我在Activity上有一个简单的登录名，其中包含两个文本和一个按钮，一个用于电子邮件，另一个用于密码。
按下登录按钮后，将启动一个名为 profile 的新Activity。我对大量信息进行了硬编码以使其与输入匹配，以便该意图启动第二个Activity。效果很好。
但是，当我按下电话上的“后退”按钮时，它将返回到登录Activity。但是当我再次按下登录按钮时，即使更改输入，它也会显示相同的结果：
如果我输入ArrayList中已经存在的电子邮件和密码，它将启动第二个Activity。现在，如果通过按电话上的“后退”按钮返回登录名Activity，则电子邮件和密码文本框仍保留这些值。现在，如果我删除密码并按登录，它会显示相同的结果，与我登录的配置文件相同，但是由于密码不正确，它必须阻止我登录
注意：硬编码的信息与一个自定义类一起存储在Arraylist中，该自定义类只包含5个基本信息字符串。而且，该类实现了Serializable，因此可以通过Intent传递此自定义类的对象。
登录Activity：
package just.innovates.isra;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.hanks.htextview.base.HTextView;
import java.util.ArrayList;
public class LoginActivity extends AppCompatActivity {
public static final String EXTRA_LOGIN = "just.innovates.isra.EXTRA_LOGIN";
private ArrayList<Profile> arrayList = new ArrayList<>();
private Profile profile;
private EditText editTextEmail;
private EditText editTextPassword;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
findViewById(R.id.tv_login_register).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startActivity(new Intent(LoginActivity.this, RegisterActivity.class));
}
});
editTextEmail = findViewById(R.id.et_login_email);
editTextPassword = findViewById(R.id.et_login_password);
arrayList.add(new Profile("Alaa", "Zarnaji", "aLaaZ@gmail.com", "alaa", "01145874123", R.drawable.alaa));
arrayList.add(new Profile("Ola", "Ahmed", "olaA@gmail.com", "ola", "0123654585", R.drawable.ola));
arrayList.add(new Profile("Muhammad", "Magdy", "magdyM@gmail.com", "magdy", "01014525874", R.drawable.magdy));
arrayList.add(new Profile("Isra", "Ahmed", "israA@gmail.com", "isra", "01145214587", R.drawable.isra));
findViewById(R.id.btn_login_sign_in).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getProfile();
if (profile != null) {
Intent intent = new Intent(LoginActivity.this, ProfileActivity.class);
intent.putExtra(EXTRA_LOGIN, profile);
startActivity(intent);
} else {
Toast.makeText(LoginActivity.this, "Wrong Email or password", Toast.LENGTH_SHORT).show();
}
}
});
}
private void getProfile() {
String email = editTextEmail.getText().toString();
String password = editTextPassword.getText().toString();
if (!email.trim().isEmpty() || !password.trim().isEmpty()) {
if (email.equals("alaaZ@gmail.com") && password.equals("alaa")) {
profile = arrayList.get(0);
} else if (email.equals("olaA@gmail.com") && password.equals("ola")) {
profile = arrayList.get(1);
} else if (email.equals("magdyMX@gmail.com") && password.equals("magdy")) {
profile = arrayList.get(2);
} else if (email.equals("israAh@gmail.com") && password.equals("isra")) {
profile = arrayList.get(3);
}
}
}
}
个人资料Activity：
package just.innovates.isra;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
public class ProfileActivity extends AppCompatActivity {
private TextView textViewNameFirst;
private TextView textViewNameLast;
private TextView textViewEmail;
private TextView textViewPassword;
private TextView textViewPhone;
private ImageView imageView;
private Profile profile;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_profile);
Intent intent = getIntent();
if (intent.hasExtra(RegisterActivity.EXTRA_PROFILE)) {
profile = (Profile) intent.getSerializableExtra(RegisterActivity.EXTRA_PROFILE);
}else if (intent.hasExtra(LoginActivity.EXTRA_LOGIN)){
profile = (Profile) intent.getSerializableExtra(LoginActivity.EXTRA_LOGIN);
}
setUI();
assert profile != null;
if (profile.isImage()) {
imageView.setImageResource(profile.getImageURL());
} else {
imageView.setVisibility(View.GONE);
}
textViewNameFirst.setText(profile.getFirstName());
textViewNameLast.setText(profile.getSecondName());
