本文是 github 上 Trinea-common 和 Trinea-Demo 项目的一部分。（不知道此人攒了多久~
）
假设，现在有个下载 apk 包的需求，你大概能想到什么？
- 下载本身；
- 下载进度；
- 期间还能取消；
- 由于网络不好或中断，下载失败，还要能重试；
- 因为下载的是 apk，下载完还要能提示安装更好，而且，很多手机管理 app，还能静默安装；
- 还能在手机通知栏看到下载提示；
- 这些就涉及到 android.app.DownloadManager、android.content.BroadcastReceiver 和 android.os.Handler。
自己下载 Demo 调试一下~
图 1 项目结构
图 2 主程序
图 2 主程序
图 3 下载
（注意：顶部通知栏，是有下载图标的~）
package com.example.download.ui;
import java.io.File; import java.text.DecimalFormat; import com.example.download.R; import com.example.download.utils.DownloadManagerPro; import com.example.download.utils.PreferencesUtils; import android.annotation.SuppressLint; import android.app.Activity; import android.app.DownloadManager; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.database.ContentObserver; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.os.Handler; import android.os.Message; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.ProgressBar; import android.widget.TextView; import android.widget.Toast; /** * DownloadManagerDemo * * @author LN * @since 2014-1-8 * @version 1.0 */ public class DownloadManagerDemo extends Activity { public static final String DOWNLOAD_FOLDER_NAME = "Trinea"; public static final String DOWNLOAD_FILE_NAME = "MeiLiShuo.apk"; public static final String APK_URL = "http://img.meilishuo.net/css/images/AndroidShare/Meilishuo_3.6.1_10006.apk"; public static final String KEY_NAME_DOWNLOAD_ID = "downloadId"; private Button downloadButton; private ProgressBar downloadProgress; private TextView downloadTip; private TextView downloadSize; private TextView downloadPrecent; private Button downloadCancel; private DownloadManager downloadManager; private DownloadManagerPro downloadManagerPro; private long downloadId = 0; private MyHandler handler; private DownloadChangeObserver downloadObserver; private CompleteReceiver completeReceiver; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.download_manager_demo); handler = new MyHandler(); downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE); downloadManagerPro = new DownloadManagerPro(downloadManager); // see android mainfest.xml, // accept minetype of cn.trinea.download.file Intent intent = getIntent(); if (intent != null) { /** * below android 4.2, intent.getDataString() is * file:///storage/sdcard1/Trinea/MeLiShuo.apk<br/> * equal or above 4.2 intent.getDataString() is * content://media/external/file/29669 */ Uri data = intent.getData(); if (data != null) { Toast.makeText(getApplicationContext(), data.toString(), Toast.LENGTH_LONG) .show(); } } initView(); initData(); downloadObserver = new DownloadChangeObserver(); completeReceiver = new CompleteReceiver(); /** register download success broadcast **/ registerReceiver(completeReceiver, new IntentFilter( DownloadManager.ACTION_DOWNLOAD_COMPLETE)); } @Override protected void onResume() { super.onResume(); /** observer download change **/ getContentResolver().registerContentObserver( DownloadManagerPro.CONTENT_URI, true, downloadObserver); updateView(); } @Override protected void onPause() { super.onPause(); getContentResolver().unregisterContentObserver(downloadObserver); } @Override protected void onDestroy() { super.onDestroy(); unregisterReceiver(completeReceiver); } private void initView() { downloadButton = (Button) findViewById(R.id.download_button); downloadCancel = (Button) findViewById(R.id.download_cancel); downloadProgress = (ProgressBar) findViewById(R.id.download_progress); downloadTip = (TextView) findViewById(R.id.download_tip); downloadTip .setText(getString(R.string.tip_download_file) + Environment .getExternalStoragePublicDirectory(DOWNLOAD_FOLDER_NAME)); downloadSize = (TextView) findViewById(R.id.download_size); downloadPrecent = (TextView) findViewById(R.id.download_precent); } private void initData() { /** * get download id from preferences.