Android实验参考目录
常用知识点总结
服务绑定bind Service
MathService.java，提供绑定，解绑定，加法的服务
package com.example.pprp.servicebind;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.widget.Toast;
public class MathService extends Service {
private final IBinder mBinder = new LocalBinder();
public class LocalBinder extends Binder
{
MathService getService(){
return MathService.this;
}
}
public MathService() {
}
@Override
public IBinder onBind(Intent intent) {
Toast.makeText(this,"本地邦定：mathservice",Toast.LENGTH_SHORT).show();
return mBinder;
}
@Override
public boolean onUnbind(Intent intent) {
Toast.makeText(this,"取消绑定：mathservice",Toast.LENGTH_SHORT).show();
return false;
}
public long Add(long a, long b)
{
return a+b;
}
}
MainActivity.java
bindService（）需要参数：ServiceConnection对象，在ServiceConnection对象中可以获得一个mathService对象。依然用Intent来开启service
package com.example.pprp.servicebind;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
private Button btn_bind, btn_unbind,btn_calc;
private TextView tv;
private MathService mathService;
private boolean isBind =false;
private ServiceConnection mCon = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
mathService = ((MathService.LocalBinder)iBinder).getService();
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
mathService = null;
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main1);
tv = (TextView)findViewById(R.id.tv);
btn_bind = (Button)findViewById(R.id.btn_bind);
btn_calc = (Button)findViewById(R.id.btn_calc);
btn_unbind = (Button)findViewById(R.id.btn_unbind);
btn_bind.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(!isBind)
{
final Intent serviceIntent = new Intent(MainActivity.this,MathService.class);
//startService(serviceIntent);
bindService(serviceIntent,mCon, Context.BIND_AUTO_CREATE);
isBind = true;
}
}
});
btn_calc.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(mathService == null)
{
tv.setText("UNBIND!");
return;
}
long a = Math.round(Math.random()*100);
long b = Math.round(Math.random()*100);
long result = mathService.Add(a,b);
String msg = String.valueOf(a)+"+"+String.valueOf(b)+"="+String.valueOf(result);
tv.setText(msg);
}
});
btn_unbind.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(isBind)
{
isBind=false;
unbindService(mCon);
mathService=null;
}
}
});
}
}
注册问题：貌似只要是通过new出来的service就不用人工注册了
ThreadService使用总结
MyThreadService.java文件：
构造一个Runnable对象（用于产生随机数），分别在onCreate()中new一个thread，在onStart()中开启thread，在onDestory()中中断thread。
package com.example.pprp.threadtest;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.widget.Toast;
public class MyThreadService extends Service {
public MyThreadService() {
}
private Thread workThread;
private Runnable backWork = new Runnable() {
@Override
public void run() {
try{
while(!Thread.interrupted())
{
double randomDouble = Math.random();
MainActivity.UpdateGUI(randomDouble);
Thread.sleep(1000);
}
}catch(InterruptedException e)
{
e.printStackTrace();
}
}
};
@Override
public void onCreate() {
super.onCreate();
Toast.makeText(this,"oncreate()",Toast.LENGTH_SHORT).show();
workThread = new Thread(null,backWork,"workThread");
}
@Override
public void onStart(Intent intent, int startId) {
super.onStart(intent, startId);
Toast.makeText(this,"onstart()",Toast.LENGTH_SHORT).show();
if(!workThread.isAlive())
{
workThread.start();
}
}
@Override
public void onDestroy() {
super.onDestroy();
Toast.makeText(this,"ondestroy()",Toast.LENGTH_SHORT).show();
workThread.interrupt();
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
return null;
}
}
MainActivity.java:
创建一个Runnable对象（用来更新线程，必须使用handler），声明静态TextView, new 一个静态Handler, new一个Intent来开启service, 通过button的事件函数触发事件，分别开启服务和关闭服务。
package com.example.pprp.threadtest;
import android.app.Activity;
import android.content.Intent;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity {
static TextView tv;
Button st,ed;
private static double randomDouble;
private static Handler handler = new Handler();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main1);
tv = (TextView)findViewById(R.id.tv);
st = (Button)findViewById(R.id.btn_start);
ed = (Button)findViewById(R.id.btn_stop);
final Intent serviceIntent = new Intent(this,MyThreadService.class);
st.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startService(serviceIntent);
}
});
ed.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
stopService(serviceIntent);
}
});
}
public static void UpdateGUI(double refreshDouble)
{
randomDouble = refreshDouble;
handler.post(refreshRunnable);
}
private static Runnable refreshRunnable = new Runnable() {
@Override
public void run() {
tv.setText("output"+String.valueOf(randomDouble));
}
};
}
Service用法总结
new一个service出来：
package com.example.pprp.servicetest;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.widget.Toast;
public class MyService extends Service {
public MyService() {
}
@Override
public void onCreate() {
super.onCreate();
Toast.makeText(this,"oncreate()!!",Toast.LENGTH_LONG).show();
}
@Override
public void onStart(Intent intent, int startId) {
super.onStart(intent, startId);
Toast.makeText(this,"onstart()!!",Toast.LENGTH_LONG).show();
double randomDouble = Math.random();
String msg = "RANDOM OUOTPUT :" + String.valueOf(randomDouble);
Toast.makeText(this,msg,Toast.LENGTH_LONG).show();
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
return null;
}
@Override
public void onDestroy() {
super.onDestroy();
Toast.makeText(this,"ondestory()!!",Toast.LENGTH_LONG).show();
}
}
注册，修改AndroidManifest.xml文件中的内容
<service
android:name=".MyService"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="com.example.pprp.servicetest"/>
</intent-filter>
</service>
在主Activity中的用法：
package com.example.pprp.servicetest;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainA extends AppCompatActivity {
Button st,ed;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main1);
st = (Button)findViewById(R.id.btn_start);
ed = (Button)findViewById(R.id.btn_stop);
final Intent ServiceIntent = new Intent(this,MyService.class);
st.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startService(ServiceIntent);
}
});
ed.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
stopService(ServiceIntent);
}
});
}
}
Broadcast Receiver用法
broadcast receiver应该通过new的方式新建，比较好，需要添加几行代码
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.pprp.intenttest">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".childA" />
<receiver
android:name=".MyReceiver"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="tttesttt"/>
</intent-filter>
</receiver>
</application>
</manifest>
MyReceiver.java
package com.example.pprp.intenttest;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
public class MyReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
// TODO: This method is called when the BroadcastReceiver is receiving
// an Intent broadcast.
