利用反射机制编写校验参数（对象及属性）为空的情况

Posted 2020-09-22 doubledumbao

  2 
  3 import java.lang.reflect.Field;
  4 import java.lang.reflect.InvocationTargetException;
  5 import java.lang.reflect.Method;
  6 import java.util.ArrayList;
  7 import java.util.Arrays;
  8 import java.util.List;
  9 
 10 public class MyCheck {
 11     public static void main(String[] args) throws IllegalAccessException,
 12             IllegalArgumentException, InvocationTargetException {
 13         MyCheck check = new MyCheck();
 14         Student student = new Student();
 15         student.setName("zzzz");
 16         student.setAddress("sss");
 17         student.setIdno("");
 18 //        student.setPhone("sss");
 19         check.test1(student);
 20 
 21     }
 22 
 23     public void test(Student student) throws IllegalAccessException,
 24             IllegalArgumentException, InvocationTargetException {
 25         CheckParamUtil<Student> checkParamUtil = new CheckParamUtil<Student>();
 26         checkParamUtil.checkParam(student);
 27         System.out.println("student:" + student);
 28     }
 29 
 30     public void test1(Student student) throws IllegalAccessException,
 31             IllegalArgumentException, InvocationTargetException {
 32         CheckParamUtil<Student> checkParamUtil = new CheckParamUtil<Student>();
 33         checkParamUtil.checkParam(student, "name", "address", "idno");
 34         System.out.println("student:" + student);
 35     }
 36 
 37 }
 38 
 39 class Student {
 40     private String name;
 41     private int age;
 42     private String address;
 43     private String idno;
 44     private String phone;
 45 
 46     public Student() {
 47     }
 48 
 49     public Student(String name, int age, String address, String idno,
 50             String phone) {
 51         super();
 52         this.name = name;
 53         this.age = age;
 54         this.address = address;
 55         this.idno = idno;
 56         this.phone = phone;
 57     }
 58 
 59     public String getName() {
 60         return name;
 61     }
 62 
 63     public void setName(String name) {
 64         this.name = name;
 65     }
 66 
 67     public int getAge() {
 68         return age;
 69     }
 70 
 71     public void setAge(int age) {
 72         this.age = age;
 73     }
 74 
 75     public String getAddress() {
 76         return address;
 77     }
 78 
 79     public void setAddress(String address) {
 80         this.address = address;
 81     }
 82 
 83     public String getIdno() {
 84         return idno;
 85     }
 86 
 87     public void setIdno(String idno) {
 88         this.idno = idno;
 89     }
 90 
 91     public String getPhone() {
 92         return phone;
 93     }
 94 
 95     public void setPhone(String phone) {
 96         this.phone = phone;
 97     }
 98 
 99     @Override
100     public String toString() {
101         return "Student [name=" + name + ", age=" + age + ", address="
102                 + address + ", idno=" + idno + ", phone=" + phone + "]";
103     }
104 
105     public void a() {
106         System.out.println("haha");
107     }
108 }
109 
110 class CheckParamUtil<T> {
111     /**
112      * 
113      * @Title:checkParam
114      * @Description:(该方法用来校验对象及其属性是否为空)
115      * @param t
116      * @param args
117      * @author
118      * @throws InvocationTargetException
119      * @throws IllegalArgumentException
120      * @throws IllegalAccessException
121      * @修改时间：2017年6月9日 下午2:18:54
122      * @修改内容：创建
123      */
124     public void checkParam(T t, String... args) throws IllegalAccessException,
125             IllegalArgumentException, InvocationTargetException {
126         // 如果传入的对象为空，则直接跑出异常
127         if (t == null) {
128             throw new IllegalArgumentException("This object cann‘t be empty!");
129         }
130         Class<? extends Object> clazz = t.getClass();
131         // 定义属性列表
132         List<String> argsList = new ArrayList<String>();
133         // 如果传入的属性名不为空，则将传入的属性名放入属性列表
134         if (args != null && args.length > 0) {
135             argsList = Arrays.asList(args);
136         } else {// 如果传入的属性名为空，则将所有属性名放入属性列表
137             Field[] fields = clazz.getDeclaredFields();
138             for (Field field : fields) {
139                 argsList.add(field.getName());
140             }
141         }
142         // 获取该类自定义的方法数组
143         Method[] methods = clazz.getDeclaredMethods();
144         for (Method method : methods) {
145             // 方法名
146             String methodName = method.getName();
147             // 获取方法对应的属性名
148             String fieldName = "";
149             if (methodName.length() >= 4) {
150                 fieldName = methodName.substring(3, 4).toLowerCase()
151                         + methodName.substring(4);
152                 // 如果方法是“get方法”，并且属性列表中包含该方法对应的属性名
153                 if (methodName.startsWith("get")
154                         && argsList.contains(fieldName)) {
155                     // 如果为null，抛出异常
156                     if (method.invoke(t) == null) {
157                         throw new IllegalArgumentException(fieldName
158                                 + " cann‘t be null!");
159                     }
160                     // 如果该方法返回类型为String,返回结果为空字符串，抛出异常。
161                     Class<?> returnType = method.getReturnType();
162                     String returnTypeName = returnType.getSimpleName();
163                     if (returnTypeName.equals("String")
164                             && "".equals(method.invoke(t))) {
165                         throw new IllegalArgumentException(fieldName
166                                 + " cann‘t be empty String!");
167                     }
168                 }
169             }
170 
171         }
172 
173     }
174 }