Android之ProgressBar初步應用，androidprogressbar

Android之ProgressBar初步應用，androidprogressbar

這裡利用 ProgressBar 即時顯示下載進度。

途中碰到的問題：

1、主線程中不能打開 URL，和只能在主線程中使用 Toast 等

2、子線程不能修改 UI

3、允許網絡協議

4、暫停下載和繼續下載

　 ........

 

 

fragment_main 布局文件

1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 tools:context="com.dragon.android.textbar.MainActivity$PlaceholderFragment" > 6 7 <!-- prigressBar 進度條 --> 8 <!-- progress 當前進度 --> 9 <!-- indeterminate 不明確的 默認false --> 10 <ProgressBar 11 android:id="@+id/progressBar1" 12 13 android:layout_width="match_parent" 14 android:layout_height="wrap_content" 15 android:layout_centerInParent="true" 16 android:max="100" 17 android:progress="0" 18 android:indeterminate="true"/> 19 20 <Button 21 android:id="@+id/button1" 22 android:layout_width="wrap_content" 23 android:layout_height="wrap_content" 24 android:layout_alignParentTop="true" 25 android:layout_centerHorizontal="true" 26 android:onClick="startLoad" 27 android:layout_marginTop="86dp" 28 android:background="#009FEE" 29 android:text="@string/start" 30 android:textColor="#ffffff" /> 31 32 <TextView 33 android:id="@+id/textView1" 34 android:layout_width="wrap_content" 35 android:layout_height="wrap_content" 36 android:layout_above="@+id/progressBar1" 37 android:background="@null" 38 android:layout_alignParentLeft="true" /> 39 40 </RelativeLayout> fragment_main

strings.xml

1 <?xml version="1.0" encoding="utf-8"?> 2 <resources> 3 4 <string name="app_name">hwdownload</string> 5 <string name="hello_world">Hello world!</string> 6 <string name="action_settings">Settings</string> 7 <string name="start">開始</string> 8 <string name="stop">暫停</string> 9 <string name="contin">繼續</string> 10 11 </resources> strings

（問題3）在 AndroidManifest 文件中配置

1 <!-- 請求網絡權限 -->
2     <uses-permission  android:name="android.permission.INTERNET"/>

MainActivity（問題1、2）

package com.dragon.android.textbar;

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

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

/**
 * 只有創建一個 View 的線程才可以改變這個 View 的UI!!! 主線程也叫 UI 線程
 */
public class MainActivity extends Activity {
    private ProgressBar progressBar1;
    private Button button1;
    private TextView textView1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_main);

        progressBar1 = (ProgressBar) findViewById(R.id.progressBar1);
        button1 = (Button) findViewById(R.id.button1);
        textView1 = (TextView) findViewById(R.id.textView1);

    }

    public void startLoad(View view) {
         String text = (String) button1.getText();
        // 設置按鈕內容 ----並沒有用...
        button1.setText(text.equals(getResources().getString(R.string.start)) ? R.string.stop
                : (text.equals(getResources().getString(R.string.stop)) ? R.string.contin
                        : R.string.stop));
        progressBar1.setIndeterminate(false);

        new Thread(new Runnable() {
            private int percent;

            @Override
            public void run() {
                try {
                    // 打開 URL 必須在子線程
                    URL url = new URL(
                            "http://b.zol-img.com.cn/sjbizhi/images/9/540x960/1472549276394.jpg");
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    // conn.setRequestMethod("GET");
                    // conn.setReadTimeout(5000);
                    // conn.setConnectTimeout(5000);

                    int contentLength = conn.getContentLength();

                    if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
                        InputStream is = conn.getInputStream();

                        byte[] buffer = new byte[1024];
                        int len = -1;
                        int sum = 0;
                        while ((len = is.read(buffer)) != -1) {
                            sum += len;
                            // 注意強轉方式，防止一直為0
                            percent = (int) (100.0 * sum / contentLength);

                            // 在主線程上運行的子線程
                            runOnUiThread(new Runnable() {

                                @Override
                                public void run() {
                                    progressBar1.setProgress(percent);
                                    textView1.setText(percent + "%");
                                    if (percent == progressBar1.getMax()) {
                                        Toast.makeText(MainActivity.this,
                                                "下載完成!", Toast.LENGTH_SHORT)
                                                .show();
                                    }
                                }
                            });
                        }
                        is.close();
                        conn.disconnect();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
}

**************然而並沒有解決問題4,要用斷點續傳,但是還不會存放assets資源.....***************