title: 安卓开发
date: 2020-11-13 10:31:26
tags: 安卓开发
- android studio 4.0 Device Monitor 在哪里?
[参考博客][https://blog.csdn.net/qq_42023080/article/details/105842271]："%SDK路径% oolslibmonitor-x86_64monitor.exe"
问题
快捷键
https://docs.oracle.com/javase/tutorial/tutorialLearningPaths.html
https://developer.android.google.cn/studio/intro
沙盒是在受限的安全环境中运行应用程序的一种做法，这种做法是要限制授予应用程序的代码访问权限。
1.1 显示端口被占用
1.1.1 如何查看windows 端口占用情况
window+R组合键
`netstat -ano`，列出所有端口的情况
查看被占用端口对应的PID，输入命令：netstat -aon|findstr "49157"，回车，记下最后一位数字，即PID,这里是2720
继续输入tasklist|findstr "2720"，回车，查看是哪个进程或者程序占用了2720端口
<intent-filter></intent-filter>
一个APP中有多个Acitivity，默认首页是哪个
权限的概念：比如要在APP中显示一张网上的图片需要在AndroidManifest文档中加入<uses-permission android:name="android.permission.INTERNET"></uses-permission>
03、单击事件
输入错误的提示
限制密码个数
-
程序中实现事件监听器，通常有以下四种形式
- Activity本身作为事件监听器：通过Activity实现监听器接口，并实现事件处理方法
- 匿名内部类形式：使用匿名内部类创建事件监听器对象，内部类或外部类形式，将事件监听类定义为当前的内部类或普通外部类
- 绑定标签：在布局文件xml中为指定标签绑定事件处理方法
使用onClick属性 使用OnClickListener实例 1重写onClick()方法选中变量；CTRL ALT + F，从方法中创建全局变量
04、登录页面的单击事件
如果获取前端组件的信息，并在后端做出业务处理，反馈到前端
05、按钮设计+页面跳转 页面跳转Demo_1
[在Android Studio的drawable文件下创建XML文件][https://blog.csdn.net/liqian321/article/details/48519349]
页面跳转Demo_1
[类的访问控制，public,private,protect][https://baijiahao.baidu.com/s?id=1630621164727182416&wfr=spider&for=pc]
06、相对布局
07、相对布局和线性布局结合的实例 Demo_03
08、欢迎界面的实现
3s后自动跳转
09、单向数据传递
// 传递
Intent intent = new Intent();
intent.putExtra("data",str);//设置键值对
startActivity(intent);//激活意图
// 获取
Intent intent = new Intent();//获取意图
String str = Intent.getStringExtra("data");//获取传递的值
10、双向数据传递 Demo_06
如果想在Activity中得到新打开Activity关闭后返回的数据，需要使用系统提供的startActivityForResult(Intent intent,int requestCode)方法`打开新的Activity，新Activity关闭前需要向前面的Activity返回数据需要使用系统提供的setResult(int resultCode,Intent data)方法实现；为了得到返回的数据，必须在前面的Activity中重写onActivityResult(int requestCode,int resultCode,Intent data) 方法
//MainActivity.class
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getApplicationContext(),MainActivity2.class);
intent.putExtra("001",eT1.getText().toString());
startActivityForResult(intent,0x01);
}
});//发送请求
//接收来自MainActivity2.class数据
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
String stringExtra = data.getStringExtra("002");
eT2.setText(stringExtra);
}
jieshou = (EditText) findViewById(R.id.jieshou);
jieshou.setText(getIntent().getStringExtra("001"));
fasong = findViewById(R.id.fasong);
btn2 = (Button) findViewById(R.id.button2);
btn2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getApplicationContext(),MainActivity.class);
intent.putExtra("002",fasong.getText().toString());
setResult(RESULT_OK,intent);
finish();//只有调用finish()第二个页面才会自动关闭回到第一个界面
}
});
11、音乐生日卡Demo_07
需求：点击图片的任意区域都可以开始播放视频
可以给Linerout.setOnclick(new )
12、单选按钮 Deom_08_Activity
-
如何正确加载单选按钮：
-
添加
RadioGroup，在其中添加RadioButton -
btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { for (int i = 0;i< radioGroup.getChildCount();i++){ radioButton = (RadioButton) radioGroup.getChildAt(i); if (radioButton.isChecked()){ Toast.makeText(getApplicationContext(), "您的选择是"+radioButton.getText().toString(), Toast.LENGTH_SHORT).show(); } } } }); -
radioGroup.getChildAt() ；radioGroup.getChildCount()；radioButton.isChecked()
-
13、复选框_Demo_
-
CheckBox与普通按钮的不同在于多了一个可选中的的功能，多了一个Android:checked属性，该属性用于RadioButton、CheckBox初始时是否被选中
