问题描述

android下载图片过大导致报错

package tarena.day2801;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;

public class MainActivity extends Activity {

private Button button;
private ImageView img;
private String image_Path = "http://2.javatl.sinaapp.com/images/51d8c1d77fed4.jpg";
private ProgressDialog dialog;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    button = (Button) findViewById(R.id.button1);
    img = (ImageView) findViewById(R.id.imageView1);
    LinearLayout rl = (LinearLayout) findViewById(R.id.lr);

    ImageView img = new ImageView(this);
    DisplayMetrics dm = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(dm);
    int height = dm.heightPixels/3;
    int width = dm.widthPixels / 2;
    LayoutParams params = new LayoutParams(width, height);
    img.setLayoutParams(params);
    rl.setGravity(Gravity.CENTER);
    img.setImageResource(R.drawable.ic_launcher);

    dialog = new ProgressDialog(this);
    dialog.setTitle("提示信息");
    dialog.setMessage("正在下载，请稍候...");
    button.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            new MYTask().execute(image_Path);
        }
    });
}

/**
 * 使用异步任务的规则： 1、申明的类继承AsyncTask 标注三个参数的类型
 * 2、第一个参数表示要执行的任务，通常是网络的路径；第二个参数表示进度的刻度，第三个参数表示任务执行的返回结果
 *
 * @author liende
 *
 */
public class MYTask extends AsyncTask<String, Void, Bitmap> {
    /**
     * 表示任务执行之前的操作
     */
    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        super.onPreExecute();
        dialog.show();
    }

    /**
     * 主要是完成耗时的操作
     */
    @Override
    protected Bitmap doInBackground(String... arg0) {
        // TODO Auto-generated method stub
        // 使用网络连接类HttpClient类王城对网络数据的提取
        HttpClient httpClient = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet(arg0[0]);
        Bitmap bitmap = null;
        try {
            HttpResponse httpResponse = httpClient.execute(httpGet);
            if (httpResponse.getStatusLine().getStatusCode() == 200) {
                HttpEntity httpEntity = httpResponse.getEntity();
                byte[] data = EntityUtils.toByteArray(httpEntity);
                bitmap = BitmapFactory
                        .decodeByteArray(data, 0, data.length);

//在这里调用压缩方法

                                    bitmap = compressImage(bitmap);
            }
        } catch (Exception e) {
            // TODO: handle exception
        }

        return bitmap;

    }

    /**
     * 主要是更新UI的操作
     */
    @Override
    protected void onPostExecute(Bitmap bitmap) {
        // TODO Auto-generated method stub

        super.onPostExecute(bitmap);
         Bitmap bmcopy = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
            Paint paint = new Paint();
            Canvas canvas = new Canvas(bmcopy);
            Matrix mt = new Matrix();
            mt.setRotate(30, bmcopy.getWidth()/2, bmcopy.getHeight()/2);
            //mt.setScale(0.5f, 2);
            canvas.drawBitmap(bitmap, mt, paint);           

        img.setImageBitmap(bmcopy);
        dialog.dismiss();
    }

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

** //图片压缩方法**

 private Bitmap compressImage(Bitmap image) {

    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    image.compress(Bitmap.CompressFormat.JPEG, 100, baos);//质量压缩方法，这里100表示不压缩，把压缩后的数据存放到baos中
    int options = 100;
    while ( baos.toByteArray().length / 1024>100) {    //循环判断如果压缩后图片是否大于100kb,大于继续压缩
        baos.reset();//重置baos即清空baos
        image.compress(Bitmap.CompressFormat.JPEG, options, baos);//这里压缩options%，把压缩后的数据存放到baos中
        options -= 10;//每次都减少10

    }
    ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());//把压缩后的数据baos存放到ByteArrayInputStream中
    Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);//把ByteArrayInputStream数据生成图片
    return bitmap;
}

}

明明调用了图片压缩方法，但是不知道为什么运行的时候还是崩溃

解决方案

你那个压缩循环有问题，压缩已经压缩过的东西基本没有效果的。所以，如果你第一次JPEG压缩不能达到100kb一下的话，那么这个while基本就是个死循环。

解决方案二：

推荐使用Universal-ImageLoader.