【求教】如何设置javabean中某几个属性的默认值 - 黑马程序员技术交流社区

package com.itheima;
import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/**
* 存在一个JavaBean，它包含以下几种可能的属性： 1:boolean/Boolean 2:int/Integer 3:String
* 4:double/Double 属性名未知，现在要给这些属性设置默认值，以下是要求的默认值： String类型的默认值为字符串
* www.itheima.com int/Integer类型的默认值为100 boolean/Boolean类型的默认值为true
* double/Double的默认值为0.01D.
* 只需要设置带有getXxx/isXxx/setXxx方法的属性，非JavaBean属性不设置，请用代码实现
* @author Liu wangfang
*/
public class Test_5 {
public static void main(String[] args) throws IntrospectionException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
//1.创建一个javaBean对象;
JavaBean jb = new JavaBean();
//2.使用內省中方法获得BeanInfo对象;
BeanInfo bi = Introspector.getBeanInfo(jb.getClass());
//3.获得BeanInfo中的属性描述器数组;
PropertyDescriptor[] pds = bi.getPropertyDescriptors();
//4.遍历数组,判断属性的类型是否是要求的类型,如果是,就设置默认值;
for(PropertyDescriptor pd : pds){
//5.遍历每个属性描述器时,先获得其set方法;
Method method = pd.getWriteMethod();
//6.判断属性的类型是否是题目要求的类型
if(pd.getPropertyType()==boolean.class ||pd.getPropertyType()==Boolean.class){
//7.set方法的调用,赋值
method.invoke(jb,true);
} if(pd.getPropertyType()==int.class ||pd.getPropertyType()==Integer.class){
method.invoke(jb,100);
} if(pd.getPropertyType()==double.class ||pd.getPropertyType()==Double.class){
method.invoke(jb,0.01D);
} if(pd.getPropertyType()==String.class ){
method.invoke(jb,"www.itheima.com");
}
}
// System.out.println(jb);
}
}
class JavaBean{
private boolean flag;
private int num;
private String name;
private double db;
private char c;
public boolean isFlag() {
return flag;
}
public void setFlag(boolean flag) {
this.flag = flag;
}
public int getNum() {
return num;
}
public void setNum(int num) {
this.num = num;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getDb() {
return db;
}
public void setDb(double db) {
this.db = db;
}
// public String toString(){
// return name +"**"+ db + "**"+num +"**"+ flag;
// }
}

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public class Test8 {
public static void main(String[] args) throws Exception {
//给一个实例化对象
Worker worker = new Worker();
//因worker的属性名未知，故要用内省
BeanInfo beanInfo = Introspector.getBeanInfo(worker.getClass());
//拿到所有的属性
PropertyDescriptor[] pds = beanInfo.getPropertyDescriptors();
//遍历属性
for(PropertyDescriptor pd : pds){
//给String类型的属性设置默认值
if(pd.getPropertyType() == (String.class)){
Method methodSetStr = pd.getWriteMethod();
methodSetStr.invoke(worker, "www.itheima.com");
Method methodGetStr = pd.getReadMethod();
//打印出属性名和属性值
System.out.println(pd.getName()+": "+methodGetStr.invoke(worker));
}
//给int/Integer类型的属性设置默认值
else if(pd.getPropertyType()==(int.class) || pd.getPropertyType()==(Integer.class)){
Method methodSetInt = pd.getWriteMethod();
methodSetInt.invoke(worker, 100);
Method methodGetInt = pd.getReadMethod();
//打印出属性名和属性值
System.out.println(pd.getName()+": "+methodGetInt.invoke(worker));
}
//给boolean/Boolean类型的属性设置默认值
else if(pd.getPropertyType()==(boolean.class) || pd.getPropertyType()==(Boolean.class)){
Method methodSetBool = pd.getWriteMethod();
methodSetBool.invoke(worker, true);
Method methodGetBool = pd.getReadMethod();
//打印出属性名和属性值
System.out.println(pd.getName()+": "+methodGetBool.invoke(worker));
}
//给double/Double类型的属性设置默认值
else if(pd.getPropertyType()==(double.class) || pd.getPropertyType()==(Double.class)){
Method methodSetDou = pd.getWriteMethod();
methodSetDou.invoke(worker, 0.01D);
Method methodGetDou = pd.getReadMethod();
//打印出属性名和属性值
System.out.println(pd.getName()+": "+methodGetDou.invoke(worker));
}
}
}
}
//JavaBean类
class Worker {
private String workCompanyName; //员工所属公司
private boolean married; //结婚与否
private int id; //员工号
private double income; //月薪
public String getWorkCompanyName() {
return workCompanyName;
}
public void setWorkCompanyName(String workCompanyName) {
this.workCompanyName = workCompanyName;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public double getIncome() {
return income;
}
public void setIncome(double income) {
this.income = income;
}
public boolean isMarried(){
return this.married;
}
public void setMarried(boolean married){
this.married = married;
}
}

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