Android编程实现下载图片及在手机中展示的方法

本文实例讲述了android编程实现下载图片及在手机中展示的方法。分享给大家供大家参考，具体如下：

在项目开发中从互联网上下载图片是经常用到的功能，再次总结一下

1.普通的下载方式

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<linearlayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent">
 <imageview android:src="@drawable/icon"
   android:layout_width="wrap_content"
   android:id="@+id/imgpic"
   android:layout_gravity="center|center_vertical"
   android:layout_height="fill_parent">
 </imageview>
</linearlayout>

java文件

public class downloadimage extends activity {
  private imageview imgpic;
  @override
  protected void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.download_image);
    imgpic = (imageview) findviewbyid(r.id.imgpic);
    string url = "http://ww1.sinaimg.cn/bmiddle/6834c769jw1djjf4p3p9rj.jpg";
    loadrmoteimage(url);
  }
  /**
   * @param imgurl
   *   远程图片文件的url
   *
   *   下载远程图片
   */
  private void loadrmoteimage(string imgurl) {
    url fileurl = null;
    bitmap bitmap = null;
    try {
      fileurl = new url(imgurl);
    } catch (malformedurlexception err) {
      err.printstacktrace();
    }
    try {
      httpurlconnection conn = (httpurlconnection) fileurl
          .openconnection();
      conn.setdoinput(true);
      conn.connect();
      inputstream is = conn.getinputstream();
      int length = (int) conn.getcontentlength();
      if (length != -1) {
        byte[] imgdata = new byte[length];
        byte[] buffer = new byte[512];
        int readlen = 0;
        int destpos = 0;
        while ((readlen = is.read(buffer)) > 0) {
          system.arraycopy(buffer, 0, imgdata, destpos, readlen);
          destpos += readlen;
        }
        bitmap = bitmapfactory.decodebytearray(imgdata, 0,
            imgdata.length);
      }
    } catch (ioexception e) {
      e.printstacktrace();
    }
    imgpic.setimagebitmap(bitmap);
  }

2.带进度条的下载

有时候网络差，或者是图片太大，会出现黑屏的情况，用户体验比较差，那么增加一个进度条是提高用户体验的好方法

/**
 * @author xushilin xsl [e-mail]
 * @version： 创建时间：2011-7-27 下午02:55:56
 * 说 明: android中下载图片
 * 修改历史：
 */
public class downloadimage extends activity {
  private imageview imgpic;
  private progressbar progressbar;
  private int totalsize=0;
  private int size=0;
  private handler mhandler;
  string url = "http://ww1.sinaimg.cn/bmiddle/6834c769jw1djjf4p3p9rj.jpg";
  private bitmap bitmap=null;
  @override
  protected void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.download_image);
    imgpic = (imageview) findviewbyid(r.id.imgpic);
    progressbar = (progressbar) findviewbyid(r.id.progressbar);
    progressbar.setprogress(getprogressint(progressbar.getmax()));
    mhandler = new handler() {
      public void handlemessage(message msg) {
        progressbar.setprogress(getprogressint(progressbar.getmax()));
        if(bitmap!=null){
          imgpic.setimagebitmap(bitmap);
        }
      }
    };
    new thread(){
      public void run(){
        loadrmoteimage(url);
      }
    }.start();
  }
  /**
   * @param imgurl
   *   远程图片文件的url
   *
   *   下载远程图片
   */
  private void loadrmoteimage(string imgurl) {
    url fileurl = null;
    try {
      fileurl = new url(imgurl);
    } catch (malformedurlexception err) {
      err.printstacktrace();
    }
    try {
      httpurlconnection conn = (httpurlconnection) fileurl
          .openconnection();
      conn.setdoinput(true);
      conn.connect();
      inputstream is = conn.getinputstream();
      int length = (int) conn.getcontentlength();
      totalsize=length;
      if (length != -1) {
        byte[] imgdata = new byte[length];
        byte[] buffer = new byte[512];
        int readlen = 0;
        int destpos = 0;
        while ((readlen = is.read(buffer)) > 0) {
          system.arraycopy(buffer, 0, imgdata, destpos, readlen);
          destpos += readlen;
          size=destpos;
          mhandler.sendemptymessage(1);
          thread.sleep(100);
        }
        bitmap = bitmapfactory.decodebytearray(imgdata, 0,
            imgdata.length);
        mhandler.sendemptymessage(1);
      }
    } catch (ioexception e) {
      e.printstacktrace();
    } catch (interruptedexception e) {
      e.printstacktrace();
    }
  }
  private int getprogressint(int max) {
    int result = (totalsize > 0) ? (int) (size * max * 1.0 / totalsize) : 0;
    return result;
  }
}

效果如下：

下载过程：

下载完成：

更多关于android相关内容感兴趣的读者可查看本站专题：《android图形与图像处理技巧总结》、《android开发入门与进阶教程》、《android调试技巧与常见问题解决方法汇总》、《android基本组件用法总结》、《android视图view技巧总结》、《android布局layout技巧总结》及《android控件用法总结》

希望本文所述对大家android程序设计有所帮助。