Android《第一行代码》——第三章 UI开发_android studio 第一行代码第三章-优快云博客

常用控件

Android提供了大量的UI控件，合理地使用这些控件就可以非常轻松地编写出相当不错的界
面，下面我们就挑选几种常用的控件，详细介绍下它们的使用方法。

TextView

用于在界面上显示一段信息。

	<TextView
        android:id="@+id/text_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:textSize="24sp"
        android:textColor="#00ff00"
        android:text="This is TextView"/>

Button

在界面上显示一个按钮，可以在ManiActivity中为其注册监听器来实现对按钮事件的监听。

	<Button
    android:id="@+id/button"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Button"/>

android:textAllCaps="false"：避免系统自动对所有字母更换大写。

EditText

允许用户在控件里输入和编辑内容，并可以在程序中对这些内容进行处理。

	<EditText
        android:id="@+id/edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Type something here"
        android:maxLines="2" />

ImageView

展示图片

	<ImageView
        android:id="@+id/image_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/img_1"
        />

ProgressBar

在界面上显示一个进度条，默认环形进度条，可以增加属性style="?android:attr/progressBarStyleHorizontal"
将进度条设置为长条形，之后还可以添加android:max="100"属性给进度条设置一个最大值

	 <ProgressBar
        android:id="@+id/progress_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        style="?android:attr/progressBarStyleHorizontal"
        android:max="100" />

AlertDialog

弹出一个对话框，置顶于所有界面元素之上，屏蔽掉其他控件的交互能力，一般用于提示一些非常重要的内容或者警告信息。

	 AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.this);
                        dialog.setTitle("This is Dialog");
                        dialog.setMessage("Something important");
                        dialog.setCancelable(false);
                        dialog.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {

                            }
                        });
                        dialog.setNegativeButton("Canel", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                            }
                        });
                        dialog.show();

在这里插入图片描述

ProgressDialog

弹出一个对话框，显示进度条

	 @Override
            public void onClick(View v) {
                switch (v.getId()){
                    case R.id.button:
                      ProgressDialog progressDialog = new ProgressDialog(MainActivity.this);
                        progressDialog.setTitle("This is ProgressDialog");
                        progressDialog.setMessage("Loading...");
                        progressDialog.setCancelable(true);
                        progressDialog.show();
                        break;
                    default:
                        break;
                }
            }
         }

4种基本布局

线性布局

将它所包含的控件在线性方向上依次排列，通过android:orentation属性指定排列方向是vertical使其排列方向垂直，如果是horizontal则水平排列

	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
  
</LinearLayout>

android:layout_gravity：指定控件在布局中的对齐方式。
android:layout_weight：使用比例控制控件大小。

相对布局

相对父布局定位

android:layout_alignParentTop
android:layout_centerInParent
android:layout_alignParentBottom
android:layout_alignParentLeft
android:layout_alignParentRight

	<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/button_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:text="Button1" />

    <Button
        android:id="@+id/button_2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:text="Button2 "/>

    <Button
        android:id="@+id/button_3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="Button3" />

    <Button
        android:id="@+id/button_4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentBottom="true"
        android:text="Button4" />

    <Button
        android:id="@+id/button_5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentBottom="true"
        android:text="Button5" />


</RelativeLayout>

相对控件布局

android:layout_above
android:layout_below
android:layout_toLeftOf
android:layout_toRightOf

	<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/button_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@id/button_3"
        android:layout_toLeftOf="@id/button_3"
        android:text="Button1" />

    <Button
        android:id="@+id/button_2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@id/button_3"
        android:layout_toRightOf="@id/button_3"
        android:text="Button2 "/>

    <Button
        android:id="@+id/button_3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="Button3" />

    <Button
        android:id="@+id/button_4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/button_3"
        android:layout_toLeftOf="@id/button_3"
        android:text="Button4" />

    <Button
        android:id="@+id/button_5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/button_3"
        android:layout_toRightOf="@id/button_3"
        android:text="Button5" />


</RelativeLayout>

帧布局

所有控件默认放在布局的左上角

	<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    
</FrameLayout>

自定义控件

引入布局

创建布局，在活动布局引入该布局即可

	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/back_bg">


    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/title_back"
        android:layout_gravity="center"
        android:layout_margin="5dp"
        android:background="#EFCECE"
        android:text="Back"
        android:textColor="#BC3131"/>

    <TextView
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:id="@+id/title_text"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:gravity="center"
        android:text="Title Text"
        android:textColor="#fff"
        android:textSize="24sp"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/title_edit"
        android:layout_gravity="center"
        android:layout_margin="5dp"
        android:background="@drawable/back"
        android:text="Edit"
        android:textColor="#fff"/>

</LinearLayout>
//在主活动布局中引入
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <include layout="@layout/title"/>

</LinearLayout>

//隐藏标题栏
	ActionBar actionbar = getSupportActionBar();
        if(actionbar != null){
            actionbar.hide();
        }

