Gson-使用数组或字符串的字段解析json [英] Gson - parsing json with field that is array or string
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问题描述
我正在尝试使用Gson解析一些json,但是我遇到了以下问题:
I'm trying to parse some json with Gson and I have following problem:
这是我的json:
[{
"label": "Check Digit",
"value": "W"
},
{
"label": "Equipment",
"value": [
"With Standard Liftgate",
"(-) Version Packages"
]
}]
这是我的java类:
public class Decode {
private String label;
private List<String> value = new ArrayList<>();
public String getLabel() {
return label;
}
public void setLabel(String label) {
this.label = label;
}
public List<String> getValue() {
return value;
}
public void setValue(List<String> value) {
this.value = value;
}
}
如何让Gson解析它并始终将value
用作字符串数组?
How to make Gson to parse it and use value
as Array of String always?
推荐答案
我的建议如下:-
第1步:请对您的Decode
类进行以下小的更改.
Step 1: Please make following little changes to your Decode
class.
Decode.java
Decode.java
import java.util.ArrayList;
import java.util.List;
public class Decode {
private String label;
private List<String> values = new ArrayList<>(); // in json it is "value"
public String getLabel() {
return label;
}
public void setLabel(String label) {
this.label = label;
}
public List<String> getValues() {
return values;
}
public void setValues(List<String> values) {
this.values = values;
}
@Override
public String toString() {
return "Decode [label=" + label + ", values=" + values + "]";
}
}
第2步:请创建以下JsonDeserializer
.
MyDeserializer.java
MyDeserializer.java
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;
import com.google.gson.Gson;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import com.google.gson.reflect.TypeToken;
public class MyDeserializer implements JsonDeserializer<Decode> {
@Override
public Decode deserialize(JsonElement arg0, Type arg1, JsonDeserializationContext arg2) throws JsonParseException {
JsonObject decodeObj = arg0.getAsJsonObject();
Gson gson = new Gson();
Decode decode = gson.fromJson(arg0, Decode.class);
List<String> values = null;
if (decodeObj.get("value").isJsonArray()) {
values = gson.fromJson(decodeObj.get("value"), new TypeToken<List<String>>() {
}.getType());
} else {
String single = gson.fromJson(decodeObj.get("value"), String.class);
values = new ArrayList<String>();
values.add(single);
}
decode.setValues(values);
return decode;
}
}
第3步:现在是时候该按如下所示deserialize
您的json了:
Step 3: Now its time to deserialize
your json as follows:
GsonMain.java
GsonMain.java
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.util.Arrays;
import com.google.gson.GsonBuilder;
public class GsonMain{
public static void main(String[] args) throws IOException {
String filename = "d:/test.json"; // contains the json
String content = new String(Files.readAllBytes(new File(filename).toPath()));
GsonBuilder b = new GsonBuilder();
b.registerTypeAdapter(Decode.class, new MyDeserializer());
Decode[] array = b.create().fromJson(content, Decode[].class);
System.out.println(Arrays.toString(array));
}
}
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