weiweisoftroad-优快云博客

原创 mongodb schema design

数据模型的创建，相对于传统关系型数据库而言，mongodb没有严格的设计模式，这是因为模式设计或我们称之为数据建模的成败往往是取决于实际系统的需求，很多时候需求是不同的，所以反而使得数据模型的创建各有所不同，很难说存在一套标准的数据建模方法。mongodb schema design 时需要考虑：[b]问题1、数据模型最小单位是什么？[/b] 关系型数据库：数据存放在表中，...

2012-02-26 11:31:27 165

原创 NOSQL数据库代表：couchDB

最近花了些时间关注couchDB,对它的特点做以下总结一、key/value型分布式数据库。二、支持海量数据存储，提供高于传统数据库性能优势。三、按照CAP原理：支持[b]分区容忍性[/b]和[b]数据可用性[/b]。四、数据一致性:couchDB支持数据[b]最终一致性[/b]。五、提供 rest 方式数据访问API，个人感觉可以很大程度简化开发过程。六、支持不同节点数...

2011-12-30 14:19:08 201

原创 map/reduce

[align=center][b][size=medium]map函数：[/size][/b] [/align]它的输入是一个LIST 数据集合；它的输出也是一个LIST数据集合。该函数中常常是调用内置emit函数，emit函数通常有两个参数(key,value)，map函数最终执行结果是输出一个LIST数据集合，其中每条数据格式必定是emit函数的参数key,value所对应的数据（...

2011-12-20 17:48:11 133

原创 Intents and Intent Filters--Intent filters

[b]Intent filters[/b] To inform the system which implicit intents they can handle, activities, services, and broadcast receivers can have one or more intent filters. Each filter describes a capa...

2010-09-03 10:21:33 139

原创 Intents and Intent Filters---Intent Resolution

[b]Intent Resolution[/b]Intents 可以分成两类: 1、[b]Explicit intents [/b]（显式intents-指定了目标组件名） designate the target component by its name (the component name field, mentioned earlier, has a value s...

2010-09-03 09:45:22 140

原创 Intents and Intent Filters---Intent Objects

[b]Intent Objects[/b] An Intent object is a bundle of information. It contains information of interest to the component that receives the intent (such as the action to be taken and the data to a...

2010-09-02 11:15:18 128

原创 Intents and Intent Filters---序言

[b]Intents and Intent Filters[/b]Key classes 1. Intent 2. IntentFilter 3. Activity 4. Service 5. BroadcastReceiver 6. PackageManager本文中将包含以下内容： 1. Intent Object...

2010-09-01 16:06:19 120

原创 Application Fundamentals--Processes and lifecycles（进程生命周期）

[b]Processes and lifecycles---进程生命周期[/b] The Android system tries to maintain an application process for as long as possible, but eventually it will need to remove old processes when memory runs...

2010-08-30 09:23:18 135

原创 Application Fundamentals--Broadcast receiver lifecycle（广播接收组件生命周期）

[b]Broadcast receiver lifecycle---广播接收组件生命周期[/b]A broadcast receiver has single callback method:--翻译：广播接收组件只有唯一一个回调方法：[code="java"]void onReceive(Context curContext, Intent broadcastMsg)[/code...

2010-08-30 09:20:05 218

原创 Application Fundamentals--Service lifecycle（服务组件的生命周期）

[b]Service lifecycle--服务组件的生命周期[/b]A service can be used in two ways--翻译：服务组件有两种使用方式: * It can be started and allowed to run until someone stops it or it stops itself. In this mode, it's st...

2010-08-30 09:18:52 156

原创 Application Fundamentals--Coordinating activities（activity实例间协调）

Coordinating activities---activity实例间协调When one activity starts another, they both experience lifecycle transitions. One pauses and may stop, while the other starts up. On occasion, you may need t...

2010-08-30 09:15:26 132

原创 Application Fundamentals--Saving activity state（保存activity实例的状态信息）

[b]Saving activity state--保存activity实例的状态信息[/b]When the system, rather than the user, shuts down an activity to conserve memory, the user may expect to return to the activity and find it in its pr...

2010-08-27 10:06:55 110

原创 Application Fundamentals--Component Lifecycles（组件生命周期）

[b]Component Lifecycles--组件生命周期[/b]Application components have a lifecycle — a beginning when Android instantiates them to respond to intents through to an end when the instances are destroyed. In...