自定义控件

避免同一点击事件，在每一个活动中都重新注册一遍。

	public class TitleLayout extends LinearLayout {
    public TitleLayout(Context context, AttributeSet attrs) {
        super(context);
        LayoutInflater.from(context).inflate(R.layout.title,this);
   Button titleBack = (Button) findViewById(R.id.title_back);
        Button titleView = (Button) findViewById(R.id.title_edit);
        titleBack.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                ((Activity)getContext()).finish();
            }
        });
        titleView.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(getContext(),"You clicked Edit button",Toast.LENGTH_SHORT).show();
            }
        });
    }
}

在指明控件时，我们要指明其完整的类名，包名在这是不可以省略的。

	<com.example.uicustomviews.TitleLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

ListView

允许用户通过手指上下滑动的方式将屏幕外的数据滚动到屏幕内。

定制ListView界面

布局中加入ListView
创建ListView子布局
创建内容类
定义ListView适配器类
主活动中初始化内容并且为其设置适配器

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ListView
        android:id="@+id/list_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/fruit_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <TextView
        android:id="@+id/fruit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="10dp"/>

</LinearLayout>

	public class Fruit {
    private String name;
    private int imageId;
    public Fruit(String name,int imageId){
        this.name = name;
        this.imageId = imageId;
    }
    public String getName(){
        return name;
    }
    public int getImageId(){
        return imageId;
    }
}

	public class FruitAdapter extends ArrayAdapter<Fruit> {
	
    private int resourceId
    
      public FruitAdapter( Context context, int textViewResourceId,List<Fruit> objects) {
        super(context, resource, objects);
        resourceId = textViewResourceId;
    }
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        Fruit fruit = getItem(position);  //获取当前项的Fruit实例

        View view = LayoutInflater.from(getContext()).inflate(resourceId,parent,false);
        ImageView fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
        TextView fruitName = (TextView) view.findViewById(R.id.fruit_name);
        fruitImage.setImageResource(fruit.getImageId());
        fruitName.setText(fruit.getName());
        return view;
    }
}

	public class MainActivity extends AppCompatActivity {
    private List<Fruit> fruitList = new ArrayList<Fruit>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //定制ListView
        initFruits();  //初始化水果数据
        FruitAdapter adapter = new FruitAdapter(MainActivity.this,R.layout.fruit_item,fruitList);
        ListView listView = (ListView)findViewById(R.id.list_view);
        listView.setAdapter(adapter);
    }

    private void initFruits() {
        for(int i = 0;i < 2; i++){
            Fruit apple = new Fruit("Apple",R.drawable.apple);
            fruitList.add(apple);
            Fruit orange = new Fruit("Orange",R.drawable.orange);
            fruitList.add(orange);
            Fruit banana = new Fruit("Banana",R.drawable.banana);
            fruitList.add(banana);
            Fruit watermelon = new Fruit("Watermelon",R.drawable.watermelon);
            fruitList.add(watermelon);
            Fruit pear = new Fruit("Pear",R.drawable.pear);
            fruitList.add(pear);
            Fruit grape = new Fruit("Grape",R.drawable.grape);
            fruitList.add(grape);
            Fruit pineapple = new Fruit("Pineapple",R.drawable.pineapple);
            fruitList.add(pineapple);
            Fruit cherry = new Fruit("Cherry",R.drawable.cherry);
            fruitList.add(cherry);
            Fruit peach = new Fruit("Peach",R.drawable.peach);
            fruitList.add(peach);
        }
    }
}

提升ListView的运行效率

两种方法：

缓存布局内容
缓存控件的实例

public class FruitAdapter extends ArrayAdapter<Fruit> {
    private int resourceId;
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Fruit fruit = getItem(position);  //获取当前项的Fruit实例
        View view = LayoutInflater.from(getContext()).inflate(resourceId,parent,false);
        ViewHolder viewHolder;
        //快速滚动
        if(convertView == null){
            view = LayoutInflater.from(getContext()).inflate(resourceId,parent,false);
            viewHolder = new ViewHolder();
            viewHolder.fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
            viewHolder.fruitName = (TextView)view.findViewById(R.id.fruit_name);
            view.setTag(viewHolder);  //将ViewHolder存入View
        }else{
            view = convertView;
            viewHolder = (ViewHolder) view.getTag();  //重新获取ViewHolder
        //提升运行效率
        viewHolder.fruitImage.setImageResource(fruit.getImageId());
        viewHolder.fruitName.setText(fruit.getName());
        return view;
    }
    class ViewHolder{
        ImageView fruitImage;
        TextView fruitName;
    }
}

ListView的点击事件

在活动中为Listview注册监听器即可

	initFruits();  //初始化水果数据
        FruitAdapter adapter = new FruitAdapter(MainActivity.this,R.layout.fruit_item,fruitList);
        ListView listView = (ListView)findViewById(R.id.list_view);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Fruit fruit = fruitList.get(i);
                Toast.makeText(MainActivity.this,fruit.getName(),Toast.LENGTH_SHORT).show();
            }
        });

