Two classes have similar fields, but they don't have superclass. In my code : First and Second classes. I need to write method convertToAnother, what will be return object of class resultClassObject with values of fields from object one.
Both classes have Json annotation. That annotation have vaule of property equals name of class in lowercase (in my code class First have className = "first".
import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
import java.io.StringReader
public class Solution {
public static void main(String[] args) throws IOException {
Second s = (Second) convertOneToAnother(new First(), Second.class);
First f = (First) convertOneToAnother(new Second(), First.class);
}
public static Object convertOneToAnother(Object one, Class resultClassObject) throws IOException {
try {
ObjectMapper mapper = new ObjectMapper();
String obj = mapper.writeValueAsString(one);
obj = obj.replace("\"className\":\"" + one.getClass().getSimpleName().toLowerCase() + "\"", "\"className\":\"" + resultClassObject.getSimpleName().toLowerCase() + "\"");
return new ObjectMapper().readValue(new StringReader(obj), resultClassObject);
}
catch (Exception e) {
e.printStackTrace();
}
return null;
}
#JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property="className")
#JsonSubTypes(#JsonSubTypes.Type(value=First.class, name="first"))
public static class First {
public int i;
public String name;
}
#JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property="className")
#JsonSubTypes(#JsonSubTypes.Type(value=Second.class, name="second"))
public static class Second {
public int i;
public String name;
}
}
Maybe another decision exist?
The only correct way to do that using jackson is to marshall instance to json and then unmarshall. I would recommend to use convertion on the level of java objects - using Dozer: http://dozer.sourceforge.net
I want to offer such a solution, example for class First:
First first = new First();
first.i = 1;
first.name = "first";
Second s = (Second) convertOneToAnother(first, Second.class);
System.out.println(s.name); // first
ObjectMapper mapper = new ObjectMapper();
// here we disable uses annototions, since by the condition of the
// problem, we have two classes have similar fields
mapper.disable(MapperFeature.USE_ANNOTATIONS);
StringWriter writer = new StringWriter();
mapper.writeValue(writer, one);
//writer.toString() == {"i":1,"name":"first"}
mapper.readValue(writer.toString, resultClassObject);
if we don't use method mapper.disable(), we'll have for writer, such string {"className":"first","i":1,"name":"first"}
You can write code like below for model mapping:
public class ModelConverter {
public static void main(String[] args) throws IOException {
Test1 t1 = new Test1();
ObjectMapper mapper1 = new ObjectMapper();
String jsonString = mapper1.writeValueAsString(t1);
System.out.println(jsonString);
Test2 t2 = mapper1.readValue(jsonString, Test2.class);
System.out.println(t2);
}
}
public class Test1 implements Serializable {
private int i = 10;
private String name = "demo1";
private Test3 test3 = new Test3();
public int getI() {
return i;
}
public void setI(int i) {
this.i = i;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Test3 getTest3() {
return test3;
}
public void setTest3(Test3 test3) {
this.test3 = test3;
}
#Override
public String toString() {
return "test1 [i=" + i + ", name=" + name + ", Test3=" + test3 + "]";
}
}
public class Test2 implements Serializable {
private int i = 11;
private String name = "demo2";
private Test3 test3;
public int getI() {
return i;
}
public void setI(int i) {
this.i = i;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Test3 getTest3() {
return test3;
}
public void setTest3(Test3 test3) {
this.test3 = test3;
}
#Override
public String toString() {
return "test2 [i=" + i + ", name=" + name + ", Test3=" + test3 + "]";
}
}
public class Test3 implements Serializable {
private int i = 12;
private String name = "demo3";
public int getI() {
return i;
}
public void setI(int i) {
this.i = i;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#Override
public String toString() {
return "test3 [i=" + i + ", name=" + name + "]";
}
}
For this kind of task would be right to use object mappers like Dozer (http://dozer.sourceforge.net/)
You can replace value of className without String manipulations
ObjectReader reader = mapper.reader();
JsonNode node = reader.readTree(writer.toString());
((ObjectNode)node).put("className",resultClassObject.getSimpleName().toLowerCase());
Also if you don't know the name of the field where name of the class is stored, but you know it is in the annotations, you can try and get the first field from JsonNode (in your code you assume that the field name is "className", but what if it is not).
