint=" 请输入用户名"
            />
        <EditText
            android:id="@+id/zhucepass"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint=" 请输入密码"
            />
    
    </LinearLayout>

## 3.LoginActivity页面的代码： ##

public class LoginActivity extends AppCompatActivity {
    
        private EditText editName;
        private EditText editPass;
        private Button login;
        private Button zhuce;
        private Button update;
        private MySqlHelper helper;
        private SQLiteDatabase read;
        private SQLiteDatabase write;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_login);
    
            initView();
    
            initData();
        }
        /*获取控件，创建数据库对象*/
        private void initView() {
            editName = (EditText) findViewById(R.id.name);
            editPass = (EditText) findViewById(R.id.pass);
            login = (Button) findViewById(R.id.login);
            zhuce = (Button) findViewById(R.id.zhuce);
            update = (Button) findViewById(R.id.update);
            //数据库helper对象
            helper = new MySqlHelper(LoginActivity.this, "user", null, 2);
            //读取数据库数据的对象
            read = helper.getReadableDatabase();
            //写入数据库数据的对象
            write = helper.getWritableDatabase();
        }
        private void initData() {
            //登陆点击事件
            login.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Toast.makeText(LoginActivity.this,"登录",Toast.LENGTH_SHORT).show();
                    String name = editName.getText().toString();
                    String pass = editPass.getText().toString();
                    //查询语句
                    String sql = "select * from user where uname=? and upass=?";
                    Cursor query = read.rawQuery(sql,new String[]{name,pass});
                    if(query.moveToNext()==true){
                        Toast.makeText(LoginActivity.this,"登陆成功",Toast.LENGTH_SHORT).show();
                    }else{
                        Toast.makeText(LoginActivity.this,"账号或密码错误，请注册",Toast.LENGTH_SHORT).show();
                    }
    
                }
            });
    
            zhuce.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Toast.makeText(LoginActivity.this,"注册",Toast.LENGTH_SHORT).show();
    
                    AlertDialog.Builder dialog = new AlertDialog.Builder(LoginActivity.this);
                    final View view1 = LayoutInflater.from(LoginActivity.this).inflate(R.layout.zhuce_item,null);
    
                    dialog.setView(view1);
                    dialog.setTitle("注册页面")
                    .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            EditText newname = (EditText) view1.findViewById(R.id.zhucename);
                            EditText newpass = (EditText) view1.findViewById(R.id.zhucepass);
                            String name = newname.getText().toString();
                            String pass = newpass.getText().toString();
                            //添加语句
                            String sql = "insert into user(uname,upass) values(?,?)";
                            write.execSQL(sql,new String[]{name,pass});
                        }
                    })
                    .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
    
                        }
                    })
                    .show();
                }
            });
    
            update.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Toast.makeText(LoginActivity.this,"忘记密码",Toast.LENGTH_SHORT).show();
                    AlertDialog.Builder dialog = new AlertDialog.Builder(LoginActivity.this);
                    //引入Dialog的布局
                    final View view1 = LayoutInflater.from(LoginActivity.this).inflate(R.layout.zhuce_item,null);
                    dialog.setView(view1);
                    dialog.setTitle("修改密码")
                    .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            EditText newname = (EditText) view1.findViewById(R.id.zhucename);
                            EditText newpass = (EditText) view1.findViewById(R.id.zhucepass);
                            String name = newname.getText().toString();
                            String pass = newpass.getText().toString();
                            //修改语句
                            String sql1 = "update user set uname=?,upass=?where uname=?";
                            write.execSQL(sql1,new String[]{name,pass,name});
                        }
                    })
                    .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
    
                        }
                    })
                    .show();
                }
            });
        }
    }

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