<br/> * if download id bigger than 0, means it has been downloaded, then * query status and show right text; */ downloadId = PreferencesUtils.getLong(getApplicationContext(), KEY_NAME_DOWNLOAD_ID); updateView(); downloadButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { File folder = new File(DOWNLOAD_FOLDER_NAME); if (!folder.exists() || !folder.isDirectory()) { folder.mkdirs(); } DownloadManager.Request request = new DownloadManager.Request( Uri.parse(APK_URL)); request.setDestinationInExternalPublicDir(DOWNLOAD_FOLDER_NAME, DOWNLOAD_FILE_NAME); request.setTitle(getString(R.string.download_notification_title)); request.setDescription("meilishuo desc"); request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED); request.setVisibleInDownloadsUi(false); // request.allowScanningByMediaScanner(); // request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI); // request.setShowRunningNotification(false); // request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_HIDDEN); request.setMimeType("application/cn.trinea.download.file"); downloadId = downloadManager.enqueue(request); /** save download id to preferences **/ PreferencesUtils.putLong(getApplicationContext(), KEY_NAME_DOWNLOAD_ID, downloadId); updateView(); } }); downloadCancel.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { downloadManager.remove(downloadId); updateView(); } }); } /** * install app * * @param context * @param filePath * @return whether apk exist */ public static boolean install(Context context, String filePath) { Intent i = new Intent(Intent.ACTION_VIEW); File file = new File(filePath); if (file != null && file.length() > 0 && file.exists() && file.isFile()) { i.setDataAndType(Uri.parse("file://" + filePath), "application/vnd.android.package-archive"); i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); context.startActivity(i); return true; } return false; } class DownloadChangeObserver extends ContentObserver { public DownloadChangeObserver() { super(handler); } @Override public void onChange(boolean selfChange) { updateView(); } } class CompleteReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { /** * get the id of download which have download success, if the id is * my id and it's status is successful, then install it **/ long completeDownloadId = intent.getLongExtra( DownloadManager.EXTRA_DOWNLOAD_ID, -1); if (completeDownloadId == downloadId) { initData(); updateView(); // if download successful, install apk if (downloadManagerPro.getStatusById(downloadId) == DownloadManager.STATUS_SUCCESSFUL) { String apkFilePath = new StringBuilder(Environment .getExternalStorageDirectory().getAbsolutePath()) .append(File.separator) .append(DOWNLOAD_FOLDER_NAME) .append(File.separator).append(DOWNLOAD_FILE_NAME) .toString(); install(context, apkFilePath); } } } }; public void updateView() { int[] bytesAndStatus = downloadManagerPro.getBytesAndStatus(downloadId); handler.sendMessage(handler.obtainMessage(0, bytesAndStatus[0], bytesAndStatus[1], bytesAndStatus[2])); } @SuppressLint("HandlerLeak") private class MyHandler extends Handler { @Override public void handleMessage(Message msg) { super.handleMessage(msg); switch (msg.what) { case 0: int status = (Integer) msg.obj; if (isDownloading(status)) { downloadProgress.setVisibility(View.VISIBLE); downloadProgress.setMax(0); downloadProgress.setProgress(0); downloadButton.setVisibility(View.GONE); downloadSize.setVisibility(View.VISIBLE); downloadPrecent.setVisibility(View.VISIBLE); downloadCancel.setVisibility(View.VISIBLE); if (msg.arg2 < 0) { downloadProgress.setIndeterminate(true); downloadPrecent.setText("0%"); downloadSize.setText("0M/0M"); } else { downloadProgress.setIndeterminate(false); downloadProgress.setMax(msg.arg2); downloadProgress.setProgress(msg.arg1); downloadPrecent.setText(getNotiPercent(msg.arg1, msg.arg2)); downloadSize.setText(getAppSize(msg.arg1) + "/" + getAppSize(msg.arg2)); } } else { downloadProgress.setVisibility(View.GONE); downloadProgress.setMax(0); downloadProgress.setProgress(0); downloadButton.setVisibility(View.VISIBLE); downloadSize.setVisibility(View.GONE); downloadPrecent.setVisibility(View.GONE); downloadCancel.setVisibility(View.GONE); if (status == DownloadManager.STATUS_FAILED) { downloadButton .setText(getString(R.string.app_status_download_fail)); } else if (status == DownloadManager.STATUS_SUCCESSFUL) { downloadButton .setText(getString(R.string.app_status_downloaded)); } else { downloadButton .setText(getString(R.string.app_status_download)); } } break; } } } static final DecimalFormat DOUBLE_DECIMAL_FORMAT = new DecimalFormat("0.