📄 package-summary.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Frameset//EN""http://www.w3.org/TR/REC-html40/frameset.dtd">
<!--NewPage-->
<HTML>
<HEAD>
<!-- Generated by javadoc on Wed Sep 24 14:57:47 PDT 2003 -->
<TITLE>
MID Profile: Package javax.microedition.rms
</TITLE>
<LINK REL ="stylesheet" TYPE="text/css" HREF="../../../stylesheet.css" TITLE="Style">
</HEAD>
<BODY BGCOLOR="white">
<!-- ========== START OF NAVBAR ========== -->
<A NAME="navbar_top"><!-- --></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0">
<TR>
<TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1">
<A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3">
<TR ALIGN="center" VALIGN="top">
<TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD>
<TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Package</B></FONT> </TD>
<TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <FONT CLASS="NavBarFont1">Class</FONT> </TD>
<TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-use.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A> </TD>
<TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD>
<TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD>
<TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD>
<TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD>
</TR>
</TABLE>
</TD>
<TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM>
<strong>MID Profile</strong></EM>
</TD>
</TR>
<TR>
<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
<A HREF="../../../javax/microedition/pki/package-summary.html"><B>PREV PACKAGE</B></A>
NEXT PACKAGE</FONT></TD>
<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
<A HREF="../../../index.html" TARGET="_top"><B>FRAMES</B></A>
<A HREF="package-summary.html" TARGET="_top"><B>NO FRAMES</B></A></FONT></TD>
</TR>
</TABLE>
<!-- =========== END OF NAVBAR =========== -->
<HR>
<H2>
Package javax.microedition.rms
</H2>
The Mobile Information Device Profile provides a mechanism for MIDlets to persistently store data and later retrieve it.
<P>
<B>See: </B>
<BR>
<A HREF="#package_description"><B>Description</B></A>
<P>
<TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TD COLSPAN=2><FONT SIZE="+2">
<B>Interface Summary</B></FONT></TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="RecordComparator.html"><I>RecordComparator</I></A></B></TD>
<TD>An interface defining a comparator which compares two records (in an implementation-defined manner) to see if they match or what their relative sort order is.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="RecordEnumeration.html"><I>RecordEnumeration</I></A></B></TD>
<TD>An interface representing a bidirectional record store Record enumerator.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="RecordFilter.html"><I>RecordFilter</I></A></B></TD>
<TD>An interface defining a filter which examines a record to see if it matches (based on an application-defined criteria).</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="RecordListener.html"><I>RecordListener</I></A></B></TD>
<TD>A listener interface for receiving Record Changed/Added/Deleted events from a record store.</TD>
</TR>
</TABLE>
<P>
<TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TD COLSPAN=2><FONT SIZE="+2">
<B>Class Summary</B></FONT></TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="RecordStore.html">RecordStore</A></B></TD>
<TD>A class representing a record store.</TD>
</TR>
</TABLE>
<P>
<TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TD COLSPAN=2><FONT SIZE="+2">
<B>Exception Summary</B></FONT></TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="InvalidRecordIDException.html">InvalidRecordIDException</A></B></TD>
<TD>Thrown to indicate an operation could not be completed because the record ID was invalid.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="RecordStoreException.html">RecordStoreException</A></B></TD>
<TD>Thrown to indicate a general exception occurred in a record store operation.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="RecordStoreFullException.html">RecordStoreFullException</A></B></TD>
<TD>Thrown to indicate an operation could not be completed because the record store system storage is full.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="RecordStoreNotFoundException.html">RecordStoreNotFoundException</A></B></TD>
<TD>Thrown to indicate an operation could not be completed because the record store could not be found.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="RecordStoreNotOpenException.html">RecordStoreNotOpenException</A></B></TD>
<TD>Thrown to indicate that an operation was attempted on a closed record store.</TD>
</TR>
</TABLE>
<P>
<A NAME="package_description"><!-- --></A><H2>
Package javax.microedition.rms Description
</H2>
<P>
