Android10--Android之异步任务加载网页和图片

来源：互联网发布：电子图书数据库有哪些编辑：程序博客网时间：2024/06/04 19:34

今天介绍的是一个简单的从网上获取网页和图片,我们将其做成工具类,再使用时只需要传入相应的参数即可.

首先我们定义一个要获取的一个类型Entry:因为设计到Gson解析,我们不要忘记给没个属性加上注解.

public class Entry {    @SerializedName("title")    private String title;    @SerializedName("message")    private String message;    @SerializedName("img")    private String image;    public String getTitle() {        return title;    }    public void setTitle(String title) {        this.title = title;    }    public String getMessage() {        return message;    }    public void setMessage(String message) {        this.message = message;    }    public String getImage() {        return image;    }    public void setImage(String image) {        this.image = image;    }}

图片加载类工具类:通用
这里对图片的加载做了三种处理:加载之前加载完成加载失败

public class ImageLoader extends AsyncTask<String, Void, Bitmap> {    private ImageView image;    public ImageLoader(ImageView image) {        this.image = image;    }    @Override    protected void onPreExecute() {        super.onPreExecute();        image.setImageResource(R.mipmap.coming);    }    @Override    protected Bitmap doInBackground(String... params) {        String url = params[0];        try {            HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();            connection.setRequestMethod("GET");            connection.setDoInput(true);            int code = connection.getResponseCode();            if (code == 200) {                InputStream is = connection.getInputStream();                return BitmapFactory.decodeStream(is);            }        } catch (IOException e) {            e.printStackTrace();        }        return null;    }    @Override    protected void onPostExecute(Bitmap bitmap) {        super.onPostExecute(bitmap);        if (bitmap != null) {            image.setImageBitmap(bitmap);        } else {            image.setImageResource(R.mipmap.ic_launcher);        }    }}

解析一个网页工具类:通用
只需传入要解析的网址,和要解析成的Class,之后再去开启这个异步线程

public class NetworkTask<T> extends AsyncTask<NetworkTask.Callback<T>, Void, Object> {    private Callback<T> callback;    private String url;    private Class<T> t;    public NetworkTask(String url, Class<T> t) {        this.url = url;        this.t = t;    }    @Override    protected Object doInBackground(Callback<T>... params) {        callback = params[0];        try {            HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();            connection.setRequestMethod("GET");            connection.setDoInput(true);            int code = connection.getResponseCode();            if (code == 200) {                InputStream is = connection.getInputStream();                ByteArrayOutputStream bos = new ByteArrayOutputStream();                int length;                byte[] buffer = new byte[102400];                while ((length = is.read(buffer)) != -1){                    bos.write(buffer, 0, length);                }                Gson gson = new Gson();                return gson.fromJson(bos.toString("UTF-8"), t);            } else {                return new RuntimeException("ResponseCode: " + code);            }        } catch (IOException e) {            return e;        }    }    @Override    protected void onPostExecute(Object o) {        super.onPostExecute(o);        if (t.isInstance(o)) {            callback.onSuccess((T) o);        } else if (o instanceof Exception) {            callback.onFail((Exception) o);        }    }    public interface Callback<S> {        void onSuccess(S text);        void onFail(Exception e);    }}

为了让加载之后的图片显示和网页内容一起滑动:我们使用的ScrollView,但是要注意ScrollView中只能放置一个控件.一般是一个布局

<ScrollView        android:layout_width="match_parent"        android:layout_height="match_parent">        <LinearLayout            android:layout_width="match_parent"            android:layout_height="match_parent"            android:orientation="vertical">            <ImageView                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:id="@+id/main2_image"/>            <WebView                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:id="@+id/main2_web"/>        </LinearLayout>    </ScrollView>

测试类:
用webView承载一个网页的内容时,如果是图文混排,里面的图片可能会超出屏幕的宽度,我们可以加上:
private static final String CSS = "<style>img{max-width:100%}</style>";

public class Main2Activity extends AppCompatActivity implements NetworkTask.Callback<Entry>{    private WebView web;    private ImageView image;    private static final String CSS = "<style>img{max-width:100%}</style>";    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main2);        web = (WebView) findViewById(R.id.main2_web);        image = (ImageView) findViewById(R.id.main2_image);        new NetworkTask<>("http://www.tngou.net/api/top/show?id=13122", Entry.class).execute(this);    }    @Override    public void onSuccess(Entry entry) {        setTitle(entry.getTitle());        new ImageLoader(image).execute("http://tnfs.tngou.net/img" + entry.getImage());        web.loadDataWithBaseURL("http://www.tngou.net", CSS + entry.getMessage(), "text/html; charset=utf-8", "UTF-8", null);    }    @Override    public void onFail(Exception e) {        e.printStackTrace();        Toast.makeText(Main2Activity.this, "网络错误", Toast.LENGTH_SHORT).show();    }}

这里写图片描述

下一篇讲引入动态接口:将之中的工具类打包为另一个Liabray,在喜爱次使用时只要import即可..
http://blog.csdn.net/u012954720/article/details/52398370

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