##"); public static final int MB_2_BYTE = 1024 * 1024; public static final int KB_2_BYTE = 1024; /** * @param size * @return */ public static CharSequence getAppSize(long size) { if (size <= 0) { return "0M"; } if (size >= MB_2_BYTE) { return new StringBuilder(16).append( DOUBLE_DECIMAL_FORMAT.format((double) size / MB_2_BYTE)) .append("M"); } else if (size >= KB_2_BYTE) { return new StringBuilder(16).append( DOUBLE_DECIMAL_FORMAT.format((double) size / KB_2_BYTE)) .append("K"); } else { return size + "B"; } } public static String getNotiPercent(long progress, long max) { int rate = 0; if (progress <= 0 || max <= 0) { rate = 0; } else if (progress > max) { rate = 100; } else { rate = (int) ((double) progress / max * 100); } return new StringBuilder(16).append(rate).append("%").toString(); } public static boolean isDownloading(int downloadManagerStatus) { return downloadManagerStatus == DownloadManager.STATUS_RUNNING || downloadManagerStatus == DownloadManager.STATUS_PAUSED || downloadManagerStatus == DownloadManager.STATUS_PENDING; } }
以及自定义的 DownloadManagerPro 和 PreferencesUtils 类，代码如下所示：、
package com.example.download.utils;
import java.lang.reflect.Method;
import android.app.DownloadManager;
import android.app.DownloadManager.Request;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
/**
* DownloadManagerPro
*/
public class DownloadManagerPro {
public static final Uri CONTENT_URI = Uri
.parse("content://downloads/my_downloads");
/** represents downloaded file above api 11 **/
public static final String COLUMN_LOCAL_FILENAME = "local_filename";
/** represents downloaded file below api 11 **/
public static final String COLUMN_LOCAL_URI = "local_uri";
public static final String METHOD_NAME_PAUSE_DOWNLOAD = "pauseDownload";
public static final String METHOD_NAME_RESUME_DOWNLOAD = "resumeDownload";
private static boolean isInitPauseDownload = false;
private static boolean isInitResumeDownload = false;
private static Method pauseDownload = null;
private static Method resumeDownload = null;
private DownloadManager downloadManager;
public DownloadManagerPro(DownloadManager downloadManager) {
this.downloadManager = downloadManager;
}
/**
* get download status
*
* @param downloadId
* @return
*/
public int getStatusById(long downloadId) {
return getInt(downloadId, DownloadManager.COLUMN_STATUS);
}
/**
* get downloaded byte, total byte
*
* @param downloadId
* @return a int array with two elements
* <ul>
* <li>result[0] represents downloaded bytes, This will initially be
* -1.</li>
* <li>result[1] represents total bytes, This will initially be -1.</li>
* </ul>
*/
public int[] getDownloadBytes(long downloadId) {
int[] bytesAndStatus = getBytesAndStatus(downloadId);
return new int[] { bytesAndStatus[0], bytesAndStatus[1] };
}
/**
* get downloaded byte, total byte and download status
*
* @param downloadId
* @return a int array with three elements
* <ul>
* <li>result[0] represents downloaded bytes, This will initially be
* -1.</li>
* <li>result[1] represents total bytes, This will initially be -1.</li>
* <li>result[2] represents download status, This will initially be
* 0.</li>
* </ul>
*/
public int[] getBytesAndStatus(long downloadId) {
int[] bytesAndStatus = new int[] { -1, -1, 0 };
DownloadManager.Query query = new DownloadManager.Query()
.setFilterById(downloadId);
Cursor c = null;
try {
c = downloadManager.query(query);
if (c != null && c.moveToFirst()) {
bytesAndStatus[0] = c
.getInt(c
.getColumnIndexOrThrow(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR));
bytesAndStatus[1] = c
.getInt(c
.getColumnIndexOrThrow(DownloadManager.COLUMN_TOTAL_SIZE_BYTES));
bytesAndStatus[2] = c.getInt(c
.getColumnIndex(DownloadManager.COLUMN_STATUS));
}
} finally {
if (c != null) {
c.close();
}
}
return bytesAndStatus;
