JSON(JavaScript Object Notation) 是一种轻量级的数据交换格式，她是 JavaScript原生态的数据格式。
她独立于任何编程语言、可读性高、易于生成和解析、体积轻量，这些优雅的特性，让JSON成为非常理想的数据交换的语言。
在使用Java操作JSON时，我们用到了Jackson框架。
Jackson可以轻松的将Java对象转换成json对象和xml文档，同样也可以将json、xml转换成Java对象。
Jackson相关
下载依赖库jar包
Jackson的jar all下载地址：http://jackson.codehaus.org/1.7.6/jackson-all-1.7.6.jar
然后在工程中导入这个jar包即可开始工作
官方示例：http://wiki.fasterxml.com/JacksonInFiveMinutes
下面为基于Jackson的JsonUtils操作工具类：
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public class JSONUtils {
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private static Logger logger = Logger.getLogger(JSONUtils.class);
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public static Map<String, String> JsonToMap(String jsonStr) {
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try {
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ObjectMapper objectMapper = new ObjectMapper();
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Map<String, String> params = objectMapper.readValue(jsonStr,Map.class);
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return params;
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} catch (Exception e) {
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logger.error("JsonToMap Error " + jsonStr, e);
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return null;
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}
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}
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public static Map<String, Object> readJson2Map(String jsonStr) {
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try {
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ObjectMapper objectMapper = new ObjectMapper();
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Map<String, Object> params = objectMapper.readValue(jsonStr,Map.class);
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return params;
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} catch (Exception e) {
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logger.error("JsonToMap Error " + jsonStr, e);
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return null;
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}
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}
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public static <T> T readJson2Bean(String jsonStr,Class<T> clazz) {
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try {
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ObjectMapper objectMapper = new ObjectMapper();
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T t = objectMapper.readValue(jsonStr,clazz);
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return t;
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} catch (Exception e) {
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logger.error("readJson2Bean Error " + jsonStr, e);
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return null;
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}
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}
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public static List<HashMap<String, Object>> JsonToMapList(String jsonStr) {
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try {
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ObjectMapper objectMapper = new ObjectMapper();
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List<HashMap<String, Object>> params = objectMapper.readValue(jsonStr,List.class);
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for (int i = 0; i < params.size(); i++) {
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Map<String, Object> map = params.get(i);
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Set<String> set = map.keySet();
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for (Iterator<String> it = set.iterator();it.hasNext();) {
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String key = it.next();
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}
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}
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return params;
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} catch (Exception e) {
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logger.error("JsonToMap Error " + jsonStr, e);
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return null;
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}
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}
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public static String WriteToJson(Object... paramObjs){
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try {
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if(paramObjs==null||paramObjs.length==0){
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logger.error("参数实例为空");
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}
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Map<String,Object> paramMap = new HashMap<String, Object>();
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for(int i=0;i<paramObjs.length;i+=2){
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paramMap.put((String) paramObjs[i], paramObjs[i+1]);
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}
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ObjectMapper objectMapper = new ObjectMapper();
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return objectMapper.writeValueAsString(paramMap);
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} catch (Exception e) {
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return "";
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}
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}
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public static Map<String, String> JsonToMapAndDecode(String result) {
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Map<String, String> params = JsonToMap(result);
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for (String key : params.keySet()) {
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params.put(key, HttpUtils.urlDecode(params.get(key), "UTF-8"));
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}
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return params;
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}
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public static String toJson(Object target){
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String result = null;
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try {
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ObjectMapper objectMapper = new ObjectMapper();
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result = objectMapper.writeValueAsString(target);
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} catch (Exception e) {
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logger.error("convert to Json Str Fail !");
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e.printStackTrace();
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}
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return result;
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}
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}
最后,Jackson对XML的支持
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public void writeObject2Xml() {
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System.out.println("XmlMapper");
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XmlMapper xml = new XmlMapper();
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try {
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StringWriter sw = new StringWriter();
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xml.writeValue(sw, bean);
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System.out.println(sw.toString());
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List<AccountBean> list = new ArrayList<AccountBean>();
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list.add(bean);
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list.add(bean);
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System.out.println(xml.writeValueAsString(list));
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Map<String, AccountBean> map = new HashMap<String, AccountBean>();
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map.put("A", bean);
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map.put("B", bean);
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System.out.println(xml.writeValueAsString(map));
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} catch (JsonGenerationException e) {
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e.printStackTrace();
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} catch (JsonMappingException e) {
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e.printStackTrace();
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
Java使用jackson操作Json格式数据
原文：http://blog.csdn.net/oydaybreak/article/details/45170557