ObjectMapper mapper1 = new ObjectMapper();
Map<String, Object> result = mapper1.convertValue(node, Map.class);
String key1 = result.keySet().toArray()[0].toString();
And now you can replace the value for the key1 field, which should be the field where class name is stored.
Related
I have two POJOs (Person.java and User.java) that contain similar information. See below:
public class Person {
private String first_name;
private String last_name;
private Integer age;
private Integer weight;
private Integer height;
public String getFirst_name() {
return first_name;
}
public void setFirst_name(String first_name) {
this.first_name = first_name;
}
public String getLast_name() {
return last_name;
}
public void setLast_name(String last_name) {
this.last_name = last_name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Integer getWeight() {
return weight;
}
public void setWeight(Integer weight) {
this.weight = weight;
}
public Integer getHeight() {
return height;
}
public void setHeight(Integer height) {
this.height = height;
}
}
public class User {
private String name_first;
private String name_last;
private Integer my_age;
private Integer my_weight;
private String social_security;
public String getName_first() {
return name_first;
}
public void setName_first(String name_first) {
this.name_first = name_first;
}
public String getName_last() {
return name_last;
}
public void setName_last(String name_last) {
this.name_last = name_last;
}
public Integer getMy_age() {
return my_age;
}
public void setMy_age(Integer my_age) {
this.my_age = my_age;
}
public Integer getMy_weight() {
return my_weight;
}
public void setMy_weight(Integer my_weight) {
this.my_weight = my_weight;
}
public String getSocial_security() {
return social_security;
}
public void setSocial_security(String social_security) {
this.social_security = social_security;
}
}
I have defined a mapping.json file as shown below using GSON.
{
"columnMap": [
{
"userColumn": "name_first",
"personColumn": "first_name"
},
{
"userColumn": "last_first",
"personColumn": "first_last"
},
{
"userColumn": "my_age",
"personColumn": "age"
},
{
"userColumn": "my_weight",
"personColumn": "weight"
}
]
}
public class Mapping {
private ArrayList<Pair> columnMap;
public Mapping(){
columnMap = new ArrayList<>();
}
public ArrayList<Pair> getColumnMap() {
return columnMap;
}
public void setColumnMap(ArrayList<Pair> columnMap) {
this.columnMap = columnMap;
}
}
I am writing a utility class helper function that converts between a Person and User object the mapped pairs.
public class Pair {
private String userColumn;
private String personColumn;
public String getUserColumn() {
return userColumn;
}
public void setUserColumn(String userColumn) {
this.userColumn = userColumn;
}
public String getPersonColumn() {
return personColumn;
}
public void setPersonColumn(String personColumn) {
this.personColumn = personColumn;
}
public static void main(String args[]){
}
}
My question is below:
As you can see the returnVal object is being set by me (the programmer) to convert from a User POJO to a Person POJO. How do I leverage the pre-defined mapping.json to do this? The reason I am asking is in the future, the mapping.json file may change (maybe the weight mapping no longer exists). So I am trying to avoid re-programming this Utility.userToPerson() function. How can I achieve this? I am thinking Java reflection is the way to go, but I would like to hear back from the Java community.
public class Utility {
public static Person userToPerson(User u){
Person returnVal = new Person();
returnVal.setAge(u.getMy_age()); // <-- Question How do I leverage mapping.json here?
returnVal.setFirst_name(u.getName_first());
returnVal.setLast_name(u.getName_last());
returnVal.setWeight(u.getMy_weight());
return returnVal;
}
}
You can introspect the beans (i.e. User and Person) for the field names and call corresponding getter from User to fetch the value. Later call corresponding setter in Person.
Here I have taken userToPersonFieldsMap for mapping the field, you can load mapping from JSON file and construct the map accordingly.
