java - GWT 编译器找不到 javax 库

Question

我是 GWT 的新手，正在尝试运行我的第一个 GWT 应用程序。我有使用 javax.persistence 包中的 API 的类。当我尝试使用 GWT 编译器编译代码时，由于无法在类路径中找到提到的包而失败。不过，我已将库添加到类(class)中。

<property name="gwt.sdk" location="C:/gwt-2.4.0" />
<!-- Arguments to gwtc and devmode targets -->
<property name="gwt.args" value="" />
<path id="gwt.class.path">
    <fileset dir="${devLib}"> <!-- here is all the dependent libraries-->
        <include name="*.jar" />
    </fileset>
    <pathelement location="${gwt.sdk}/gwt-user.jar"/>
    <fileset dir="${gwt.sdk}" includes="gwt-dev*.jar"/>
</path>

<target name="gwtc" description="GWT compile to JavaScript (production mode)">
    <echo message="${gwt.class.path}"/>
    <java failonerror="true" fork="true" classname="com.google.gwt.dev.Compiler">
        <classpath>
            <path refid="gwt.class.path"/>
            <pathelement location="gwt/project/src"/>
        </classpath>
        <!-- add jvmarg -Xss16M or similar if you see a StackOverflowError -->
        <jvmarg value="-Xmx256M"/>
        <arg line="-war"/>
        <arg value="web/five/gwtUI"/>
        <!-- Additional arguments like -style PRETTY or -logLevel DEBUG -->
        <arg line="${gwt.args}"/>
        <arg value="org.scheduling.Scheduling"/>
    </java>
</target>

这是我在运行 ant 目标 gwtc 时看到的错误。有人可以帮我改正吗？

[java] Compiling module org.scheduling.Scheduling
 [java]    Validating newly compiled units
 [java]       Ignored 91 units with compilation errors in first pass.
 [java] Compile with -strict or with -logLevel set to TRACE or DEBUG to see all errors.
 [java]    Computing all possible rebind results for 'com.google.gwt.user.client.UserAgentAsserter'
 [java]       Rebinding com.google.gwt.user.client.UserAgentAsserter
 [java]          Checking rule <generate-with class='com.google.gwt.editor.rebind.SimpleBeanEditorDriverGenerator'/>
 [java]             [WARN] Detected warnings related to 'com.google.gwt.editor.client.SimpleBeanEditorDriver'.   Are validation-api-<version>.jar and validation-api-<version>-sources.jar on the classpath?
 [java]             Specify -logLevel DEBUG to see all errors.
 [java]             [WARN] Unknown type 'com.google.gwt.editor.client.SimpleBeanEditorDriver' specified in deferred binding rule
 [java]    Scanning for additional dependencies: file:/C:/Tolven_skandula/org.component.scheduling/gwt/project/src/org/scheduling/gwt/common/client/SchedulingEntryPoint.java
 [java]       Computing all possible rebind results for 'org.scheduling.common.service.SchedulingService'
 [java]          Rebinding org.scheduling.common.service.SchedulingService
 [java]             Checking rule <generate-with class='com.google.gwt.user.rebind.rpc.ServiceInterfaceProxyGenerator'/>
 [java]                [ERROR] Errors in 'file:/C:/Tolven_skandula/org.component.scheduling/gwt/project/src/org/scheduling/common/model/Appointment.java'
 [java]                   [ERROR] Line 5: The import javax.persistence cannot be resolved
 [java]                   [ERROR] Line 6: The import javax.persistence cannot be resolved
 [java]                   [ERROR] Line 7: The import javax.persistence cannot be resolved
 [java]                   [ERROR] Line 8: The import javax.persistence cannot be resolved
 [java]                   [ERROR] Line 9: The import javax.persistence cannot be resolved

Answer 1

看看http://code.google.com/intl/de-DE/webtoolkit/doc/latest/RefJreEmulation.html ，它描述了正在模拟的标准 JRE GWT 中的类。似乎不支持 javax.persistence。

gwt 就是这样。仅支持标准 JRE 的一小部分(因为 JavaScript 永远不会具有相同的功能，因为它在浏览器环境中运行)。此外，虽然谷歌人员正在尝试集成越来越多的类，但他们的速度只有那么快。

但您始终可以创建自己的类和库。