Jackson工具类（各种转换）

首先要在项目中引入jackson的jar包（在此不做说明）
下面直接上代码

```java public class JacksonUtils {

private final static ObjectMapper objectMapper = new ObjectMapper();

private JacksonUtils() {

}

public static ObjectMapper getInstance() {
return objectMapper;
}

/**
* javaBean、列表数组转换为json字符串
*/
public static String obj2json(Object obj) throws Exception {
return objectMapper.writeValueAsString(obj);
}

/**
* javaBean、列表数组转换为json字符串,忽略空值
*/
public static String obj2jsonIgnoreNull(Object obj) throws Exception {
ObjectMapper mapper = new ObjectMapper();
mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
return mapper.writeValueAsString(obj);
}

/**
* json 转JavaBean
*/

public static T json2pojo(String jsonString, Class clazz) throws Exception {
objectMapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);
return objectMapper.readValue(jsonString, clazz);
}

/**
* json字符串转换为map
*/
public static Map<String, Object> json2map(String jsonString) throws Exception {
ObjectMapper mapper = new ObjectMapper();
mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
return mapper.readValue(jsonString, Map.class);
}

/**
* json字符串转换为map
*/
public static Map<String, T> json2map(String jsonString, Class clazz) throws Exception {
Map<String, Map<String, Object>> map = objectMapper.readValue(jsonString, new TypeReference<Map<String, T>>() {
});
Map<String, T> result = new HashMap<String, T>();
for (Map.Entry<String, Map<String, Object>> entry : map.entrySet()) {
result.put(entry.getKey(), map2pojo(entry.getValue(), clazz));
}
return result;
}

/**
* 深度转换json成map
*
* @param json
* @return
*/
public static Map<String, Object> json2mapDeeply(String json) throws Exception {
return json2MapRecursion(json, objectMapper);
}

/**
* 把json解析成list，如果list内部的元素存在jsonString，继续解析
*
* @param json
* @param mapper 解析工具
* @return
* @throws Exception
*/
private static List