ButterKnife 8

成员变量和方法的依赖注入框架

资料

Github

官网

ButterKnife-Zelezny Github
ButterKnife 插件

导入

项目中使用

• 配置模组的 build.gradle

dependencies {
    compile 'com.jakewharton:butterknife:8.4.0'
    annotationProcessor 'com.jakewharton:butterknife-compiler:8.4.0'
}

库中使用

• 配置项目的 build.gradle

buildscript {
    repositories {
      mavenCentral()
     }
    dependencies {
      classpath 'com.jakewharton:butterknife-gradle-plugin:8.4.0'
    }
}

• 配置模组的 build.gradle

apply plugin: 'com.android.library'
apply plugin: 'com.jakewharton.butterknife'

• 在注解中使用R2代替R

基本用法

初始化

• Activity 中初始化

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.simple_activity);
    ButterKnife.bind(this);
    // ...
}

• Fragment 中初始化

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment, container, false);
    ButterKnife.bind(this, view);
    // ...
    return view;
}

• ViewHolder 中初始化

static class ViewHolder {
    public ViewHolder(View view) {
        ButterKnife.bind(this, view);
    }
}

• 注意
  • <merge>标签布局，可在构造器重填充后初始化
  • 在xml中填充自定义View，须在onFinishInflate()中初始化

View绑定

@BindView、@BindViews

不能绑定 private、static

@BindView(R.id.name)
EditText nameView; // 替代 findViewById

@BindViews({ R.id.first_name, R.id.middle_name, R.id.last_name })
List<EditText> nameViews;

资源绑定

@BindString、@BindBool、@BindInt、@BindFloat、@BindArray、@BindDimen、@BindColor、@BindBitmap、@BindDrawable

@BindString(R.string.username_error)
String usernameErrorText;

@BindBool(R.bool.is_tablet)
boolean isTablet;

@BindInt(R.int.columns)
int columns;

// 可绑定 float 类型的 dimen 资源
@BindFloat(R.dimen.image_ratio)
float imageRatio;

// 可绑定String、int、Text 数组和 android.content.res.TypedArray
@BindArray(R.array.countries)
String[] countries;

@BindArray(R.array.phones)
int[] phones;

@BindArray(R.array.options)
CharSequence[] options;

@BindArray(R.array.icons)
TypedArray icons;

// 可绑定 int (像素尺寸), float (具体大小值)
@BindDimen(R.dimen.horizontal_gap)
int gapPx;

@BindDimen(R.dimen.horizontal_gap)
float gap;

// 可绑定 int, ColorStateList
@BindColor(R.color.background_green)
int green;

@BindColor(R.color.background_green_selector)
ColorStateList greenSelector;

@BindBitmap(R.drawable.logo)
Bitmap logo;

@BindDrawable(R.drawable.placeholder)
Drawable placeholder;

@BindDrawable(value = R.drawable.placeholder, tint = R.attr.colorAccent)
Drawable tintedPlaceholder;

监听绑定

@OnClick、@OnLongClick、@OnTouch、@OnCheckedChanged、@OnEditorAction、@OnFocusChange、@OnTextChanged、@OnItemClick、@OnItemLongClickListener、@OnItemSelected、@OnPageChange

• 参数数量不固定，可为参数的子类
• 多回掉方法的监听，使用 value 和 callback

// View.OnClickListener
@OnClick(R.id.submit)
public void submit(View view) {
}

@OnClick(R.id.submit)
public void submit() {  // 无参
}

@OnClick(R.id.submit)
public void sayHi(Button button) {  // 任意参数，默认强转，可为绑定View的子类
  button.setText("Hello!");
}

@OnClick({ R.id.door1, R.id.door2, R.id.door3 })  // 多 IDs 绑定
public void pickDoor(DoorView door) {
    if (door.hasPrizeBehind()) {
      Toast.makeText(this, "You win!", LENGTH_SHORT).show();
    } else {
      Toast.makeText(this, "Try again", LENGTH_SHORT).show();
    }
}

