android从网络中获得一张图片，并显示在屏幕上

1：androidmanifest.xml的内容

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="cn.capinftotech.image"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".MainActivity"
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>
<uses-sdk android:minSdkVersion="8" />
<uses-permission android:name="android.permission.INTERNET" />

</manifest>

注意访问网络中的数据需要添加android.permission.INTERNET权限
2：MainActivity的内容

package cn.capinftotech.image;

import java.io.IOException;

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

import com.capinfotech.service.ImageService;

public class MainActivity extends Activity {
private static final String TAG = "MainActivity";

private EditText urlPath = null;
private Button button = null;
private ImageView imageView = null;

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

urlPath = (EditText)findViewById(R.id.urlpath);
button = (Button)findViewById(R.id.button);
imageView = (ImageView)findViewById(R.id.imageView);

button.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
String urlPathContent = urlPath.getText().toString();
try {
byte[] data = ImageService.getImage(urlPathContent);
Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);  //生成位图
imageView.setImageBitmap(bitmap);   //显示图片
} catch (IOException e) {
Toast.makeText(MainActivity.this, R.string.error, Toast.LENGTH_LONG).show();  //通知用户连接超时信息
Log.i(TAG, e.toString());
}

}
});
}
}

3：ImageService类的内容

package com.capinfotech.service;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import com.capinfotech.utils.StreamTool;

public class ImageService {

public static byte[] getImage(String path) throws IOException {
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestMethod("GET");   //设置请求方法为GET
conn.setReadTimeout(5*1000);    //设置请求过时时间为5秒
InputStream inputStream = conn.getInputStream();   //通过输入流获得图片数据
byte[] data = StreamTool.readInputStream(inputStream);     //获得图片的二进制数据
return data;

}
}

4：StreamTool的内容

package com.capinfotech.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class StreamTool {

/*
* 从数据流中获得数据
*/
public static  byte[] readInputStream(InputStream inputStream) throws IOException {
byte[] buffer = new byte[1024];
int len = 0;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
while((len = inputStream.read(buffer)) != -1) {
bos.write(buffer, 0, len);
}
bos.close();
return bos.toByteArray();

}
}

5：程序中用到的字符串资源strings.xml里的内容

<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="hello">Hello World, MainActivity!</string>
<string name="app_name">图片浏览器</string>
<string name="urlpath">网络图片地址</string>
<string name="button">显示</string>
<string name="error">网络连接超时</string>
</resources>

6：程序布局文件main.xml的内容

<?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"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/urlpath"
/>
<EditText
android:id="@+id/urlpath"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="http://www.eoeandroid.com/data/attachment/forum/201107/18/142935bbi8d3zpf3d0dd7z.jpg"
/>
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/button"
/>
<ImageView
android:id="@+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</LinearLayout>

7：程序界面及测试结果