Important code section is the for loop, where it dynamically calls getter and setter and does the job.
import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.Map;
public class UserToPersonMapper {
public static void main(String[] args) throws IntrospectionException, InvocationTargetException, IllegalAccessException {
Map<String, String> userToPersonFieldsMap = new HashMap<>();
userToPersonFieldsMap.put("name_first", "first_name");
userToPersonFieldsMap.put("last_first", "first_last");
userToPersonFieldsMap.put("age", "personAge");
//existing user
User user = new User("Tony", "Stark", 20);
//new person - to be initialised with values from user
Person person = new Person();
for (Map.Entry<String, String> entry : userToPersonFieldsMap.entrySet()) {
Object userVal = new PropertyDescriptor(entry.getKey(), User.class).getReadMethod().invoke(user);
new PropertyDescriptor(entry.getValue(), Person.class).getWriteMethod().invoke(person, userVal);
}
System.out.println(user);
System.out.println(person);
}
}
class User {
private String name_first;
private String last_first;
private int age;
public User(String name_first, String last_first, int age) {
this.name_first = name_first;
this.last_first = last_first;
this.age = age;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName_first() {
return name_first;
}
public String getLast_first() {
return last_first;
}
public void setName_first(String name_first) {
this.name_first = name_first;
}
public void setLast_first(String last_first) {
this.last_first = last_first;
}
#Override
public String toString() {
return "User{" +
"name_first='" + name_first + '\'' +
", last_first='" + last_first + '\'' +
", age=" + age +
'}';
}
}
class Person {
private String first_name;
private String first_last;
private int personAge;
public void setFirst_name(String first_name) {
this.first_name = first_name;
}
public void setFirst_last(String first_last) {
this.first_last = first_last;
}
public String getFirst_name() {
return first_name;
}
public String getFirst_last() {
return first_last;
}
public int getPersonAge() {
return personAge;
}
public void setPersonAge(int personAge) {
this.personAge = personAge;
}
#Override
public String toString() {
return "Person{" +
"first_name='" + first_name + '\'' +
", first_last='" + first_last + '\'' +
", personAge=" + personAge +
'}';
}
}
You can tweak and try it out this example to make it more align with your requirement.
Note:
This solution uses reflection.
I am getting Fortify issue Dynamic Code Evaluation: Unsafe Deserialization on the lines below:
#RequestMapping(value="/v2/doc", method=RequestMethod.POST)
public JsonDocVerifyResponse verify(#RequestBody JsonDocVerifyRequestV3 request)
JsonDocVerifyRequestV3 temp = (JsonDocVerifyRequestV3)SerializationUtils.clone(request);
The solution for unsafe deserialization is this https://www.ibm.com/developerworks/library/se-lookahead/
But as you can see in my codes I am not using ByteArrayOutputStream to deserialize the object.
Is this a false positive by Fortify? If not, how can I use
org.apache.commons.io.serialization.ValidatingObjectInputStream
to validate the class? Any code sample will be of great help!
These are the snippets:
#RequestMapping(value="/v2/doc", method=RequestMethod.POST)
public JsonDocVerifyResponse verify(#RequestBody JsonDocVerifyRequestV3 request) {
debugJsonRequest(request, DOC_TYPE.khIdBack);
JsonDocVerifyResponse response = new JsonDocVerifyResponse();
return response;
}
public void debugJsonRequest(JsonDocVerifyRequestV3 request, DOC_TYPE docType) {
try {
JsonDocVerifyRequestV3 temp(JsonDocVerifyRequestV3) SerializationUtils.clone(request);
LOGGER.debug("{}|{}", docType, CommonUtil.debugJsonObject(temp));
} catch(Exception e) {
LOGGER.error("Error in debug json object", e);
}
}
You can use accept and reject methods to safer deserialization operation.
