Android实现长按图片保存至相册功能

前言：前面写了一篇reactnative的学习笔记，说reactnative的android框架中有很多福利，确实是的，也说到了我们app中的一个把图片保存到相册的功能，好吧，还是准备写一篇博客，就当笔记了～

先上几张app的图片：

一进app就是一个进度条加载图片（我待会也会说一下进度条view跟怎么监听图片加载过程）：

图片加载完毕后：

长按图片进入相册可以看到我们保存的图片：

监听图片加载的loaddingview源码（不是很难，我就直接贴代码了）：

package com.leo.camerroll;

import android.animation.valueanimator;
import android.content.context;
import android.graphics.canvas;
import android.graphics.color;
import android.graphics.paint;
import android.graphics.rectf;
import android.util.attributeset;
import android.util.typedvalue;
import android.view.view;
import android.view.animation.animation;
import android.view.animation.linearinterpolator;
import android.widget.progressbar;

/**
 * created by leo on 17/1/22.
 */

public class loadingview extends progressbar {
  private final int default_radius = dp2px(15);
  private final int default_reach_color = 0xffffffff;
  private final int default_unreach_color = 0x88000000;
  private final long anim_duration = 1000;
  private final string base_text = "00%";
  private boolean isstop;

  private int mradius = default_radius;
  private int mstrokewidth;
  private paint reachpaint;
  private paint unreachpaint;
  private paint textpaint;
  private paint bgpaint;

  private int mstartangle=0;
  private float msweepangle=360*0.382f;

  private valueanimator anim;

  public loadingview(context context) {
    this(context, null);
  }

  public loadingview(context context, attributeset attrs) {
    this(context, attrs, 0);
  }

  public loadingview(context context, attributeset attrs, int defstyleattr) {
    super(context, attrs, defstyleattr);
    initview();
  }

  private void initview() {
    reachpaint = new paint(paint.anti_alias_flag | paint.dither_flag);
    reachpaint.setstrokecap(paint.cap.round);
    reachpaint.setstyle(paint.style.stroke);
    unreachpaint = new paint(reachpaint);
    reachpaint.setcolor(default_reach_color);
    unreachpaint.setcolor(default_unreach_color);
    textpaint = new paint(paint.anti_alias_flag | paint.dither_flag);
    textpaint.setstyle(paint.style.stroke);
    textpaint.setcolor(color.white);
    textpaint.setfakeboldtext(true);

    bgpaint=new paint(paint.anti_alias_flag|paint.dither_flag);
    bgpaint.setstrokecap(paint.cap.round);
    bgpaint.setcolor(color.argb(44,0,0,0));
    setmax(100);
  }

  @override
  protected synchronized void onmeasure(int widthmeasurespec, int heightmeasurespec) {
    int defwidth = resolvesize(getsuggestedminimumwidth(), widthmeasurespec);
    int defheight = resolvesize(getsuggestedminimumheight(), heightmeasurespec);
    int expectsize = math.min(defheight, defwidth);
    if (expectsize <= 0) {
      expectsize = mradius * 2;
    } else {
      mradius = expectsize / 2;
    }
    mstrokewidth = mradius / 5;
    reachpaint.setstrokewidth(mstrokewidth);
    unreachpaint.setstrokewidth(mstrokewidth);

    setmeasureddimension(expectsize, expectsize);

    float textsize=0;
    while(true){
      textsize+=0.1;
      textpaint.settextsize(textsize);
      if(textpaint.measuretext(base_text,0,base_text.length())>=mradius){
        break;
      }
    }
  }

