使用直接导入这两个注解类
package com.ybf.testa;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import java.lang.annotation.ElementType;
import java.lang.annotation.RetentionPolicy;
/**
* Use this annotation to mark the fields of your Activity as being injectable.
* <p>
* See the {@link Injector} class for more details of how this operates.
*/
@Target({ ElementType.FIELD })
@Retention(RetentionPolicy.RUNTIME)
public @interface InjectView {
/**
* The resource id of the View to find and inject.
*/
public int value();
}
package com.ybf.testa;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import android.app.Activity;
/**
* Very lightweight form of injection, inspired by RoboGuice, for injecting common ui elements.
* <p>
* Usage is very simple. In your Activity, define some fields as follows:
*
* <pre class="code">
* @InjectView(R.id.fetch_button)
* private Button mFetchButton;
* @InjectView(R.id.submit_button)
* private Button mSubmitButton;
* @InjectView(R.id.main_view)
* private TextView mTextView;
* </pre>
* <p>
* Then, inside your Activity's onCreate() method, perform the injection like this:
*
* <pre class="code">
* setContentView(R.layout.main_layout);
* Injector.get(this).inject();
* </pre>
* <p>
* See the {@link #inject()} method for full details of how it works. Note that the fields are
* fetched and assigned at the time you call {@link #inject()}, consequently you should not do this
* until after you've called the setContentView() method.
*/
public final class Injector {
private final Activity mActivity;
private Injector(Activity activity) {
mActivity = activity;
}
/**
* Gets an {@link Injector} capable of injecting fields for the given Activity.
*/
public static Injector get(Activity activity) {
return new Injector(activity);
}
/**
* Injects all fields that are marked with the {@link InjectView} annotation.
* <p>
* For each field marked with the InjectView annotation, a call to
* {@link Activity#findViewById(int)} will be made, passing in the resource id stored in the
* value() method of the InjectView annotation as the int parameter, and the result of this call
* will be assigned to the field.
*
* @throws IllegalStateException if injection fails, common causes being that you have used an
* invalid id value, or you haven't called setContentView() on your Activity.
*/
public void inject() {
for (Field field : mActivity.getClass().getDeclaredFields()) {
for (Annotation annotation : field.getAnnotations()) {
if (annotation.annotationType().equals(InjectView.class)) {
try {
Class<?> fieldType = field.getType();
int idValue = InjectView.class.cast(annotation).value();
field.setAccessible(true);
Object injectedValue = fieldType.cast(mActivity.findViewById(idValue));
if (injectedValue == null) {
throw new IllegalStateException("findViewById(" + idValue
+ ") gave null for " +
field + ", can't inject");
}
field.set(mActivity, injectedValue);
field.setAccessible(false);
} catch (IllegalAccessException e) {
throw new IllegalStateException(e);
}
}
}
}
}
}
使用:
package com.ybf.testa;
public class MainActivity extends Activity {
@InjectView(R.id.tv)
private Button tv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Injector.get(this).inject();// init views
tv.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, SecondActivity.class);
startActivity(intent);
finish();
}
});
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
}
}