}
/**
* pause download
*
* @param ids
* the IDs of the downloads to be paused
* @return the number of downloads actually paused, -1 if exception or
* method not exist
*/
public int pauseDownload(long... ids) {
initPauseMethod();
if (pauseDownload == null) {
return -1;
}
try {
return ((Integer) pauseDownload.invoke(downloadManager, ids))
.intValue();
} catch (Exception e) {
/**
* accept all exception, include ClassNotFoundException,
* NoSuchMethodException, InvocationTargetException,
* NullPointException
*/
e.printStackTrace();
}
return -1;
}
/**
* resume download
*
* @param ids
* the IDs of the downloads to be resumed
* @return the number of downloads actually resumed, -1 if exception or
* method not exist
*/
public int resumeDownload(long... ids) {
initResumeMethod();
if (resumeDownload == null) {
return -1;
}
try {
return ((Integer) resumeDownload.invoke(downloadManager, ids))
.intValue();
} catch (Exception e) {
/**
* accept all exception, include ClassNotFoundException,
* NoSuchMethodException, InvocationTargetException,
* NullPointException
*/
e.printStackTrace();
}
return -1;
}
/**
* whether exist pauseDownload and resumeDownload method in
* {@link DownloadManager}
*
* @return
*/
public static boolean isExistPauseAndResumeMethod() {
initPauseMethod();
initResumeMethod();
return pauseDownload != null && resumeDownload != null;
}
private static void initPauseMethod() {
if (isInitPauseDownload) {
return;
}
isInitPauseDownload = true;
try {
pauseDownload = DownloadManager.class.getMethod(
METHOD_NAME_PAUSE_DOWNLOAD, long[].class);
} catch (Exception e) {
// accept all exception
e.printStackTrace();
}
}
private static void initResumeMethod() {
if (isInitResumeDownload) {
return;
}
isInitResumeDownload = true;
try {
resumeDownload = DownloadManager.class.getMethod(
METHOD_NAME_RESUME_DOWNLOAD, long[].class);
} catch (Exception e) {
// accept all exception
e.printStackTrace();
}
}
/**
* get download file name
*
* @param downloadId
* @return
*/
public String getFileName(long downloadId) {
return getString(
downloadId,
(Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB ? COLUMN_LOCAL_URI
: COLUMN_LOCAL_FILENAME));
}
/**
* get download uri
*
* @param downloadId
* @return
*/
public String getUri(long downloadId) {
return getString(downloadId, DownloadManager.COLUMN_URI);
}
/**
* get failed code or paused reason
*
* @param downloadId
* @return <ul>
* <li>if status of downloadId is
* {@link DownloadManager#STATUS_PAUSED}, return
* {@link #getPausedReason(long)}</li>
* <li>if status of downloadId is
* {@link DownloadManager#STATUS_FAILED}, return
* {@link #getErrorCode(long)}</li>
* <li>if status of downloadId is neither
* {@link DownloadManager#STATUS_PAUSED} nor
* {@link DownloadManager#STATUS_FAILED}, return 0</li>
* </ul>
*/
public int getReason(long downloadId) {
return getInt(downloadId, DownloadManager.COLUMN_REASON);
}
/**
* get paused reason
*
* @param downloadId
* @return <ul>
* <li>if status of downloadId is
* {@link DownloadManager#STATUS_PAUSED}, return one of
* {@link DownloadManager#PAUSED_WAITING_TO_RETRY}<br/>
* {@link DownloadManager#PAUSED_WAITING_FOR_NETWORK}<br/>
* {@link DownloadManager#PAUSED_QUEUED_FOR_WIFI}<br/>
* {@link DownloadManager#PAUSED_UNKNOWN}</li>
* <li>else return {@link DownloadManager#PAUSED_UNKNOWN}</li>
* </ul>
*/
public int getPausedReason(long downloadId) {
return getInt(downloadId, DownloadManager.COLUMN_REASON);
}
/**
* get failed error code
*
* @param downloadId
* @return one of {@link DownloadManager#ERROR_*}
*/
public int getErrorCode(long downloadId) {
return getInt(downloadId, DownloadManager.COLUMN_REASON);
}
public static class RequestPro extends DownloadManager.Request {
public static final String METHOD_NAME_SET_NOTI_CLASS = "setNotiClass";
public static final String METHOD_NAME_SET_NOTI_EXTRAS = "setNotiExtras";
private static boolean isInitNotiClass = false;
private static boolean isInitNotiExtras = false;
private static Method setNotiClass = null;
private static Method setNotiExtras = null;
/**
* @param uri
* the HTTP URI to download.
