getType()： 获取属性声明时类型对象（返回class对象）
getGenericType() ： 返回属性声的Type类型
getName() ： 获取属性声明时名字
getAnnotations() ： 获得这个属性上所有的注释
getModifiers() ： 获取属性的修饰
isEnumConstant() ： 判断这个属性是否是枚举类
isSynthetic() ： 判断这个属性是否是 复合类
get(Object obj) ： 取得obj对象这个Field上的值
set(Object obj, Object value) ： 向obj对象的这个Field设置新值value
Field类中最常用的是get(Object obj)和set(Object obj, Object value)这两个方法，所以这两个方法是最重要的。
getType() 和 getGenericType()的区别 ：
1.首先是返回的类型不一样，一个是Class对象一个是Type接口
2.如果属性是一个泛型，从getType（）只能得到这个属性的接口类型。但从getGenericType（）还能得到这个泛型的参数类型。
isEnumConstant()和isSynthetic() ：
对象中如果有属性是枚举类或复合类，用这两个方法返回的值并不是我们想象的true而是false。其实这两个方法是对编译生成的才有效。
二.试验代码
<span style="font-family:Microsoft YaHei;">package test.fortest; import static java.lang.System.out; import java.lang.reflect.Field; import javassist.Modifier;import test.model.Role; public class FieldTest { enum Color { Blue, Red } class Inner { } public static void main(String args[]) { Role role = new Role(); role.setId("role1"); role.setUserId("user1"); role.setRoleName("Role 1"); Field idField = getDeclaredField(role.getClass(), "id"); Field childrenField = getDeclaredField(role.getClass(), "children"); Field roleTypeField = getDeclaredField(role.getClass(), "roleType"); Field userField = getDeclaredField(role.getClass(), "user"); //获取属性声明时类型对象（返回class对象） System.out.println(idField.getType()); //返回属性声的Type类型 System.out.println(idField.getGenericType()); //如果属性是一个泛型，从getType只能得到这个属性的接口类型 System.out.println(childrenField.getType()); //如果属性是一个参数化类型，从getGenericType还能得到这个泛型的参数类型 System.out.println(childrenField.getGenericType()); //获取属性声明时名字 System.out.println(idField.getName()); //获得这个属性上所有的注释 System.out.println(idField.getAnnotations().length); //获取属性的修饰 System.out.println(Modifier.toString(idField.getModifiers())); //判断这个属性是否是枚举类 System.out.println(roleTypeField.isEnumConstant()); //判断这个属性是否是 复合类 System.out.println(userField.isSynthetic()); //FieldTest$Color是Color枚举类编译后的名字。 isSyntheticOrEnumConstant("test.fortest.FieldTest$Color"); //FieldTest$Inner是Inner类编译后的名字。 isSyntheticOrEnumConstant("test.fortest.FieldTest$Inner"); try { //取得对象这个Field上的值 System.out.println(idField.get(role)); //向对象的这个Field重新设置值 idField.set(role, "role2"); System.out.println(idField.get(role)); } catch (IllegalArgumentException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } } public static Field getDeclaredField(final Class cla, final String fieldName) { for (Class superClass = cla; superClass != null; superClass = superClass.getSuperclass()) { try { return superClass.getDeclaredField(fieldName); } catch (NoSuchFieldException e) {// e.printStackTrace(); } } return null; } public static void isSyntheticOrEnumConstant (String completePackageName) { try { Class<?> c = Class.forName(completePackageName); Field[] flds = c.getDeclaredFields(); for (Field f : flds) { out.format("%-8s [ synthetic=%-5b enum_constant=%-5b ]%n", c.getName() + ":" + f.getName(), f.isSynthetic(), f.isEnumConstant()); } } catch (ClassNotFoundException e) { e.printStackTrace(); } }}</span>
结果：
<span style="font-family:Microsoft YaHei;">class java.lang.Stringclass java.lang.Stringinterface java.util.Listjava.util.List<test.model.User>id5publicfalsefalsetest.fortest.FieldTest$Color:Blue [ synthetic=false enum_constant=true ]test.fortest.FieldTest$Color:Red [ synthetic=false enum_constant=true ]test.fortest.FieldTest$Color:ENUM$VALUES [ synthetic=true enum_constant=false ]test.fortest.FieldTest$Inner:this$0 [ synthetic=true enum_constant=false ]role1role2</span>
三.用到的类
<span style="font-family:Microsoft YaHei;">package test.model; import java.util.List; import javax.persistence.Entity;import javax.persistence.Table; import test.enu.RoleType; @Entity@Table(schema = "public")public class Role extends AbsEntity implements IEntity{ public String roleName; public String userId; public List<User> children; private RoleType roleType = RoleType.Manager; private User user; public Role() {} private Role(String roleName) { this.roleName = roleName; } public String getRoleName() { return roleName; } public void setRoleName(String roleName) { this.roleName = roleName; } public String getUserId() { return userId; } public void setUserId(String userId) { this.userId = userId; } public String getDisplayString() { System.out.println("I am a Role"); return "Role"; } }</span><span style="font-family:Microsoft YaHei;">packagetest.enu; publicenum RoleType{ Manager,Employee;}</span><span style="font-family:Microsoft YaHei;">packagetest.model; importjavax.persistence.Column;importjavax.persistence.Entity;importjavax.persistence.GeneratedValue;importjavax.persistence.Id;importjavax.persistence.ManyToOne;importjavax.persistence.Table; importorg.hibernate.annotations.AccessType;importorg.hibernate.annotations.GenericGenerator; @Entity@Table(name = "users", schema = "public")publicclass User { @Id @GeneratedValue(generator = "system-uuid") @GenericGenerator(name = "system-uuid", strategy = "uuid.hex") @Column(length = 40) @AccessType("property") privateString id; privateString loginName; privateString password; privateString address; @ManyToOne privateRole role; publicString getId() { returnid; } protectedvoid setId(String id) { this.id = id; } publicString getLoginName() { returnloginName; } publicvoid setLoginName(String loginName) { this.loginName = loginName; } publicString getPassword() { returnpassword; } publicvoid setPassword(String password) { this.password = password; } publicString getAddress() { returnaddress; } publicvoid setAddress(String address) { this.address = address; } publicRole getRole() { returnrole; } publicvoid setRole(Role role) { this.role = role; }}</span>
