Cloneable --shadow clone --deep clone

java 随笔

什么场景应实现Cloneable接口 --共享、缓存数据。

java的Cloneable接口是一个对象(堆)的拷贝技术，类似于serializable接口。

java中的全部对象和变量都存放在堆栈中。Cloneable接口就是在堆栈中新建立一个与被copy对象在堆栈中一样的地址块。

package zl.a.clone;

/**

* java对象的copy功能

* <p>

* shadow clone

*/

public class ClientContext implements Cloneable{

private String protocol;

private String host;

private int port;

private Object client;

// 从新定义构造

public ClientContext(Object client,String protocol,String host,int port){

this.protocol = protocol;

this.port = port;

this.host = host;

this.client = client;

}

public ClientContext(String protocol,String host,int port){

this.protocol = protocol;

this.port = port;

this.host = host;

}

@Override

public Object clone() {

ClientContext clientCtx = null;

try {

clientCtx = (ClientContext) super.clone();

} catch (CloneNotSupportedException e) {

e.printStackTrace();

}

return clientCtx;

}

public String getProtocol() {

return protocol;

}

public void setProtocol(String protocol) {

this.protocol = protocol;

}

public String getHost() {

return host;

}

public void setHost(String host) {

this.host = host;

}

public int getPort() {

return port;

}

public void setPort(int port) {

this.port = port;

}

public Object getClient() {

return client;

}

public void setClient(Object client) {

this.client = client;

}

}

import static org.junit.Assert.*;

import static zl.a.impor.StringUtils.isEmpty;

import org.junit.Test;

/**

* 显示静态导入

*/

public class StringUtilsTest {

@Test

public void testIsEmpty() {

String tem = "123";

assertTrue(isEmpty(tem));

}

}

package zl.a.clone;

import static org.junit.Assert.*;

import java.util.Date;

import org.junit.Test;

import zl.a.impor.StringUtils;

public class ClientContextTest {

@Test

public void test() {

DeepCloneObj deepObj = new DeepCloneObj();

deepObj.setName("007");

deepObj.setPwd("123456789");

ClientContext clientCtx = new ClientContext(deepObj, "http", "127.0.0.1", 8080);

ClientContext clientCtxCopy = (ClientContext)clientCtx.clone();

assertEquals("http", clientCtxCopy.getProtocol());

assertEquals("127.0.0.1", clientCtxCopy.getHost());

assertEquals(8080,clientCtxCopy.getPort());

DeepCloneObj temp = (DeepCloneObj)clientCtxCopy.getClient();

assertFalse(clientCtxCopy.getClient() == null);

assertEquals("007", temp.getName());

deepObj.setName("008");

assertEquals("008", temp.getName());

}

}

--------------------------------------以上文章仅说明了 shadow clone---------------------------------deepClone 下文--------------------------------------------------------------------

package zl.a.clone;

public class DeepCloneObj implements Cloneable{

private String name;

private String pwd;

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getPwd() {

return pwd;

}

public void setPwd(String pwd) {

this.pwd = pwd;

}

@Override

public Object clone() {

DeepCloneObj deepObj = null;

try {

deepObj = (DeepCloneObj) super.clone();

} catch (CloneNotSupportedException e) {

e.printStackTrace();

}

return deepObj;

}

}

package zl.a.clone;

import static org.junit.Assert.*;

import java.util.Date;

import org.junit.Test;

import zl.a.impor.StringUtils;

public class ClientContextTest {

@Test

public void test() {

DeepCloneObj deepObj = new DeepCloneObj();

deepObj.setName("007");

deepObj.setPwd("123456789");

ClientContext clientCtx = new ClientContext(deepObj, "http", "127.0.0.1", 8080);

ClientContext clientCtxCopy = (ClientContext)clientCtx.clone();

assertEquals("http", clientCtxCopy.getProtocol());

assertEquals("127.0.0.1", clientCtxCopy.getHost());

assertEquals(8080,clientCtxCopy.getPort());

DeepCloneObj temp_1 = (DeepCloneObj)clientCtxCopy.getClient();

DeepCloneObj temp = (DeepCloneObj) temp_1.clone();

assertFalse(clientCtxCopy.getClient() == null);

assertEquals("007", temp.getName());

temp_1.setName("008");

assertEquals("008", temp.getName());

}

}