安卓开发之Collections.sort方法对list按时间排序

Comparator是个接口，可重写compare()及equals()这两个方法,用于比价功能；如果是null的话，就是使用元素的默认顺序，如a,b,c,d,e,f,g，就是a,b,c,d,e,f,g这样，当然数字也是这样的。

compare（a,b）方法:根据第一个参数小于、等于或大于第二个参数分别返回负整数、零或正整数。
equals（obj）方法：仅当指定的对象也是一个 Comparator，并且强行实施与此 Comparator 相同的排序时才返回 true。
Collections.sort(list, new PriceComparator());的第二个参数返回一个int型的值，就相当于一个标志，告诉sort方法按什么顺序来对list进行排序。

一直都没有接触排序，突然要实现对List的排序，找了一下资料，发现Collections.sort( )这个方法。

Collections.sort( )分为两部分，一部分为排序规则，一部分为排序算法 。

规则用来判断对象，算法则考虑如何进行排序。

对于自定义对象，sort()不知道规则，所以无法比较，这种情况下一定要定义排序规则。方式有两种：

第一种，java.lang下面的一个接口：Comparable。可以让自定义对象实现一个Comparable接口，这个接口只有一个方法comparableTo（Object o）

其规则是当前对象与o对象进行比较，返回一个int值，系统根据此值进行排序。

如当前对象>o对象，则返回值>0；

如当前对象=o对象，则返回值=0；

如当前对象<o对象，则返回值<0；

第二种方式，java.util下有一个Comparator（比较器）。它拥有compare( )方法，用来比较两个对象。

至此，我采用了第二种方式。下面是定义的排序规则：

public class JsonComparator implements Comparator&lt;NewRecordEntity&gt;{
    
    @Override
    public int compare(NewRecordEntity arg0, NewRecordEntity arg1) {
        
        String data1=TimeStamp2Date(arg0.getOldtime()+"", "yyyy-MM-dd HH:mm:ss");
        String data2=TimeStamp2Date(arg1.getOldtime()+"", "yyyy-MM-dd HH:mm:ss");
        //设定时间的模板
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                //得到指定模范的时间
                try {
                    Date d1 = sdf.parse(data1);
                    Date d2 = sdf.parse(data2);
                    if(d1.getTime() - d2.getTime()&gt;0){
                        return -1;
                    }else if(d1.getTime() - d2.getTime()&lt;0){
                        return 1;
                    }
                    
                    
                } catch (ParseException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                
        
        return 0;
    }
    public String TimeStamp2Date(String timestampString, String formats){  
          Long timestamp = Long.parseLong(timestampString)*1000;  
          String date = new java.text.SimpleDateFormat(formats).format(new java.util.Date(timestamp));  
          return date;  
        }
}

使用：

//排序操作
JsonComparator pComparator =  new JsonComparator();
Collections.sort(list, pComparator);
 

这样就实现了排序功能。如果是对数组进行排序，同样的原理，只不过换成Arrays.sort（）方法。

毛玻璃效果就是屏幕上有一些水珠一样的东西了，我们在苹果的壁纸中可以看到这种效果，下面来看在安卓中实现毛玻璃模糊效果代码，具体的如下所示。

手机API等级在16以上的，可以用这个方法：

if (VERSION.SDK_INT > 16) {
    Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
    final RenderScript rs = RenderScript.create(context);
    final Allocation input = Allocation.createFromBitmap(rs, sentBitmap, Allocation.MipmapControl.MIPMAP_NONE,
            Allocation.USAGE_SCRIPT);
    final Allocation output = Allocation.createTyped(rs, input.getType());
    final ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
    script.setRadius(radius /* e.g. 3.f */);
    script.setInput(input);
    script.forEach(output);
    output.copyTo(bitmap);
    return bitmap;
}

假设手机API等级小于16，那就用这个方法:

  @SuppressLint("NewApi")
    public static Bitmap fastblur(Context context, Bitmap sentBitmap, int radius) {

        Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
        if (radius < 1) {
            return (null);
        }
        int w = bitmap.getWidth();
        int h = bitmap.getHeight();
        int[] pix = new int[w * h];
//        Log.e("pix", w + " " + h + " " + pix.length);
        bitmap.getPixels(pix, 0, w, 0, 0, w, h);
        int wm = w - 1;
        int hm = h - 1;
        int wh = w * h;
        int div = radius + radius + 1;
        int r[] = new int[wh];
        int g[] = new int[wh];
        int b[] = new int[wh];
        int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
        int vmin[] = new int[Math.max(w, h)];
        int divsum = (div + 1) >> 1;
        divsum *= divsum;
        int temp = 256 * divsum;
        int dv[] = new int[temp];
        for (i = 0; i < temp; i++) {
            dv[i] = (i / divsum);
        }
        yw = yi = 0;
        int[][] stack = new int[div][3];
        int stackpointer;
        int stackstart;
        int[] sir;
        int rbs;
        int r1 = radius + 1;
        int routsum, goutsum, boutsum;
        int rinsum, ginsum, binsum;
        for (y = 0; y < h; y++) {
            rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
            for (i = -radius; i <= radius; i++) {
                p = pix[yi + Math.min(wm, Math.max(i, 0))];
                sir = stack[i + radius];
                sir[0] = (p & 0xff0000) >> 16;
                sir[1] = (p & 0x00ff00) >> 8;
                sir[2] = (p & 0x0000ff);
                rbs = r1 - Math.abs(i);
                rsum += sir[0] * rbs;
                gsum += sir[1] * rbs;
                bsum += sir[2] * rbs;
                if (i > 0) {
                    rinsum += sir[0];
                    ginsum += sir[1];
                    binsum += sir[2];
                } else {
                    routsum += sir[0];
                    goutsum += sir[1];
                    boutsum += sir[2];
                }
            }
            stackpointer = radius;
            for (x = 0; x < w; x++) {
                r[yi] = dv[rsum];
                g[yi] = dv[gsum];
                b[yi] = dv[bsum];
                rsum -= routsum;
                gsum -= goutsum;
                bsum -= boutsum;
                stackstart = stackpointer - radius + div;
                sir = stack[stackstart % div];
                routsum -= sir[0];
                goutsum -= sir[1];
                boutsum -= sir[2];
                if (y == 0) {
                    vmin[x] = Math.min(x + radius + 1, wm);
                }
                p = pix[yw + vmin[x]];
                sir[0] = (p & 0xff0000) >> 16;
                sir[1] = (p & 0x00ff00) >> 8;
                sir[2] = (p & 0x0000ff);
                rinsum += sir[0];
                ginsum += sir[1];
                binsum += sir[2];
                rsum += rinsum;
                gsum += ginsum;
                bsum += binsum;
                stackpointer = (stackpointer + 1) % div;
                sir = stack[(stackpointer) % div];
                routsum += sir[0];
                goutsum += sir[1];
                boutsum += sir[2];
                rinsum -= sir[0];
                ginsum -= sir[1];
                binsum -= sir[2];
                yi++;
            }
            yw += w;
        }
        for (x = 0; x < w; x++) {
            rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
            yp = -radius * w;
            for (i = -radius; i <= radius; i++) {
                yi = Math.max(0, yp) + x;
                sir = stack[i + radius];
                sir[0] = r[yi];
                sir[1] = g[yi];
                sir[2] = b[yi];
                rbs = r1 - Math.abs(i);
                rsum += r[yi] * rbs;
                gsum += g[yi] * rbs;
                bsum += b[yi] * rbs;
                if (i > 0) {
                    rinsum += sir[0];
                    ginsum += sir[1];
                    binsum += sir[2];
                } else {
                    routsum += sir[0];
                    goutsum += sir[1];
                    boutsum += sir[2];
                }
                if (i < hm) {
                    yp += w;
                }
            }
            yi = x;
            stackpointer = radius;
            for (y = 0; y < h; y++) {
                // Preserve alpha channel: ( 0xff000000 & pix[yi] )
                pix[yi] = (0xff000000 & pix[yi]) | (dv[rsum] << 16) | (dv[gsum] << 8) | dv[bsum];
                rsum -= routsum;
                gsum -= goutsum;
                bsum -= boutsum;
                stackstart = stackpointer - radius + div;
                sir = stack[stackstart % div];
                routsum -= sir[0];
                goutsum -= sir[1];
                boutsum -= sir[2];
                if (x == 0) {
                    vmin[y] = Math.min(y + r1, hm) * w;
                }
                p = x + vmin[y];
                sir[0] = r[p];
                sir[1] = g[p];
                sir[2] = b[p];
                rinsum += sir[0];
                ginsum += sir[1];
                binsum += sir[2];
                rsum += rinsum;
                gsum += ginsum;
                bsum += binsum;
                stackpointer = (stackpointer + 1) % div;
                sir = stack[stackpointer];
                routsum += sir[0];
                goutsum += sir[1];
                boutsum += sir[2];
                rinsum -= sir[0];
                ginsum -= sir[1];
                binsum -= sir[2];
                yi += w;
            }
        }
//        Log.e("pix", w + " " + h + " " + pix.length);
        bitmap.setPixels(pix, 0, w, 0, 0, w, h);
        return (bitmap);
    }
毛玻璃效果，直接拿去用就行了。

ToolBar工具昨天介绍过相关的教程今天我们来看看关于android中ToolBar设置NavigationIcon图标不显示、失败、没反应，绝对管用问题的解决办法。

最近开发android app，程序中用到ToolBar控件，想设置ToolBar的NavigationIcon图标图标可是怎么设置都不管用，一直显示控件自带的。
异常:
在布局XML中设置android:navigationIcon=”@drawable/icon”或者在代码中设置都无法自定义成自己需要设置的NavigationIcon图片。
代码设置NavigationIcon如下:

Toolbar toolbar = (Toolbar)findViewById(R.id.my_toolbar);
toolbar.setNavigationIcon(R.drawable.icon);
toolbar.setTitle("Title");
toolbar.setSubtitle("Sub");
toolbar.setLogo(R.drawable.ic_launcher);
setSupportActionBar(toolbar);

解决办法:

如果你在XML布局中设置ToolBar设置NavigationIcon，那么现在需要放弃这种做法，否则始终无法显示出你设置的NavigationIcon；
必须使用代码方式：

setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("");
toolbar.setSubtitle("");
setSupportActionBar(toolbar);
 
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
        this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
toolbar.setNavigationIcon(R.mipmap.userphoto);

本文章来为各位介绍一篇关于android中使用Post方法调用asp.net webapi接口方法了，这个是以HttpURLConnection使用为例子了，具体如下。

android开发想接口获取数据是必须的操作，一般获取数据有post和get两种方式，本文讲解客户端使用post方法调取服务器端使用asp.net webapi开发接口数据。
1、访问接口类

package http;
 
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
 
import android.widget.Toast;
 
public class HttpUtils {
    public static String getJsonContent(String urlPath,String data) {
        String webServiceUrl="http://hayi.8888.com";
        try {
            URL url = new URL(webServiceUrl+urlPath);
            HttpURLConnection connection = (HttpURLConnection) url
                    .openConnection();
            connection.setConnectTimeout(3000);
            connection.setRequestMethod("POST");
            connection.setDoOutput(true); // 发送POST请求必须设置允许输出
            connection.setDoInput(true);
            //获取输出流
            OutputStream os = connection.getOutputStream();
            os.write(data.getBytes());
            os.flush();
            int code = connection.getResponseCode();
            if (code == 200) {
                return changeInputStream(connection.getInputStream());
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
        return "";
    }
 
    private static String changeInputStream(InputStream inputStream) {
        // TODO Auto-generated method stub
        String JsonString = "";
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        int len = 0;
        byte[] data = new byte[1024];
        try {
            while ((len = inputStream.read(data)) != -1) {
                outputStream.write(data, 0, len);
            }
            JsonString = new String(outputStream.toByteArray());
        } catch (IOException e) {
            e.printStackTrace();
        }
        return JsonString;
    }
}

2、使用方法

// 传递的数据
                String dataPare = "userName=" + URLEncoder.encode(usernameTxt.getText().toString().trim(), "UTF-8")
                        + "&userPass=" + URLEncoder.encode(userpassTxt.getText().toString().trim(), "UTF-8");
                jsonString = HttpUtils
                        .getJsonContent("/api/Values/PostUserLogin",dataPare );