在未知类对象的情况下，通过反射得到对象，然后设置新值

在未知类对象的情况下，通过反射得到对象，然后设置新值，然后打印出来 public class BeanDto { private Integer id; private String name; private String age; private String sex; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAge() { return age; } public void setAge(String age) { this.age = age; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } } import java.beans.BeanInfo; import java.beans.IntrospectionException; import java.beans.Introspector; import java.beans.PropertyDescriptor; import java.lang.reflect.Constructor; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.HashMap; import java.util.Map; /** * 类BeanUtil.java的实现描述：在未知类对象的情况下，通过反射得到对象，然后设置新值 * * 方法1，方法2都有效 * * @author wangdawei wangdw2000@gmail.com * @version 1.0 Date 2009-8-5 * @see java.lang.Class History: * * */ @SuppressWarnings("unchecked") public class BeanUtil { /** * 获取[BeanDto]里的属性，并且设置新值 * * @param dto * 测试BeanDto */ public void getBeanInfo1(Object obj) { // 通过实例获得类名 Class dtoClass = obj.getClass(); // 获得构造子，用于实例化对象 Constructor[] cons = dtoClass.getConstructors(); // 获取字段名称，存放到数组 Field[] field = dtoClass.getDeclaredFields(); Object[] arg = { 3, "wangdawei", "28", "男" }; // 构造Class数组，用于存放参数类型 Class[] ddd = new Class[arg.length]; try { for (int j = 0; j < cons.length; j++) { Method method; // 构造实例相当于new Object（） Object object = cons[j].newInstance(); for (int i = 0; i < field.length; i++) { // 根据字段数组的长度，构造set方法 String stt = field[i].getName(); // 取第一个字母 String fisrt = stt.substring(0, 1); // 将第一个字母转换为大写 String upFisrt = fisrt.toUpperCase(); // 合成set方法 String seter = "set" + upFisrt + stt.substring(1); // 指定调用方法的类型 ddd[i] = arg[i].getClass(); // 通过方法名获取dtoClass的方法，参数类型为ddd[i]的类型 method = dtoClass.getMethod(seter, ddd[i]); // 通过dtoClass的实例调用seter方法，arg[i]为参数值 method.invoke(object, arg[i]); } // 输出 print(object, "getBeanInfo1"); } } catch (Exception e) { e.printStackTrace(); } } /** * 获取[BeanDto]里的属性，并且设置新值 * * @param obj * 测试BeanDto */ public void getBeanInfo2(Object obj) { try { Class beanClass = obj.getClass(); BeanInfo beanInfo = Introspector.getBeanInfo(beanClass); PropertyDescriptor[] pds = beanInfo.getPropertyDescriptors(); Map valueMap = new HashMap(); // 付值过程 valueMap.put("id", 3); valueMap.put("name", "wangdawei"); valueMap.put("age", "28"); valueMap.put("sex", "男"); for (int i = 0; i < pds.length; i++) { PropertyDescriptor pd = pds[i]; // 属性名(如:age) String propertyName = pd.getName(); // 属性方法名(如:setAge) String methodName = null; if (pd.getWriteMethod() != null) { methodName = pd.getWriteMethod().getName(); Method method = beanClass.getMethod(methodName.trim(), valueMap.get(propertyName).getClass()); method.invoke(obj, valueMap.get(propertyName)); } } // 输出 print(obj, "getBeanInfo2"); } catch (IntrospectionException e) { e.printStackTrace(); } catch (SecurityException e) { e.printStackTrace(); } catch (NoSuchMethodException e) { e.printStackTrace(); } catch (IllegalArgumentException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (InvocationTargetException e) { e.printStackTrace(); } } /** * 打印出[BeanDto]的值 * * @param obj [BeanDto]对象 * @param methodName 方法名 * @throws SecurityException * @throws NoSuchMethodException * @throws IllegalArgumentException * @throws IllegalAccessException * @throws InvocationTargetException */ private void print(Object obj, String methodName) throws SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException { Class beanClass = obj.getClass(); Field[] field = beanClass.getDeclaredFields(); for (int i = 0; i < field.length; i++) { String stt = field[i].getName(); String fisrt = stt.substring(0, 1); String upFisrt = fisrt.toUpperCase(); String geter = "get" + upFisrt + stt.substring(1); Method method = beanClass.getMethod(geter); System.out.println(methodName + ":" + stt + "==" + method.invoke(obj)); } } public static void main(String[] a) { BeanUtil bu = new BeanUtil(); String className = "BeanDto"; try { Object obj = Class.forName(className).newInstance(); // 测试方法1 bu.getBeanInfo1(obj); // 测试方法2 bu.getBeanInfo2(obj); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } } }