一、網狀圖片查看器需求
存在一個Web伺服器,其中存在一個圖片,在Android用戶端能夠訪問這張圖片並在Android用戶端顯示;
當點擊“提交”後,則會顯示指定伺服器的圖片;
需要注意的一點是:我們不能使用localhost表示本機,而需要使用區域網路的IP地址,否則會拋Connection confused異常;
二、核心代碼介紹
在AndroidManifest.xml中加入:
<uses-permission android:name="android.permission.INTERNET"/>
(1)URL url = new URL("http://....."); //將字串轉為URL類型
(2)HttpURLConnection conn = (HttpURLConnection)url.openConnection();
(3)conn.setRequestMethod("GET"); //佈建要求方法,如GET POST
(4)conn.setReadTimeout(milliseconds); //設定讀逾時時間
(5)int code = conn.getResponseCode(); //獲得響應碼,如200表示OK,404表示無資源
(6)InputStream in = conn.getInputStream(); //獲得輸入資料流
(7)Bitmap bitmap = BitmapFactory.decodeByteArray(byte[]data,int begin,int length); // 根據byte[] 轉變為位元影像
(8)imageView.setImageBitmap(Bitmap bitmap);
三、全部代碼
搭建Web伺服器的過程我就忽略了,此處我們使用最常用的Tomcat,版本為7.0.6;
MainActivity.java
package org.xiazdong.view.image;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Bundle;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 MainActivity extends Activity {private EditText editText;private Button button;private ImageView imageView;private OnClickListener listener = new OnClickListener(){@Overridepublic void onClick(View v) {Bitmap bitmap = null;try {bitmap = getImage(editText.getText().toString());} catch (Exception e) {e.printStackTrace();Toast.makeText(MainActivity.this, "擷取圖片失敗",Toast.LENGTH_SHORT).show();}if(bitmap!=null)imageView.setImageBitmap(bitmap);else{Toast.makeText(MainActivity.this, "擷取圖片失敗",Toast.LENGTH_SHORT).show();}}private Bitmap getImage(String path) throws Exception {URL url = new URL(path);HttpURLConnection con = (HttpURLConnection) url.openConnection();byte[]data ;con.setRequestMethod("GET");if(con.getResponseCode()==200){InputStream in = con.getInputStream();data = read2Byte(in);return BitmapFactory.decodeByteArray(data, 0, data.length);}else return null;}};@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); editText = (EditText)this.findViewById(R.id.imagepath); button = (Button)this.findViewById(R.id.button); imageView = (ImageView)this.findViewById(R.id.imageview); button.setOnClickListener(listener); }private byte[] read2Byte(InputStream in) throws IOException {byte[] data;ByteArrayOutputStream bout = new ByteArrayOutputStream();byte[]buf = new byte[1024];int len = 0;while((len = in.read(buf))!=-1){bout.write(buf, 0, len);}data = bout.toByteArray();return data;}}
main.xml
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 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="圖片路徑" /> <!-- 此處不能用localhost,一定要用ip地址 --> <EditText android:id="@+id/imagepath" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="http://192.168.0.103:8080/Server/logo.png" /> <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="提交" /> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/imageview" /></LinearLayout>