帮我用android studio写一个简单计算器，并用SQLite实现历史查询，使用java语言

好的，下面是实现步骤：

1. 新建一个Android Studio项目，命名为Calculator，选择Empty Activity作为模板

2. 在res/layout文件夹下，新建一个xml布局文件，命名为activity_main.xml，用于显示计算器界面，代码如下：

<?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/editText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="number"
        android:layout_marginBottom="16dp"
        android:hint="0"
        android:textSize="30sp"
        android:padding="16dp"/>

    <GridLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:columnCount="4"
        android:rowCount="5"
        android:padding="16dp">

        <Button
            android:id="@+id/button7"
            android:text="7"
            android:layout_column="0"
            android:layout_row="1"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/button8"
            android:text="8"
            android:layout_column="1"
            android:layout_row="1"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/button9"
            android:text="9"
            android:layout_column="2"
            android:layout_row="1"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/buttonDivide"
            android:text="/"
            android:layout_column="3"
            android:layout_row="1"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/button4"
            android:text="4"
            android:layout_column="0"
            android:layout_row="2"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/button5"
            android:text="5"
            android:layout_column="1"
            android:layout_row="2"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/button6"
            android:text="6"
            android:layout_column="2"
            android:layout_row="2"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/buttonMultiply"
            android:text="*"
            android:layout_column="3"
            android:layout_row="2"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/button1"
            android:text="1"
            android:layout_column="0"
            android:layout_row="3"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/button2"
            android:text="2"
            android:layout_column="1"
            android:layout_row="3"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/button3"
            android:text="3"
            android:layout_column="2"
            android:layout_row="3"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/buttonMinus"
            android:text="-"
            android:layout_column="3"
            android:layout_row="3"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/button0"
            android:text="0"
            android:layout_column="0"
            android:layout_row="4"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/buttonDot"
            android:text="."
            android:layout_column="1"
            android:layout_row="4"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/buttonEquals"
            android:text="="
            android:layout_column="2"
            android:layout_row="4"
            android:layout_gravity="fill"/>

        <Button
            android:id="@+id/buttonPlus"
            android:text="+"
            android:layout_column="3"
            android:layout_row="4"
            android:layout_gravity="fill"/>

    </GridLayout>

</LinearLayout>

3. 在MainActivity.java中实现计算器逻辑和历史记录功能，代码如下：

package com.example.calculator;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private EditText editText;
    private Button button0, button1, button2, button3, button4, button5, button6, button7, button8, button9;
    private Button buttonDot, buttonPlus, buttonMinus, buttonMultiply, buttonDivide, buttonEquals;
    private DBHelper dbHelper;

    private double num1 = 0, num2 = 0;
    private String operator = "";
    private boolean isOperatorClicked = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        editText = findViewById(R.id.editText);
        button0 = findViewById(R.id.button0);
        button1 = findViewById(R.id.button1);
        button2 = findViewById(R.id.button2);
        button3 = findViewById(R.id.button3);
        button4 = findViewById(R.id.button4);
        button5 = findViewById(R.id.button5);
        button6 = findViewById(R.id.button6);
        button7 = findViewById(R.id.button7);
        button8 = findViewById(R.id.button8);
        button9 = findViewById(R.id.button9);
        buttonDot = findViewById(R.id.buttonDot);
        buttonPlus = findViewById(R.id.buttonPlus);
        buttonMinus = findViewById(R.id.buttonMinus);
        buttonMultiply = findViewById(R.id.buttonMultiply);
        buttonDivide = findViewById(R.id.buttonDivide);
        buttonEquals = findViewById(R.id.buttonEquals);

        dbHelper = new DBHelper(this, "Calculator.db", null, 1);

        button0.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editText.setText(editText.getText() + "0");
            }
        });

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editText.setText(editText.getText() + "1");
            }
        });

