Get generic instance __java by reflection in Java

First, create a students entity class

Package com.jackie.day11;
Import java.io.Serializable;

Import Java.util.Date;

    public class Students implements serializable{private static final long serialversionuid = -8655172670979705548l;
    private int sid;
    private String name;
    Private String gender;
    Private Date birthday;
    private int score;

    private int CID;
    public int GetSID () {return SID;
    public void Setsid (int sid) {this.sid = SID;
    Public String GetName () {return name;
    public void SetName (String name) {this.name = name;
    Public String Getgender () {return gender;
    } public void Setgender (String gender) {This.gender = gender;
    Public Date Getbirthday () {return birthday;
    The public void Setbirthday (Date birthday) {this.birthday = birthday;
    public int Getscore () {return score;
The public void SetScore (int score) {This.score = score;    public int getcid () {return CID;
    public void Setcid (int cid) {this.cid = CID; @Override public String toString () {return "Student [sid= + Sid +", name= "+ name +", gender= "+ gen
    Der + ", birthday=" + Birthday + ", score=" + score + ", cid=" + CID + "];
 }

}

Core code

Package com.jackie.day11;
Import Java.lang.reflect.Field;
Import Java.lang.reflect.ParameterizedType;
Import Java.util.HashMap;

Import Java.util.Map;
     /** * Get generic instance through reflection * @author Administrator * */Public abstract class Genericity<t> {/** * type information for the entity currently operating

    * * @SuppressWarnings ("rawtypes") protected Class clazz;  @SuppressWarnings ("unchecked") public genericity () {//through the reflection mechanism gets the type information of the entity class passed over by a subclass Parameterizedtype type
        = (Parameterizedtype) this.getclass (). Getgenericsuperclass ();
    Clazz = (class<t>) type.getactualtypearguments () [0];
     /** * Gets a map instance of all property names and corresponding values of the specified instance * * @param entity * instance * @return Field name and map instance of corresponding value */protected Map<string, object> Getfieldvaluemap (T entity) {//key is the property name, value is the corresponding values Map<str

        ing, object> fieldvaluemap = new hashmap<string, object> (); Gets all the properties (fields) field[] fields = This.clazz.getDeclaredFiel in the currently loaded entity classDS ();
            for (int i = 0; i < fields.length i++) {Field f = fields[i]; String key = F.getname ();//property name Object value = null;//property value if (! 
                    ' Serialversionuid '. Equals (key) {//Ignore serialized version ID number f.setaccessible (true);/Cancel Java language access check try {
                Value =f.get (entity);
                catch (IllegalArgumentException e) {e.printstacktrace ();
                catch (Illegalaccessexception e) {e.printstacktrace ();
            } fieldvaluemap.put (key, value);
    } return Fieldvaluemap;
 }
}

Test class:

Package com.jackie.day11;

Import java.util.Date;
Import Java.util.Map;
Import Java.util.Set;

/**
 * Test: Get generic instance through reflection
 * @author Administrator * * */Public

class Genericitytest extends Genericity <Students> {public

    static void Main (string[] args) {

        genericitytest GT = new Genericitytest ();

        Students ss = new Students ();
        Ss.setbirthday (New Date ());
        Ss.setcid ();
        Ss.setgender ("male");
        Ss.setname ("John");
        Ss.setscore ();
        Ss.setsid (4);

        map<string,object> map = gt.getfieldvaluemap (ss);
        Traverse this Map object
        set<map.entry<string, object>> entryset = Map.entryset ();
        For (map.entry<string, object> entry:entryset) {
            String key = Entry.getkey ();
            Object value = Entry.getvalue ();
            SYSTEM.OUT.PRINTLN (key + ">>>>>>>" + value);}}