Android作业10/21

作业:
1.建立学生数据库student. db
2.创建学生表stu(id，姓名，年龄)
3.设计注册界面，界面上2个文本框1个按钮(姓名，年龄，注册按钮)
4.实现注册功能（插入)并在sqlite expert perfesonal中查看表数据。
5.更新数据库版本，新增一张表bj(id，班级名)
6.再次在sqlite expert perfesonal中查看表数据。

版本1

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:background="@mipmap/back"
    >
 
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:layout_marginTop="12dp"
            android:text="姓名"
            android:textColor="#DE9898"
            android:id="@+id/tv1">
        </TextView>
 
        <EditText
            android:id="@+id/et1"
            android:layout_width="200dp"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@id/tv1">
        </EditText>
 
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="12dp"
            android:text="年龄"
            android:textColor="#DE9898"
            android:id="@+id/tv2"
            android:layout_below="@id/tv1">
        </TextView>
 
        <EditText
            android:id="@+id/et2"
            android:layout_width="200dp"
            android:layout_height="wrap_content"
            android:layout_below="@id/tv1"
            android:layout_toRightOf="@id/tv2">
        </EditText>
 
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="12dp"
            android:text="注册"
            android:textColor="#DE9898"
            android:background="#898888"
            android:layout_below="@id/tv2"
            android:layout_marginHorizontal="135dp"
            android:onClick="click1">
        </Button>
 
    </RelativeLayout>
 
</androidx.constraintlayout.widget.ConstraintLayout>

package com.example.myhomework5;
 
import androidx.appcompat.app.AppCompatActivity;
 
import android.content.ContentValues;
import android.content.Intent;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
 
public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        this.setTitle("注册界面");
        StudentDB studentDB = new StudentDB(this);
        studentDB.getWritableDatabase();
    }
 
    public void click1(View view){
        String username = ((EditText)findViewById(R.id.et1)).getText().toString();
        String age = ((EditText)findViewById(R.id.et2)).getText().toString();
        insert(username,age);
        Toast.makeText(MainActivity.this,"注册成功",Toast.LENGTH_LONG).show();
    }
 
    public void insert(String name , String age){
        StudentDB studentDB = new StudentDB(this);
        SQLiteDatabase sqLiteDatabase = studentDB.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put("name",name);
        contentValues.put("age",age);
        sqLiteDatabase.insert("Stu",null,contentValues);
        sqLiteDatabase.close();
    }
}

package com.example.myhomework5;
 
import android.content.Context;
import android.content.Intent;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
 
import androidx.annotation.Nullable;
 
 
public class StudentDB extends SQLiteOpenHelper{
 
    public StudentDB(Context context) {
        super(context, "stu.db", null, 1);
    }
 
    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        String sql = "CREATE TABLE Stu(id INTEGER PRIMARY KEY autoincrement, NAME VARCHAR(20), age VARCHAR(10))";
        sqLiteDatabase.execSQL(sql);
 
    }
 
    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
 
    }
}

 版本2

package com.example.myhomework5;
 
import android.content.Context;
import android.content.Intent;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
 
import androidx.annotation.Nullable;
 
 
public class StudentDB extends SQLiteOpenHelper{
 
    public StudentDB(Context context) {
        super(context, "stu.db", null, 3);
    }
 
    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        String sql = "CREATE TABLE Stu(id INTEGER PRIMARY KEY autoincrement, NAME VARCHAR(20), age VARCHAR(10))";
        sqLiteDatabase.execSQL(sql);
 
    }
     
    // 数据库版本更新被调用,版本只能升不能降
    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
        String sql2 = "CREATE TABLE bj(id INTEGER PRIMARY KEY autoincrement, Class_NAME VARCHAR(20))";
        sqLiteDatabase.execSQL(sql2);
    }
}