*/
public RequestPro(Uri uri) {
super(uri);
}
/**
* set noti class, only init once
*
* @param className
* full class name
*/
public void setNotiClass(String className) {
synchronized (this) {
if (!isInitNotiClass) {
isInitNotiClass = true;
try {
setNotiClass = Request.class.getMethod(
METHOD_NAME_SET_NOTI_CLASS, CharSequence.class);
} catch (Exception e) {
// accept all exception
e.printStackTrace();
}
}
}
if (setNotiClass != null) {
try {
setNotiClass.invoke(this, className);
} catch (Exception e) {
/**
* accept all exception, include ClassNotFoundException,
* NoSuchMethodException, InvocationTargetException,
* NullPointException
*/
e.printStackTrace();
}
}
}
/**
* set noti extras, only init once
*
* @param extras
*/
public void setNotiExtras(String extras) {
synchronized (this) {
if (!isInitNotiExtras) {
isInitNotiExtras = true;
try {
setNotiExtras = Request.class
.getMethod(METHOD_NAME_SET_NOTI_EXTRAS,
CharSequence.class);
} catch (Exception e) {
// accept all exception
e.printStackTrace();
}
}
}
if (setNotiExtras != null) {
try {
setNotiExtras.invoke(this, extras);
} catch (Exception e) {
/**
* accept all exception, include ClassNotFoundException,
* NoSuchMethodException, InvocationTargetException,
* NullPointException
*/
e.printStackTrace();
}
}
}
}
/**
* get string column
*
* @param downloadId
* @param columnName
* @return
*/
private String getString(long downloadId, String columnName) {
DownloadManager.Query query = new DownloadManager.Query()
.setFilterById(downloadId);
String result = null;
Cursor c = null;
try {
c = downloadManager.query(query);
if (c != null && c.moveToFirst()) {
result = c.getString(c.getColumnIndex(columnName));
}
} finally {
if (c != null) {
c.close();
}
}
return result;
}
/**
* get int column
*
* @param downloadId
* @param columnName
* @return
*/
private int getInt(long downloadId, String columnName) {
DownloadManager.Query query = new DownloadManager.Query()
.setFilterById(downloadId);
int result = -1;
Cursor c = null;
try {
c = downloadManager.query(query);
if (c != null && c.moveToFirst()) {
result = c.getInt(c.getColumnIndex(columnName));
}
} finally {
if (c != null) {
c.close();
}
}
return result;
}
}package com.example.download.utils;
import android.content.Context;
import android.content.SharedPreferences;
/**
* PreferencesUtils, easy to get or put data
*/
public class PreferencesUtils {
public static String PREFERENCE_NAME = "TrineaAndroidCommon";
/**
* put string preferences
*
* @param context
* @param key
* The name of the preference to modify
* @param value
* The new value for the preference
* @return True if the new values were successfully written to persistent
* storage.
*/
public static boolean putString(Context context, String key, String value) {
SharedPreferences settings = context.getSharedPreferences(
PREFERENCE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putString(key, value);
return editor.commit();
}
/**
* get string preferences
*
* @param context
* @param key
* The name of the preference to retrieve
* @return The preference value if it exists, or null. Throws
* ClassCastException if there is a preference with this name that
* is not a string
* @see #getString(Context, String, String)
*/
public static String getString(Context context, String key) {
return getString(context, key, null);
}
/**
* get string preferences
*
* @param context
* @param key
* The name of the preference to retrieve
* @param defaultValue
* Value to return if this preference does not exist
* @return The preference value if it exists, or defValue. Throws
* ClassCastException if there is a preference with this name that
* is not a string
*/
public static String getString(Context context, String key,
String defaultValue) {
SharedPreferences settings = context.getSharedPreferences(
PREFERENCE_NAME, Context.MODE_PRIVATE);
return settings.getString(key, defaultValue);
}
/**
* put int preferences
*
* @param context
* @param key
* The name of the preference to modify
* @param value
* The new value for the preference
* @return True if the new values were successfully written to persistent
* storage.