2010-08-27 09:56:04 123

原创 Application Fundamentals--Thread-safe methods（线程安全方法）

[b]Thread-safe methods--线程安全方法[/b]In a few contexts, the methods you implement may be called from more than one thread, and therefore must be written to be thread-safe. 翻译：某些场景下，方法的实现需要考虑线程安全。...

2010-08-27 09:51:12 123

原创 Application Fundamentals--Remote procedure calls（远程过程调用）

[b]Remote procedure calls--远程过程调用[/b]Android has a lightweight mechanism for remote procedure calls (RPCs) — where a method is called locally, but executed remotely (in another process), with any ...

2010-08-27 09:41:07 121

原创 Application Fundamentals--Processes and Threads（进程与线程）

[b]Processes and Threads--进程与线程[/b]When the first of an application's components needs to be run, Android starts a Linux process for it with a single thread of execution. By default, all component...

2010-08-27 09:36:29 117

原创 Application Fundamentals--Starting tasks

Starting tasksAn activity is set up as the entry point for a task by giving it an intent filter with "android.intent.action.MAIN" as the specified action and "android.intent.category.LAUNCHER" as ...

2010-08-27 09:34:33 104

原创 Application Fundamentals--Clearing the stack（堆栈清理）

Clearing the stack--堆栈清理If the user leaves a task for a long time, the system clears the task of all activities except the root activity. When the user returns to the task again, it's as the user ...

2010-08-27 09:28:25 158

原创 Application Fundamentals--Launch modes-启动模式

Launch modes-启动模式There are four different launch modes that can be assigned to an element's launchMode attribute:翻译：activity元素的launchMode属性可以设定为以下四种值："standard" (the default mode)"singleTop...

2010-08-27 09:27:31 131

原创 Application Fundamentals--Affinities and new tasks

Affinities and new tasksBy default, all the activities in an application have an affinity for each other — that is, there's a preference for them all to belong to the same task. However, an indivi...

2010-08-27 08:45:14 92

原创 Application Fundamentals--Activities and Tasks

Activities and TasksAs noted earlier, one activity can start another, including one defined in a different application. Suppose, for example, that you'd like to let users display a street map of s...

2010-08-27 08:42:41 105

原创 Application Fundamentals--Intent 过滤器

Intent 过滤器Intent 对象可以显式指定目标组件.一旦显式指定了目标组件，Android 操作系统直接根据指定的目标组件名在AndroidManifest.xml文件中查找该组件声明，找到之后立即激活该组件。如果Intent 对象没有显式指定目标组件, Android 操作系统必须从AndroidManifest.xml文件中的所有intent过滤器中定位到一个最佳匹配的inte...

2010-08-27 08:41:25 96

原创 Application Fundamentals--The manifest file

The manifest fileAndroid启动应用程序组件之前，首先必须知道被启动的应用中都有哪些组件.所以应用程序需要在manifest文件中声明该应用都绑定了什么组件，在应用程序对应的.apk文件中同时也包含了应用程序代码、文件以及相关的资源。manifest是一个 XML 文件，总是被命名为AndroidManifest.xml，其中，并非仅仅是声明组件，同时该文件中...

2010-08-27 08:40:27 82

原创 Application Fundamentals--Activating components: intents（组件的激活）

Activating components: intents----组件的激活Content providers are activated when they're targeted by a request from a ContentResolver. The other three components — activities, services, and broadcast r...

2010-08-27 08:38:23 128

原创 Application Fundamentals--Application Components（应用组件）

Application Components-应用组件A central feature of Android is that one application can make use of elements of other applications (provided those applications permit it). For example, if your applica...

2010-08-27 08:32:15 161

原创 Application Fundamentals 前言

Android applications are written in the Java programming language. The compiled Java code — along with any data and resource files required by the application — is bundled by the aapt tool into an ...

2010-08-26 16:59:26 102

jexcelapi JDK版本问题

这几天在用jexcelapi，去下载了最新的jexcelapi：jexcelapi_2_6_11.zip，解压后把其中的jxl.jar添加到工程类库中。做了个测试测序，遇到以下错误：java.lang.UnsupportedClassVersionError: Bad version number in .class file at java.lang.ClassLoader.define...

2009-10-12 13:16:28 283

片甲