Android Studio的下载和安装
下载和安装

Android Support v4\v7\v13和AndroidX的区别及应用场景
区别及应用场景

项目的实践
问候欢迎界面
跳转界面
点击注册按钮跳转到注册界面
Button tvRegister = findViewById(R.id.register_login);
tvRegister.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent =new Intent(LoginActivity.this,RegisterActivity.class);
startActivity(intent);
}
});

Toolbar顶部导航栏的设置
<include layout="@layout/tool_bar" />
1
登录界面的顶部导航栏

private void initToolbar(){
toolbar = findViewById(R.id.title_toolbar);
toolbar.setTitle("登录");
setSupportActionBar(toolbar);

    ActionBar actionBar = getSupportActionBar();
    if (actionBar != null) {
        actionBar.setDisplayHomeAsUpEnabled(true);//设置返回键

// actionBar.setHomeButtonEnabled(true);//设置是否是首页
}
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
LoginActivity.this.finish();
}
});
}

登录注册功能
验证用户名和密码，正确后跳转到我的界面
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
initToolbar();
initView();
initData();
btnLogin.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
String username=etUsername.getText().toString();
String password=etPassword.getText().toString();
SharedPreferences pref = getSharedPreferences("data", MODE_PRIVATE);
String name = pref.getString("username", "");
String pwd = pref.getString("password", "");
if (TextUtils.isEmpty(username)) {
Toast.makeText(LoginActivity.this, "用户名不能为空", Toast.LENGTH_SHORT).show();
} else if (TextUtils.isEmpty(password)) {
Toast.makeText(LoginActivity.this, "密码不能为空", Toast.LENGTH_SHORT).show();
// } else if (!username.equals(name)) {
// Toast.makeText(LoginActivity.this, "用户名错误"+username+","+name , Toast.LENGTH_SHORT).show();
} else if (!MD5Utils.md5(password).equals(pwd)) {
Toast.makeText(LoginActivity.this, "密码错误", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(LoginActivity.this, "登录成功", Toast.LENGTH_SHORT).show();
saveLoginStatus(username,true);

                //返回我的界面
                Intent intent = new Intent();
                intent.putExtra("isLogin" , true);
                intent.putExtra("longinUser",username);
                setResult(RESULT_OK,intent);
                LoginActivity.this.finish();
            }
        }
    });
}

底部导航栏
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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">

<LinearLayout
    android:id="@+id/main_body"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/white"
    android:orientation="vertical">

</LinearLayout>

<RadioGroup
    android:id="@+id/btn_group"
    android:layout_width="match_parent"
    android:layout_height="56dp"
    android:layout_alignParentBottom="true"
    android:background="#F2F2F2"
    android:orientation="horizontal">

    <RadioButton
        android:id="@+id/btn_course"
        style="@style/TabMenuItem"
        android:drawableTop="@drawable/selector_nav_course"
        android:text="课程" />

    <RadioButton
        android:id="@+id/btn_execise"
        style="@style/TabMenuItem"
        android:drawableTop="@drawable/selector_nav_execise"
        android:text="习题" />

    <RadioButton
        android:id="@+id/btn_message"
        style="@style/TabMenuItem"
        android:drawableTop="@drawable/selector_nav_message"
        android:text="资讯" />

    <RadioButton
        android:id="@+id/btn_my"
        style="@style/TabMenuItem"
        android:drawableTop="@drawable/selector_nav_my"
        android:checked="true"
        android:text="我" />
</RadioGroup>

</RelativeLayout>

登出功能
// 退出登录
exitLayout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(SettingActivity.this, "退出登录", Toast.LENGTH_SHORT).show();

           new AlertDialog.Builder(SettingActivity.this)
                   .setTitle("退出")
                   .setMessage("确认退出登录？")
                   .setPositiveButton("确认", new DialogInterface.OnClickListener() {
                       @Override
                       public void onClick(DialogInterface dialog, int which) {
                           SharedUtils.clearLoginInfo(SettingActivity.this);

                           // 返回我的界面
                           Intent intent = new Intent();
                           intent.putExtra("isLogin", false);
                           setResult(RESULT_OK, intent);
                           SettingActivity.this.finish();
                       }
                   })
                   .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                       @Override
                       public void onClick(DialogInterface dialog, int which) {
                           dialog.dismiss();
                       }
                   })
                   .show();

       }
   });