-
btn2.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //定义字符串存储喜欢的东西 love = ""; CheckBox[] checks = new CheckBox[] {checkBox1,checkBox2,checkBox3}; for (int i = 0;i<checks.length;i++){ if (checks[i].isChecked()){ love += checks[i].getText().toString()+"、"; } } love = love.substring(0,love.length()-1); Toast.makeText(getApplicationContext(),"您的选择是"+love,Toast.LENGTH_SHORT).show(); } }); }
14、ToggleButton、Switch Demo_08_MainActivity2
ToggleButton（开关按钮）:具有选中和未选择状态双状态的按钮，并且需要为不同的状态设置不同的显示文本
<ToggleButton
android:id="@+id/toggleButton"
android:textOn="关 闭"
android:textOff="开 启"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="ToggleButton" />
<!--ToggleButton的属性，textOn匹配按钮被点击后的状态，-->
toggleButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if(isChecked){
imageView.setImageResource(R.drawable.on);
} else {
imageView.setImageResource(R.drawable.off);
}
}
});
switch和ToggleButton相类似：
switch1 = (Switch) findViewById(R.id.switch1);
switch1.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (isChecked){
imageView.setImageResource(R.drawable.on);
} else{
imageView.setImageResource(R.drawable.off);
}
}
});
15、简单对话框Demo_08_
使用AlertDialog，创建各种功能和风格的对话框。该类对话框可以只是显示对话框消息，也可以为按钮注册监听器实现相应的功能
btn_activity_3 = (Button) findViewById(R.id.buton);
btn_activity_3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity3.this);
builder.setIcon(R.drawable.ic_launcher_background);
builder.setTitle("提示");
builder.setMessage("这里是");
// 确定和取消的按钮
builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Toast.makeText(getApplicationContext(),"Ok",Toast.LENGTH_SHORT).show();
}
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Toast.makeText(getApplicationContext(),"NO",Toast.LENGTH_SHORT).show();
}
});
builder.show();//注意，AlterDialog需要show()
}
});
16、简单列表项对话框
AlterDialog.Builder调用setltems()方法可设置简单列表对话框，需要注意的是调用该方法时需要传入一个数组或数组资源的ID，其中参数which为选择哪一项编号
btn = (Button) findViewById(R.id.button); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity1.this); builder.setIcon(R.drawable.ic_launcher_foreground); builder.setTitle("啥是Title"); builder.setMessage("简单对话列表"); //关键↓：给builder.setItems()中出入String[]和 builder.setItems(item, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { Toast.makeText(getApplicationContext(),"您选择的是："+item[which],Toast.LENGTH_SHORT).show(); } }); builder.show(); } });
18、单选列表对话框Deom_09_Activity2
AlterDialog.Bulider调用setSingleChoiceItems()方法即可创建带单选列表项的对话框
btn_2 = (Button) findViewById(R.id.button_Activity2);btn_2.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity2.this); builder.setTitle("性别"); //设置单选列表，参数1是某人选择item[1] builder.setSingleChoiceItems(item, 1, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { content=item[which]; } }); builder.setPositiveButton("确定", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { Toast.makeText(getApplicationContext(),content,Toast.LENGTH_SHORT).show(); } }); builder.setNegativeButton("取消", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { Toast.makeText(getApplicationContext(),"您已取消："+content,Toast.LENGTH_SHORT).show(); } }); builder.show(); }});
19、多选列表对话框Demo_10
builder.setMultiChoiceItems(字符数组，布尔数组，监听器)
20、适配器的使用Adapter/Demo_11
Adapter接口
在Android中大量的使用到了ListView，而ListView需要与各种适配器结合才能够使用。ArrayAdapter(数组适配器)一般用于显示一行文本信息，所以比较容易。
