JAVA内省机制

 

内省是反射的一种特例

由于在框架底层中要频繁地操作javabean,而利用反射操作比较麻烦。所以为了方便操作javabean，sun公司开发出一套API提高效率

 

Java内省机制是针对JavaBean进行操作的

 

public class Person {
    
    private String name;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    private int age;
 
}

 

 

 

 

public class TestIntrospector {
 
    @Test
    public void tes1() throws Exception {
        Class<?> cl = Class.forName("com.irish.aop.cc.Person");
        //在bean上进行内省
        BeanInfo beaninfo = Introspector.getBeanInfo(cl, Object.class);
        PropertyDescriptor[] pro = beaninfo.getPropertyDescriptors();
        Person p = new Person();
        System.out.print("Person的属性有:");
        for (PropertyDescriptor pr : pro) {
            System.out.print(pr.getName() + " ");
        }
        System.out.println("");
        for (PropertyDescriptor pr : pro) {
            Method writeme = pr.getWriteMethod();
            if (pr.getName().equals("name")) {
                writeme.invoke(p, "xiong");
            }
            if (pr.getName().equals("age")) {
                writeme.invoke(p, 23);
            }
            Method method = pr.getReadMethod();
            System.out.print(method.invoke(p) + " ");
 
        }
    }
 
    @Test
    public void test2() throws Exception {
        PropertyDescriptor pro = new PropertyDescriptor("name", Person.class);
        Person preson=new Person();
        Method  method=pro.getWriteMethod();
        method.invoke(preson, "xiong");
        System.out.println(pro.getReadMethod().invoke(preson));
    }
}

 

 

 

怎么让后台的Model对象统一的接收表单提交过来的参数

Servlet

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        user u=new user();
        populate(request.getParameterMap(),u);
        System.out.println(u);
        
    }
    
    private void populate(Map<String,String[]> map,user u){
        try {
            Map<String,String[]> params=map;
            //1 获得 java Bean的描述信息
            BeanInfo info =Introspector.getBeanInfo(user.class);
            //2 获得 User中的属性信息
            PropertyDescriptor [] pds =info.getPropertyDescriptors();
            //3 遍历属性信息
            for (PropertyDescriptor pd : pds) {
                String[] param=params.get(pd.getName());
                if (param!=null && param.length>0) {
                    pd.getWriteMethod().invoke(u, param[0]);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

 

JavaBean

public class user {
    private String name;
    private String password;
    public user(){
        
        super();
    }
    
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public String getPassword() {
        return password;
    }
 
    public void setPassword(String password) {
        this.password = password;
    }
    
    @Override
    public String toString() {
        return "user [name=" + name + ", password=" + password + " ]";
    }
}

Jsp

    <body>
        <form action="/JavaBean/BServlet" method="post" >
            用户名:<input type="text" name="name" /><br>
            密码:<input type="password" name="password" /><br>
        
            <input type="submit" /><br>
        </form>
    </body>

 

posted @ 2019-06-06 16:32  踏月而来  阅读(208)  评论(0)  编辑  收藏  举报