Example:
import com.sun.xml.internal.ws.util.ByteArrayBuffer;
import org.apache.commons.io.serialization.ValidatingObjectInputStream;
import java.io.*;
public class Main {
public static void main(String[] args) throws IOException, ClassNotFoundException {
Bar bar = new Bar("bar-test");
Foo foo = new Foo("test-foo", bar);
// write into an array buffer
ByteArrayBuffer buffer = new ByteArrayBuffer();
try (ObjectOutputStream serializeStream = new ObjectOutputStream(buffer)) {
serializeStream.writeObject(foo);
}
try (ValidatingObjectInputStream stream = new ValidatingObjectInputStream(buffer.newInputStream())) {
// add validated classes
stream.accept(Foo.class);
stream.accept(Bar.class);
Foo foo2 = (Foo) stream.readObject();
System.out.println(foo2);
}
}
public static class Foo implements Serializable {
private String name;
private Bar bar;
public Foo(String name, Bar bar) {
this.name = name;
this.bar = bar;
}
#Override
public String toString() {
return "Foo{" +
"name='" + name + '\'' +
", bar=" + bar +
'}';
}
}
public static class Bar implements Serializable {
private String name;
public Bar(String name) {
this.name = name;
}
#Override
public String toString() {
return "Bar{" +
"name='" + name + '\'' +
'}';
}
}
}
lets asume i have a Interface like that:
public interface User extends Element {
String getName();
String getPassword();
}
and a implementing class like that:
public class BaseUser implements User {
#Override
public String getId() {
return id;
}
#Override
public String getName() {
return name;
}
#Override
public String getPassword() {
return password;
}
public void setId(String id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
System.out.println("Set name to " + name);
}
public void setPassword(String password) {
this.password = password;
}
private String id;
private String name;
private String password;
}
Now i want to use bytebuddy to create a interceptor/proxy which catches the call onto the setter, store the changed value and call the real method also.
At the end i want to "ask" the interceptor/proxy for the called setter and the changed values.
I tried a lot considering also the tutorials but up to now i found no working solution. Maybe someone could help me pls.
And here is the Interceptor:
public class GenericInterceptor implements InvocationHandler {
#Override
#RuntimeType
public Object invoke(#This Object proxy, #Origin Method method, #AllArguments Object[] args) throws Throwable {
if (isSetter(method, args)) {
intercept(proxy, method, args);
}
return method.invoke(proxy, args);
}
}
Here is my current 'test' code:
public static void main(String[] args) {
final ByteBuddy bb = new ByteBuddy();
final GenericInterceptor interceptor = new GenericInterceptor();
bb.subclass(BaseUser.class)
.method(isDeclaredBy(BaseUser.class).and(isSetter()))
.intercept(MethodDelegation.to(interceptor))
.make()
.load(BaseUser.class.getClassLoader(), ClassLoadingStrategy.Default.WRAPPER);
final BaseUser user = new BaseUser();
user.setName("my name");
}
EDIT:
public interface Element {
String getId();
}
public class GenericInterceptor<T extends Element> {
public GenericInterceptor(Class<T> type) {
this.type = type;
}
public Map<String, Object> getChanges(T obj) {
final String id = obj.getId();
return changes.get(id);
}
#RuntimeType
public void invoke(#This T proxy, #Origin Method method, #AllArguments Object[] args) throws Throwable {
System.out.println("invoke " + method.getName() + " " + Arrays.toString(args));
intercept(proxy, method, args);
}
private Object getCurrentValue(T proxy, final Field field) {
try {
return field.get(proxy);
} catch (IllegalArgumentException | IllegalAccessException e) {
return null;
}
}
private Field getSetterField(Method setter) {
final String setterName = setter.getName();
Field f = assignedFields.get(setterName);
if (f != null) return f;
final String fieldName = Character.toLowerCase(setterName.charAt(3)) + setterName.substring(4);
try {
f = type.getDeclaredField(fieldName);
if (f == null) return null;
f.setAccessible(true);
assignedFields.put(setterName, f);
return f;
} catch (NoSuchFieldException | SecurityException e) {
return null;
}
}
private void intercept(T proxy, Method setter, Object[] args) {
final Field field = getSetterField(setter);
if (field == null)
return;
final Object currentValue = getCurrentValue(proxy, field);
final Object newValue = args[0];
System.out.println("Set from " + currentValue + " to " + newValue);
final String id = proxy.getId();
Map<String, Object> changeMap = changes.get(id);
if (changeMap == null) {
changeMap = new HashMap<>();
}
changeMap.put(field.getName(), currentValue);
changes.put(id, changeMap);
}
private final Map<String, Field> assignedFields = new HashMap<>();
private final Map<String, Map<String, Object>> changes = new LinkedHashMap<>();
private final Class<T> type;
}
You can call orignal method using MethodDelegation.to(...).andThen(SuperMethodCall.INSTANCE).
