效果图如下:
1、AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.lesson" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="7" android:targetSdkVersion="7" /> <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=".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> </manifest>
2、activity_main.xml
<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" tools:context="${relativePackage}.${activityClass}" > <Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:layout_marginBottom="18dp" android:text="加载图片" /> <ImageView android:id="@+id/imageView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:layout_marginTop="20dp" /> </RelativeLayout>
3、MainActivity.java
package com.lesson; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import org.apache.http.HttpResponse; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.DefaultHttpClient; import android.app.Activity; import android.app.ProgressDialog; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.ImageView; import android.widget.ProgressBar; public class MainActivity extends Activity { private Button button; private ProgressDialog progerssDialog; private ImageView imageView;//要加载的图片 private int Thread1=1; private final String url="http://pic.4j4j.cn/upload/pic/20130701/d363891105.jpg"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); button=(Button)findViewById(R.id.button1); imageView=(ImageView)findViewById(R.id.imageView1); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { //加载图片时的进度显示对话框 progerssDialog=new ProgressDialog(MainActivity.this); progerssDialog.setTitle("loading"); progerssDialog.setMessage("正在加载中..."); //设置进度条水平加载 progerssDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); progerssDialog.show(); //添加子线程,用于发送消息给主线程 new Thread(new MyThread(url,Thread1,new MyHandler())).start(); } }); } class MyHandler extends Handler{ @Override public void handleMessage(Message msg) { super.handleMessage(msg); if(msg.what==Thread1){ imageView.setImageBitmap((Bitmap)msg.obj); progerssDialog.dismiss(); } } } class MyThread implements Runnable{ //声明用来标识url地址参数的变量 private String url; //声明用来标识线程id的变量 private int threadId=0; private Handler handler=null; //构造函数 public MyThread(String url,int threadId,Handler handler){ this.url=url; this.threadId=threadId; this.handler=handler; } @Override public void run() { HttpGet httpGet=new HttpGet(url); InputStream inputStream; byte[] result=null; byte[] data=new byte[1024]; HttpClient client = new DefaultHttpClient(); ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); try { HttpResponse httpResponse=client.execute(httpGet);//得到响应 if(httpResponse.getStatusLine().getStatusCode()==200){ inputStream=httpResponse.getEntity().getContent(); //文件总长度 int filelenth=(int) httpResponse.getEntity().getContentLength(); int readlength=0; int totallenth=0; while((readlength=inputStream.read(data))!=-1){ totallenth+=readlength; int progressValue= (int)((totallenth/(float)filelenth)*100); Log.i("progressValue",progressValue+""); progerssDialog.setProgress(progressValue); outputStream.write(data, 0, readlength); } result=outputStream.toByteArray(); //向handler发送消息 Message msg = new Message(); msg.what = threadId; Bitmap bitmap=BitmapFactory.decodeByteArray(result, 0, result.length); msg.obj=bitmap; handler.sendMessage(msg); } } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); }finally{ client.getConnectionManager().shutdown(); } } } }
注:ProgressDialog加载几种方式及注意点
// 方式一:new Dialog final ProgressDialog dialog = new ProgressDialog(this); dialog.show();
// 方式二:使用静态方式创建并显示,这种进度条只能是圆形条,设置title和Message提示内容 ProgressDialog dialog2 = ProgressDialog.show(this, "提示", "正在登陆中");
// 方式三 使用静态方式创建并显示,这种进度条只能是圆形条,这里最后一个参数boolean indeterminate设置是否是不明确的状态 ProgressDialog dialog3 = ProgressDialog .show(this, "提示", "正在登陆中", false);
// 方式四 使用静态方式创建并显示,这种进度条只能是圆形条,这里最后一个参数boolean cancelable 设置是否进度条是可以取消的 ProgressDialog dialog4 = ProgressDialog.show(this, "提示", "正在登陆中", false, true);
// 方式五 使用静态方式创建并显示,这种进度条只能是圆形条,这里最后一个参数 DialogInterface.OnCancelListener // cancelListener用于监听进度条被取消 ProgressDialog dialog5 = ProgressDialog.show(this, "提示", "正在登陆中", true, true, cancelListener);