无废话Android之内容观察者ContentObserver、获取和保存系统的联系人信息、网络图片查看器、网络html查看器、使用异步框架Android-Async-Http（4）

1.内容观察者ContentObserver
如果ContentProvider的访问者需要知道ContentProvider中的数据发生了变化，可以在ContentProvider 发生数据变化时调用getContentResolver().notifyChange(uri, null)来通知注册在此URI上的访问者，例子如下：
private static final Uri URI = Uri.parse("content://person.db");
public class PersonContentProvider extends ContentProvider {
    public Uri insert(Uri uri, ContentValues values) {
        db.insert("person", "personid", values);
        getContext().getContentResolver().notifyChange(uri, null);
    }
}
如果ContentProvider的访问者需要得到数据变化通知，必须使用ContentObserver对数据（数据采用uri描述）进行监听，当监听到数据变化通知时，系统就会调用ContentObserver的onChange()方法：
getContentResolver().registerContentObserver(Uri.parse("content://person.db"),
                true, new PersonObserver(new Handler()));
public class PersonObserver extends ContentObserver{
    public PersonObserver(Handler handler) {
        super(handler);
     }
    public void onChange(boolean selfChange) {
        //此处可以进行相应的业务处理
        Toast.makeText(MainActivity.this, "数据库内容发送变化了！", 0).show();
    }
}

.获取系统的联系人信息
public void getContacts(View view) {
        ContentResolver resolver = this.getContentResolver();
        Uri uri = Uri.parse("content://com.android.contacts/raw_contacts");
        Uri dataUri = Uri.parse("content://com.android.contacts/data");
        Cursor cursor = resolver.query(uri, null, null, null, null);
        if (cursor.moveToLast()) {
            String id = cursor.getString(cursor.getColumnIndex("contact_id"));
            if (id != null) {
                Cursor dataCursor = resolver.query(dataUri, null,"raw_contact_id=?", new String[] { id }, null);
                while (dataCursor.moveToNext()) {
                    String data1 = dataCursor.getString(dataCursor.getColumnIndex("data1"));
                    String mimetype = dataCursor.getString(dataCursor.getColumnIndex("mimetype"));
                    Toast.makeText(this, data1 + " = " + mimetype, 0).show();
                }
                dataCursor.close();
            } else {
                Toast.makeText(this, "空！", 0).show();
            }
        }

        cursor.close();
    }

 <uses-permission android:name="android.permission.READ_CONTACTS" />

 .保存联系人到系统通讯录
 public void writeContact(View view) {
        ContentResolver resolver = this.getContentResolver();
        Uri uri = Uri.parse("content://com.android.contacts/raw_contacts");
        Uri dataUri = Uri.parse("content://com.android.contacts/data");
        Cursor cursor = resolver.query(uri, new String[] { "_id" }, null, null,
                null);
        if (cursor.moveToLast()) {
            int lastId = cursor.getInt(0);
            int newId = lastId + 1;
            ContentValues values = new ContentValues();
            values.put("contact_id", newId);
            resolver.insert(uri, values);

            ContentValues phoneValues = new ContentValues();
            phoneValues.put("data1", "13500001111");
            phoneValues.put("mimetype", "vnd.android.cursor.item/phone_v2");
            phoneValues.put("raw_contact_id", newId);
            resolver.insert(dataUri, phoneValues);

            ContentValues emaiValues = new ContentValues();
            emaiValues.put("data1", "reality_jie@qq.com");
            emaiValues.put("mimetype", "vnd.android.cursor.item/email_v2");
            emaiValues.put("raw_contact_id", newId);
            resolver.insert(dataUri, emaiValues);
            ContentValues nameValues = new ContentValues();
            nameValues.put("data1", "weijie");
            nameValues.put("mimetype", "vnd.android.cursor.item/name");
            nameValues.put("raw_contact_id", newId);
            resolver.insert(dataUri, nameValues);
        }
        cursor.close();
        Toast.makeText(this, "保存成功", 0).show();

