有3个主要的库来处理json
json-simple.jar
前任：

List arr = new ArrayList();  
arr.add("sonoo");    
arr.add(new Integer(27));    
arr.add(new Double(600000));   
String jsonText = JSONValue.toJSONString(arr);

第二，使用gson库

new Gson().toJson(arr);

第三，使用jackson

ObjectMapper mapper = new ObjectMapper();

    ArrayNode arrayNode = mapper.createArrayNode();

    /**
     * Create three JSON Objects objectNode1, objectNode2, objectNode3
     * Add all these three objects in the array
     */

    ObjectNode objectNode1 = mapper.createObjectNode();
    objectNode1.put("bookName", "Java");
    objectNode1.put("price", "100");

    ObjectNode objectNode2 = mapper.createObjectNode();
    objectNode2.put("bookName", "Spring");
    objectNode2.put("price", "200");

    ObjectNode objectNode3 = mapper.createObjectNode();
    objectNode3.put("bookName", "Liferay");
    objectNode3.put("price", "500");

    /**
     * Array contains JSON Objects
     */
    arrayNode.add(objectNode1);
    arrayNode.add(objectNode2);
    arrayNode.add(objectNode3);

    /**
     * We can directly write the JSON in the console.
     * But it wont be pretty JSON String
     */
    System.out.println(arrayNode.toString());

    /**
     * To make the JSON String pretty use the below code
     */
       System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(arrayNode));