public class ByteBuddyTest {
public static void main(String[] args) throws IllegalAccessException, InvocationTargetException, InstantiationException {
GenericInterceptor interceptor = new GenericInterceptor ();
Class<?> clazz = new ByteBuddy()
.subclass(BaseUser.class)
.method(ElementMatchers.isDeclaredBy(BaseUser.class).and(ElementMatchers.isSetter()))
.intercept(SuperMethodCall.INSTANCE.andThen(MethodDelegation.to(interceptor))))
.make()
.load(ByteBuddyTest.class.getClassLoader())
.getLoaded();
BaseUser user1 = (BaseUser) clazz.getConstructors()[0].newInstance();
BaseUser user2 = (BaseUser) clazz.getConstructors()[0].newInstance();
user1.setName("user1");
user1.setPassword("password1");
user2.setName("user2");
user2.setPassword("password2");
System.out.println(interceptor.getInterceptedValue("user1", "name"));
System.out.println(interceptor.getInterceptedValue("user1", "password"));
System.out.println(interceptor.getInterceptedValue("user2", "name"));
System.out.println(interceptor.getInterceptedValue("user2", "password"));
user1.setPassword("password2");
user1.setPassword("password3");
}
public static class GenericInterceptor {
private Map<String, Object> interceptedValuesMap = new HashMap();
public void set(String obj, #This User user, #Origin Method setter) {
// assume that user name is unique so we can use it as a key in values map.
// or define equals/hashcode in GenericUser object and use it as a key directly
String setterName = setter.getName();
String propertyName = setterName.substring(3, setterName.length()).toLowerCase();
String key = user.getName() + "_" + propertyName;
System.out.println("Setting " + propertyName + " to " + obj);
System.out.println("Previous value " + interceptedValuesMap.get(key));
interceptedValuesMap.put(key, obj);
}
public Object getInterceptedValue(String userName, String fieldName) {
return interceptedValuesMap.get(userName + "_" + fieldName);
}
}
public static interface User {
String getName();
String getPassword();
}
public static class BaseUser implements User {
#Override
public String getName() {
return name;
}
#Override
public String getPassword() {
return password;
}
public void setName(String name) {
this.name = name;
}
public void setPassword(String password) {
this.password = password;
}
private String name;
private String password;
}
}
I have super class called pojo. I have a subclass called ExtendPojo.
pojo.java
package com.java.pojo;
public class pojo {
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;
}
public long getNumber() {
return number;
}
public void setNumber(long number) {
this.number = number;
}
public String toString() {
return "pojo [name=" + name + ", age=" + age + ", number=" + number + "]";
}
private String name;
private int age;
private long number;
}
ExtendPojo.java
package com.java.pojo;
public class ExtendPojo extends pojo{
public static void main(String[] args) {
pojo obj = new pojo();
obj.setName("santhosh");
ExtendPojo exObj = new ExtendPojo();
exObj.setName("mahesh");//It is not overriding
System.out.println(obj.getName());//it prints santhosh.
}
public void setName(String name){
super.setName(name);
}
}
You are creating two independent objects.
First you create an object and name it santhosh. This object is referenced by the obj variable.
pojo obj = new pojo();
obj.setName("santhosh");
Then you create a second object, which is referenced by the exObj variable.
ExtendPojo exObj = new ExtendPojo();
It doesn't have a name yet, since it's a new object and you haven't assigned the name. You then give it a name.
exObj.setName("mahesh");//It is not overriding
Now you print the name of the first object, which hasn't changed.