    }

<uses-permission android:name="android.permission.WRITE_CONTACTS" />

.网络图片查看器
public class MainActivity extends Activity {

        protected static final int UPDATE_UI = 1;
        protected static final int ERROR = 2;
        private ImageView iv_beauty;
        private EditText et_path;

        // 主线程创建消息处理器
        Handler handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                if (msg.what == UPDATE_UI) {
                    iv_beauty.setImageBitmap((Bitmap) msg.obj);
                } else {
                    Toast.makeText(getApplicationContext(), "图片获取失败！", 0)
                            .show();
                }
            }
        };

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            this.iv_beauty = (ImageView) this.findViewById(R.id.iv_beauty);
            this.et_path = (EditText) this.findViewById(R.id.et_path);
        }

        public void watch(View view) {
            final String path = this.et_path.getText().toString().trim();
            if (TextUtils.isEmpty(path)) {
                Toast.makeText(this, "路径不能为空", 0).show();
            } else {
                new Thread() {
                    @Override
                    public void run() {
                        try {
                            URL url = new URL(path);
                            HttpURLConnection connection = (HttpURLConnection) url
                                    .openConnection();
                            // 设置请求方式
                            connection.setRequestMethod("GET");
                            // 设置超时时间
                            connection.setConnectTimeout(10000);

                            // connection.setRequestProperty(field, newValue)

                            int code = connection.getResponseCode();
                            if (code == 200) {
                                InputStream is = connection.getInputStream();
                                Bitmap bitmap = BitmapFactory.decodeStream(is);

                                // 告诉主线程一个消息，帮我更新ui，内容：bitmap
                                Message msg = new Message();
                                msg.what = UPDATE_UI;
                                msg.obj = bitmap;
                                handler.sendMessage(msg);
                            } else {
                                Message msg = new Message();
                                msg.what = ERROR;
                                handler.sendMessage(msg);
                            }
                        } catch (Exception e) {
                            e.printStackTrace();
                            Message msg = new Message();
                            msg.what = ERROR;
                            handler.sendMessage(msg);
                        }
                    }

                }.start();

            }
        }
    }

.网络html查看器
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity" >

    <EditText
        android:id="@+id/et_path"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入网址" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="确定"
        android:onClick="click" />

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

        <TextView
            android:id="@+id/tv_content"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </ScrollView>

</LinearLayout>

public class MainActivity extends Activity {

        protected static final int ERROR = 0;
        protected static final int SHOW_CONTENT = 1;
        private EditText et_path;
        private TextView tv_content;

        private Handler handler = new Handler() {
            public void handleMessage(android.os.Message msg) {
                switch (msg.what) {
                case ERROR:
                    Toast.makeText(MainActivity.this, "获取网页信息失败",
                            Toast.LENGTH_SHORT).show();
                    break;
                case SHOW_CONTENT:
                    tv_content.setText((String) msg.obj);
                    break;
                }

            };

        };

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            this.et_path = (EditText) this.findViewById(R.id.et_path);
            this.tv_content = (TextView) this.findViewById(R.id.tv_content);
        }

        public void click(View view) {
            final String path = this.et_path.getText().toString().trim();
            if (TextUtils.isEmpty(path)) {
                Toast.makeText(this, "路径不能为空！", Toast.LENGTH_SHORT).show();
            } else {
                new Thread() {

                    public void run() {
                        try {
                            URL url = new URL(path);
                            HttpURLConnection conn = (HttpURLConnection) url
                                    .openConnection();
                            conn.setRequestMethod("GET");
                            conn.setReadTimeout(5000);
                            int code = conn.getResponseCode();
                            if (code == 200) {
                                InputStream is = conn.getInputStream();
                                String result = StreamTool.readInputStream(is);
                                Message msg = new Message();
                                msg.what = SHOW_CONTENT;
                                msg.obj = result;
                                handler.sendMessage(msg);
                            } else {
                                Message msg = new Message();
                                msg.what = ERROR;
                                handler.sendMessage(msg);
                            }
                        } catch (Exception e) {
                            e.printStackTrace();
                            Message msg = new Message();
                            msg.what = ERROR;
                            handler.sendMessage(msg);
                        }
                    };