textViewEmail.setText(profile.getEmail());
textViewPassword.setText(profile.getPassword());
textViewPhone.setText(profile.getPhone());
}
private void setUI() {
textViewNameFirst = findViewById(R.id.nameFirst);
textViewNameLast = findViewById(R.id.nameLast);
textViewEmail = findViewById(R.id.email);
textViewPassword = findViewById(R.id.password);
textViewPhone = findViewById(R.id.phone);
imageView = findViewById(R.id.image);
}
}
答案 0 :(得分：1)
当您输入ArrayList中包含的电子邮件和密码，并通过登录登录启动SecondActivity时，let onLoadPassed = false;
let videoLoaded = false;
let clipSource = 'https://mysite/myVideo.mp4';
preload();
// Make sure the video clip is fully loaded
function preload(){
(function (global, factory) {
typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
typeof define === 'function' && define.amd ? define(factory) :
(global.Preload = factory());
}(this, (function () { 'use strict';
function preloadOne(url, done) {
const xhr = new XMLHttpRequest();
xhr.open('GET', url, true);
xhr.responseType = 'blob';
xhr.onprogress = event => {
if (!event.lengthComputable) return false
let item = this.getItemByUrl(event.target.responseURL);
item.completion = parseInt((event.loaded / event.total) * 100);
item.downloaded = event.loaded;
item.total = event.total;
this.updateProgressBar(item);
};
xhr.onload = event => {
let type = event.target.response.type;
let blob = new Blob([event.target.response], { type: type });
let url = URL.createObjectURL(blob);
let responseURL = event.target.responseURL;
let item = this.getItemByUrl(responseURL);
item.blobUrl = url;
item.fileName = responseURL.substring(responseURL.lastIndexOf('/') + 1);
item.type = type;
item.size = blob.size;
done(item);
};
xhr.onerror = event => {
console.log('Error has happend so we restart the video preloading..');
preload();
};
xhr.onloadend = function() {
if(xhr.status == 404){
console.log('404 not found');
onLoadPassed = false;
} else {
console.log('File exist');
onLoadPassed = true;
}
}
xhr.send();
}
function updateProgressBar(item) {
var sumCompletion = 0;
var maxCompletion = this.status.length * 100;
for (var itemStatus of this.status) {
if (itemStatus.completion) {
sumCompletion += itemStatus.completion;
}
}
var totalCompletion = parseInt((sumCompletion / maxCompletion) * 100);
if (!isNaN(totalCompletion)) {
this.onprogress({
progress: totalCompletion,
item: item
});
}
}
function getItemByUrl(rawUrl) {
for (var item of this.status) {
if (item.url == rawUrl) return item
}
}
function fetch(list) {
return new Promise((resolve, reject) => {
this.loaded = list.length;
for (let item of list) {
this.status.push({ url: item });
this.preloadOne(item, item => {
this.onfetched(item);
this.loaded--;
if (this.loaded == 0) {
this.oncomplete(this.status);
resolve(this.status);
}
});
}
})
}
function Preload() {
return {
status: [],
loaded: false,
onprogress: () => {},
oncomplete: () => {},
onfetched: () => {},
fetch,
updateProgressBar,
preloadOne,
getItemByUrl
}
}
return Preload;
})));
const preload = Preload();
preload.fetch([
clipSource
]).then(items => {
// Fired when we are sure that video clip has finished loading completely
let check = setInterval(passedFunc, 50);
function passedFunc() {
if(onLoadPassed === true){
videoLoaded = true;
clearInterval(check);
console.log('videoLoaded: ' + videoLoaded);
};
}
});
};对象将存储这些值。然后您按回去，删除密码，然后再次按登录，您所做的所有检查就是确定profile对象的值...实际上不干扰登录过程。因此，当您返回并更改值时，您的配置文件仍保留先前使用的数组中的旧值。当没有任何条件匹配时，您应该添加另一个else语句，并将您的个人资料设置为空，以便侦听器中的检查显示吐司。
因此，在所有其他if语句之后，在您的profile方法中添加此最终else语句
getProfile()或者当两次都为空或字段不匹配时，也不必编写两次else条件，而只需在每次调用else {
profile = null;
}
时将其设置为null。
方法应该像这样
getProfile()