RecyclerView

RecyclerView的基本用法

新增控件，先添加以依赖，在build.gradle中导入
布局中加入RecyclerView
创建RecyclerView子布局
创建内容类
定义RecyclerView适配器类
主活动中初始化内容并且为其设置适配器

	dependencies {
	implementation 'androidx.recyclerview:recyclerview:1.1.0'
}

	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/fruit_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/fruit_name"
        android:gravity="center"
        android:layout_marginLeft="10dp"
        android:textSize="30sp"
        android:layout_width="wrap_content"
        android:layout_height="match_parent" />

</LinearLayout>

	public class Fruit {
    String name;
    int image;

    public Fruit(String name,int image){
        this.image=image;
        this.name=name;
    }

    public String getName() {
        return name;
    }

    public int getImage() {
        return image;
    }
}

	public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder> {
    private List<Fruit> mFruitList;
    static class ViewHolder extends RecyclerView.ViewHolder{
        ImageView fruitImage;
        TextView fruitName;

        public ViewHolder(View itemView) {
            super(itemView);
            fruitImage = (ImageView) itemView.findViewById(R.id.fruit_image);
            fruitName = (TextView) itemView.findViewById(R.id.fruit_name);
        }
    }

    public FruitAdapter(List<Fruit> fruitList){
        mFruitList = fruitList;
    }
    @Override
    public FruitAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fruit_item,parent,false);
        ViewHolder holder = new ViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(FruitAdapter.ViewHolder holder, int position) {
        Fruit fruit = mFruitList.get(position);
        holder.fruitImage.setImageResource(fruit.getImageId());
        holder.fruitName.setText(fruit.getName());
    }

    @Override
    public int getItemCount() {
        return mFruitList.size();
    }
}

	public class MainActivity extends AppCompatActivity {
    private List<Fruit> fruitList=new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initFruits();
        RecyclerView recyclerView=(RecyclerView) findViewById(R.id.recycler_view);
        LinearLayoutManager manager=new LinearLayoutManager(this);//获取manager实例，并为RecyclerView设置manager
        recyclerView.setLayoutManager(manager);
        FruitAdapter adapter=new FruitAdapter(fruitList);//获取适配器实例，并为RecyclerView设置适配器
        recyclerView.setAdapter(adapter);
    }

    private void initFruits(){//给RecyclerView初始化内容
        for(int i=0;i<50;i++){
            Fruit apple=new Fruit("apple",R.drawable.apple);
            fruitList.add(apple);
        }
    }
}

实现横向滚动和瀑布流布局

横向滚动

首先在子布局文件中修改

	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="100dp"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/fruit_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"/>

    <TextView
        android:id="@+id/fruit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="10dp"/>

</LinearLayout>

在活动主代码中加入

 RecyclerView recyclerView=(RecyclerView) findViewById(R.id.recycler_view);
 LinearLayoutManager manager=new LinearLayoutManager(this);
 manager.setOrientation(RecyclerView.HORIZONTAL);//将manager设置为横向即可
 recyclerView.setLayoutManager(manager);
 FruitAdapter adapter=new FruitAdapter(fruitList);
 recyclerView.setAdapter(adapter);

网格布局

	RecyclerView recyclerView=(RecyclerView) findViewById(R.id.recycler_view);
GridLayoutManager manager=new GridLayoutManager(this,2);//将manager换为这种形式，第二个参数就是列数
recyclerView.setLayoutManager(manager);
FruitAdapter adapter=new FruitAdapter(fruitList);
recyclerView.setAdapter(adapter);

瀑布流布局

       RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);
        recyclerView.setLayoutManager(layoutManager);
        FruitAdapter adapter = new FruitAdapter(fruitList);
        recyclerView.setAdapter(adapter);

RecyclerView的点击事件

不同于ListView，RecyclerView并不能给子布局注册监听器，只能给每个子项注册监听器，所有的点击事件都由具体的View去注册。并且RecyclerView的监听器是在适配器中注册的

public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder> {
    private List<Fruit> mFruitList;
    static class ViewHolder extends RecyclerView.ViewHolder{
        View fruitView;
        ImageView fruitImage;
        TextView fruitName;

        public ViewHolder(View itemView) {
            super(itemView);
            fruitView = itemView;
            fruitImage = (ImageView) itemView.findViewById(R.id.fruit_image);
            fruitName = (TextView) itemView.findViewById(R.id.fruit_name);
        }
    }

    public FruitAdapter(List<Fruit> fruitList){
        mFruitList = fruitList;
    }
    @Override
    public FruitAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fruit_item,parent,false);
        final ViewHolder holder = new ViewHolder(view);
        holder.fruitView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int position = holder.getAdapterPosition();
                Fruit fruit = mFruitList.get(position);
                Toast.makeText(view.getContext(),"you clicked View"+fruit.getName(),Toast.LENGTH_SHORT).show();
            }
        });
        holder.fruitImage.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int position = holder.getAdapterPosition();
                Fruit fruit = mFruitList.get(position);
                Toast.makeText(view.getContext(),"you clicked Image"+fruit.getName(),Toast.LENGTH_SHORT).show();
            }
        });
        return holder;
    }