  @override
  protected synchronized void ondraw(canvas canvas) {
    if(isstop){
      setvisibility(view.gone);
      return;
    }
    //drawbackground transparent
    canvas.drawcircle(getwidth()/2,getwidth()/2,mradius-mstrokewidth,bgpaint);
    //draw reach
    drawprogressreach(canvas);
    //draw progress text
    drawprogresstext(canvas);
  }

  private void drawprogresstext(canvas canvas) {
    string text=string.valueof((int)(getprogress()*1.0f/getmax()*100))+"%";
    int centerx=getwidth()/2;
    int centery=getwidth()/2;
    int basex= (int) (centerx-textpaint.measuretext(text,0,text.length())/2);
    int basey= (int) (centery-(textpaint.getfontmetrics().ascent+textpaint.getfontmetrics().descent)/2);
    canvas.drawtext(text,basex,basey,textpaint);
  }

  private void drawprogressreach(canvas canvas) {
    canvas.drawarc(new rectf(0 + mstrokewidth / 2, 0 + mstrokewidth / 2, mradius * 2 - mstrokewidth / 2, mradius * 2 - mstrokewidth / 2), mstartangle, msweepangle, false, reachpaint);
    //drawonreach
    canvas.drawarc(new rectf(0 + mstrokewidth / 2, 0 + mstrokewidth / 2, mradius * 2 - mstrokewidth / 2, mradius * 2 - mstrokewidth / 2), mstartangle+msweepangle, 360-msweepangle,false, unreachpaint);
  }

  @override
  protected void onattachedtowindow() {
    super.onattachedtowindow();
    if(anim==null){
      anim=valueanimator.ofint(0,360);
      anim.setinterpolator(new linearinterpolator());
      anim.setduration(anim_duration);
      anim.setrepeatcount(animation.infinite);
      anim.addupdatelistener(new valueanimator.animatorupdatelistener() {
        @override
        public void onanimationupdate(valueanimator animation) {
          if(animation!=null&&animation.getanimatedvalue()!=null){
            int startangle= (int) animation.getanimatedvalue();
            mstartangle=startangle;
            postinvalidate();
          }
        }
      });
    }else{
      anim.cancel();
      anim.removeallupdatelisteners();
    }
    anim.start();
  }

  public void loadcompleted() {
    isstop=true;
    if(anim!=null){
      anim.cancel();
      anim.removeallupdatelisteners();
      this.setvisibility(view.gone);
    }
  }

  /**
   * @param size
   * @return px
   */
  private int dp2px(int size) {
    return (int) typedvalue.applydimension(typedvalue.complex_unit_dip, size, getcontext().getresources().getdisplaymetrics());
  }
}

实现起来还是很简单的，就是动态改变两端弧的起点和终点，通过属性动画不断的在（0－360）循环，代码应该还算比较清晰哈！～～～～

图片加载用了一个asynctask:

private class downimagetask extends asynctask<string, long, bitmap> {
    private imageview imageview;
    private long contentlength;
    public downimagetask(imageview imageview) {
      this.imageview = imageview;
    }

    @override
    protected bitmap doinbackground(string... params) {
      bitmap bitmap = null;
      bufferedinputstream bis = null;
      bytearrayoutputstream bos = null;
      try {
        file filedir=new file(getapplication().getexternalcachedir(),"images");
        if(filedir==null||!filedir.isdirectory()){
          filedir.mkdir();
        }
        file file=new file(filedir.getabsolutepath()+"/"+params[0].hashcode()+".png");
        if(file!=null&&file.length()>0){
          return bitmap=bitmapfactory.decodefile(file.getabsolutepath());
        }
        bos=new bytearrayoutputstream();
        byte[] buffer = new byte[512];
        long total=0;
        int len ;
        url url = new url(params[0]);
        httpurlconnection conn = (httpurlconnection) url.openconnection();
        this.contentlength = conn.getcontentlength();
        bis = new bufferedinputstream(conn.getinputstream());
        while ((len = bis.read(buffer)) != -1) {
          total+=len;
          publishprogress(total);
          thread.sleep(100);
          bos.write(buffer, 0, len);
          bos.flush();
        }
        bitmap= bitmapfactory.decodebytearray(bos.tobytearray(),0,bos.tobytearray().length);
        savebitmaptodisk(bos,params[0]);
      } catch (exception e) {
        e.printstacktrace();
      } finally {
        try {
          if (bis != null) {
            bis.close();
          }
          if (bos != null) {
            bos.close();
          }
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
      return bitmap;
    }

