更新:Oracle 已确认这是一个错误。

摘要:某些自定义BeanInfo s 和 PropertyDescriptor在 JDK 1.6 中工作的 s 在 JDK 1.7 中失败，有些仅在垃圾收集运行并清除某些 SoftReferences 后才会失败。

Edit: This will also break the ExtendedBeanInfo in Spring 3.1 as noted at the bottom of the post.

Edit: If you invoke sections 7.1 or 8.3 of the JavaBeans spec, explain exactly where those parts of the spec require anything. The language is not imperative or normative in those sections. The language in those sections is that of examples, which are at best ambiguous as a specification. Furthermore, the BeanInfo API specifically allows one to change the default behavior, and it is clearly broken in the second example below.

new PropertyDescriptor("foo", MyClass.class, "getFoo", "setFoo");

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import org.testng.annotations.*;

/**
 * Shows what has worked up until JDK 1.7.
 */
public class PropertyDescriptorTest
{
    private int i;
    public int getI() { return i; }
    // A setter that my people call "fluent".
    public PropertyDescriptorTest setI(final int i) { this.i = i; return this; }

    @Test
    public void fluentBeans() throws IntrospectionException
    {
        // This throws an exception only in JDK 1.7.
        final PropertyDescriptor pd = new PropertyDescriptor("i",
                           PropertyDescriptorTest.class, "getI", "setI");

        assert pd.getReadMethod() != null;
        assert pd.getWriteMethod() != null;
    }
}

@@ -240,11 +289,16 @@
        }

        if (writeMethodName == null) {
-       writeMethodName = "set" + getBaseName();
+                writeMethodName = Introspector.SET_PREFIX + getBaseName();
        }

-       writeMethod = Introspector.findMethod(cls, writeMethodName, 1, 
-                 (type == null) ? null : new Class[] { type });
+            Class[] args = (type == null) ? null : new Class[] { type };
+            writeMethod = Introspector.findMethod(cls, writeMethodName, 1, args);
+            if (writeMethod != null) {
+                if (!writeMethod.getReturnType().equals(void.class)) {
+                    writeMethod = null;
+                }
+            }
        try {
        setWriteMethod(writeMethod);
        } catch (IntrospectionException ex) {

@Test
public void fluentBeansByMethod()
    throws IntrospectionException, NoSuchMethodException
{
    final Method readMethod = PropertyDescriptorTest.class.getMethod("getI");
    final Method writeMethod = PropertyDescriptorTest.class.getMethod("setI",
                                                                 Integer.TYPE);

    final PropertyDescriptor pd = new PropertyDescriptor("i", readMethod,
                                                         writeMethod);

    assert pd.getReadMethod() != null;
    assert pd.getWriteMethod() != null;
}

@Test
public void nonStandardWriteMethodOnly() throws IntrospectionException {
    @SuppressWarnings("unused") class C {
        public C setFoo(String foo) { return this; }
    }

    BeanInfo bi = Introspector.getBeanInfo(C.class);
    ExtendedBeanInfo ebi = new ExtendedBeanInfo(bi);

    assertThat(hasReadMethodForProperty(bi, "foo"), is(false));
    assertThat(hasWriteMethodForProperty(bi, "foo"), is(false));

    assertThat(hasReadMethodForProperty(ebi, "foo"), is(false));
    assertThat(hasWriteMethodForProperty(ebi, "foo"), is(true));
}

最佳答案

看起来规范没有改变(它需要 void setter)但实现已经更新为只允许 void setter。

规范:

http://www.oracle.com/technetwork/java/javase/documentation/spec-136004.html

更具体地说，请参阅第 7.1 节(访问器方法)和第 8.3 节(简单属性的设计模式)

请参阅此 stackoverflow 问题中的一些稍后答案:

Does Java bean's setter permit return this?

关于java - 为什么 PropertyDescriptor 行为从 Java 1.6 更改为 1.7？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/10806895/