                }.start();
            }
        }

    }

public class StreamTool {

    public static String readInputStream(InputStream is) {
        try {

            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int length = 0;
            byte[] buffer = new byte[];
            if ((length = is.read(buffer)) != -1) {
                out.write(buffer, 0, length);
            }
            byte[] result = out.toByteArray();
            String temp = new String(result);//默认utf-8
            if(temp.contains("gb2312")){
                return new String(result,"gb2312");
            }
            return temp;
        } catch (Exception e) {
            // TODO: handle exception
        }
        return "转换失败";
    }

}

<uses-permission android:name="android.permission.INTERNET"/>

6.使用异步框架Android-Async-Http
1、下载：https://github.com/loopj/android-async-http
2、在工程中加入jar包，或直接把源文件加到工程中
3、android-async-http文档：http://loopj.com/android-async-http/

AsyncHttp使用回调的方法处得请求的结果。

AsyncHttpClient client = new AsyncHttpClient();
client.get("http://www.google.com", new AsyncHttpResponseHandler() {
    @Override
    public void onSuccess(String response) {
        System.out.println(response);
    }
});

最好建一个静态的AsyncHttpClient

public class HttpUtil {

    private static AsyncHttpClient client = new AsyncHttpClient(); // 实例话对象

    static {

        client.setTimeout(10000); // 设置链接超时，如果不设置，默认为10s
    }

    // 用一个完整url获取一个string对象
    public static void get(String urlString, AsyncHttpResponseHandler res)
    {

        client.get(urlString, res);

    }

    // url里面带参数
    public static void get(String urlString, RequestParams params,
            AsyncHttpResponseHandler res){

        client.get(urlString, params, res);

    }

    // 不带参数，获取json对象或者数组
    public static void get(String urlString, JsonHttpResponseHandler res) {
        client.get(urlString, res);

    }

    // 带参数，获取json对象或者数组
    public static void get(String urlString, RequestParams params,
            JsonHttpResponseHandler res) {

        client.get(urlString, params, res);

    }

    // 下载数据使用，会返回byte数据
    public static void get(String uString, BinaryHttpResponseHandler bHandler) {

        client.get(uString, bHandler);

    }

    public static AsyncHttpClient getClient(){

        return client;
    }

}

下载：

    public void downloadClick(View view) {
        String url = "http://f.hiphotos.baidu.com/album/w%3D2048/sign=38c43ff7902397ddd6799f046dbab3b7/9c16fdfaaf51f3dee973bf7495eef01f3b2979d8.jpg";
        HttpUtil.get(url, new BinaryHttpResponseHandler() {
            @Override
            public void onSuccess(byte[] arg0) {
                super.onSuccess(arg0);
                File file = Environment.getExternalStorageDirectory();
                File file2 = new File(file, "cat");
                file2.mkdir();
                file2 = new File(file2, "cat.jpg");
                try {
                    FileOutputStream oStream = new FileOutputStream(file2);
                    oStream.write(arg0);
                    oStream.flush();
                    oStream.close();
                    textView.setText("可爱的猫咪已经保存在sdcard里面");
                } catch (Exception e) {
                    e.printStackTrace();
                    Log.i("hck", e.toString());
                }
            }
        });
    }

上传：
    public void uploadClick(View view){
        String path="http://10.0.2.2:8080/jsontest/servlet/UploadServlet";
        File myFile = new File("/sdcard/cat/cat.jpg");
        RequestParams params = new RequestParams();
        try {
            params.put("filename", myFile);

            AsyncHttpClient client = new AsyncHttpClient();
            client.post(path, params, new AsyncHttpResponseHandler(){

                @Override
                public void onSuccess(int statusCode, String content) {
                    // TODO Auto-generated method stub
                    super.onSuccess(statusCode, content);
                    Toast.makeText(MainActivity.this, "上传成功！", Toast.LENGTH_LONG).show();
                }

            });

        } catch(FileNotFoundException e) {

        }
    }