使用Java反射机制Demo

    public static void main(String[] args) {
        try {
            Class myclass = Class.forName("cn.bluejoe.elfinder.test.Hello");
            Object myObjecg = myclass.newInstance();
            Method method = myclass.getMethod("sayHello",int.class);
            method.invoke(myObjecg,1234);
        }catch (Exception e){
            e.printStackTrace();
        }
    }

package com.circle.core.util;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import com.circle.test.controller.TestAnnotaion;
import com.dcc.common.entity.IInterfileEntity;
import com.circle.core.utilv2.CheckUtils;

/**
 * @author tianming.fan
 *
 */
public class BeanHelper {
	
	public static void main(String[] args) {
		IInterfileEntity obj = new IInterfileEntity();
		obj.setId("123123");
		obj.setUserName("dfdsfdsfsda");
		obj.setTitle("");
		try {
			//System.out.println(checkBeanAttr(obj));
		} catch (Exception e) {
			e.printStackTrace();
		}
		//System.out.println("end");
	}
	public static void main2(String[] args) {
		Map<String, String> tipMap = new HashMap<String, String>();
		//System.out.println(tipMap.get("as"));
	}
	
	/**
	 * 检查对象属性的必填项检查方法
	 * 
	 * @param bean 对象
	 * @return 检查通过返回空字符串
	 * @throws Exception
	 */
	public static String checkBeanAttr(Object bean) throws Exception{
		if (null != bean) {
			//获取所有的字段包括public,private,protected,private
			
            Field[] fields = bean.getClass().getDeclaredFields();
			//Field[] fields = bean.getClass().getFields();
			//System.out.println("fields:"+fields.length);
            for (int i = 0; i < fields.length; i++) {
                Field field = fields[i];
                //System.out.println("Key"+i+":"+field.getName());
                if ("java.lang.String".equals(field.getType().getName())) {
                	String key = field.getName();//获取字段名
                	Object value = getFieldValue(bean, key);
                    if (CheckUtils.checkIsNull(value)) {
                    	//判断字段是否为必填
                    	Map<String, Boolean> requiredMap = (Map<String, Boolean>)getFieldValue(bean, "requiredMap");
                    	if (!requiredMap.get(key)) {
                    		continue;
						}
                    	try {
                        	Map<String, String> tipMap = (Map<String, String>)getFieldValue(bean, "tipMap");
                        	String tipMsg = tipMap.get(key);
                            return tipMsg;
						} catch (Exception e) {
							return key+"不能为空";
						}
                    
                    }
                }
            }
		}
		
		return "";
	}
	/**/
	
	
	/**
     * 去掉bean中所有属性为字符串的前后空格
     * @param bean
     * @throws Exception
     */
    public static void beanAttributeValueTrim(Object bean) throws Exception {
        if(bean!=null){
            //获取所有的字段包括public,private,protected,private
            Field[] fields = bean.getClass().getDeclaredFields();
            for (int i = 0; i < fields.length; i++) {
                Field f = fields[i];
                if (f.getType().getName().equals("java.lang.String")) {
                    String key = f.getName();//获取字段名
                    Object value = getFieldValue(bean, key);
                    if (value == null) {
                        continue;
                    }
                    
                    setFieldValue(bean, key, value.toString().trim());
                }
            }
        }
    }

    //=============================================================================
    /**
     * 利用反射通过get方法获取bean中字段fieldName的值
     * @param bean
     * @param fieldName
     * @return
     * @throws Exception
     */
    private static Object getFieldValue(Object bean, String fieldName)
            throws Exception {
        StringBuffer result = new StringBuffer();
        String methodName = result.append("get")
                .append(fieldName.substring(0, 1).toUpperCase())
                .append(fieldName.substring(1)).toString();

        Object rObject = null;
        Method method = null;

        @SuppressWarnings("rawtypes")
        Class[] classArr = new Class[0];
        method = bean.getClass().getMethod(methodName, classArr);
        rObject = method.invoke(bean, new Object[0]);

        return rObject;
    }

    /**
     * 利用发射调用bean.set方法将value设置到字段
     * @param bean
     * @param fieldName
     * @param value
     * @throws Exception
     */
    private static void setFieldValue(Object bean, String fieldName, Object value)
            throws Exception {
        StringBuffer result = new StringBuffer();
        String methodName = result.append("set")
                .append(fieldName.substring(0, 1).toUpperCase())
                .append(fieldName.substring(1)).toString();

        /**
         * 利用发射调用bean.set方法将value设置到字段
         */
        Class[] classArr = new Class[1];
        classArr[0]="java.lang.String".getClass();
        Method method=bean.getClass().getMethod(methodName,classArr);
        method.invoke(bean,value);
    }
    
    //-----------------------
    /**
     * @Author Nxy
     * @Date 2020/2/15 14:14
     * @Description 汇总加减分原因
     */
    public static void setMarkReasons(Object bean) throws Exception {
        Class beanClass = bean.getClass();
        Field[] fields = beanClass.getDeclaredFields();
        if (fields == null || fields.length == 0) {
            throw new RuntimeException(bean + " has no field");
        }
        //Field targetField = beanClass.getDeclaredField("markReasons");
        //遍历属性
        for (Field field : fields) {//判断该属性是否被　MarkReason  注解修饰
            if (field.isAnnotationPresent(TestAnnotaion.class)) {
                //允许私有属性访问
                field.setAccessible(true);
                TestAnnotaion reasonAnno = field.getAnnotation(TestAnnotaion.class);
                
                //拼装加减分原因
                String value = reasonAnno.value().toString().trim();
                //System.out.println("value: "+value);
                setFieldValue(bean, field.getName(), value);
                //reasonsSb.append();
            }
        }
        
    }
}