    private void savebitmaptodisk(final bytearrayoutputstream baos, final string url) {
      new thread(){
        @override
        public void run() {bufferedoutputstream bos=null;
          try{
            if(!environment.media_mounted.equals(environment.getexternalstoragestate())){
              log.e("tag","内存卡不存在");
              return;
            }
            log.e("tag","开始保存图片至内存卡～～");
            byte[] bytes = baos.tobytearray();
            file filedir=new file(getapplication().getexternalcachedir(),"images");
            if(filedir==null||!filedir.isdirectory()){
              filedir.mkdir();
            }
            file file=new file(filedir.getabsolutepath()+"/"+url.hashcode()+".png");
            file.createnewfile();
            bos=new bufferedoutputstream(new fileoutputstream(file));
            bos.write(bytes);
            bos.flush();
            log.e("tag","图片已经保存至内存卡～～");
          }catch (exception e){
            e.printstacktrace();
          }finally {
            if(bos!=null){
              try {
                bos.close();
              } catch (ioexception e) {
                e.printstacktrace();
              }
            }
          }
        }
      }.start();
    }

    @override
    protected void onprogressupdate(long... values) {
      mloadingview.setprogress((int) ((values[0].longvalue() * 1.0f / contentlength) * 100));
    }

    @override
    protected void onpostexecute(bitmap bitmap) {
      if (imageview != null && bitmap != null) {
        imageview.setimagebitmap(bitmap);
        mloadingview.loadcompleted();
      }
    }
  }

加载完毕后把图片存放在了内存卡中（当然，这是我随便写的一个图片加载，大家换成自己的加载框架哈，）：

private void savebitmaptodisk(final bytearrayoutputstream baos, final string url) {
      new thread(){
        @override
        public void run() {bufferedoutputstream bos=null;
          try{
            if(!environment.media_mounted.equals(environment.getexternalstoragestate())){
              log.e("tag","内存卡不存在");
              return;
            }
            log.e("tag","开始保存图片至内存卡～～");
            byte[] bytes = baos.tobytearray();
            file filedir=new file(getapplication().getexternalcachedir(),"images");
            if(filedir==null||!filedir.isdirectory()){
              filedir.mkdir();
            }
            file file=new file(filedir.getabsolutepath()+"/"+url.hashcode()+".png");
            file.createnewfile();
            bos=new bufferedoutputstream(new fileoutputstream(file));
            bos.write(bytes);
            bos.flush();
            log.e("tag","图片已经保存至内存卡～～");
          }catch (exception e){
            e.printstacktrace();
          }finally {
            if(bos!=null){
              try {
                bos.close();
              } catch (ioexception e) {
                e.printstacktrace();
              }
            }
          }
        }
      }.start();
    }

这里我们是需要把图片保存到内存卡中，所以考虑到了android 6.0的运行时权限，所以小伙伴们也一定要判断哦，我在oncreate的时候就判断了：

if (build.version.sdk_int >= build.version_codes.m) {
      if (contextcompat.checkselfpermission(this, manifest.permission.write_external_storage)
          != packagemanager.permission_granted) {
        requestalertwindowpermission();
      }
    }

private static final int request_code = 1;
  private void requestalertwindowpermission() {
    activitycompat.requestpermissions(this,new string[]{manifest.permission.write_external_storage},request_code);
  }

