安卓開發：SmartImageView簡單實現和應用

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通常從伺服器端擷取的圖片是URL地址，如果簡單地通過URL地址擷取圖片？

有一個開源項目：SmartImageView，做到了這個功能，同時還有其他功能，下載不便，過於龐大

這裡自己實現它的這個簡易功能

 

代碼：

package org.dreamtech.smartimageview;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;import android.annotation.SuppressLint;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Handler;import android.os.Message;import android.util.AttributeSet;import android.widget.ImageView;public class MySmartImageView extends ImageView {    protected static final int REQUESTSUCCESS = 1;    protected static final int REQUESTFAIL = 2;    protected static final int ERROR = 3;    @SuppressLint("HandlerLeak")    private Handler handler = new Handler() {        public void handleMessage(android.os.Message msg) {            switch (msg.what) {            case REQUESTSUCCESS:                Bitmap bitmap = (Bitmap) msg.obj;                MySmartImageView.this.setImageBitmap(bitmap);                break;            case REQUESTFAIL:                int default_resource = (Integer) msg.obj;                MySmartImageView.this.setBackgroundResource(default_resource);                break;            case ERROR:                int resource = (Integer) msg.obj;                MySmartImageView.this.setBackgroundResource(resource);                break;            }        };    };    // The construction methods of the parent class    public MySmartImageView(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);    }    public MySmartImageView(Context context, AttributeSet attrs) {        super(context, attrs);    }    public MySmartImageView(Context context) {        super(context);    }    // A method of displaying pictures    // path:The parameters of URL transmission    public void setImageUrl(final String path) {        new Thread() {            public void run() {                try {                    URL url = new URL(path);                    HttpURLConnection conn = (HttpURLConnection) url                            .openConnection();                    conn.setRequestMethod("GET");                    conn.setConnectTimeout(5000);                    int code = conn.getResponseCode();                    if (code == 200) {                        InputStream in = conn.getInputStream();                        Bitmap bitmap = BitmapFactory.decodeStream(in);                        Message msg = Message.obtain();                        msg.obj = bitmap;                        handler.sendMessage(msg);                    }                } catch (Exception e) {                    e.printStackTrace();                }            };        }.start();    }    // A method of displaying pictures(Overloading method)    // path:The parameters of URL transmission    // resource:Default resources(If you can‘t find a resource through this URL)    public void setImageUrl(final String path, final int resource) {        new Thread() {            public void run() {                try {                    URL url = new URL(path);                    HttpURLConnection conn = (HttpURLConnection) url                            .openConnection();                    conn.setRequestMethod("GET");                    conn.setConnectTimeout(5000);                    int code = conn.getResponseCode();                    if (code == 200) {                        InputStream in = conn.getInputStream();                        Bitmap bitmap = BitmapFactory.decodeStream(in);                        Message msg = Message.obtain();                        msg.what = REQUESTSUCCESS;                        msg.obj = bitmap;                        handler.sendMessage(msg);                    } else {                        Message msg = Message.obtain();                        msg.what = REQUESTFAIL;                        msg.obj = resource;                        handler.sendMessage(msg);                    }                } catch (Exception e) {                    Message msg = Message.obtain();                    msg.what = ERROR;                    msg.obj = resource;                    handler.sendMessage(msg);                }            };        }.start();    }}

 

 

兩個重載方法：

1：明確URL地址正確、不會失誤，直接調用

2：防止圖片URL出錯，設定預設資源，傳兩個參數

 

測試下：

package org.dreamtech.smartimageview;import android.os.Bundle;import android.app.Activity;import android.view.Menu;public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        MySmartImageView iv = (MySmartImageView) findViewById(R.id.iv);        iv.setImageUrl(                "http://fanyi.bdstatic.com/static/translation/img/header/logo_cbfea26.png",                R.drawable.default_ic);    }}

 

布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <org.dreamtech.smartimageview.MySmartImageView        android:id="@+id/iv"        android:layout_width="wrap_content"        android:layout_height="wrap_content"         /></RelativeLayout>

 

 

這裡是一個正確地URL地址，結果如下：

 

 

接下來，我把URL地址改成錯誤的：

 

結果：

 

好的，完成！

安卓開發：SmartImageView簡單實現和應用