Exception in thread "main"
java.lang.RuntimeException: No-args constructor for class java.sql.Timestamp does not exist. Register an InstanceCreator with Gson for this type to fix this problem.
#关于使用Google GSON 实现Json协议字符协议序列化和反序列化 时间戳到Timestame类型转换失败问题。
解决方式：定义自己的类型适配器。
下面代码演示了两个问题：
1.解决上面说的时间戳到Timestame类型互转问题。
2.扩展了一个基于HTTP协议URL字符串解析到POJO HttpProtocol 的互转。
Code 例如以下：
package com.kevin.luan.service; import java.lang.reflect.Type;
import java.sql.Timestamp; import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonParseException;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer; /**
* 实现一个自己定义的实行适配器
* <p>
* 基于Google GSON 实现JSON解析
* </p>
*
* @author kevin LUAN
*
*/
public class GsonTypeAdapterDemo {
public static void main(String[] args) {
Gson gson = new GsonBuilder().registerTypeAdapter(Timestamp.class, new TimestampAdapter()).registerTypeAdapter(HttpProtocol.class, new HttpProtocolAdapter()).create();
String json = "{\"price\":\"1.1001\",\"times\":\"" + System.currentTimeMillis() + "\",\"protocol\":\"http://www.koudai.com/abc/test.do?url=abc\"}";
Test pojo = gson.fromJson(json, Test.class);
System.out.println("JSON TO POJO:" + pojo);
json = gson.toJson(pojo);
System.err.println("POJO TO JSON:" + json);
} /**
* 实现一个类型适配器(TypeAdapter)
*
* @author kevin LUAN
*
*/
public static class TimestampAdapter implements JsonSerializer<Timestamp>, JsonDeserializer<Timestamp> { @Override
public Timestamp deserialize(JsonElement json, Type type, JsonDeserializationContext context) throws JsonParseException {
if (json != null) {
try {
return new Timestamp(json.getAsLong());
} catch (JsonParseException e) {
throw e;
}
}
return null;
} @Override
public JsonElement serialize(Timestamp value, Type type, JsonSerializationContext context) {
if (value != null) {
return new JsonPrimitive(value.getTime());
}
return null;
} } /**
* 基于HttpProtocol的类型适配器
*
* @author kevin LUAN
*
*/
public static class HttpProtocolAdapter implements JsonSerializer<HttpProtocol>, JsonDeserializer<HttpProtocol> { @Override
public HttpProtocol deserialize(JsonElement json, Type arg1, JsonDeserializationContext arg2) throws JsonParseException {
if (json == null) {
return null;
} else {
try {
return new HttpProtocol(json.toString());
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
} @Override
public JsonElement serialize(HttpProtocol src, Type arg1, JsonSerializationContext arg2) {
return new JsonPrimitive(src.toString());
} } /**
* 測试
* <p>
* JSON->POJO
* </p>
* <p>
* POJO->JSON
* </p>
*
* @author kevin LUAN
*
*/
public static class Test {
private Float price = 1.0f;
private Timestamp times;
private HttpProtocol protocol; @Override
public String toString() {
return "price:" + price + "|times:" + times + "|protocl:" + protocol + "";
} } /**
* HTTP协议POJO
*
* @author kevin LUAN
*
*/
public static class HttpProtocol {
private String protocol;
private String host;
private int port = -1;
private String uri;
private String paramQuery; @Override
public String toString() {
return protocol + "://" + host + ":" + port + uri + "?" + paramQuery + "}";
} public HttpProtocol(String value) {
if (value.startsWith("\"") && value.endsWith("\"")) {
value = value.substring(1, value.length() - 1);
}
parserProtocol(value);
} private void parserProtocol(String value) {
int endIndex = value.indexOf("://");
if (endIndex != -1) {
protocol = value.substring(0, endIndex);
parserHost(value, endIndex + 3);
}
} private void parserHost(String value, int startIndex) {
int endIndex = value.indexOf("/", startIndex);
if (endIndex != -1) {
host = value.substring(startIndex, endIndex);
splitHostPort();
parserUri(value, endIndex);
} else {
host = value.substring(startIndex);
splitHostPort();
}
} private void splitHostPort() {
if (host.indexOf(":") != -1) {
String host_port[] = host.split(":");
host = host_port[0];
port = Integer.parseInt(host_port[1]);
} else {
port = 80;
}
} private void parserUri(String value, int startIndex) {
if (value.indexOf("?", startIndex) == -1) {
uri = value.substring(startIndex);
} else {
int endIndex = value.indexOf("?", startIndex);
uri = value.substring(startIndex, endIndex);
parserQuery(value, endIndex);
}
} private void parserQuery(String value, int startIndex) {
if (value.indexOf("?", startIndex) != -1) {
int paramQueryIndex = value.indexOf("?", startIndex);
paramQuery = value.substring(paramQueryIndex + 1);
}
} }
}
执行Main结果：
JSON TO POJO:price:1.1001|times:2014-06-22 13:06:54.138|protocl:http://www.koudai.com:80/abc/test.do?url=abc}
POJO TO JSON:{"price":1.1001,"times":1403413614138,"protocol":"http://www.koudai.com:80/abc/test.do?url\u003dabc}"}