下面就是讲长按图片保存至相册了：

 mimageview.setonlongclicklistener(new view.onlongclicklistener(){
      @override
      public boolean onlongclick(view v) {
        if(mimageview.getdrawable() instanceof bitmapdrawable){
          toast.maketext(getapplicationcontext(),"长按保存图片至相册",toast.length_short).show();
          file filedir=new file(getapplication().getexternalcachedir(),"images");
          file file=new file(filedir.getabsolutepath()+"/"+image_url.hashcode()+".png");
          if(file!=null&&file.length()>0){
            camerarollmanager rollmanager=new camerarollmanager(mainactivity.this, uri.parse(file.getabsolutepath()));
            rollmanager.execute();
          }
        }
        return false;
      }
    });

camerarollmanager是我直接copy的reactnatvie中的android模块的代码：

camerarollmanager.java

package com.leo.camerroll.camera;

import android.content.context;
import android.content.intent;
import android.media.mediascannerconnection;
import android.net.uri;
import android.os.environment;
import android.os.handler;
import android.os.looper;
import android.os.message;
import android.widget.toast;

import java.io.file;
import java.io.fileinputstream;
import java.io.fileoutputstream;
import java.io.ioexception;
import java.nio.channels.filechannel;

/**
 * created by leo on 17/1/22.
 */

public class camerarollmanager extends guardedasynctask{
  private static context mcontext;
  private final uri muri;
  private static handler handler=new handler(looper.getmainlooper()){
    @override
    public void handlemessage(message msg) {
      toast.maketext(mcontext,"保存成功！",toast.length_short).show();
      intent intent = new intent();
      intent.settype("image/*");
      intent.setaction(intent.action_get_content);
      mcontext.startactivity(intent);
    }
  };
  public camerarollmanager(context context, uri uri) {
    super(context);
    mcontext = context;
    muri = uri;
  }

  @override
  protected void doinbackgroundguarded(object[] params) {
    file source = new file(muri.getpath());
    filechannel input = null, output = null;
    try {
      file exportdir = environment.getexternalstoragepublicdirectory(environment.directory_pictures);
      exportdir.mkdirs();
      if (!exportdir.isdirectory()) {
        return;
      }
      file dest = new file(exportdir, source.getname());
      int n = 0;
      string fullsourcename = source.getname();
      string sourcename, sourceext;
      if (fullsourcename.indexof('.') >= 0) {
        sourcename = fullsourcename.substring(0, fullsourcename.lastindexof('.'));
        sourceext = fullsourcename.substring(fullsourcename.lastindexof('.'));
      } else {
        sourcename = fullsourcename;
        sourceext = "";
      }
      while (!dest.createnewfile()) {
        dest = new file(exportdir, sourcename + "_" + (n++) + sourceext);
      }
      input = new fileinputstream(source).getchannel();
      output = new fileoutputstream(dest).getchannel();
      output.transferfrom(input, 0, input.size());
      input.close();
      output.close();

      mediascannerconnection.scanfile(
          mcontext,
          new string[]{dest.getabsolutepath()},
          null,
          new mediascannerconnection.onscancompletedlistener() {
            @override
            public void onscancompleted(string path, uri uri) {
              handler.sendemptymessage(0);
            }
          });
    } catch (ioexception e) {
    } finally {
      if (input != null && input.isopen()) {
        try {
          input.close();
        } catch (ioexception e) {
        }
      }
      if (output != null && output.isopen()) {
        try {
          output.close();
        } catch (ioexception e) {
        }
      }
    }
  }
}

guardedasynctask.java:

package com.leo.camerroll.camera;

import android.content.context;
import android.os.asynctask;

/**
 * created by leo on 17/1/22.
 */

public abstract class guardedasynctask <params, progress>
    extends asynctask<params, progress, void> {

  private final context mreactcontext;

  protected guardedasynctask(context reactcontext) {
    mreactcontext = reactcontext;
  }

  @override
  protected final void doinbackground(params... params) {
    try {
      doinbackgroundguarded(params);
    } catch (runtimeexception e) {
    }
    return null;
  }

  protected abstract void doinbackgroundguarded(params... params);
}

好啦！！！ 看着简单哈，花了我一个上午的时间，还是自己不熟练的原因额，感觉高了一段时间rn，结果android原生又生疏了，小伙伴们如果也像我一样的话，一定要常练习哦，两个东西都是需要常敲的那种，不然又忘记了！！！

最后附上demo的git链接：
https://github.com/913453448/camerroll

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。