android studio开发小笔记1

1、点击空白处隐藏软键盘

 /*
   隐藏软键盘
   * */
    public boolean dispatchTouchEvent(MotionEvent ev) {
        if (ev.getAction() == MotionEvent.ACTION_DOWN) {
            View v = getCurrentFocus();
            if (isShouldHideInput(v, ev)) {

                InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
                if (imm != null) {
                    imm.hideSoftInputFromWindow(v.getWindowToken(), 0);
                }
            }
            return super.dispatchTouchEvent(ev);
        }

        if (getWindow().superDispatchTouchEvent(ev)) {
            return true;
        }
        return onTouchEvent(ev);
    }

    public  boolean isShouldHideInput(View v, MotionEvent event) {
        if (v != null && (v instanceof EditText)) {
            int[] leftTop = { 0, 0 };

            v.getLocationInWindow(leftTop);
            int left = leftTop[0];
            int top = leftTop[1];
            int bottom = top + v.getHeight();
            int right = left + v.getWidth();
            if (event.getX() > left && event.getX() < right
                    && event.getY() > top && event.getY() < bottom) {

            } else {
                return true;
            }
        }
        return false;
    }

2、沉浸式状态栏

        //设置沉浸式状态栏 android 4.4 及以上支持
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            //透明状态栏
            getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
            //透明导航栏
            getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
        }

3、设置导航栏

xml代码：

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:background="#5caef9"
        android:minHeight="50dp"
        android:gravity="center"
        android:textAlignment="center"
        >
    </android.support.v7.widget.Toolbar>

后台代码：

        //设置导航栏
      Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar1);//鑾峰彇椤甸潰鐨勫伐鍏锋爮

        toolbar.setTitle("设置服务");
        toolbar.setTitleMarginStart(370);
        toolbar.setTitleTextColor(Color.WHITE);
        toolbar.setTitleMarginTop(10);
        toolbar.setNavigationIcon(R.mipmap.allback);
        toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(SettingServiceActivity.this,MyselfLoginActivity.class);
                startActivity(intent);
            }
        });

4、获取屏幕宽高和设置控件宽高

        //设置输入框宽高
        EditText tvservicepath = (EditText)findViewById(R.id.tvservicepath);
        tvservicepath.setText(R.string.serverpath);//获取资源文件
        //获取屏幕高宽
        WindowManager wm = (WindowManager) this.getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics dm = new DisplayMetrics();
        wm.getDefaultDisplay().getMetrics(dm);
        int width = dm.widthPixels;         // 屏幕宽度（像素）
        int height = dm.heightPixels;       // 屏幕高度（像素）
        float density = dm.density;         // 屏幕密度（0.75 / 1.0 / 1.5）
        int densityDpi = dm.densityDpi;     // 屏幕密度dpi（120 / 160 / 240）
        // 屏幕宽度算法:屏幕宽度（像素）/屏幕密度
        int screenWidth = (int) (width / density);  // 屏幕宽度(dp)
        int screenHeight = (int) (height / density);// 屏幕高度(dp)

        ViewGroup.LayoutParams para;
        para = tvservicepath.getLayoutParams();
        para.height = screenHeight/2;
        para.width = width-50;
        tvservicepath.setLayoutParams(para);

5、在手机本地保存数据和读取(参考：https://blog.csdn.net/acm_th/article/details/50009575)

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.savedatademo.MainActivity" >

    <EditText
        android:id="@+id/input"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入" />

    <Button
        android:id="@+id/btn1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/input"
        android:text="保存数据" />

    <Button
        android:id="@+id/btn2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/btn1"
        android:text="读取数据"/>

</RelativeLayout>

package com.example.savedatademo;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.util.Scanner;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

    private Button saveBtn = null;
    private Button readBtn = null;
    private EditText input = null;
    private final static String FILE_NAME = "xth.txt"; // 设置文件的名称

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);

        input = (EditText) findViewById(R.id.input);
        saveBtn = (Button) findViewById(R.id.btn1);
        readBtn = (Button) findViewById(R.id.btn2);

        saveBtn.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                String data = input.getText().toString();
                save(data);
                Toast.makeText(MainActivity.this, "保存数据成功！", Toast.LENGTH_SHORT)
                        .show();
            }
        });
        readBtn.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                StringBuffer sb = read();
                Toast.makeText(MainActivity.this, "读取数据为：" + sb,
                        Toast.LENGTH_SHORT).show();
            }
        });
    }

    private StringBuffer read() {
        FileInputStream in = null;
        Scanner s = null;
        StringBuffer sb = new StringBuffer();
        try {
            in = super.openFileInput(FILE_NAME);
            s = new Scanner(in);
            while (s.hasNext()) {
                sb.append(s.next());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return sb;
    }

    private void save(String data) {
        FileOutputStream out = null;
        PrintStream ps = null;
        try {
            out = super.openFileOutput(FILE_NAME, Activity.MODE_APPEND);
            ps = new PrintStream(out);
            ps.println(data);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (out != null) {
                try {
                    out.close();
                    ps.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

这是追加内容的，如果覆盖，改成：

out = super.openFileOutput(FILE_NAME, Activity.MODE_WORLD_WRITEABLE);

6、代码设置按钮被点击使用performClick（）方法。

7、设置控件的显示与隐藏：

View缺省为可见的，在应用可以通过setVisibility 修改View的可见性，

View.VISIBLE View可见，View.INVISIBLE View不可以见，但仍然占据可见时的大小和位置。

View.GONE View不可见，且不占据空间。