基于Android移动终端的U盘系统的设计与实现

发布时间：2018-03-20 20:49

本文选题：Android系统　切入点：磁盘管理　出处：《上海交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：Android系统存在以下规定，即应用软件只能安装在“主存储器”之中，且主存储器的映射关系是固定的、不可改变的。对于中低端android手机，由于手机内部存储空间小，通常使用大容量的扩展外存（如外置SD卡）映射为主存储器来支持更多软件的安装，，这意味着手机安装的外置SD卡不允许用户随意移除、更换，否则系统无法正常工作，如无法使用已有应用，无法安装新应用。针对以上问题，本文提出并设计了一种可动态切换“主存储器”映射的U盘工作机制，终端用户可通过自己的选择，决定“主存储器”映射关系。当手机安装了外置SD卡，用户可以选择外置SD卡映射为“主存储器”，保证用户在内部存储空间小的手机上有充足的应用安装空间；当外置SD卡被移除，手机将自动切换为内部存储器映射成“主存储器”，防止“主存储器”映射丢失造成的应用软件无法安装和使用。本文的研究工作包括如下几方面： 1）动态映射“主存储空间”机制的分析与设计：本文首先分析了国内外对Android平台存储空间的研究现状，指出了固定主存储器映射关系会导致用户应用无法安装使用的问题，接着，结合分析Android操作系统在磁盘存储框架的原生设计，从硬件层、驱动层、文件系统、系统管理等几个层面，设计了一种可动态切换“主存储器”映射的U盘工作机制。 2）动态切换机制相关开发实现工作：动态切换机制的实现涉及系统管理、文件系统、驱动程序、空间管理等几个层面。首先，手机内部存储空间以内置U盘的形式存在，调整eMMC分区表结构，增加内置U盘分区；其次，调整内核USB驱动节点，提供内置U盘和外置SD卡两块大容量存储区域的文件系统访问能力；同时，本文重构了Vold服务和Android Framework框架，将fstab分区表和storage_list磁盘管理文件动态配置，实现可动态切换“主存储器”映射功能。 3）系统验证与测试：针对本功能，设计了测试用例，覆盖所有功能点，验证了本文提出的可动态切换“主存储器”映射机制可用，并通过兼容性测试和性能压力测试，保证本方案的稳定性和健壮性。本文提出的设计方案已在android4.2/leadcore L1813处理器平台上予以实现，通过对依赖于大容量主存的主流应用测试表明，本文提出的可动态切换“主存储器”映射的U盘系统在系统功能、系统性能、软件稳定性等方面表现良好。
[Abstract]:The Android system has the following stipulation: the application software can only be installed in the "main memory", and the mapping relationship of the main memory is fixed and immutable. In general, a large capacity of extended external memory (such as external SD card) is used to map the main memory to support more software installation, which means that the external SD card installed on the mobile phone does not allow the user to remove and replace it at will, otherwise the system will not work properly. If you cannot use an existing application, you cannot install a new application. In order to solve the above problems, this paper proposes and designs a mechanism for dynamically switching "main memory" mapping. End users can decide the mapping relationship of "main memory" by their own choice. When the mobile phone installs an external SD card, The user can choose to map the external SD card to "main memory" to ensure that the user has sufficient application installation space on the mobile phone with small internal storage space; when the external SD card is removed, Mobile phone will automatically switch to internal memory mapping to "main memory" to prevent the "main memory" mapping caused by the loss of application software can not be installed and used. The research work of this paper includes the following aspects:. 1) the analysis and design of "main storage space" mechanism of dynamic mapping: firstly, this paper analyzes the research status of Android platform storage space at home and abroad, and points out that fixed main memory mapping relationship will lead to user application can not be installed and used. Then, combining with the analysis of the native design of Android operating system in disk storage framework, from the hardware layer, driver layer, file system, system management and other layers, a dynamic switching "main memory" mapping of the U disk working mechanism is designed. 2) Development and implementation of dynamic switching mechanism: the implementation of dynamic switching mechanism involves several aspects, such as system management, file system, driver, space management and so on. First, the internal storage space of mobile phone exists in the form of built-in U disk. Adjust the structure of the eMMC partition table to increase the built-in U disk partition; secondly, adjust the kernel USB driver node to provide file system access for the two bulk storage areas, the built-in U disk and the external SD card; at the same time, This paper reconstructs the framework of Vold service and Android Framework, dynamically configures fstab partition table and storage_list disk management file, and realizes the mapping function of "main memory". 3) system verification and testing: for this function, a test case is designed to cover all function points. It is verified that the dynamic switchable "main memory" mapping mechanism proposed in this paper is available, and the compatibility test and performance stress test are passed. Ensure the stability and robustness of the scheme. The proposed design scheme has been implemented on android4.2/leadcore L1813 processor platform. By testing the mainstream applications that rely on large capacity main memory, it is shown that the USB disk system which can dynamically switch "main memory" mapping in this paper is functional in the system. System performance, software stability and other aspects of good performance.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP333.2;TP311.52

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