-
创建ArrayAdapter
listView = (ListView) findViewById(R.id.listView)
public ArrayAdapter(Context context,int textViewResourceld,List<T> objects)ArrayAdapter接口
R.layout.item.xml 文件，设置一个模板的布局据
<?xml version="1.0" encoding="utf-8"?><TextViewxmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="66dp"android:textSize="20dp"android:textColor="#2196F3"android:orientation="vertical"android:gravity="center"></TextView>
-
<?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" tools:context=".MainActivity" android:orientation="vertical"> <ListView android:id="@+id/listview" android:layout_width="match_parent" android:layout_height="match_parent" /></LinearLayout>
public class MainActivity extends AppCompatActivity { String items[] = new String[] {"大数据","云计算","互联网","大数据","云计算","互联网","大数据","云计算","互联网"}; private ListView listview; private ArrayAdapter<String> arrayAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); listview = (ListView) findViewById(R.id.listview); arrayAdapter = new ArrayAdapter<>(getApplicationContext(), R.layout.item, items); //R.layout.item.xml定义“单元格”的样式 listview.setAdapter(arrayAdapter);//数据和样式相联系 listview.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Toast.makeText(getApplicationContext(),""+items[position],Toast.LENGTH_SHORT).show(); } }); }/* public interface OnItemClickListener { /** * Callback method to be invoked when an item in this AdapterView has * been clicked. * <p> * Implementers can call getItemAtPosition(position) if they need * to access the data associated with the selected item. * * @param parent The AdapterView where the click happened. * @param view The view within the AdapterView that was clicked (this * will be a view provided by the adapter) * @param position The position of the view in the adapter. * @param id The row id of the item that was clicked. void onItemClick(AdapterView<?> parent, View view, int position, long id);}*/}
21、 SimpleAdapter-Adapter接口2 Demo_12
适配器：在安卓中，顾名思义就是把数据变成符合界面风格的形式，并且通过List View显示出来。适配器是数据和界面之间的桥梁。
class MainActivity extends AppCompatActivity { String items[] = new String[] {"1","2","3","4","5","6","7","8"}; int images[] =new int[]{R.drawable.ie,R.drawable.map,R.drawable.music,R.drawable.wc,R.drawable.ie,R.drawable.map,R.drawable.music,R.drawable.wc}; String advertise[] = new String[] {"月榜第一","日活第一","涨粉第一","下载第一","年度最佳","拉跨不行","年度最佳","拉跨不行"}; private ArrayList<Map<String, Object>> list; private SimpleAdapter simpleAdapter; private ListView listview; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //1 抽取列表视图 listview = (ListView) findViewById(R.id.listview); //2 实现list中具体的数据 list = new ArrayList<>(); for(int i=0;i<items.length;i++){ Map<String,Object> map = new HashMap<>(); map.put("001",images[i]); map.put("002",items[i]); map.put("003",advertise[i]); list.add(map);//将map键值对装填进入list中 } //3. 设计布局文件 simpleAdapter = new SimpleAdapter(getApplicationContext(), list, R.layout.bg, new String[]{"001", "002","003"}, new int[]{R.id.imageView, R.id.textView1,R.id.textView2}); //4.设置adapter文件 listview.setAdapter(simpleAdapter); listview.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Toast.makeText(getApplicationContext(),items[position],Toast.LENGTH_SHORT).show(); } }); }}