String msg = intent.getStringExtra("key1");
Toast.makeText(context,msg,Toast.LENGTH_SHORT).show();
}
}
onCreate中涉及到的部分：这里tttesttt跟AndroidManifest.xml文件中的一致
String UNIQUE_STRING="tttesttt";
btn_broad.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(UNIQUE_STRING);
intent.putExtra("key1","thisis1test");
sendBroadcast(intent);
}
});
Intent使用注意事项
首先，应该使用new Activity的方法来创建子程序，尽量不要手动创建，如果手动创建还需在AndroidManifest.xml文件中添加相应的部分
然后，调用子activity的时候，如果用startActivityForResult，才会有返回值，才能写onActivityResult函数；如果用startAcitivity则不会运行该函数。
1. Intent使用方法
如果发送Intent是：
Uri data = Uri.parse("message string");
Intent intent = new Intent(null,data);
setResult(intent);
那么解析的时候应该是：(父部分的处理)
Uri uridata = data.getData();
tv.setText(uridata.toString());
如果发送Intent是：
Intent intent = new Intent();
intent.putExtra("Name",et.getText().toString());
那么应该用以下方式进行解析：
Uri uridata = data.getData();
tv.setText(uridata.getStringExtra("Name"));
2. 父activity得到子activity的消息
父Activity在btn事件函数中调用子Activity:
Intent intent = new Intent(MainActivity.this,Subsub.class);
startActivityForResult(intent,SUB);
子Activity在btn事件函数中进行Intent发送:
Uri data = Uri.parse(et.getText().toString());
Intent result = new Intent(null,data);
setResult(RESULT_OK,result);
finish();
父Activity中的onActivityResult函数中的内容，用于处理子Activity发送内容
if(requestCode == SUB)
{
if(resultCode == RESULT_OK)
{
Uri uriData = data.getData();
System.out.println("result: " + uriData.toString());
tvs.setText(uriData.toString());
}
}
3. 子activity得到父activity的内容
父activity:
Intent intent = new Intent(MainActivity.this,ChildActivity.class);
intent.putExtra("Name",et.getText().toString());
startActivityForResult(intent,SUBACTIVITY);
子Activity进行接收：
Intent data = getIntent();
tv.setText(data.getStringExtra("Name"));
ListView用法总结
提前需要做的工作：在res目录下new一个menu文件，添加一个Item
主要的用法：
//声明ArrayList, ArrayAdapter
ListView lv;
ArrayList<String> list;
ArrayAdapter<String> adp;
//在onCreate函数中进行如下操作：
lv = (ListView)findViewById(R.id.lv);
list = new ArrayList<String>();
adp = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,list);
lv.setAdapter(adp);
//btn事件函数操作：
String ans = "";
ans += et_cls.getText().toString();
ans += et_stuno.getText().toString();
ans += et_name.getText().toString();
ArrayAdapter temp_adp = (ArrayAdapter) lv.getAdapter();
temp_adp.add(ans);
//listView的事件函数：
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, final int pos, long l) {
if(l > 0)
{
System.out.println("test");
PopupMenu popup = new PopupMenu(MainActivity.this,view);
popup.getMenuInflater().inflate(R.menu.del,popup.getMenu());
popup.show();
popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
@Override
public boolean onMenuItemClick(MenuItem item) {
switch(item.getItemId())
{
case R.id.del:
ArrayAdapter temp = (ArrayAdapter)lv.getAdapter();
temp.remove(temp.getItem(pos));
return true;
default:
return false;
}
}
});
}
}
});
完整代码：
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String msg = et.getText().toString();
ArrayAdapter tp = (ArrayAdapter)lv.getAdapter();
tp.add(msg);
}
});
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, final int pos, long l) {
if(l > 0)
{
PopupMenu popup = new PopupMenu(MainActivity.this,view);
popup.getMenuInflater().inflate(R.menu.menu1,popup.getMenu());
popup.show();
popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
@Override
