json序列化通用工具類(java)

>為了支持此工具類的正常使用，先導入以下jar包

1.lombok包是一個簡化java冗余代碼的jar包，實際開發中很方便

在maven的pom文件中導入lombok坐標

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.16.18</version>
</dependency>

2.json序列化jar包

在maven的pom文件中導入lombok坐標

<dependency>
    <groupId>org.codehaus.jackson</groupId>
    <artifactId>jackson-mapper-asl</artifactId>
    <version>1.9.12</version>
</dependency>

3.String處理的jar包

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.5</version>
</dependency>

工具類如下：

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang.StringUtils;
import org.codehaus.jackson.map.DeserializationConfig;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig;
import org.codehaus.jackson.map.annotate.JsonSerialize;
import org.codehaus.jackson.type.JavaType;
import org.codehaus.jackson.type.TypeReference;

import java.text.SimpleDateFormat;

@Slf4j
public class JsonUtil {

    private static ObjectMapper objectMapper = new ObjectMapper();
    private static final String STANDARD_FORMAT = "yyyy-MM-dd HH:mm:ss";

    static {
        //對象的所有字段全部列入
        objectMapper.setSerializationInclusion(JsonSerialize.Inclusion.ALWAYS);
        //取消默認轉換timestamps形式
        objectMapper.configure(SerializationConfig.Feature.WRITE_DATES_AS_TIMESTAMPS, false);
        //忽略空Bean轉json的錯誤
        objectMapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS, false);
        //所有的日期格式都統一為以下的樣式，即yyyy-MM-dd HH:mm:ss
        objectMapper.setDateFormat(new SimpleDateFormat(STANDARD_FORMAT));
        //忽略 在json字符串中存在，但是在java對象中不存在對應屬性的情況。防止錯誤
        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) {
            log.warn("Parse Object to String error", e);
            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) {
            log.warn("Parse Object to String error", e);
            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) {
            log.warn("Parse String to Object error", e);
            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) {
            log.warn("Parse String to Object error", e);
            return null;
        }
    }


    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) {
            log.warn("Parse String to Object error", e);
            return null;
        }
    }

此工具類非常通用，建議使用，裏面的參數可根據自己的需求自行調整。

Json序列化java工具類