// 自定义 View，绑定自己的监听，不指定 ID
public class FancyButton extends Button {
    @OnClick
    public void onClick() {
    }
}

// TextWatcher
@OnTextChanged(R.id.example)
void onTextChanged(CharSequence s, int start, int before, int count) {
}

@OnTextChanged(value = R.id.example, callback = BEFORE_TEXT_CHANGED)
void onBeforeTextChanged(CharSequence s, int start, int count, int after) {
}

@OnTextChanged(value = R.id.example, callback = AFTER_TEXT_CHANGED)
void onAfterTextChanged(Editable s) {
}

// View.OnLongClickListener
@OnLongClick(R.id.example)
boolean onLongClick(View v) {
    return true;
}

// View.OnTouchListener
@OnTouch(R.id.example)
boolean onTouch(View v, MotionEvent event) {
    return false;
}

// CompoundButton.OnCheckedChangeListener
@OnCheckedChanged(R.id.example)
void onChecked(CompoundButton buttonView, boolean isChecked) {
}

// TextView.OnEditorActionListener
@OnEditorAction(R.id.example)
boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
    return true;
}

// View.OnFocusChangeListener
@OnFocusChange(R.id.example)
void onFocusChanged(View v, boolean hasFocus) {
}

// AdapterView.OnItemClickListener
@OnItemClick(R.id.example_list)
void onItemClick(AdapterView<?> parent, View view, int position, long id) {
}

// AdapterView.OnItemLongClickListener
@OnItemLongClick(R.id.example_list)
boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
    return true;
}

// AdapterView.OnItemSelectedListener
@OnItemSelected(R.id.example_list)
void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
}

@OnItemSelected(value = R.id.example_list, callback = NOTHING_SELECTED)
void onNothingSelected() {
}

// ViewPager.OnPageChangeListener
@OnPageChange(R.id.example_pager)
void onPageSelected(int position) {
}

@OnPageChange(value = R.id.example_pager, callback = PAGE_SCROLL_STATE_CHANGED)
void onPageStateChanged(int state) {
}

@OnPageChange(value = R.id.example_pager, callback = PAGE_SCROLLED)
void onPageStateChanged(int position, float positionOffset, int positionOffsetPixels) {
}

选择绑定

默认情况下，如果不能找到目标视图，则将抛出异常。@Nullable、@Optional，存在即绑定，不存在即忽略，不抛异常

@Nullable @BindView(R.id.might_not_be_there)
TextView mightNotBeThere;

@Optional @OnClick(R.id.maybe_missing)
void onMaybeMissingClicked() {}

绑定重置

public class FancyFragment extends Fragment {
    private Unbinder unbinder;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fancy_fragment, container, false);
        unbinder = ButterKnife.bind(this, view);
        // ...
        return view;
    }

    @Override public void onDestroyView() {
        super.onDestroyView();
        unbinder.unbind();
    }
}

额外

ButterKnife.findById()自动强转，第一个参数可为 View, Activity, Dialog

ImageView photo = ButterKnife.findById(view, R.id.photo);

进阶用法

ButterKnife.apply()

// 绑定View
@BindViews({ R.id.first_name, R.id.middle_name, R.id.last_name })
List<EditText> nameViews;

// 实现 Action 和 Setter 接口，定义动作
static final ButterKnife.Action<View> DISABLE = new ButterKnife.Action<View>() {
    @Override
    public void apply(View view, int index) {
        view.setEnabled(false);
    }
};
static final ButterKnife.Setter<View, Boolean> ENABLED = new ButterKnife.Setter<View, Boolean>() {
    @Override
    public void set(View view, Boolean value, int index) {
        view.setEnabled(value);
    }
};

// 调用
ButterKnife.apply(nameViews, DISABLE);
ButterKnife.apply(nameViews, ENABLED, false);
ButterKnife.apply(nameViews, View.ALPHA, 0.0f);