GSON序列化Pojo的阵列序列的麻烦
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25-10-2019 - |
题
我一直在计划使用SimpleXML来满足我的序列化需求,但是我想我会尝试json,以学习新的东西。
这是我使用的代码使用GSON 1.7.1尝试序列化测试POJO的阵列列表。
注意:我删除了字符串“ S”的读者/作家,以简化代码。
package test;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import com.google.gson.Gson;
public class TestGsonSerialDeserialList {
public static void main(String[] args) throws IOException{
Gson gson = new Gson();
//Make Serial
String s;
List<TestObject> list = Collections.synchronizedList(new ArrayList<TestObject>() );
list.add(new TestObject());
list.add(new TestObject());
s = gson.toJson(list, ArrayList.class);
System.out.println(s);
//Eat Serial
List<TestObject> list2 = Collections.synchronizedList(gson.fromJson(s, ArrayList.class) );
System.out.println(list2.get(0) );
System.out.println(list2.get(1) );
}
}
这是我得到的输出:
[{"objectID":1,"i1":12345,"name":"abcdefg","s":["a","b","c"]},{"objectID":2,"i1":12345,"name":"abcdefg","s":["a","b","c"]}]
java.lang.Object@5c74c3aa
java.lang.Object@75d9fd51
在我的新手眼中,这看起来正确。仅,对象的供应列表包含基本对象,而不是testObject的i序列化。谁能向我解释一下,如果有的话,我可以做什么来完成这项工作?
编辑:
修正了测试:感谢Colind
package test;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
public class TestGsonSerialDeserialList {
public static void main(String[] args) throws IOException{
System.out.println("--- Serialize / Deserialize Started ---");
String fileName = "json\\testList.json";
Gson gson = new Gson();
Type listOfTestObject = new TypeToken<List<TestObject>>(){}.getType();
//Make Serial
Writer osWriter = new OutputStreamWriter( new FileOutputStream(fileName));
List<TestObject> list = Collections.synchronizedList(new ArrayList<TestObject>() );
list.add(new TestObject());
list.add(new TestObject());
list.add(new TestObject());
list.add(new TestObject());
gson.toJson(list, osWriter);
osWriter.close();
//Eat Serial
Reader isReader = new InputStreamReader( new FileInputStream((fileName) ) );
List<TestObject> list2 = Collections.synchronizedList(
(List<TestObject>)gson.fromJson(isReader, listOfTestObject)
);
isReader.close();
System.out.println(list2.get(0) );
System.out.println(list2.get(1) );
System.out.println(list2.get(2) );
System.out.println(list2.get(3) );
System.out.println("--- Serialize / Deserialize Ended ---");
}
}
输出:
--- Serialize / Deserialize Started ---
ID#: 1, i1: 12345, name: abcdefg, s[]: [Ljava.lang.String;@95c083
ID#: 2, i1: 12345, name: abcdefg, s[]: [Ljava.lang.String;@6791d8c1
ID#: 3, i1: 12345, name: abcdefg, s[]: [Ljava.lang.String;@182d9c06
ID#: 4, i1: 12345, name: abcdefg, s[]: [Ljava.lang.String;@5a5e5a50
--- Serialize / Deserialize Ended ---
edit2:
老实说,我不知道为什么,但是当我用阵列列表中嵌入在我的testobject中的简单字符串[]时,它开始正确地序列化。
--- Serialize / Deserialize Started ---
ID#: 1, i1: 12345, name: abcdefg, s[]: [a, b, c]
ID#: 2, i1: 12345, name: abcdefg, s[]: [a, b, c]
ID#: 3, i1: 12345, name: abcdefg, s[]: [a, b, c]
ID#: 4, i1: 12345, name: abcdefg, s[]: [a, b, c]
--- Serialize / Deserialize Ended ---
解决方案
您需要提供有关特定通用类型的GSON信息 List
您正在使用(或与之使用的任何通用类型)。尤其是当对JSON进行估算时,它需要该信息才能确定其应将每个数组元素的对象类型化。
Type listOfTestObject = new TypeToken<List<TestObject>>(){}.getType();
String s = gson.toJson(list, listOfTestObject);
List<TestObject> list2 = gson.fromJson(s, listOfTestObject);
这是在 GSON用户指南.
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