Question

这是我第一次发帖，在输入我的头衔之后，我已经完成了所有相关问题并且仍然遇到了麻烦。简单明了，人们将图像网址输入和EditText，他们点击一个按钮，图像出现在按钮下面。我正在使用BitmapFactory并需要保持这种方式。我还有AndroidManifest.xml已经包含相应的INTERNET权限。

Java就是这样：

package com.display.picture;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;

import android.app.Activity;
import android.os.Bundle;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;

public class DisplayPictureActivity extends Activity {

    private EditText et;
    private Button btn;
    private ImageView iv;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        et = (EditText) findViewById(R.id.et1);
        iv = (ImageView) findViewById(R.id.iv1);
        btn = (Button) findViewById(R.id.btn1);

        btn.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                try
                {
                    URL url = new URL(et.getText().toString());
                    URLConnection connection = url.openConnection();
                    connection.connect();
                    InputStream is = connection.getInputStream();
                    BufferedInputStream bis = new BufferedInputStream(is);
                    Bitmap bitmap = BitmapFactory.decodeStream(bis);
                    ImageView myImage = (ImageView) findViewById(R.id.iv1);
                    myImage.setImageBitmap(bitmap);
                    bis.close();
                    is.close();
                }
                catch (Exception e) {
                    Toast toast = Toast.makeText(getBaseContext(), "Failed to Download Image", Toast.LENGTH_LONG);
                    toast.show();
                }
                Bitmap image = null;
                iv.setImageBitmap(image);
            }
        });
    }
}

我在这里看到的大部分问题涉及硬编码的超链接。在这里，我应该允许用户输入图像网址然后通过位图传递，并在按下按钮后在图像视图中显示它

我的清单：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.display.picture"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".DisplayPictureActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

Answer 1

确保您在清单文件中设置了互联网权限

<uses-permission android:name="android.permission.INTERNET"/>

您正在尝试关闭输入流和使用输入流的缓冲输入流，删除其中一个关闭将修复抛出的异常。

您可能还想使用AsyncTask来执行下载，因为在下载过程中阻止UI通常不是一个好主意。

以下是修改后的代码以使用AsyncTask下载：

public class DisplayPictureActivity extends Activity {
private Button btn;
private EditText et;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    btn = (Button)findViewById(R.id.button1);
    et = (EditText)findViewById(R.id.editText1);

    btn.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            try {
                URL url = new URL(et.getText().toString());
                //URL url = new URL("http://farm7.static.flickr.com/6138/5935946400_934994190e_s_d.jpg");
                new MyDownloadTask().execute(url);                                  
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

private class MyDownloadTask extends AsyncTask<URL, Integer, Bitmap> {
    @Override
    protected Bitmap doInBackground(URL... params) {
        URL url = params[0];
        Bitmap bitmap = null;
        try {
            URLConnection connection = url.openConnection();
            connection.connect();
            InputStream is = connection.getInputStream();
            BufferedInputStream bis = new BufferedInputStream(is);
            bitmap = BitmapFactory.decodeStream(bis);
            bis.close();
            //is.close(); THIS IS THE BROKEN LINE
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }

        return bitmap;
    }

    @Override
    protected void onPostExecute(Bitmap bitmap) {
        if (bitmap != null) {
            ImageView myImage = (ImageView) findViewById(R.id.imageView1);
            myImage.setImageBitmap(bitmap);
        } else {
            Toast.makeText(getApplicationContext(), "Failed to Download Image", Toast.LENGTH_LONG).show();
        }
    }       
}

}

使用输入的URL和按钮显示URL中的图像

1 个答案: