Java 如何使用Jackson JsonGenerator向JSON添加列表
我正在尝试使用Jackson JsonGenerator将对象列表写入JSON。 我想知道这是否可能 我有一个hashmap,形成为键,列表 我正在使用Jackson JsonGenerator创建JSON。并且希望能够简单地添加对象列表,而不是单独处理/循环列表中的每个对象 这可能吗Java 如何使用Jackson JsonGenerator向JSON添加列表,java,json,arraylist,jackson,Java,Json,Arraylist,Jackson,我正在尝试使用Jackson JsonGenerator将对象列表写入JSON。 我想知道这是否可能 我有一个hashmap,形成为键,列表 我正在使用Jackson JsonGenerator创建JSON。并且希望能够简单地添加对象列表,而不是单独处理/循环列表中的每个对象 这可能吗 JsonFactory factory = new JsonFactory(); StringWriter sw = new StringWriter(); JsonGenerator g
JsonFactory factory = new JsonFactory();
StringWriter sw = new StringWriter();
JsonGenerator generator = factory.createGenerator(sw);
generator.setPrettyPrinter(new DefaultPrettyPrinter());
generator.writeStartObject(); // {
generator.writeFieldName("tags"); // {"tags":
generator.writeStartArray(); // {"tags": [
for ( String key : hm.keySet() ) {
log.info("Record to Convert to JSON: " + key);
generator.writeStartObject(); // {
generator.writeStringField("tagId", key); // { "tagId": "SAGE.esn.tag_name"
generator.writeFieldName("data"); // { "tagId": "SAGE.esn.tag_name", "data"
generator.writeStartArray(); // { "tagId": "SAGE.esn.tag_name", "data" : [
// generator.writeStartObject(); // { "tagId": "SAGE.esn.tag_name", "data" : [{
generator.write(hm.get(key));
generator.writeStringField("ts", data[0].trim()); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [{"ts":"2017-11-15T19:55:00"
generator.writeEndObject(); // { "tagId": "SAGE.esn.tag_name", "data" : [{"ts":"2017-11-15T19:55:00","v" : "100","q":"3"}
generator.writeEndArray(); // { "tagId": "SAGE.esn.tag_name", "data" : [{"ts":"2017-11-15T19:55:00","v" : "100","q":"3"}]
generator.writeEndObject(); // { "tagId": "SAGE.esn.tag_name", "data" : [{"ts":"2017-11-15T19:55:00","v" : "100","q":"3"}]}
}
generator.writeEndArray(); // {"tags": [ { "tagId": "SAGE.esn.tag_name", "data" : [{"ts":"2017-11-15T19:55:00","v" : "100","q":"3"}]} ]
generator.writeEndObject(); // {"tags": [ { "tagId": "SAGE.esn.tag_name", "data" : [{"ts":"2017-11-15T19:55:00","v" : "100","q":"3"}]} ]}
generator.flush();
generator.close();
是的,你几乎做到了。 您应该反复浏览您的列表:
for ( String key : hm.keySet() ) {
log.info("Record to Convert to JSON: " + key);
generator.writeStartObject(); // {
generator.writeStringField("tagId", key); // { "tagId": "NST_MD1_CRANK_CASE"
generator.writeFieldName("data"); // { "tagId": "NST_MD1_CRANK_CASE", "data"
generator.writeStartArray(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [
generator.writeStartObject(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [{
List<String> data = hm.get(key);
generator.writeStringField("ts", data.get(0).trim()); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [{"ts":"2017-11-15T19:55:00"
generator.writeStringField("v", data.get(1).trim()); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [{"ts":"2017-11-15T19:55:00", "v":"100"
generator.writeStringField("q", data.get(2).trim()); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [{"ts":"2017-11-15T19:55:00", "v":"100", "q":"3"
generator.writeEndObject(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [{"ts":"2017-11-15T19:55:00", "v":"100", "q":"3"}
generator.writeEndArray(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [{"ts":"2017-11-15T19:55:00", "v":"100", "q":"3"}]
generator.writeEndObject(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [{"ts":"2017-11-15T19:55:00", "v":"100", "q":"3"}]}
}
如果需要将数据写入数组,可以使用以下方法:
for ( String key : hm.keySet() ) {
log.info("Record to Convert to JSON: " + key);
generator.writeStartObject(); // {
generator.writeStringField("tagId", key); // { "tagId": "NST_MD1_CRANK_CASE"
generator.writeFieldName("data"); // { "tagId": "NST_MD1_CRANK_CASE", "data"
generator.writeStartArray(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [
List<String> data = hm.get(key);
for (String s : data) {
generator.writeString(s);
}
generator.writeEndArray(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : ["2017-11-15T19:55:00", "100", "3"]
generator.writeEndObject(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : ["2017-11-15T19:55:00", "100", "3"]}
}
{
"tags" : [ {
"tagId" : "NST_MD1_CRANK_CASE",
"data" : [ {
"ts" : "2017-11-15T19:55:00",
"v" : "100",
"q" : "3"
} ]
}, {
"tagId" : "SAGE.esn.tag_name",
"data" : [ {
"ts" : "2017-11-15T19:55:00",
"v" : "100",
"q" : "3"
} ]
} ]
}
for ( String key : hm.keySet() ) {
log.info("Record to Convert to JSON: " + key);
generator.writeStartObject(); // {
generator.writeStringField("tagId", key); // { "tagId": "NST_MD1_CRANK_CASE"
generator.writeFieldName("data"); // { "tagId": "NST_MD1_CRANK_CASE", "data"
generator.writeStartArray(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : [
List<String> data = hm.get(key);
for (String s : data) {
generator.writeString(s);
}
generator.writeEndArray(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : ["2017-11-15T19:55:00", "100", "3"]
generator.writeEndObject(); // { "tagId": "NST_MD1_CRANK_CASE", "data" : ["2017-11-15T19:55:00", "100", "3"]}
}
{
"tags" : [ {
"tagId" : "NST_MD1_CRANK_CASE",
"data" : [ "2017-11-15T19:55:00", "100", "3" ]
}, {
"tagId" : "SAGE.esn.tag_name",
"data" : [ "2017-11-15T19:55:00", "100", "3" ]
} ]
}