4.4

个人作业主页面
• 所花时间：2
• 代码行数：427
• 博客容量：1
• 代码如下：

package com.example.undertaking;

import androidx.activity.result.ActivityResult;
import androidx.activity.result.ActivityResultCallback;
import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.appcompat.app.AppCompatActivity;

import android.app.Application;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

import com.example.undertaking.userDB.User;
import com.example.undertaking.userDB.UserDAO;
import com.example.undertaking.userDB.UserDbUtil;
import com.example.undertaking.util.ToastUtil;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private EditText stuID;
    private EditText stuPassword;
    private User user;
    private SharedPreferences preferences;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.bt_login).setOnClickListener(this);
        findViewById(R.id.bt_register).setOnClickListener(this);
        preferences = getSharedPreferences("config", MODE_PRIVATE);
        stuID = findViewById(R.id.stu_id);
        stuPassword=findViewById(R.id.stu_pass);
        reload();
    }

    private void reload() {
        String id=preferences.getString("id",null);
        String password=preferences.getString("password",null);
        if(id!=null){
            stuID.setText(id);
        }
        if (password!=null){
            stuPassword.setText(password);
        }
    }


    @Override
    public void onClick(View v) {
        if(v.getId()==R.id.bt_login){
            UserDAO.findUserByIDListener findUserByIDListener=new UserDAO.findUserByIDListener() {
                @Override
                public void onOperationCompleted(User user) {
                    if (user != null) {
                        if (user.password.equals(stuPassword.getText().toString())) {
                            ToastUtil.show(MainActivity.this, "登陆成功");
                            SharedPreferences.Editor edit = preferences.edit();
                            edit.putString("id", stuID.getText().toString());
                            edit.putString("password", stuPassword.getText().toString());
                            edit.commit();
                            Intent intent;
                            if (user.select == 0) {
                                intent = new Intent(MainActivity.this, homePage.class);
                            } else {
                                intent = new Intent(MainActivity.this, teacherHomePage.class);
                            }
                            MyApplication.user=user;
                            startActivity(intent);
                        } else {
                            ToastUtil.show(MainActivity.this, "密码输入错误");
                        }
                    } else {
                        ToastUtil.show(MainActivity.this, "用户名输入错误");
                    }
                }
            };
            UserDAO.findUserById(stuID.getText().toString(),findUserByIDListener);
        }else if(v.getId()==R.id.bt_register){
            Intent intent =new Intent(this,registerWindow.class);
            startActivity(intent);
        }
    }
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:background="@color/mainBackground"
    android:orientation="vertical">


    <TextView
        android:layout_marginTop="100dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="登录"
        android:textColor="@color/white"
        android:textSize="35sp"
        android:layout_gravity="center"
        android:layout_marginBottom="25dp"
        />


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        >

        <TextView
            android:text="请输入学号:"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:textColor="@color/white"
            android:textSize="17sp"
            />
        <EditText
            android:inputType="text"
            android:id="@+id/stu_id"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:background="@drawable/my_edit"
            android:maxLength="30"
            android:textColor="@color/white"
            />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        >

        <TextView
            android:text="请输入密码:"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:textColor="@color/white"
            android:textSize="17sp"
            />
        <EditText
            android:id="@+id/stu_pass"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:inputType="textPassword"
            android:layout_height="wrap_content"
            android:background="@drawable/my_edit"
            android:maxLength="30"
            android:textColor="@color/white"
            />
    </LinearLayout>

    <Button
        android:id="@+id/bt_login"
        android:layout_marginTop="10dp"
        android:layout_gravity="center"
        android:layout_width="120dp"
        android:layout_height="40dp"
        android:background="@drawable/my_button"
        android:text="登录"
        android:textColor="@color/white"
        android:textSize="22sp"
        android:gravity="center"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_marginTop="50dp"
        >
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="@color/white"
            android:text="没有账号？"
            />
        <Button
            android:id="@+id/bt_register"
            android:layout_width="60dp"
            android:layout_height="30dp"
            android:background="@drawable/my_button"
            android:text="注册"
            android:textColor="@color/white"/>

    </LinearLayout>
</LinearLayout>