public boolean onMenuItemClick(MenuItem item) {
if(item.getItemId() == R.id.ddelete)
{ Toast.makeText(MainActivity.this,"ddlete",Toast.LENGTH_SHORT).show();
ArrayAdapter<String> tmp = (ArrayAdapter)lv.getAdapter();
tmp.remove(tmp.getItem(pos));
}
else if(item.getItemId() == R.id.oopen)
{
Toast.makeText(MainActivity.this,"oopen",Toast.LENGTH_SHORT).show();
}
else if(item.getItemId() == R.id.nnew)
{
Toast.makeText(MainActivity.this,"nnew",Toast.LENGTH_SHORT).show();
}
return false;
}
});
}
}
});
spinner 用法
spn = (Spinner)findViewById(R.id.spinner);
List<String> list = new ArrayList<String>();
list.add(0,"test1");
list.add(1,"test2");
list.add(2,"test3");
ArrayAdapter<String> adp = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,list);
adp.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spn.setAdapter(adp);
spn.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
if(l > 0)
{ tv.setText(adapterView.getItemAtPosition(i).toString());
}
}
@Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
});
ArrayAdapter的用法总结
lv = (ListView)findViewById(R.id.lv);
list = new ArrayList<String>();
adp = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,list);
ArrayAdapter tp = (ArrayAdapter)lv.getAdapter();
tp.add("your String");
tp.remove(tp.getItem(pos));
遇到的问题
Installation failed with message Invalid File
这个问题详细报错如下：
Installation failed with message Invalid File:
C:AndroidworkspaceCalculatorappuildintermediatessplit-apkdebugslicesslice_9.apk.
It is possible that this issue is resolved by uninstalling an existing version of the apk if it is present, and then re-installing.
通过谷歌搜索到stackoverflow上的内容：
其中最好的解决方案如下：
Click Build tab ---> Clean Project
Click Build tab ---> Build APK
Run.
亲测有效
版本不匹配导致的gradle编译出错
这时候应该打开GradleScripts目录下的 build.gradle(Module:app)，
然后进行修改：
android {
compileSdkVersion 26
buildToolsVersion "27.0.3"
defaultConfig {
applicationId "com.example.administrator.calculator"
minSdkVersion 25
targetSdkVersion 26
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
修改：minSdkVersion 和 compileSdkVersion 等，到你想要的版本
Error:Failed to find target with hash string 'android-26' in: D:programFile
国内无法访问google的关于android的库，可以选择国内的镜像网站（百度经验中就有），也可以使用VPN(百度搜索android studio VPN)就可以了，
除此以外有时候真的还是要靠运气
需要注意：
版本高的API兼容版本低的API,反之不可行。
- 模拟器已经打开但是运行时找不到对应的模拟器
找到模拟器的adb文件，如果用的是Android原装adb：
cd C:Androidsdkplatform-tools
adb connect 127.0.0.1:62001
即可。
如果使用的是夜神模拟器：
cd ../..
cd "Program Files (x86)"/Nox/bin
nox_adb connect 127.0.0.1:62001
即可。
sqlite3 进入运行时遇见报错：
error: no devices/emulators found
解决方案：首先需要明确，必须要先打开模拟器，然后使用哪个模拟器，就要找对应模拟器的adb可执行文件：
如果用的是Android的原装sdk中的模拟器：
cd C:Androidsdkplatform-tools
adb shell
如果用的是夜神模拟器：
cd "Program Files (x86)"/Nox/bin
nox_adb shell
即可。
sqlite3中进入shell以后，如果遇到以下报错：
mkdir failed for , Read-only file system
可以用以下命令进行解决：
adb shell
mount -o remount rw /
Android Studio快捷键
| 快捷键 | 说明 |
|---|---|
| Ctrl+D | 复制一行 |
| Ctrl+Y | 删除当前行 |
| Ctrl+G | 快捷定位某行 |
| Ctrl+/ | 注释一行 |
| Ctrl+E | 查看最近打开的文件 |
| Ctrl+N | 查找类名，文件名 |
| Ctrl+O | 显示父类中可覆写方法(常用) |
| Ctrl+F | 类内搜索 |
| Ctrl+R | 查找替换 |
| Ctrl+J | 自动代码（自动提示） |
| Ctrl+H | 显示类的继承结构 |
| Ctrl+W | 选中代码，类似双击效果 |
| Ctrl+shift+"+/-" | 折叠，展开代码块 |
| Alt+Q | 上下文信息 |
| Ctrl+Alt+Shift+f8 | 临时断电 |
| Ctrl+Shift+J | 合并行和文本，例如多行注释，if(){} |
| Alt+Shift+Up/Down | 移动上下行 |
| shift+f6 | 全局重命名（或者quick fix） |