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題目: IOC 后臺(tái)機(jī)制學(xué)習(xí)
給定:
配置文件 config.txt, 文件內(nèi)容
className = test.JavaBean1
field = username
value = ABC
該文件中的三個(gè)值會(huì)隨時(shí)可能變化, 唯一不變的是 className 指定的都是一個(gè) JavaBean(為了簡(jiǎn)化, 我們假定里面已經(jīng)有一個(gè) username 屬性, 例如:
class JavaBeanxxxx {
?? ?private String username;
?? ?public String getUsername() {
?? ??? ?return username;
?? ?}
?? ?public void setUsername(String uname) {
?? ??? ?this.username = uname;
?? ?}
}
要求: 寫一段代碼, 讀取配置文件 config.txt, 然后實(shí)現(xiàn)把 className 指定的 JavaBean 類加載(注意這個(gè)類名是可以修改的, 可配置的), 然后生成一個(gè)實(shí)例,
并把配置文件中field字段指定的值作為這個(gè)實(shí)例的屬性名(這里是username)所對(duì)應(yīng)的值設(shè)置為 ABC(字符串), 并且要讀出最后設(shè)置的值.
此題已經(jīng)被 TigerTian 解答出來, 歡迎學(xué)習(xí), 也感謝 TigerTian:
package?com.gcoresoft.ioc;
import?java.io.*;
import?java.lang.reflect.*;
import?java.util.*;
import?java.beans.*;
public?class?IOCStudy?{
????
????//Load?the?properties?file
????private?Properties?prop=new?Properties();
????
????public?void?loadPropFile(String?filename)
????{
????????try
????????{
????????????FileInputStream?fin=new?FileInputStream(filename);
????????????prop.load(fin);
????????????fin.close();
????????}catch(Exception?e){
????????????System.out.println(e.toString());
????????}
????}
????
????private?String?getValueByName(String?Name)
????{
????????return?prop.getProperty(Name);
????}
????
????public?static?void?main(String[]?args)
????{
????????IOCStudy?ioc=new?IOCStudy();
????????ioc.loadPropFile("E:\\Work\\GetInIOC\\src\\com\\gcoresoft\\ioc\\Config.txt");
????????try
????????{
????????????Class?bean=Class.forName(ioc.getValueByName("className"));
????????????try?{
????????????????java.beans.BeanInfo?info=java.beans.Introspector.getBeanInfo(bean);
????????????????java.beans.PropertyDescriptor?pd[]=info.getPropertyDescriptors();
????????????????try?{
????????????????????Method?mSet=null,mRead=null;
????????????????????Object?obj=bean.newInstance();
????????????????????for(int?i=0;i<pd.length;i++)
????????????????????????if(pd[i].getName().equalsIgnoreCase(ioc.getValueByName("field")))
????????????????????????{
????????????????????????????mSet=pd[i].getWriteMethod();
????????????????????????????mRead=pd[i].getReadMethod();????????????????????????????
????????????????????????}
????????????????????try?{
????????????????????????mSet.invoke(obj,?ioc.getValueByName("value"));
????????????????????????String?str=(String)mRead.invoke(obj,?null);
????????????????????????System.out.println(str);
????????????????????}?catch?(IllegalArgumentException?e)?{
????????????????????????//?TODO?Auto-generated?catch?block
????????????????????????e.printStackTrace();
????????????????????}?catch?(InvocationTargetException?e)?{
????????????????????????//?TODO?Auto-generated?catch?block
????????????????????????e.printStackTrace();
????????????????????}
????????????????}?catch?(InstantiationException?e)?{
????????????????????//?TODO?Auto-generated?catch?block
????????????????????e.printStackTrace();
????????????????}?catch?(IllegalAccessException?e)?{
????????????????????//?TODO?Auto-generated?catch?block
????????????????????e.printStackTrace();
????????????????}
????????????????
????????????}?catch?(IntrospectionException?e)?{
????????????????//?TODO?Auto-generated?catch?block
????????????????e.printStackTrace();
????????????}
????????????
????????????
????????}catch(ClassNotFoundException?e){
????????????System.out.println(e.toString());
????????}
????????
????}
????
}