if (trim(r)!=""){if(Pos("成功",r)>0){mymsg("保存成功！")} else {myalert(r);} } [@@@@]
反射Field、Method、Constructor
2022-12-08 21:48:32
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转载:kaotop.com/it/1077896.html
一些要用到的方法：getFields():获取public修饰的属性
getDeclaredFields():获取所有属性
getModifiers():获取修饰符（输出时要用Modifier.toString()包裹）
getType():获取属性的类型，返回Class类型，输出需要.getName()
getReturnType():获取方法的返回值类型
getName():获取完整类名
getSimpleName():获取简单类名称
getParameterTypes():获取参数列表的数据类型，返回值是个数组类型
一、反射Field （通过反射机制访问属性很重要）
Student.java
main:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 | try{
Class studentClass = Class.forName("com.example.test.Student");
Object obj = studentClass.newInstance();
Field[] fields = studentClass.getFields();
System.out.println(fields.length);
Field[] fs = studentClass.getDeclaredFields();
System.out.println(fs.length);
for(Field field: fs) {
System.out.println(Modifier.toString(field.getModifiers())+" "+field.getType().getSimpleName() +" "+field.getName());
}
Field noField = studentClass.getDeclaredField("no");
Field nameField = studentClass.getDeclaredField("name");
Field sexField = studentClass.getDeclaredField("sex");
Field ageField = studentClass.getDeclaredField("age");
noField.set(obj,201883);
nameField.setAccessible(true);
nameField.set(obj,"宇航员");
sexField.set(obj,true);
ageField.set(obj,21);
System.out.println(noField.get(obj) +" "+ nameField.get(obj) +" "+ sexField.get(obj) +" "+ ageField.get(obj));
}catch(ClassNotFoundException e) {
e.printStackTrace();
}catch(IllegalAccessException e) {
e.printStackTrace();
}catch(InstantiationException e) {
e.printStackTrace();
}catch(NoSuchFieldException e) {
e.printStackTrace();
}
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二、反射Method
Method.java:
main:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | try{
Class methodClass = Class.forName("com.example.test.Method");
Object m = methodClass.newInstance();
Method[] ms = methodClass.getDeclaredMethods();//可获取到私有方法
System.out.println(ms.length);
for(Method method:ms) {
System.out.println(Modifier.toString(method.getModifiers()) +" "+
method.getReturnType().getSimpleName() +" "+ method.getName() +"{n"+
method.getParameterTypes());//parameter返回的是数组，通过for循环输出
}
}catch(ClassNotFoundException e) {
e.printStackTrace();
}catch(IllegalAccessException e) {
e.printStackTrace();
}catch(InstantiationException e) {
e.printStackTrace();
}
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三、反射机制调用方法（非常重要）
1 2 3 4 5 | Classclass= Class.forName("com.example.test.Method");
Object obj =class.newInstance();
Method method =class.getDeclaredMethod("m1",String.class,Stringclass);
Object retValue = method.invoke(obj,"admin","123");
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四、反射Constructor
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | publicclassVip{
intno;
String name;
String birth;
booleansex;
publicVip(){
}
publicVip(intno){
this.no = no;
}
publicVip(intno,String name){
this.no = no;
this.name = name;
}
publicVip(intno,Srting name,String birth){
this.no = no;
this.name = name;
this.birth = birth;
}
publicVip(intno,String name,String birth,booleansex){
this.no = no;
this.name = name;
this.birth = birth;
this.sex = sex;
}
}
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main:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | //反编译一个类的构造方法
StringBuilder s =newStringBuilder();
Class vipClass = Class.forName("com.syf.java.bean.Vip");
s.append(Modifier.toString(vipClass.getModifiers()));
s.append(" class");
s.append(vipClass.getSimpleName());
s.append("{n");
s.append("}");
System.out.println(s);
Constructor[] constructors = vipClass.getDeclaredConstructors();
for(Costructor construtor : constructors){
s.append("t");
s.append(Moifier.toString(constructor.getModifiers()));
s.append(" ");
s.append(vipClass.getSimpleName());
s.append("(");
Class[] parameterTypes = constructor.getParameterTypes();
for(Class parameterType : parameterTypes){
s.append(parameterType.getSimpleName());
s.append(",");
}
//删除最后下标位置上的字符
if(parameterTypes.length ;0){
s.deleteCharAt(s.length()-1);
}
s.append("){}n");
}
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通过反射机制调用构造方法（非重点）
1 2 3 4 5 | Class c = Class.forName("com.syf.java.bean.Vip");
Object obj = c.newInstance();
Constructor con = c.getDeclaredConstructor(int.class,String.class,String.class,boolean.class);
Object newObj = con.newInstance(110,"jackson","2000-02-02",true);
System.out.println(newObj);//要重写Vip的toString方法
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五、获取类的父类和父接口（重点）
1 2 3 4 5 6 7 | Class stringClass = Class.forName("java.lang.String");
Class superClass = stringClass.getSuperClass();
System.out.println(superClass.getName());
Class[] interfaces = stringClass.getInterfaces();
for(Class in : interfaces){
System.out.println(in.getName());
}
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