下面是我的JSON，其中我只有三个reportRecords仅用于演示目的，但总的来说有时我们会得到相当大的json，那么它只有三个reportRecords，它有很大的号码reportRecords。
{
"aggRecords":{
"reportRecords":[
{
"min":1.0,
"max":1.0,
"avg":1.0,
"count":18,
"sumSq":18.0,
"stddev":0.0,
"median":1.0,
"percentileMap":{
"95":1
},
"metricName":"TotalCount",
"dimensions":{
"env":"prod",
"pool":"hawk",
"Name":"CORE_utrade11",
"Type":"Error"
},
"value":18.0
},
{
"min":1.0,
"max":1.0,
"avg":1.0,
"count":25968842,
"sumSq":2.5968842E7,
"stddev":0.0,
"median":1.0,
"percentileMap":{
"95":1
},
"metricName":"TotalCount",
"dimensions":{
"env":"prod",
"pool":"hawk",
"Name":"ResponseHeaders",
"Type":"ConnectionPool"
},
"value":2.5968842E7
},
{
"min":1.0,
"max":1.0,
"avg":1.0,
"count":44,
"sumSq":44.0,
"stddev":0.0,
"median":1.0,
"percentileMap":{
"95":1
},
"metricName":"TotalCount",
"dimensions":{
"env":"prod",
"pool":"hawk",
"Name":"read-lookup",
"Type":"ClientPool"
},
"value":44.0
}
]
},
"minRecordsMap":{
}
}
现在我正在尝试序列化上面的JSON以提取reportRecords仅Type和ClientPool的{{1}}，因此我不想在内存中加载所有内容。我正在考虑使用GSON Streaming，但到目前为止，我无法完成这项工作。
ConnectionPool以下是 private static List<HostClientMetrics> loadMetrics(String url) {
List<HostClientMetrics> metrics = new ArrayList<HostClientMetrics>();
try {
InputStream input = new URL(url).openStream();
JsonReader reader = new JsonReader(new InputStreamReader(input, "UTF-8"));
// not sure what I should do here?
} catch (Exception ex) {
// log error
}
return metrics;
}
课程
HostClientMetrics我只需要提取public class HostClientMetrics {
private String metricName;
private Map<String, Integer> percentileMap;
private String median;
private String stddev;
private String sumSq;
private String count;
private String avg;
private String max;
private String min;
public String getMetricName() {
return metricName;
}
public Map<String, Integer> getPercentileMap() {
return percentileMap;
}
public String getMedian() {
return median;
}
public String getStddev() {
return stddev;
}
public String getSumSq() {
return sumSq;
}
public String getCount() {
return count;
}
public String getAvg() {
return avg;
}
public String getMax() {
return max;
}
public String getMin() {
return min;
}
public Dimensions getDimensions() {
return dimensions;
}
public Dimensions dimensions;
public static class Dimensions {
private String env;
private String pool;
@SerializedName("Name")
private String name;
public String getEnv() {
return env;
}
public String getPool() {
return pool;
}
public String getName() {
return name;
}
}
}
仅reportRecords和Type的{{1}}。如何在我的示例中使用GSON Streaming？
答案 0 :(得分：1)
private static List<HostClientMetrics> loadMetrics(String url) {
GsonBuilder gsonBuilder = new GsonBuilder();
Gson gson = gsonBuilder.create();
List<HostClientMetrics> metrics = new ArrayList<HostClientMetrics>();
try {
InputStream input = new URL(url).openStream();
JsonReader reader = new JsonReader(new InputStreamReader(input, "UTF-8"));
reader.beginObject();
String jsonTag = null;
while(reader.hasNext()) {
jsonTag = reader.nextName();
if("aggRecords".equals(jsonTag)) {
reader.beginObject();
while(reader.hasNext()) {
jsonTag = reader.nextName();
if("reportRecords".equals(jsonTag)) {
reader.beginArray();
while (reader.hasNext()) {
HostClientMetrics hostClientMetrics = gson.fromJson(reader, HostClientMetrics.class);
if ("ClientPool".equals(hostClientMetrics.dimensions.type) || "ConnectionPool".equals(hostClientMetrics.dimensions.type)) {
metrics.add(hostClientMetrics);
}
}
reader.endArray();
}
}
reader.endObject();
} else if("minRecordsMap".equals(jsonTag)) {
reader.beginObject();
// skip
reader.endObject();
}
}
reader.endObject();
reader.close();
return metrics;
} catch (Exception ex) {
// log error
System.out.println("ex:" + ex);
}
return metrics;
}
将类型字段添加到Diemensions POJO：
public static class Dimensions {
private String env;
private String pool;
@SerializedName("Name")
private String name;
@SerializedName("Type")
private String type;
// Getters / Setters
}