System.out.println(obj.getName());//it prints santhosh.
The code is doing exactly what you asked it to do.
If you intended the two variables to reference the same object, you'd do this:
ExtendPojo exObj = new ExtendPojo();
pojo obj = exObj ;//Same object, new variable, different type
obj.setName("santhosh");
exObj.setName("mahesh");//It is working now
System.out.println(obj.getName());//it prints mahesh.
I have gone through the Inheritance and method overriding concepts and clarified my doubts :)
public class ExtendPojo extends Pojo{
public static void main(String[] args) {
Pojo obj = new Pojo();
obj.setName("santhosh");
Pojo obj1 = new ExtendPojo();
obj1.setName("mahesh");//It is overriding now
System.out.println(obj1.getName());//it prints mahesh.
}
}
I am supposed to come up with this output.
But I am getting this instead..
Here is my code:
import java.lang.*;
import java.util.*;
import java.io.*;
public class Sample{
private String name;
private Hashtable customers = new Hashtable();
private Hashtable movies = new Hashtable();
public Sample(String aName){
name = aName;
}
public String getName(){
return name;
}
public void setName(String aName){
name = aName;
}
public void addCustomer (Customer customer) {
customers.put(customer.getName(), customer);
}
public Customer getCustomer (String customerName) {
return (Customer)customers.get(customerName);
}
public void addMovie (Movie movie) {
movies.put(movie.getName(), movie);
}
public Movie getMovie (String movieName) {
return (Movie)movies.get(movieName);
}
public void error (String message) {
System.out.println ("ERROR: " + message);
}
public Enumeration getMovies() {
return movies.elements();
}
public Enumeration getCustomers() {
return customers.elements();
}
public void showAll() {
System.out.println ("name: "+ this.getName());
Enumeration kk = this.getCustomers();
while (kk.hasMoreElements()) {
Customer one = (Customer) kk.nextElement();
System.out.println (one.show());
}
Enumeration ff = this.getMovies();
while (ff.hasMoreElements()) {
Movie one = (Movie) ff.nextElement();
System.out.println (one.show());
}
}
public void test() {
Customer k1 = new Customer ("Jonah") ; this.addCustomer (k1);
Customer k2 = new Customer ("Hellen") ; this.addCustomer (k2);
Customer k3 = new Customer ("Agnes") ; this.addCustomer (k3) ;
Movie f1 = new Movie ("StarWars"); this.addMovie (f1) ;
Movie f2 = new Movie ("Shrek"); this.addMovie (f2) ;
System.out.println("-**-**- test part 1 -**-**-") ;
this.showAll();
System.out.println("-**-**- test part 2 -**-**-") ;
System.out.println("---" + k1.getName() + " rents " + f1.getName());
this.showAll();
k1.doRent(f1);
MY CUSTOMER CLASS:
package eric;
public class Customer {
String name;
public Customer(String nameCus){
name = nameCus;
}
public String getName(){
return name;
}
public String show(){
return name;
}
public void doRent(Movie f1) {
System.out.println(" -"+ " RentData" + "[" + getName() +"," + f1.getName() + "]" );
}
}
MY MOVIE CLASS:
public class Movie {
String name;
int x = 0;
public Movie(String nameMov){
name = nameMov;
}
public String getName(){
return name;
}
public String show(){
return name+"\n"+" - average: "+x +" days\n"+" - number of rentings: "+x ;
}
}
My problem is that i cannot find a way to fix -RentData [Jonah,StarWars] under the name Jonah... Instead it comes at the end of output.. I need some one to help me figure how am ganna do that.. thanks
You're calling k1.doRent(f1) before this.showAll() so naturally you will get the "RentData..." line printed before the names are printed. The way your code is now is not conducive to what you're trying to do at all. Your Customer class should have a member list called rentedMovies that is populated every time you call doRent(...) on a Customer object. Then, Customer.show() should print the name of the customer, followed by your "RentData..." stuff that comes from rentedMovies.