Android Development Foundation
Development infrastructure including
① Android development environment to build
Android Studio installed
https://developer.android.google.cn/studio/
Download the SDK and Configuration
Both methods,
1 copy all the contents of someone else's SDK folder, placed in the same directory with AndroidStudio method according to Android Studio wizard to download and install
Simulator installation and configuration
1 copy all the contents of someone else's SDK folder, placed in the same directory with AndroidStudio
Method 2 found AVD Manager In Android Studio, the wizard to download and create
Method 3 Use a third-party emulator, choose android 4.4 version, such as a god simulator 3.8 (do not use the latest)
Precautions
After downloading and installing android studio sdk, will download gradle tool when creating a project for compiling building
Directory is: C: \ Users \ your user name .gradle
If you create as well as engineering problems, generally do a little update on it.
② Android HelloWorld
Android HelloWorld
It describes how to create works of creation interface engineering, each part of the project
After you have created the project, the resulting file
The list of documents
③ Android interface development knowledge
Invisible components: the common definition of the layout property
Tangible components: buttons, controls definition file, edit text, picture control and common property settings
指定ID：android:id="@+id/imageView"
指定宽度：android:layout_width="wrap_content" android:layout_width="match_parent"
wrap_content how much control on how much content, match_parent match the parent window
Specify height: android: layout_height = "wrap_content"
图片控件指定图片源：android:src="@mipmap/ic_launcher" 编辑控件指定提示文本：android:hint="请在此输入密码"
按钮控件指定显示文本：android:text="验证"
指定控件居中：android:layout_gravity="center"
按钮响应
方法一：
设置按钮属性
添加完响应函数后。
在函数名上alt+enter实现具体函数内容
public void btnStart1(View view) {
// 启动一个新的activity
// 1. 创建Intent对象
Intent intent = new Intent();
// 2. 设置信息
intent.setClass(this,// 自己
Main2Activity.class); // 新启动的类的类型
//Main2Activity是新创建的活动界面
// 3. 启动activity
startActivity(intent);
//这句包括了三面的3句话的内容
//startActivity(new Intent(this,Main2Activity.class));
}
方法二：
先在manifests的Androidmanifest.xml添加
<activity android:name=".Main2Activity">
<intent-filter>
<action android:name="com.bluelesson.action.hello15pb" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
action android:name="com.bluelesson.action.hello15pb" 动作的名字
category android:name="android.intent.category.DEFAULT" 设置成DEFAULT默认
然后调用动作。
public void btnStart2(View view) {
// 1. 创建Intent对象
Intent intent = new Intent();
// 2. 设置动作
intent.setAction("com.bluelesson.action.hello15pb");
// 3. 启动activity
startActivity(intent);
}
打开服务
关闭服务
先新建一个服务类
用log.d做标签做标注方便观察。
package com.example.mybuttontest;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;
public class MyService extends Service {
public MyService() {
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
@Override
public void onCreate() {
super.onCreate();
Log.d("Andy", "onCreate: ");
}
@Override
public void onStart(Intent intent, int startId) {
super.onStart(intent, startId);
Log.d("Andy", "onStart: ");
