是否有任何开源Javareflection实用程序或jar？

是否有任何开源实用程序或jar用于处理java中的reflection？

我正在动态地将方法传递给类，我想获取返回值。

例如：

class Department { String name ; Employee[] employees; public void setName(String name) { this.name = name; } public String getName() { return name; } public Employee[] getEmployes() { return employees; } } 

我想将所有员工打印到控制台输出，而是在运行时获取它，如下所示：

 Department dept = new Department(); // add employees.. getEmployeeNames(dept,"getEmployees.getAddress.getStreet"); // So the user says they want employee street, but we don't know that // until run-tme. 

有没有反思的开源来容纳这样的东西？

Answer 1

当我看到它时，这种东西总会响起设计警钟。

话虽这么说，我通常认为JXPath（ http://commons.apache.org/jxpath/users-guide.html ）是解决这类问题的最合理的解决方案，如果它不能以更加设计的方式解决：

 import org.apache.commons.jxpath.JXPathContext; import java.util.ArrayList; import java.util.Iterator; import java.util.List; /** */ public class JXPather { public static void main(String[] args) { Department d = new Department(); d.employees.add(new Employee(new Address("wherever a"))); d.employees.add(new Employee(new Address("wherever b"))); d.employees.add(new Employee(new Address("wherever c"))); d.employees.add(new Employee(new Address("wherever def"))); JXPathContext context = JXPathContext.newContext(d); // access matched xpath objects by iterating over them for (Iterator iterator = context.iterate("/employees/address/street"); iterator.hasNext();) { System.out.println(iterator.next()); } // or directly via standard xpath expressions System.out.println("street of third employee is: "+context.getValue("/employees[3]/address/street")); // supports most (or all ?) xpath expressions for (Iterator iterator = context.iterate("/employees/address/street[string-length(.) > 11]"); iterator.hasNext();) { System.out.println("street length longer than 11 c'ars:"+iterator.next()); } } static public class Department { List employees = new ArrayList(); public List getEmployees() { return employees; } } static public class Employee { Address address; Employee(Address address) { this.address = address; } public Address getAddress() { return address; } } static public class Address { String street; Address(String street) { this.street = street; } public String getStreet() { return street; } } } 

Answer 2

除了使用Apache BeanUtils或直接使用java.lang.reflect API，正如其他人建议的那样，你也可以使用我创建的jOOR来减少在Java中使用reflection的冗长程度。 您的示例可以像这样实现：

 Employee[] employees = on(department).call("getEmployees").get(); for (Employee employee : employees) { Street street = on(employee).call("getAddress").call("getStreet").get(); System.out.println(street); } 

Java中具有正常reflection的相同示例：

 try { Method m1 = department.getClass().getMethod("getEmployees"); Employee employees = (Employee[]) m1.invoke(department); for (Employee employee : employees) { Method m2 = employee.getClass().getMethod("getAddress"); Address address = (Address) m2.invoke(employee); Method m3 = address.getClass().getMethod("getStreet"); Street street = (Street) m3.invoke(address); System.out.println(street); } } // There are many checked exceptions that you are likely to ignore anyway catch (Exception ignore) { // ... or maybe just wrap in your preferred runtime exception: throw new RuntimeException(e); } 

此外，jOOR以更方便的方式包装java.lang.reflect.Proxyfunction：

 interface StringProxy { String mySubString(int beginIndex); } // You can easily create a proxy of a custom type to a jOOR-wrapped object String substring = on("java.lang.String") .create("Hello World") .as(StringProxy.class) .mySubString(6); 

Answer 3

你可以使用apache beanutils： http ：//commons.apache.org/beanutils/

Answer 4

您可以像其他人建议的那样使用某些第三方库，也可以自己手动完成这个技巧，但这并不难。 以下示例应说明可以采取的方式：

class Department { Integer[] employees; public void setEmployes(Integer[] employees) { this.employees = employees; } public Integer[] getEmployees() { return employees; } } Department dept = new Department(); dept.setEmployes(new Integer[] {1, 2, 3}); Method mEmploees = Department.class.getMethod("getEmployees", new Class[] {}); Object o = mEmploees.invoke(dept, new Object[] {}); Integer[] employees = (Integer[])o; System.out.println(employees[0].doubleValue());;
class Department { Integer[] employees; public void setEmployes(Integer[] employees) { this.employees = employees; } public Integer[] getEmployees() { return employees; } } Department dept = new Department(); dept.setEmployes(new Integer[] {1, 2, 3}); Method mEmploees = Department.class.getMethod("getEmployees", new Class[] {}); Object o = mEmploees.invoke(dept, new Object[] {}); Integer[] employees = (Integer[])o; System.out.println(employees[0].doubleValue());;