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(); } } 2.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" /> 3.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", "[email protected]"); 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" /> 4.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(); } } } 5.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[1024]; 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) { } }
