JsonUtil

package com.zgw.util;

import java.io.IOException;
import java.text.SimpleDateFormat;

import org.apache.commons.lang3.StringUtils;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.DeserializationConfig;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig;
import org.codehaus.jackson.map.annotate.JsonSerialize.Inclusion;
import org.codehaus.jackson.type.JavaType;
import org.codehaus.jackson.type.TypeReference;

public class JsonUtil {

private static ObjectMapper objectMapper = new ObjectMapper();
static {
// 对象的所有字段全部列入
objectMapper.setSerializationInclusion(Inclusion.ALWAYS);

// 取消默认转换timestamps 形式
objectMapper.configure(SerializationConfig.Feature.WRITE_DATE_KEYS_AS_TIMESTAMPS, false);

// 忽略空Bean转Json的错误
objectMapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS, false);

// 所有的日期格式都统一为以下的样式，即 yyyy-MM-dd HH:mm:ss
objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));

// 忽略在 json字符串中存在，但是在 java对象中不存在对应属性的情况。防止错误
objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
}

public static <T> String obj2String(T obj) {
if (obj == null) {
return null;
}

try {
return obj instanceof String ? (String) obj : objectMapper.writeValueAsString(obj);
} catch (Exception e) {
System.err.println("Parse object to String error");
return null;
}
}

public static <T> String obj2StringPretty(T obj) {
if (obj == null) {
return null;
}

try {
return obj instanceof String ? (String) obj
: objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(obj);
} catch (Exception e) {
System.err.println("Parse object to String error");
return null;
}
}

public static <T> T string2Obj(String str, Class<T> clazz) {
if (StringUtils.isEmpty(str) || clazz == null) {
return null;
}

try {
return clazz.equals(String.class) ? (T) str : objectMapper.readValue(str, clazz);
} catch (Exception e) {
System.err.println("Parse String to Object error");

return null;
}
}

public static <T> T string2Obj(String str, TypeReference<T> typeReference) {
if (StringUtils.isEmpty(str) || typeReference == null) {
return null;
}

try {
return (T) (typeReference.getType().equals(String.class) ? str
: objectMapper.readValue(str, typeReference));
} catch (Exception e) {
System.err.println("Parse String to Object error");

return null;
}

// List<User> userListObj1 = JsonUtil.string2Obj(userListStr, new
// TypeReference<List<User>>(){});
}

public static <T> T string2Obj(String str, Class<?> collectionClass, Class<?>... elementClasses) {
JavaType javaType = objectMapper.getTypeFactory().constructParametricType(collectionClass, elementClasses);

try {
return objectMapper.readValue(str, javaType);
} catch (Exception e) {
System.err.println("Parse String to Object error");

return null;
}
}

// List<User> userListObj2 = JsonUtil.string2Obj(userListStr, List.class,
// User.class);
}