相关疑难解决方法(0)

我得到了错误Unable to locate NamespaceHandler when using context:annotation-config运行(java -jar)一个由maven-assembly-plugin组装并包含我的项目及其所有依赖项的jar.

正如其他人在forum.springsource.org 线程(消息#7/8)上正确发现的那样,问题出现是因为文件META-INF/spring.handlers和META-INF/spring.schemas存在于不同的jar中,当maven-assembly-plugin在单个文件中重新打包jar时会被覆盖.

查看两个spring - *.jar文件的内容,您可以看到文件位于相对于类路径的相同位置

$ jar tf spring-oxm-3.0.3.RELEASE.jar
META-INF/spring.handlers
META-INF/spring.schemas
org/springframework/oxm/GenericMarshaller.class
...

$ jar tf spring-context-3.0.3.RELEASE.jar
META-INF/spring.handlers
META-INF/spring.schemas
org/springframework/context/ApplicationContext.class

是不是可以将META-INF文件夹放在特定的包中？如果是这样,我建议的想法(希望它是适用的)是将META-INF/spring.shemas和META-INF/spring.handlers文件放在他们引用的包下面.

$ jar tf spring-oxm-3.0.3.RELEASE.jar
org/springframework/oxm/META-INF/spring.schemas
org/springframework/oxm/META-INF/spring.handlers
org/springframework/oxm/GenericMarshaller.class
...

$ jar tf spring-context-3.0.3.RELEASE.jar
org/springframework/context/META-INF/spring.handlers
org/springframework/context/META-INF/spring.schemas
org/springframework/context/ApplicationContext.class

这样,在单个jar中合并时它们不会发生冲突.你怎么看待这件事？

public class ReportView extends JFrame {

  Connection con=null;

  void showReport() throws SQLException, ClassNotFoundException, JRException {

    con=DriverManager.getConnection("jdbc:postgresql://localhost:5432/Test");
    JasperReport report=JasperCompileManager.compileReport("Testing.jrxml");
    JasperPrint print=JasperFillManager.fillReport(report,null,con);
    JRViewer viewer=new JRViewer(print);
    viewer.setOpaque(true);
    viewer.setVisible(true);
    this.add(viewer);
    this.setSize(300, 200);
    this.setVisible(true);
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);       
}

这是错误:

Exception in thread "main" java.sql.SQLException: No suitable driver found for jdbc:postgresql://localhost:5432/Test
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)

怎么了？