The Mobile Information Device Profile provides a mechanism for MIDlets to persistently store data and later retrieve it. This persistent storage mechanism is modeled after a simple record oriented database and is called the Record Management System. <H2>Persistent Storage</H2> <P> The MIDP provides a mechanism for MIDlets to persistently store data and retrieve it later. This persistent storage mechanism, called the Record Management System (RMS), is modeled after a simple record-oriented database.</P> <H3>Record Store</H3> <P> A record store consists of a collection of records that will remain persistent across multiple invocations of a MIDlet. The platform is responsible for making its best effort to maintain the integrity of the MIDlet's record stores throughout the normal use of the platform, including reboots, battery changes, etc.</P> <P> Record stores are created in platform-dependent locations, which are not exposed to MIDlets. The naming space for record stores is controlled at the MIDlet suite granularity. MIDlets within a MIDlet suite are allowed to create multiple record stores, as long as they are each given different names. When a MIDlet suite is removed from a platform, all record stores associated with its MIDlets MUST also be removed. MIDlets within a MIDlet suite can access one another's record stores directly. New APIs in MIDP 2.0 allow for the explicit sharing of record stores if the MIDlet creating the RecordStore chooses to give such permission.</P> <p> Sharing is accomplished through the ability to name a RecordStore in another MIDlet suite and by defining the accessibilty rules related to the Authentication of the two MIDlet suites.</p> <P> RecordStores are uniquely named using the unique name of the MIDlet suite plus the name of the RecordStore. MIDlet suites are identified by the MIDlet-Vendor and MIDlet-Name attributes from the application descriptor.</p> <p> Access controls are defined when RecordStores to be shared are created. Access controls are enforced when RecordStores are opened. The access modes allow private use or shareable with any other MIDlet suite.</p> <P> Record store names are case sensitive and may consist of any combination of up to 32 Unicode characters. Record store names MUST be unique within the scope of a given MIDlet suite. In other words, MIDlets within a MIDlet suite are not allowed to create more than one record store with the same name; however, a MIDlet in one MIDlet suite is allowed to have a record store with the same name as a MIDlet in another MIDlet suite. In that case, the record stores are still distinct and separate.</P> <P> No locking operations are provided in this API. Record store implementations ensure that all individual record store operations are atomic, synchronous, and serialized so that no corruption occurs with multiple accesses. However, if a MIDlet uses multiple threads to access a record store, it is the MIDlet's responsibility to coordinate this access, or unintended consequences may result. For example, if two threads in a MIDlet both call <CODE>RecordStore.setRecord()</CODE> concurrently on the same record, the record store will serialize these calls properly, and no database corruption will occur as a result. However, one of the writes will be subsequently overwritten by the other, which may cause problems within the MIDlet. Similarly, if a platform performs transparent synchronization of a record store or other access from below, it is the platform's responsibility to enforce exclusive access to the record store between the MIDlets and synchronization engine.</P> <P> This record store API uses long integers for time/date stamps, in the format used by <CODE>System.currentTimeMillis()</CODE> . The record store is time stamped with the last time it was modified. The record store also maintains a version, which is an integer that is incremented for each operation that modifies the contents of the record store. These are useful for synchronization engines as well as applications.</P> <H3>Records</H3> <P> Records are arrays of bytes. Developers can use <CODE>DataInputStream</CODE> and <CODE>DataOutputStream</CODE> as well as <CODE>ByteArrayInputStream</CODE> and <CODE>ByteArrayOutputStream</CODE> to pack and unpack different data types into and out of the byte arrays. </P> <P> Records are uniquely identified within a given record store by their <CODE>recordId</CODE> , which is an integer value. This <CODE>recordId</CODE> is used as the primary key for the records. The first record created in a record store will have <CODE>recordId</CODE> equal to 1, and each subsequent <CODE>recordId</CODE> will monotonically increase by one. For example, if two records are added to a record store, and the first has a <CODE>recordId</CODE> of 'n', the next will have a <CODE>recordId</CODE> of (n+1). MIDlets can create other indices by using the <CODE>RecordEnumeration</CODE> class.</P> <h3>Example:</h3><p>The example uses the Record Management System to store and retrieve high scores for a game. In the example, high scores are stored in separate records, and sorted when necessary using a RecordEnumeration.</p><pre>import javax.microedition.rms.*;import java.io.DataOutputStream;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.ByteArrayInputStream;import java.io.DataInputStream;import java.io.EOFException;/** * A class used for storing and showing game scores. */public class RMSGameScores implements RecordFilter, RecordComparator⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -