android改变程序所有View大小

实现思路：

在application里面直接设置窗体的大小

效果图：

 

1.清单文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.example.administrator.testz">

    <application
        android:name=".MyApplication"
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>

2.Application：

package com.example.administrator.testz;

import android.app.Application;

/**
 * Created by wrs on 2019/6/6,17:54
 * projectName: Testz
 * packageName: com.example.administrator.testz
 */
public class MyApplication extends Application{

    @Override
    public void onCreate() {
        super.onCreate();
        Density.setDensity(this, 960f);// 这个960f参数可以调整全局View的大小
    }
}

3.封装窗体大小类Density：

package com.example.administrator.testz;


import android.app.Activity;
import android.app.Application;
import android.content.ComponentCallbacks;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.util.DisplayMetrics;

/**
 * Created by chenxiaojin on 2018/11/2.
 */

public class Density {
    private static float appDensity;
    private static float appScaledDensity;
    private static DisplayMetrics appDisplayMetrics;
    /**
     * 用来参照的的width
     */
    private static float WIDTH;

    public static void setDensity(@NonNull final Application application, float width) {
        appDisplayMetrics = application.getResources().getDisplayMetrics();
        WIDTH = width;
        registerActivityLifecycleCallbacks(application);

        if (appDensity == 0) {
            //初始化的时候赋值
            appDensity = appDisplayMetrics.density;
            appScaledDensity = appDisplayMetrics.scaledDensity;

            //添加字体变化的监听
            application.registerComponentCallbacks(new ComponentCallbacks() {
                @Override
                public void onConfigurationChanged(Configuration newConfig) {
                    //字体改变后,将appScaledDensity重新赋值
                    if (newConfig != null && newConfig.fontScale > 0) {
                        appScaledDensity = application.getResources().getDisplayMetrics().scaledDensity;
                    }
                }

                @Override
                public void onLowMemory() {
                }
            });
        }
    }


    private static void setDefault(Activity activity) {
        setAppOrientation(activity);
    }

    private static void setAppOrientation(@Nullable Activity activity) {
        float targetDensity = 0;
        try {
            targetDensity = appDisplayMetrics.widthPixels / WIDTH;
        } catch (NumberFormatException e) {
            e.printStackTrace();
        }
        float targetScaledDensity = targetDensity * (appScaledDensity / appDensity);
        int targetDensityDpi = (int) (160 * targetDensity);

        /**
         * 最后在这里将修改过后的值赋给系统参数
         * 只修改Activity的density值
         */
        DisplayMetrics activityDisplayMetrics = activity.getResources().getDisplayMetrics();
        activityDisplayMetrics.density = targetDensity;
        activityDisplayMetrics.scaledDensity = targetScaledDensity;
        activityDisplayMetrics.densityDpi = targetDensityDpi;
    }


    private static void registerActivityLifecycleCallbacks(Application application) {
        application.registerActivityLifecycleCallbacks(new Application.ActivityLifecycleCallbacks() {
            @Override
            public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
                setDefault(activity);
            }

            @Override
            public void onActivityStarted(Activity activity) {
            }

            @Override
            public void onActivityResumed(Activity activity) {
            }

            @Override
            public void onActivityPaused(Activity activity) {
            }

            @Override
            public void onActivityStopped(Activity activity) {
            }

            @Override
            public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
            }

            @Override
            public void onActivityDestroyed(Activity activity) {

            }
        });
    }
}

4.布局页面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <Button
        android:id="@+id/button2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorAccent"
        android:text="Button" />
    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorPrimary"
        android:text="Button" />



    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="TextActivity"
        android:textSize="30sp" />
</LinearLayout>

到这里就结束了，创建一个activity来显示上面的布局，改变application传递参数的大小，可以改变整个view的大小，值越大，字体越小