jackson基本使用库

   提供json与对象之间的基本转换

  

public class JsonUtil {/** * 将对象转换为json字符串 *  * @param obj * @return * @throws Exception */public static String obj2string(Object obj) {StringWriter sw = new StringWriter();ObjectMapper mapper = new ObjectMapper();try {mapper.writeValue(sw, obj);} catch (Exception e) {}return sw.toString();}/** * 将字符串转list对象 *  * @param <T> * @param jsonStr * @param cls * @return */public static <T> List<T> str2list(String jsonStr, Class<T> cls) {ObjectMapper mapper = new ObjectMapper();List<T> objList = null;try {JavaType t = mapper.getTypeFactory().constructParametricType(List.class, cls);objList = mapper.readValue(jsonStr, t);} catch (Exception e) {}return objList;}/** * 将字符串转为对象 *  * @param <T> * @param jsonStr * @param cls * @return */public static <T> T str2obj(String jsonStr, Class<T> cls) {ObjectMapper mapper = new ObjectMapper();T obj = null;try {obj = mapper.readValue(jsonStr, cls);} catch (Exception e) {}return obj;}/** * 将字符串转为Page对象 *  * @param <T> * @param jsonStr * @param cls * @return */public static <T> Page<T> str2page(String jsonStr, Class<T> cls) {ObjectMapper mapper = new ObjectMapper();Page<T> objList = null;try {JavaType t = mapper.getTypeFactory().constructParametricType(Page.class, cls);objList = mapper.readValue(jsonStr, t);} catch (Exception e) {}return objList;}/** * 将字符串转为json节点 * @param jsonStr * @return */public static JsonNode str2node(String jsonStr) {ObjectMapper mapper = new ObjectMapper();try {return mapper.readTree(jsonStr);} catch (Exception e) {e.printStackTrace();}return null;}

使用方式：

public static void main(String[] args) {List<TestObj> list = new ArrayList<TestObj>();String listStr = JsonUtil.obj2string(list);list = JsonUtil.str2list(listStr, TestObj.class);}

下面代码因为博客原因不能删除，不可用

/** * @param args */public static void main(String[] args) {List<TestPojo> list = new ArrayList<TestPojo>();for(int i = 0; i < 10; i++) {TestPojo pojo1 = new TestPojo();pojo1.setName(i + "11");pojo1.setSex(i + "22");list.add(pojo1);}ObjectMapper mapper = new ObjectMapper();StringWriter sw = new StringWriter();try {mapper.writeValue(sw, list);} catch (JsonGenerationException e) {e.printStackTrace();} catch (JsonMappingException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}List<TestPojo> list2 = new ArrayList<TestPojo>();try {JSONArray array = new JSONArray(sw.toString());for(int i = 0; i < array.length(); i++) {TestPojo pojoReverse = mapper.readValue(array.getString(i), TestPojo.class);System.out.println(pojoReverse);list2.add(pojoReverse);}} catch (JsonParseException e) {e.printStackTrace();} catch (JsonMappingException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} catch (JSONException e) {// TODO Auto-generated catch blocke.printStackTrace();}System.out.println("list size = " + list.size());System.out.println("list2 size = " + list2.size());}