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d("Andy", "onStartCommand: ");
return super.onStartCommand(intent, flags, startId);
}
@Override
public void onDestroy() {
super.onDestroy();
Log.d("Andy", "onDestroy: ");
}
}
再调用它
<Button
android:id="@+id/btn3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="btnStart3"
android:text="启动一个服务" />
<Button
android:id="@+id/btn4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="btnStart4"
android:text="关闭服务" />
代码中设置监听器
匿名类直接new接口自动实现接口、内部类实现接口、外部类实现接口
① 匿名类直接new接口自动实现接口
在MainActivity的重写oncreate函数内
// 设置按钮响应事件
// 方法1 ： 匿名类对象
// 1. 获取按钮对象
Button button2 = findViewById(R.id.btn2);
// 2. 设置监听器
button2.setOnClickListener(new View.OnClickListener() {
//View.OnClickListener会报红，ALT+ENTER可以快速创建下面内容
@Override
public void onClick(View v) {
Toast toast = Toast.makeText(
MainActivity.this,// 只要是Context类型的this就行，activity肯定可以，因为其父类的父类。。。是Context
"按钮2",// 显示的内容
Toast.LENGTH_SHORT // 显示的时间 LENGTH_SHORT 2秒
);
toast.show();
}
});
② 内部类实现接口
// 内部类定义
public class MyOnClickListener implements View.OnClickListener {
@Override
public void onClick(View v) {
Toast toast = Toast.makeText(MainActivity.this,"按钮3",Toast.LENGTH_SHORT );
toast.show();
}
}
// 调用
// 获取按钮控件
Button button = findViewById(R.id.button);
// 设置响应监听器
button.setOnClickListener(new MyOnClickListener());
③ 外部类实现接口
public class MainActivity extends AppCompatActivity implements
// 方法3： 外部类对象
// 1. 获取按钮对象
Button button4 = findViewById(R.id.btn4);
// 2. 设置监听器
button4.setOnClickListener(this);}
@Override
public void onClick(View v) {
Toast toast = Toast.makeText( this,"按钮4",Toast.LENGTH_SHORT);
toast.show();}
提示对话框Toast、Dialog的创建与使用
// 弹出信息，自动消失
Toast.makeText(this, // 界面指针
"显示", // 显示的内容
Toast.LENGTH_SHORT // 显示的时间 LENGTH_SHORT=2秒
).show();
// 弹出信息，点击消失
AlertDialog.Builder dlg = new AlertDialog.Builder(this);
dlg.setMessage("内容");
dlg.setTitle("标题");
dlg.show();
④ Android 四大组件
Activity,BroadcastReceiver,Service,ContenProivder
Activity的生命周期
程序运行起来执行：onCreate》onStart》onResume 当activity被覆盖：onPause》onStop
当重新显示时：onRestart》onStart》onResume 当关闭时：onPause》onStop》onDestroy
广播接收者的写法
IP拨号器
创建广播接收者的子类指定拦截广播的权限(manifest.xml里面添加到包的下一句)
<uses‐permission android:name="android.permission.PROCESS_OUTGOING_CALLS" />
指定拦截广播的动作
<receiver
android:name=".MyReceiver"
android:enabled="true"
android:exported="true">
<intent‐filter>
<action
android:name="android.intent.action.NEW_OUTGOING_CALL" />
<category
android:name="android.intent.category.DEFAULT" />
</intent‐filter>
</receiver>
调用
package com.bluelesson.app34_1;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
// 广播接收器，作用是拦截广播，做一些需要做的事情
// 必备条件：
// 通过向导新建一个BroadcastReceiver的子类
// 1. 指定权限
// 2. 指定拦截的是哪个广播
// 3. 完成代码
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.
// IP拨号器 写代码
// 1. 获取打电话的号码
String num = getResultData();
// 2. 修改电话号码
setResultData("123456"+num);
}
}
开启启动
权限
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
指定拦截广播的动作
<receiver
android:name=".MyReceiver2"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</receiver>
调用
public class MyReceiver2 extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
// TODO: This method is called when the BroadcastReceiver is receiving
// an Intent broadcast.
