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                        /Android攻城狮的第二门课（第1季）

关于网络权限，访问网络图片

下面是使用到的三个文件：

为什么显示不了图片呢？

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.imooc.summenudemo"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk

android:minSdkVersion="8"

android:targetSdkVersion="18" />

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

<application

android:allowBackup="true"

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name="com.imooc.summenudemo.MainActivity"

android:label="@string/app_name"

android:theme="@android:style/Theme.Light.NoTitleBar"

<activity

android:name="com.imooc.summenudemo.ImageActivity"

android:label="@string/app_name"

android:theme="@android:style/Theme.Light.NoTitleBar"

<intent-filter>

</intent-filter>

</activity>

</application>

</manifest>

image_view.xml

<LinearLayout

xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:orientation="vertical" >

<TextView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="显示" />

<ImageView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:id="@+id/image" />

</LinearLayout>

ImageActivity.java

package com.imooc.summenudemo;

import java.io.IOException;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.MalformedURLException;

import java.net.URL;

import android.os.Bundle;

import android.app.Activity;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.widget.ImageView;

public class ImageActivity extends Activity {

/** Called when the activity is first created. */

String imageUrl = "http://content.52pk.com/files/100623/2230_102437_1_lit.jpg";

Bitmap bmImg;

ImageView imView;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

imView = (ImageView) findViewById(R.id.image);

imView.setImageBitmap(returnBitMap(imageUrl));

}

public Bitmap returnBitMap(String url){

URL myFileUrl = null;

Bitmap bitmap = null;

try {

myFileUrl = new URL(url);

} catch (MalformedURLException e) {

e.printStackTrace();

}

try {

HttpURLConnection conn = (HttpURLConnection) myFileUrl

.openConnection();

conn.setDoInput(true);

conn.connect();

InputStream is = conn.getInputStream();

bitmap = BitmapFactory.decodeStream(is);

is.close();

} catch (IOException e) {

e.printStackTrace();

}

return bitmap;

}

NeverGiveUp7

2015-12-18

源自：Android攻城狮的第二门课（第1季） 1-4

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1 回答

乔小欠儿回答被采纳 +3 积分
2015-12-18

网络请求属于耗时代码，在4.0以上的版本中是不能把耗时代码放在主线程中运行的。

你的returnBitMap(imageUrl)显示是耗时代码，放在主线程中所以不行。跟网络权限没关系，因为你已经打开网络权限了。

下面是我修改后的代码，只供测试使用，真实写项目还需优化。

public class MainActivity extends AppCompatActivity {

String imageUrl = "http://content.52pk.com/files/100623/2230_102437_1_lit.jpg";

static Bitmap bmImg;

static ImageView imView;
static MyHandler handler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imView = (ImageView) findViewById(R.id.imageview);
handler = new MyHandler();
new Thread(new Runnable() {
@Override
public void run() {
bmImg = returnBitMap(imageUrl);
handler.sendEmptyMessage(0);
}
}).start();

}

public Bitmap returnBitMap(String url){

URL myFileUrl = null;

Bitmap bitmap = null;

try {

myFileUrl = new URL(url);

} catch (MalformedURLException e) {

e.printStackTrace();

}

try {

HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();

conn.setDoInput(true);

conn.connect();

InputStream is = conn.getInputStream();

bitmap = BitmapFactory.decodeStream(is);

is.close();

} catch (IOException e) {

e.printStackTrace();

}

return bitmap;

}

public static class MyHandler extends Handler{
@Override
public void handleMessage(Message msg) {
// super.handleMessage(msg);
imView.setImageBitmap(bmImg);
}
}

}