Toast简单封装_android开发 tosat 自定义 封装

1.在AndroidManifest.XML中声明这个MyApplication

android:name=".MyApplication"

2.自定义Application【系统上下文】

 
import android.app.Application;
import android.content.Context;
 
public class MyApplication extends Application {
    /**系统上下文*/
    private static Context mAppContext;
 
    @Override
    public void onCreate() {
        super.onCreate();
        mAppContext = getApplicationContext();
 
    }
 
    /**获取系统上下文：用于ToastUtil类*/
    public static Context getAppContext(){
        return mAppContext;
    }
}

3. Toast的封装

 
import android.content.Context;
import android.view.Gravity;
import android.widget.Toast;
 
/**
 * Used 简单的Toast封装类
 */
public class ToastUtil {
    //实现不管我们触发多少次Toast调用，都只会持续一次Toast显示的时长
    private static Toast toast;
 
    /**
     * 短时间显示Toast【居下】
     * @param msg 显示的内容-字符串
     */
    public static void ToastBelowshow(String msg) {
        if (MyApplication.getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(MyApplication.getAppContext(), msg, Toast.LENGTH_SHORT);
            } else {
                toast.setText(msg);
            }
            //1、setGravity方法必须放到这里，否则会出现toast始终按照第一次显示的位置进行显示（比如第一次是在底部显示，那么即使设置setGravity在中间，也不管用）
            //2、虽然默认是在底部显示，但是，因为这个工具类实现了中间显示，所以需要还原，还原方式如下：
            toast.setGravity(Gravity.BOTTOM, 0, dip2px(MyApplication.getAppContext(), 64));
            toast.show();
        }
    }
 
    /**
     * 短时间显示Toast【居中】
     * @param msg 显示的内容-字符串
     */
    public static void ToastCentershow(String msg) {
        if (MyApplication.getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(MyApplication.getAppContext(), msg, Toast.LENGTH_SHORT);
            } else {
                toast.setText(msg);
            }
            toast.setGravity(Gravity.CENTER, 0, 0);
            toast.show();
        }
    }
 
    /**
     * 短时间显示Toast【居上】
     * @param msg 显示的内容-字符串
     */
    public static void ToastTopshow(String msg) {
        if (MyApplication.getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(MyApplication.getAppContext(), msg, Toast.LENGTH_SHORT);
            } else {
                toast.setText(msg);
            }
            toast.setGravity(Gravity.TOP, 0, 0);
            toast.show();
        }
    }
 
    /**
     * 长时间显示Toast【居下】
     * @param msg 显示的内容-字符串
     */
    public static void ToastBelowshowLong(String msg) {
        if (MyApplication.getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(MyApplication.getAppContext(), msg, Toast.LENGTH_LONG);
            } else {
                toast.setText(msg);
            }
            toast.setGravity(Gravity.BOTTOM, 0, dip2px(MyApplication.getAppContext(), 64));
            toast.show();
        }
    }
 
    /**
     * 长时间显示Toast【居中】
     * @param msg 显示的内容-字符串
     */
    public static void ToastCentershowLong(String msg) {
        if (MyApplication.getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(MyApplication.getAppContext(), msg, Toast.LENGTH_LONG);
            } else {
                toast.setText(msg);
            }
            toast.setGravity(Gravity.CENTER, 0, 0);
            toast.show();
        }
    }
 
    /**
     * 长时间显示Toast【居上】
     * @param msg 显示的内容-字符串
     */
    public static void ToastTopshowLong(String msg) {
        if (MyApplication.getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(MyApplication.getAppContext(), msg, Toast.LENGTH_LONG);
            } else {
                toast.setText(msg);
            }
            toast.setGravity(Gravity.TOP, 0, 0);
            toast.show();
        }
    }
 
    /*=================================常用公共方法============================*/
    public static int dip2px(Context context, float dpValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
    }
    //ToastUtil.ToastTopshow(MyApplication.getAppContext().getResources().getString(R.string.app_name));
    // 如果想要显示Strings.xml文件中的字符串，建议使用MyApplication.getAppContext()
}