        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editText.setText(editText.getText() + "2");
            }
        });

        button3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editText.setText(editText.getText() + "3");
            }
        });

        button4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editText.setText(editText.getText() + "4");
            }
        });

        button5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editText.setText(editText.getText() + "5");
            }
        });

        button6.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editText.setText(editText.getText() + "6");
            }
        });

        button7.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editText.setText(editText.getText() + "7");
            }
        });

        button8.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editText.setText(editText.getText() + "8");
            }
        });

        button9.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editText.setText(editText.getText() + "9");
            }
        });

        buttonDot.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!editText.getText().toString().contains(".")) {
                    editText.setText(editText.getText() + ".");
                }
            }
        });

        buttonPlus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!editText.getText().toString().isEmpty()) {
                    if (!isOperatorClicked) {
                        num1 = Double.parseDouble(editText.getText().toString());
                        operator = "+";
                        editText.setText("");
                        isOperatorClicked = true;
                    } else {
                        Toast.makeText(MainActivity.this, "请先完成上一个运算", Toast.LENGTH_SHORT).show();
                    }
                }
            }
        });

        buttonMinus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!editText.getText().toString().isEmpty()) {
                    if (!isOperatorClicked) {
                        num1 = Double.parseDouble(editText.getText().toString());
                        operator = "-";
                        editText.setText("");
                        isOperatorClicked = true;
                    } else {
                        Toast.makeText(MainActivity.this, "请先完成上一个运算", Toast.LENGTH_SHORT).show();
                    }
                }
            }
        });

        buttonMultiply.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!editText.getText().toString().isEmpty()) {
                    if (!isOperatorClicked) {
                        num1 = Double.parseDouble(editText.getText().toString());
                        operator = "*";
                        editText.setText("");
                        isOperatorClicked = true;
                    } else {
                        Toast.makeText(MainActivity.this, "请先完成上一个运算", Toast.LENGTH_SHORT).show();
                    }
                }
            }
        });

        buttonDivide.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!editText.getText().toString().isEmpty()) {
                    if (!isOperatorClicked) {
                        num1 = Double.parseDouble(editText.getText().toString());
                        operator = "/";
                        editText.setText("");
                        isOperatorClicked = true;
                    } else {
                        Toast.makeText(MainActivity.this, "请先完成上一个运算", Toast.LENGTH_SHORT).show();
                    }
                }
            }
        });

        buttonEquals.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!editText.getText().toString().isEmpty()) {
                    if (isOperatorClicked) {
                        num2 = Double.parseDouble(editText.getText().toString());
                        double result = 0;
                        switch (operator) {
                            case "+":
                                result = num1 + num2;
                                break;
                            case "-":
                                result = num1 - num2;
                                break;
                            case "*":
                                result = num1 * num2;
                                break;
                            case "/":
                                if (num2 == 0) {
                                    Toast.makeText(MainActivity.this, "除数不能为0", Toast.LENGTH_SHORT).show();
                                    return;
                                }
                                result = num1 / num2;
                                break;
                        }
                        editText.setText(String.valueOf(result));
                        isOperatorClicked = false;

                        // 将计算结果保存到历史记录中
                        SQLiteDatabase db = dbHelper.getWritableDatabase();
                        ContentValues values = new ContentValues();
                        values.put("expression", num1 + operator + num2 + "=" + result);
                        db.insert("History", null, values);
                        values.clear();
                    }
                }
            }
        });

    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        dbHelper.close();
    }

    // 查询历史记录
    public void queryHistory(View view) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        Cursor cursor = db.query("History", null, null, null, null, null, null);
        if (cursor.moveToFirst()) {
            do {
                String expression = cursor.getString(cursor.getColumnIndex("expression"));
                Toast.makeText(MainActivity.this, expression, Toast.LENGTH_SHORT).show();
            } while (cursor.moveToNext());
        }
        cursor.close();
    }

}

4. 新建一个Java类，命名为DBHelper，用于创建和管理SQLite数据库，代码如下：

package com.example.calculator;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHelper extends SQLiteOpenHelper {

    public static final String CREATE_HISTORY = "create table History ("
            + "id integer primary key autoincrement, "
            + "expression text)";

    public DBHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_HISTORY);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

}

5. 在AndroidManifest.xml中添加读写数据库的权限：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

6. 运行程序，即可使用计算器，并且可以在点击“历史记录”按钮后查看历史计算结果。