<?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" android:layout_width="match_parent" android:layout_height="90dp" android:orientation="horizontal"> <ImageView android:id="@+id/imageView" android:layout_width="50dp" android:layout_height="50dp" android:layout_marginLeft="20dp" android:layout_marginRight="20dp" android:layout_gravity="center_vertical" /> <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="vertical" android:layout_gravity="center_vertical"> <TextView android:id="@+id/textView1" android:layout_width="100dp" android:layout_height="30dp" android:textColor="#0E0E0E" android:layout_gravity="center_vertical" android:text="Test" android:textSize="20dp" /> <TextView android:id="@+id/textView2" android:layout_width="100dp" android:layout_height="30dp" android:textSize="10dp" android:textColor="#00BCD4" android:layout_gravity="center_vertical"/> </LinearLayout><!-- layout_marginLeft--> <Button android:layout_width="70dp" android:layout_height="wrap_content" android:layout_marginLeft="50dp" android:text="下载" android:layout_gravity="center_vertical"/></LinearLayout>
13、spinner高级组件 Demo_13
三个文件需要改动
res/values/strings.xml
<resources> <string name= "app_name">Demo_13</string> <string-array name="school"> <item>--您选择的学校是--</item> <item>西安电子科技大学</item> <item>成都电子科技大学</item> <item>北京邮电大学</item> </string-array></resources><!--默认会显示第一项item-->
spinner = findViewById(R.id.spinner); //设置spinner的监听器 spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() { //如何获取spinner选中的item，AdapterView.getItemAtPosition(int:position) @Override public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { String school = parent.getItemAtPosition(position).toString(); textView.setText(school); } //↓不需要理会 @Override public void onNothingSelected(AdapterView<?> parent) { } });
23、 gridview网络视图Demo_14
gradView的一些属性
| 属性 | 含义 |
|---|---|
| android:numColumns="auto_fit" | 列数设置为自动 |
| android:columnWidth="90dp" | 每列的宽度，也就是Item的宽度 |
| android:stretchMode="columnWidth" | 缩放与列宽大小同步 |
| android:verticalSpacing="10dp" | 垂直边距 |
| android:horizontalSpacing="10dp" | 水平边距 |
如何使用SimpleAdapterd
- 获取承接数据的gridView或者ListView
- 准备数据，利用ArrayList<Map<String,Object>>,HashMap<>
- SimpleAdapter类的实例化
- 给对应组件装配Adpter
public class MainActivity extends AppCompatActivity { private GridView gridView; String items[] = new String[] {"计算器","拍照","浏览器","地图","音乐","设置","微信"}; int images[] = new int[] {R.drawable.calcuat,R.drawable.camera,R.drawable.ie,R.drawable.map,R.drawable.music,R.drawable.seting,R.drawable.wc}; private ArrayList<Map<String, Object>> data; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);//1.获取承接数据的gridView或者ListView gridView = (GridView) findViewById(R.id.gridView);//2.准备数据，利用ArrayList<Map<String,Object>>,HashMap<> data = new ArrayList<Map<String, Object>>(); for (int i =0;i<items.length;i++){ Map<String,Object> map = new HashMap<>(); map.put("001",items[i]); map.put("002",images[i]); data.add(map); }//3.SimpleAdapter类的实例化 SimpleAdapter simpleAdapter = new SimpleAdapter(getApplicationContext(), data,R.layout.bg,new String[]{"001","002"},new int[]{R.id.textView,R.id.imageView});//4.给对应组件装配Adpter gridView.setAdapter(simpleAdapter); }}
14、WebView实现，enter键事件
WebView是安卓提供显示web界面的工具类，可以像PC端的浏览器那样进行显示。
实现方法：view.loadUrl(url);