*/
public static boolean putInt(Context context, String key, int value) {
SharedPreferences settings = context.getSharedPreferences(
PREFERENCE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putInt(key, value);
return editor.commit();
}
/**
* get int preferences
*
* @param context
* @param key
* The name of the preference to retrieve
* @return The preference value if it exists, or -1. Throws
* ClassCastException if there is a preference with this name that
* is not a int
* @see #getInt(Context, String, int)
*/
public static int getInt(Context context, String key) {
return getInt(context, key, -1);
}
/**
* get int preferences
*
* @param context
* @param key
* The name of the preference to retrieve
* @param defaultValue
* Value to return if this preference does not exist
* @return The preference value if it exists, or defValue. Throws
* ClassCastException if there is a preference with this name that
* is not a int
*/
public static int getInt(Context context, String key, int defaultValue) {
SharedPreferences settings = context.getSharedPreferences(
PREFERENCE_NAME, Context.MODE_PRIVATE);
return settings.getInt(key, defaultValue);
}
/**
* put long preferences
*
* @param context
* @param key
* The name of the preference to modify
* @param value
* The new value for the preference
* @return True if the new values were successfully written to persistent
* storage.
*/
public static boolean putLong(Context context, String key, long value) {
SharedPreferences settings = context.getSharedPreferences(
PREFERENCE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putLong(key, value);
return editor.commit();
}
/**
* get long preferences
*
* @param context
* @param key
* The name of the preference to retrieve
* @return The preference value if it exists, or -1. Throws
* ClassCastException if there is a preference with this name that
* is not a long
* @see #getLong(Context, String, long)
*/
public static long getLong(Context context, String key) {
return getLong(context, key, -1);
}
/**
* get long preferences
*
* @param context
* @param key
* The name of the preference to retrieve
* @param defaultValue
* Value to return if this preference does not exist
* @return The preference value if it exists, or defValue. Throws
* ClassCastException if there is a preference with this name that
* is not a long
*/
public static long getLong(Context context, String key, long defaultValue) {
SharedPreferences settings = context.getSharedPreferences(
PREFERENCE_NAME, Context.MODE_PRIVATE);
return settings.getLong(key, defaultValue);
}
/**
* put float preferences
*
* @param context
* @param key
* The name of the preference to modify
* @param value
* The new value for the preference
* @return True if the new values were successfully written to persistent
* storage.
*/
public static boolean putFloat(Context context, String key, float value) {
SharedPreferences settings = context.getSharedPreferences(
PREFERENCE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putFloat(key, value);
return editor.commit();
}
/**
* get float preferences
*
* @param context
* @param key
* The name of the preference to retrieve
* @return The preference value if it exists, or -1. Throws
* ClassCastException if there is a preference with this name that
* is not a float
* @see #getFloat(Context, String, float)
*/
public static float getFloat(Context context, String key) {
return getFloat(context, key, -1);
}
/**
* get float preferences
*
* @param context
* @param key
* The name of the preference to retrieve
* @param defaultValue
* Value to return if this preference does not exist
* @return The preference value if it exists, or defValue. Throws
* ClassCastException if there is a preference with this name that
* is not a float
*/
public static float getFloat(Context context, String key, float defaultValue) {
SharedPreferences settings = context.getSharedPreferences(
PREFERENCE_NAME, Context.MODE_PRIVATE);
return settings.getFloat(key, defaultValue);
}
/**
* put boolean preferences
*
* @param context
* @param key
* The name of the preference to modify
* @param value
* The new value for the preference
* @return True if the new values were successfully written to persistent
* storage.
*/
public static boolean putBoolean(Context context, String key, boolean value) {
SharedPreferences settings = context.getSharedPreferences(
PREFERENCE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean(key, value);
return editor.commit();
}
/**
* get boolean preferences, default is false
*
* @param context
* @param key
* The name of the preference to retrieve
* @return The preference value if it exists, or false. Throws
* ClassCastException if there is a preference with this name that
* is not a boolean
* @see #getBoolean(Context, String, boolean)
*/
public static boolean getBoolean(Context context, String key) {
return getBoolean(context, key, false);
}
/**
* get boolean preferences
*
* @param context
* @param key
* The name of the preference to retrieve
* @param defaultValue
* Value to return if this preference does not exist
* @return The preference value if it exists, or defValue. Throws
* ClassCastException if there is a preference with this name that
* is not a boolean
*/
public static boolean getBoolean(Context context, String key,
boolean defaultValue) {
SharedPreferences settings = context.getSharedPreferences(
PREFERENCE_NAME, Context.MODE_PRIVATE);
return settings.getBoolean(key, defaultValue);
}
}
原文地址：http://blog.csdn.net/androidmylove/article/details/42523509
