我需要为报表创建一个json响应。类似这样的东西:
var data = [
["", "Kia", "Nissan", "Toyota", "Honda"],
["2008", 10, 11, 12, 13],
["2009", 20, 11, 14, 13],
["2010", 30, 15, 12, 13]
];
我使用jackson库,创建了一个JsonGenerator,这是我的代码:
String[] cols = new String[5]; //Number of report columns
JsonFactory jfactory = new JsonFactory();
JsonGenerator jGenerator = jfactory.createJsonGenerator(response.getOutputStream(),JsonEncoding.UTF8);
jGenerator.writeStartArray();
jGenerator.writeStartArray();
jGenerator.writeStringField(cols[0], "");
//until...
jGenerator.writeStringField(cols[4], "Honda");
jGenerator.writeEndArray();
jGenerator.writeStartArray();
jGenerator.writeStringField(cols[0], "2008");
//until...
jGenerator.writeStringField(cols[4], "13");
jGenerator.writeEndArray();
//and the same with the next rows...
jGenerator.writeEndArray();
问题是当设置第一个值时,我得到了这个错误:
org.codehaus.jackson.JsonGenerationException: Can not write a field name, expecting a value
您能在编写数组之前将其构建为一个对象,而不是处理所有单独的部分吗?
ObjectMapper mapper = new ObjectMapper();
ArrayNode array = mapper.createArrayNode();
int i = 0;
while (i < 6) {
array.add(mapper.createArrayNode().add("" + i++).add("" + i++));
}
System.out.println(array);
结果:
[["0","1"],["2","3"],["4","5"]]
如果您不处理几兆字节的数据或非常紧张的内存限制,那么这可能也更容易维护。
JsonGenerator jg = new JsonFactory().createJsonGenerator(System.out);
jg.configure(JsonGenerator.Feature.WRITE_NUMBERS_AS_STRINGS, true);
jg.writeStartArray();
int i = 0;
while (i < 6)
{
jg.writeStartArray();
jg.writeObject(i++);
jg.writeObject(i++);
jg.writeEndArray();
}
jg.writeEndArray();
jg.flush();
输出:
[["0","1"],["2","3"],["4","5"]]
你需要这样的json吗。。。?