Log.d("15pb-log", "开机启动");
// 启动activity
// 1. 创建Intent
Intent intent1 = new Intent();
// 2. 设置信息
intent1.setClass(context,Main2Activity.class);
intent1.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);// 需要设置标志创建activity栈
// 3. 启动acitivity
context.startActivity(intent1);
}
}
服务的生命周期
启动时：onCreate》onStartCommand》onStart 退出时: onDestroy
程序入口
<!-- application标签中的android:name 可以指定一个类，这个类主要作用时全局初始化 -->
<!-- 这个类在安全领域中 主要是 用于写壳代码 -->
<application
android:name=".MyApp"
MyApp类
package com.bluelesson.app34_2;
import android.app.Application;
import android.content.Context;
import android.util.Log;
public class MyApp extends Application {
// http://androidxref.com/
@Override
protected void attachBaseContext(Context base) {
super.attachBaseContext(base);
Log.d("15pb-log", "MyApp::attachBaseContext");
}
@Override
public void onCreate() {
super.onCreate();
Log.d("15pb-log", "MyApp::onCreate");
}
}
⑤ Android 多线程与消息机制
Thread,Handler
线程中发消息代码：
// 创建消息对象
Message message = new Message();
message.what = 0x111;
message.obj = content;
// 发消息给主线程
handler.sendMessage(message);
外部handler创建
网络编程-访问网站-下载图片
权限
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
消息分发
Handler mHandler = new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
//判断对应的消息ID,获取消息内容，设置信息
if(msg.what == SET_TEXT){
TextView textView = findViewById(R.id.tv1);
textView.setText((String)msg.obj);
} else if(msg.what == GET_PIC){
ImageView imageView = findViewById(R.id.iv1);
imageView.setImageBitmap((Bitmap) msg.obj);
}
}
};
访问网站
public void onClick(View view) {
// 访问网络的一些注意事项
// 1. 访问网络需要权限
// 2. 访问网络需要在工作线程中操作
// 3. 工作线程中不能操作界面，需要发消息给主线程
// 访问百度
Thread thread = new Thread(){
@Override
public void run() {
super.run();
URL url = null;
try {
// 1. 创建url对象
url = new URL("http://www.baidu.com");
// 2. 打开连接
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
// 3. 设置信息
httpURLConnection.setConnectTimeout(2000);
httpURLConnection.setRequestMethod("GET");
// 4. 获取返回信息
// android.os.NetworkOnMainThreadException
int ret = httpURLConnection.getResponseCode();
if(ret == 200){
InputStream inputStream = httpURLConnection.getInputStream();
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
byte bytes[] = new byte[1024];
int nReadlen = -1;
while(true){
nReadlen = inputStream.read(bytes,0,1024);
if(nReadlen == -1) break;
byteArrayOutputStream.write(bytes,0,nReadlen);
}
byte bytes1[] = byteArrayOutputStream.toByteArray();
String s = new String(bytes1);
Message message = new Message();
message.what = SET_TEXT;
message.obj = s;
mHandler.sendMessage(message);
// 工作线程中不能有界面操作的
// TextView textView = MainActivity.this.findViewById(R.id.tv1);
// textView.setText(s);
Log.d("15pb-log", s);
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
};
thread.start();
}
下载图片
public void onClick1(View view) {
Thread thread = new Thread(){
@Override
public void run() {
super.run();
URL url = null;
try {
// 1. 创建url对象
url = new URL("http://ws4.sinaimg.cn/large/00745YaMly1g76yel1cf6j30u01904qy.jpg");
// 2. 打开连接
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
// 3. 设置信息
httpURLConnection.setConnectTimeout(2000);
httpURLConnection.setRequestMethod("GET");
// 4. 获取返回信息
// android.os.NetworkOnMainThreadException
int ret = httpURLConnection.getResponseCode();
if(ret == 200){
InputStream inputStream = httpURLConnection.getInputStream();
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
byte bytes[] = new byte[1024];
int nReadlen = -1;
while(true){
nReadlen = inputStream.read(bytes,0,1024);
if(nReadlen == -1) break;
byteArrayOutputStream.write(bytes,0,nReadlen);
}
byte bytes1[] = byteArrayOutputStream.toByteArray();
// 将数据转为图片
Bitmap bitmap = BitmapFactory.decodeByteArray(bytes1,0,bytes1.length);
Message message = new Message();
message.what = GET_PIC;
message.obj = bitmap;
mHandler.sendMessage(message);
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
};
thread.start();
}
}
网页要滑动屏幕的话，TextView放在activity_main.xml的ScrollView里面就可以
<ScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:text="显示内容"
android:id="@+id/tv1"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</ScrollView>
下载图片。放图片的位置直接用代码就行，注意id最好要重命名。
<ImageView
android:id="@+id/iv1"
android:layout_width="match_parent"
android:layout_height="wrap_content" />