我无法重现错误，但是请允许我更正您的属性文件，这样，如果 您使用的是SpringBoot 1.4或更高版本 ，Spring实际上可以读取您的属性。

正如我在帖子中发现的一样的错误，为了解决该问题，您正在尝试增加datasource.max-active属性和其他属性，对吗？

因此，如果属性不在此默认应用程序属性中，则必须将它们编写为

    spring.jpa.properties.*= # Additional native properties to set on the JPA provider.

据此，我建议您将application.properties文件更改为以下内容：

    spring.datasource.url = jdbc:derby:/spring-boot/db;create=true
    spring.datasource.username = admin
    spring.datasource.password = 1234

    # this one is incorrect
    # spring.datasource.driver = org.apache.derby.jdbc.EmbeddedDriver
    # replace with the one below, otherwise Spring will use his own
    # derby driver
    spring.datasource.driver-class-name = org.apache.derby.jdbc.EmbeddedDriver

    # this one is incorrect as well
    # hibernate.dialect = org.hibernate.dialect.DerbyDialect
    # use the following way
    spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.DerbyDialect

    spring.jpa.generate-ddl = true
    spring.jpa.hibernate.ddl-auto = update
    spring.jpa.properties.hibernate.current_session_context_class = org.springframework.orm.hibernate4.SpringSessionContext

    # and in order for these guys to work you have to know
    # spring.datasource.max-active=100
    # spring.datasource.max-idle=8
    # spring.datasource.min-idle=8
    # your dbcp and look for documentation
    # below is the example for Tomcat
    spring.datasource.tomcat.max-active=100
    spring.datasource.tomcat.max-idle=8
    spring.datasource.tomcat.min-idle=8

    # make sure you check out the logging
    # this is IMPORTANT to see that your 
    # properties were ACTUALLY picked up
    logging.level.org.springframework.web = DEBUG
    logging.level.org.hibernate = DEBUG

最后但并非最不重要的一点是，您必须确保 Spring确实拾取了 您的max-idle属性。这就是为什么我添加了两个最后的日志记录和调试属性。

如果您仔细查看日志文件，请检查将其设置为哪些值。这是那条线对我的外观

    2016-11-17 11:40:27.875 DEBUG 32079 --- [           main] o.hibernate.internal.SessionFactoryImpl  : Instantiating session factory with properties: {java.vendor=Oracle Corporation, sun.java.launcher=SUN_STANDARD, catalina.base=/tmp/tomcat.736868414125414090.8080, sun.management.compiler=HotSpot 64-Bit Tiered Compilers, catalina.useNaming=false, hibernate.implicit_naming_strategy=org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy, os.name=Linux, sun.boot.class.path=/usr/users/nikiforo/src/jdk1.8.0_73/jre/lib/resources.jar:/usr/users/nikiforo/src/jdk1.8.0_73/jre/lib/rt.jar:/usr/users/nikiforo/src/jdk1.8.0_73/jre/lib/sunrsasign.jar:/usr/users/nikiforo/src/jdk1.8.0_73/jre/lib/jsse.jar:/usr/users/nikiforo/src/jdk1.8.0_73/jre/lib/jce.jar:/usr/users/nikiforo/src/jdk1.8.0_73/jre/lib/charsets.jar:/usr/users/nikiforo/src/jdk1.8.0_73/jre/lib/jfr.jar:/usr/users/nikiforo/src/jdk1.8.0_73/jre/classes, hibernate.current_session_context_class=org.springframework.orm.hibernate4.SpringSessionContext, java.vm.specification.vendor=Oracle Corporation, java.runtime.version=1.8.0_73-b02, user.name=nikiforo, javax.persistence.validation.mode=AUTO, user.language=en, sun.boot.library.path=/usr/users/nikiforo/src/jdk1.8.0_73/jre/lib/amd64, PID=32079, java.version=1.8.0_73, user.timezone=Europe/Berlin, sun.arch.data.model=64, java.endorsed.dirs=/usr/users/nikiforo/src/jdk1.8.0_73/jre/lib/endorsed, sun.cpu.isalist=, sun.jnu.encoding=UTF-8, file.encoding.pkg=sun.io, file.separator=/, java.specification.name=Java Platform API Specification, java.class.version=52.0, user.country=US, java.home=/usr/users/nikiforo/src/jdk1.8.0_73/jre, java.vm.info=mixed mode, os.version=4.1.20-11-default, hibernate.boot.CfgXmlAccessService.key=org.hibernate.boot.cfgxml.spi.LoadedConfig@6abb7b7d, hibernate.connection.datasource=org.apache.tomcat.jdbc.pool.DataSource@5c7dfc05{ConnectionPool[defaultAutoCommit=null; defaultReadOnly=null; defaultTransactionIsolation=-1; defaultCatalog=null; driverClassName=org.apache.derby.jdbc.EmbeddedDriver; maxActive=100

这是一条很长的线，但是正如您所看到的，对于我而言，这max-active已经定了。

如果您想查看我在哪个简单的Spring-Data-REST应用程序中尝试了derby并遵循了以下属性，请检查此GitHub项目：derby-tomcat-
database-error分支

可能有帮助，可能没有帮助，如果我写错了，请告诉我，我将删除帖子。