jackson中的写和解析JSON的api例子
本次介绍的是在jackson中,如何去写和解析json,其中用到的都是jackson自己的
流的API.
1 JACKSON中写一个json文件使用的是JsonGenerator类,
输出为:
{
"name":"mkyong",
"age":29,
"messages":["msg 1","msg 2","msg 3"]
}
2 解析JSON
我们把上面输出的JSON文件重新读取出来,再解析, 注意在json中,解析是以TOKEN方式进行的,比如:
{
"name":"mkyong"
}
将为解析为:
Token 1 = “{“
Token 2 = “name”
Token 3 = “mkyong”
Token 4 = “}”
代码:
import java.io.File;import java.io.IOException;import org.codehaus.jackson.JsonFactory;import org.codehaus.jackson.JsonGenerationException;import org.codehaus.jackson.JsonParser;import org.codehaus.jackson.JsonToken;import org.codehaus.jackson.map.JsonMappingException; public class JacksonStreamExample { public static void main(String[] args) { try { JsonFactory jfactory = new JsonFactory(); /*** read from file ***/JsonParser jParser = jfactory.createJsonParser(new File("c:\\user.json")); // loop until token equal to "}"while (jParser.nextToken() != JsonToken.END_OBJECT) { String fieldname = jParser.getCurrentName();if ("name".equals(fieldname)) { //当前结点为name jParser.nextToken(); System.out.println(jParser.getText()); // 输出 mkyong } if ("age".equals(fieldname)) { // 当前结点为age // move to next, which is "name"'s value jParser.nextToken(); System.out.println(jParser.getIntValue()); // display 29 } if ("messages".equals(fieldname)) { jParser.nextToken(); while (jParser.nextToken() != JsonToken.END_ARRAY) { // display msg1, msg2, msg3 System.out.println(jParser.getText()); } } } jParser.close(); } catch (JsonGenerationException e) { e.printStackTrace(); } catch (JsonMappingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
最后输出:
mkyong
29
msg 1
msg 2
msg 3 1 楼 savon_cn 2012-06-16 http://www.mkyong.com/java/jackson-streaming-api-to-read-and-write-json/
转载也要说一声吧
